KR100811172B1 - Pneumatic diaphragm head having an independent retaining ring and multi-region pressure control, and method to use the same - Google Patents

Abstract

An apparatus and method for planarizing a substrate are provided. The apparatus 101 includes a plate 212 receiving a substrate 230 thereon; A first chamber 238 for applying a force to the plate in a predetermined direction; A spacer 260 coupled to the outer edge of the plate; A membrane 250 coupled to the plate through the spacer 260 and separated from the plate by the thickness of the spacer; And a carrier 202 having a second chamber 251 formed between the membrane and a plate that exerts a force in another predetermined direction on the membrane. The method includes pressing a peripheral edge of the substrate 244 against the polishing pad 226 at a first pressure, and pressing the interior of the substrate 244 against the pad 226 at a second pressure. do.

Description

PNEUMATIC DIAPHRAGM HEAD HAVING AN INDEPENDENT RETAINING RING AND MULTI-REGION PRESSURE CONTROL, AND METHOD TO USE THE SAME}

FIELD OF THE INVENTION The present invention generally relates to systems, apparatuses, and methods for polishing and planarizing semiconductor wafers, and more particularly systems, apparatuses, and methods for utilizing multiple planarization pressure zones to achieve high flattening uniformity across the surface of semiconductor wafers. It is about.

As feature sizes become smaller, densities increase, and semiconductor substrates or wafers become larger, chemical mechanical planarization (CMP) process requirements become more stringent. Wafer-to-wafer process uniformity and intra-wafer planarization uniformity are important from the standpoint of producing semiconductor products at low cost. As the size of a die or chip increases, relatively small circuits fail due to defects in one small area, resulting in relatively large economic losses in the semiconductor industry.

Many causes are known in the art that influence uniformity problems. The wafer back pressure during planarization may be desirably compensated by adjusting the way the wafer back pressure is applied to the wafer, the edge effect nonuniformity resulting from the typically different interactions between the polishing pads at the edge of the wafer relative to the center region, and the material removal profile during planarization. Uneven deposition of the metal and / or oxide layer which existed is also included in the cause. So far, efforts to solve these problems at the same time have not been completely successful.

For the nature of the wafer backside polishing pressure, a hard backed head has conventionally been used. The majority of conventional machines produced recently are provided with an insert between the carrier (or subcarrier) surface and a wafer or other substrate to be polished or planarized for the purpose of providing some softness in other rigid support systems. Often the insert is called a wafer insert. These inserts are problematic because they often lead to process variations that result in substrate-to-substrate variations. These process variations are not constant or generally defined. One component of the variation is the amount of water absorbed by the insert during its service life and over its service life. Some process uniformity improvement can be achieved by soaking the insert in water prior to initial use. This is intended to be almost identical to the beginning of the use period even after the use period, but unacceptable process variations are still observed. These process variations can be controlled to a limited extent by preconditioning the inserts with water and replacing the inserts before changing their properties beyond acceptable limits, as described.

In addition, the use of inserts required fine control of the entire surface of the subcarrier with any non-uniform and incompletely adhered inserts, and if not finely controlled, the planarity or Deviations from parallelism may have appeared. For example, in conventional heads, aluminum or ceramic plates, if manufactured, are lap and polished before being installed in the polishing head. Such fabrication increases the cost of the head and the cost of the machine, especially if multiple heads are provided.

As the size (feature size) of the structure on the semiconductor wafer surface is even smaller, it has now been reduced to a size that is typically less than approximately 0.2 micron, increasing the problems associated with non-uniform planarization. This problem is sometimes referred to as a problem with With Wafer Non-Uniformity (WIWNU).

Due to the so-called hard bearing flattening head, ie, the head pressing against the back side of the semiconductor wafer having a hard surface, the front surface of the wafer does not coincide with the surface of the polishing pad, which may result in flattening unevenness. In general, such rigid support head designs utilize relatively high polishing pressures (eg, pressures in the range between approximately 6 psi and approximately 8 psi), and these relatively high pressures effectively drive the wafer to match the surface shape of the polishing pad. Transform. When such wafer surface distortion occurs, high spots are polished at the same time as low spots giving a wide range of uniformity, but in fact result in poor planarization. That is, too much material will be removed from traces in certain areas of the wafer and little material will be removed in the remaining areas. If the amount of material removed is excessive, these dies become unusable.                 

On the other hand, when a head having an insert is used, the wafer is pressed against the polishing pad, but since the soft material of the insert does not cause the wafer to be distorted, a lower polishing pressure can be adopted, and the wafer front face with less distortion. Since conformity of is achieved, both broad polishing uniformity and good planarization can be achieved to some extent. Planarization uniformity is achieved at least to some extent because the polishing rates of similar features from die to die on the wafer are generally the same.

Several attempts have been made to utilize flexible CMP heads, but overall they are not satisfactory. In some flexible support head designs, a pressurized air layer on the entire backside of the wafer is used to press the wafer against the polishing pad during planarization. Unfortunately, this approach may provide a flexible support head, but does not allow independent adjustment of the pressure or force applied to the edge of the wafer and to the more central area to solve the wafer edge nonuniformity problem.

With respect to compensation or compensation for edge polishing effects, adjusting the shape of the retaining ring disposed around the wafer and / or modifying the retaining ring pressure so that the amount of material removed from the wafer near the retaining ring is modified Tried. Typically, edge polishing effects, i.e., edge effects, result in more material being removed from the edges of the wafer. That is, the wafer edge portion is overpolished. To compensate for this overpolishing, the retaining ring pressure is generally adjusted to be slightly higher than the wafer back pressure, so that the polishing pad in the area is somewhat compressed by the retaining ring and the wafer within a few millimeters of the retaining ring. Has been removed. However, even the above attempt was not completely satisfactory since the planarization pressure at the peripheral edge of the wafer was adjusted only indirectly based on the retaining ring pressure. In general, the effective distance of the retaining ring compensation effect cannot be extended by an arbitrary distance from the wafer edge. In addition, the retaining ring pressure, the edge pressure, or the entire backside wafer pressure may not be adjusted independently to achieve the desired results.

It is desirable to adjust the material removal profile to adjust for wafer non-uniform deposition, which will soon begin, and very few attempts have been made to provide such compensation.

Therefore, there remains a need for soft support CMP heads that provide good planarization, control edge leveling effects, and adjust wafer material removal profiles to compensate for uneven deposition of structural layers on wafer semiconductor substrates.

The present invention provides a polishing head and polishing apparatus, machine or tool (CMP tool) for polishing or planarizing the surface of a substrate or another workpiece such as a semiconductor wafer. The apparatus includes a wafer subcarrier comprising a rotatable polishing pad and a wafer or substrate receptacle that itself receives a substrate to position the substrate relative to the polishing pad; And a first pressurizing member and a second pressurizing member, wherein the first pressurizing member applies a first load pressure at an edge portion of the wafer to a polishing pad, and the second pressurizing member is a wafer against the pad. A second load pressure is applied to a central portion of the second load pressure, and the first and second load pressures include different wafer pressing members. Although the wafer subcarrier and the wafer pressing member may be used separately, in a preferred embodiment of the present invention, the polishing apparatus includes a retaining ring circumscribed to the wafer subcarrier; And a retaining ring press member for applying a third load pressure on the retaining ring to the polishing pad. The first, second and third load pressures can be adjusted independently.

In yet another embodiment, the present invention provides a method of planarizing a circular disk-shaped semiconductor wafer or other substrate. The method includes pressurizing a retaining ring surrounding the wafer against the polishing pad at a first pressure; Pressing a first peripheral edge portion of the wafer against the polishing pad at a second pressure; And pressing the second portion of the wafer in the peripheral edge portion against the polishing pad at a third pressure. In yet another embodiment, the second pressure can be provided through a mechanical member in contact with the peripheral edge portion; The second pressure is the air pressure on the back side of the wafer. The air pressure is preferably applied through the elastic membrane or by a gas that directly presses against at least a portion of the back surface of the wafer.

In still another embodiment, the present invention provides a plate having an outer surface; A first pressure chamber for applying a force to propel the plate in a predetermined direction; A spacer coupled to the periphery of the plate; A membrane coupled to the plate via the spacer and separated from the plate by the thickness of the spacer; And a second pressure chamber formed between the membrane and a surface of the plate exerting a second force to propel the membrane in a third predetermined direction.

In yet another embodiment, the present invention provides a kit comprising: a housing; A retaining ring flexibly coupled to the housing; A first pressure chamber applying a first force to propel the retaining ring in a first predetermined direction relative to the housing; A subcarrier plate having an outer surface and flexibly coupled to the housing; A second pressure chamber applying a second force to propel the subcarrier plate in a second predetermined direction relative to the housing; A retaining ring circumscribed to a portion of the subcarrier plate and forming a circular recess; A spacer coupled to a periphery of the outer surface of the subcarrier plate in a recess of the retaining ring circle; A membrane, separated from the outer surface of the subcarrier plate by the thickness of the spacer, coupled to the subcarrier plate via a space and placed in a circular recess; And a third pressure chamber formed between the membrane and an outer surface of the subcarrier plate applying a third force to propel the membrane in a third predetermined direction relative to the housing.

The present invention includes a substrate, such as a semiconductor wafer, processed or fabricated in accordance with the method of the present invention.

1 illustrates an exemplary multihead CMP polishing or planarizing machine;

2 (Prior Art) shows a conventional CMP head;

3 shows an embodiment of a flexible support CMP head having a membrane with a sealed pressure chamber, FIG. 3A illustrates an embodiment using a membrane support plate having a pressure chamber recess; 3B illustrates an embodiment using annular cornering; And FIG. 3C illustrates an embodiment using a thickened peripheral edge of the membrane to transfer a polishing force.

4 shows an embodiment of a CMP head with a membrane and an orifice;

5 shows an embodiment of a CMP head with a membrane having an orifice and a grooved backing plate;                 

FIG. 6 shows an embodiment of a CMP head with cushioning air flow over the membrane and the orifice and the surface of the wafer; FIG.

FIG. 7 shows an embodiment of a CMP head with a double sealed pressure chamber, and FIG. 7A is an embodiment of a CMP head with a membrane having a double sealed pressure chamber; And FIG. 7B illustrates an embodiment showing only a portion of the retaining ring and subcarrier without other portions of the CMP head;

FIG. 8 shows an embodiment of a CMP head with an annular tube pressure ring and a membrane sealing chamber that applies differential pressure across a portion of the membrane and wafer;

9 illustrates an embodiment of a CMP head having a plurality of concentric annular tube pressure rings and a membrane sealing chamber for applying differential pressure across a plurality of regions of the membrane and wafer;

10 shows a preferred embodiment of the head of the invention with a membrane and a sealed pressure chamber;

FIG. 11 shows an embodiment of a retaining ring suspension member used in the embodiment of FIG. 10;

12 illustrates an embodiment and an alternative example of a torque transfer member that can be used in the embodiment of FIG. 10;

FIG. 13 is a detailed view of the CMP head of FIG. 10 illustrating the attachment of a subcarrier assembly suspension member in the assembled head. FIG.

14 illustrates an embodiment of a subcarrier assembly suspension member;                 

15 illustrates an embodiment of a wafer backside membrane;

16 shows an alternative preferred embodiment of the head of the invention with a membrane with an orifice and a subcarrier with a conical cavity;

FIG. 17 shows an embodiment of a membrane support plate that can be used with the embodiment of FIG. 16;

18 is a perspective view of the membrane support plate of FIG. 17;

19 shows an embodiment of a head of the invention with an inner chamber and an outer chamber;

FIG. 20 shows an embodiment of the head of the invention similar to that shown in FIG. 19 except that the two membranes do not overlap and the outer membrane is in the form of an open annular ring;

FIG. 21 shows an embodiment of a head of the invention similar to that shown in FIG. 19 except that the two membranes do not overlap;

FIG. 22 illustrates an embodiment of a head of the invention similar to that shown in FIG. 21 except that the outer chamber includes or is formed with an inflatable inner tube or bladder;

23 shows an embodiment of the head of the invention wherein the outer chamber comprises an outer annular chamber;

24 shows an embodiment of a head of the invention having a method and structure for controlling five zones simultaneously and substantially independently;                 

FIG. 25 shows an embodiment of a double membrane head in which the outer membrane is formed in the form of an open annular ring and the pressure applied to the inner circular membrane can be varied to vary the area of the central portion of the substrate to which the force is applied;

FIG. 26 shows an embodiment of a double membrane head similar to that shown in FIG. 25 with the outer membrane formed in the form of a circular membrane and surrounding the inner membrane;

FIG. 27 shows an embodiment of a head with an outer membrane in the form of a closed annular ring, in which pressure applied to the membrane can be varied to change the area of the edge portion of the applied substrate;

The structure and method of the present invention are now described with reference to certain exemplary embodiments illustrated in the drawings. The structure and method of the present invention is directed to the wafer surface for soft-backed heads as well as many of the problems associated with conventional head designs using polymeric inserts between the backside of the wafer and the surface of the wafer subcarrier. Eliminate problems associated with pressure distribution across Different forces or pressures provide different loads on the front side of the wafer against the polishing pad to allow removal at different rates. Similarly, the pressure applied to the retaining ring changes the loading force of the retaining ring contact surface to the retaining ring and affects the removal of material at the edge of the wafer. The structure and method of the present invention is replaced by an insert with a flexible film or membrane adjacent to the backside of the wafer. In one embodiment, the membrane forms a sealed enclosure, while in the second embodiment the membrane has an opening or orifice such that at least partially pressure is applied to the backside of the wafer. The use of this backside soft surface pressure chamber or alternatively the pressure directly applied to the backside of the wafer together with other elements of the head of the present invention also allows polishing at low pressures to increase the uniformity of the wafer. Embodiments of closed chambers and open orifice embodiments are described in more detail herein.

The head of the present invention can control the uniformity of the edges by individually controlling the amount of material removed at the edge of the wafer compared to the amount of material removed near the center of the wafer. This control consists essentially of three separate independent pressure controls: (i) the back wafer pressure applied to the center of the wafer, (ii) the subcarrier pressure applied to the peripheral edge of the back of the wafer, and (iii) the ring surrounding the wafer. This can be achieved in part by providing a head having pressure control of the retaining ring applied directly to the polishing pad in the region of the shape.

In the structure to be described later, the retaining ring may be supported by the housing via a flexible material and move vertically with little friction and no restraint. A slight tolerance is provided between adjacent mechanical components so that the retaining ring can float on the polishing pad surface in a manner that accommodates small angle variations during polishing or planarization operations. In addition, the subcarrier is suspended from the housing by a flexible material so that it can be moved vertically with fine friction with little friction and no restraint. For the retaining ring, a small mechanical tolerance is provided between adjacent mechanical elements so that the subcarrier can float on the polishing pad surface in a manner that accommodates a smaller amount of change in the polishing or planarization operation. The wafer is in contact with the subcarrier through a rigid connection that closes only around all wafers. The center of the wafer inside the annular periphery of the wafer contacts the subcarrier only through a flexible film or membrane and air or other pneumatic or hydraulic cushioning volumes during polishing or planarization operations. In addition to the retaining ring and the subcarrier hanging on the head housing, the housing itself may be attached to or suspended from other elements of the flattening machine. Generally, such attachment or suspension is provided by pneumatic, mechanical or hydraulic moving means. For example, as is well known in the art, pneumatic cylinders provide this movement. This attachment allows the head to be moved vertically and vertically relative to the surface of the polishing pad so that the wafer is positioned on the subcarrier prior to polishing and can be removed from the subcarrier upon completion of polishing. Robotic devices are generally used for this purpose.

In one embodiment of the present invention, a head lifting and lowering mechanism provided with an adjustable hard physical stop down compensates for polishing pad wear and retaining ring wear. This keeps the retaining ring and the subcarrier at or near the center of the range of movement, minimizing the possibility of unnecessary mechanical effects on the operation of the head and increasing or stabilizing the process uniformity, thereby reducing the subcarrier or It is desirable to compensate for pad wear and / or retaining ring wear by adjusting the position of the head as a whole relative to the pad rather than using any vertical range of movement or stroke of the retaining ring. Such mechanical influences include, for example, an increase or decrease in the area of the sliding surface and the friction associated therewith, for example, between the housing and the retaining ring, as well as other mechanical effects caused by incomplete assembly or alignment. The characteristics of the flexible coupling between the subcarriers are changed. In essence, if the head assembly is always positioned so that important actuating elements inside the head (such as retaining rings, subcarriers and back membranes, etc.) can be operated at or near a predetermined location, any Secondary impacts may be reduced.

Providing this means of control over the head assembly to the polishing pad allows the use of a polishing pad of a certain thickness longer, and allows use of a thicker polishing pad that is initially expected to have a longer service life. Of course, in such a situation, after a predetermined number of wafers have been polished, reconditioning of the pads to these thicker polishing pads may be necessary based on the properties of the polishing pad at that time.

In general, adjustments of several millimeters are sufficient to accommodate polishing pads and retaining ring wear. For example, if the head position can be sufficiently adjusted, typically in the range of approximately 2 mm to 8 mm, the above adjustment is generally sufficient in the range of approximately 1 mm to 20 mm. These adjustments can be made via adjustment nuts or screws, by high pressure or hydraulic actuators using pressure variations, by rack and pinion gear assemblies, by ratchet mechanisms, or other as known in the art. It can be made by the mechanical means of. Alternatively, the position encoder can be used to detect the head bottom stop position and, once reached, is held by a clamp or other means. Any electronic control may be used to maintain the detected stop position, but such electronic control may be affected by noise and jitter at mechanical locations where they can achieve precise planarization of semiconductor wafers or other substrates. Not desirable

The CMP head structure and planarization method of the present invention may be used with a CMP machine having a single head or alternatively a plurality of heads which may, for example, be provided with a carousel assembly. In addition, the head of the present invention may be used in conjunction with or within other CMP and polishing machines well known in the art, as well as orbital polishing components, circular polishing components, linear and reciprocating polishing components and their polishing movements. It can be used in all manner of CMP machines, including machines using combinations.

1, a chemical mechanical polishing, i.e., planarization (CMP) comprising a carousel 102 consisting of a head mounting assembly 104 and a substrate (wafer) carrier assembly 106 and having a plurality of polishing head assemblies 103. Tool 101 is shown. As used herein, the term "polishing" is generally used to mean the polishing of a semiconductor wafer or substrate 113 (not shown) that includes a substrate, wherein the substrate has electronic circuit elements disposed on the semiconductor wafer. In the case of a substrate, it may mean planarization of the substrate. Semiconductor wafers are generally thin and somewhat brittle disks with diameters between 100 mm and 300 mm. Recently, semiconductor wafers of 100 mm, 200 mm and 300 mm have been used in the industry. The design of the present invention is applicable not only to diameters up to at least 300 mm but also to larger diameter semiconductor wafers and other substrates, where important wafer surface polishing nonuniformity is limited to the so-called exclusion around the radius of the semiconductor wafer. Generally, this exclusion is approximately 1 mm to 5 mm, but most are on the order of 2 mm to 3 mm.

The base 105 provides support for other components including a bridge 107 that supports and allows the lifting and lowering of the carousel 102 to which the head assembly 103 is attached. The head mounting assembly 104 is installed in the carousel 102, each polishing head assembly 103 is mounted to the head mounting assembly 104 for rotation, and the carousel is centered around the carousel central axis 108. Each polishing head assembly 103 has a rotation axis 111 that is substantially parallel to the rotation axis 108 of the carousel but is separate. The CMP tool, ie, the CMP machine 101, also includes a motor drive platen 109 mounted to rotate about the platen drive axis 110. The platen 109 holds the polishing pad 135 and is driven to rotate by a platen motor (not shown). This particular embodiment of the CMP tool 101 is a multihead design, meaning that it has a plurality of polishing heads 103 for each carousel 102, but a single head CMP tool is known, and The CMP head and polishing method can be used with either a multihead or single head polishing apparatus.

In addition, in this particular CMP design, each of the plurality of heads 103 is driven by a single head motor (not shown) that drives the chain (not shown), and each polishing head (not shown) via the chain and sprocket mechanism (not shown). While driving 103 in turn, the invention may be used in embodiments in which each head 103 is rotated by other than a separate motor and / or chain and sprocket drive. The CMP tool of the present invention also includes a rotary union that provides a plurality of different gas / fluid channels in communication with pressurized fluid such as air, water, vacuum, etc., between a stationary source outside the head and a position in the head. . In one embodiment, five different gas / fluid channels are provided by rotary unions. In an embodiment of the invention where a subcarrier with a chamber is included, an additional rotary union port is included to provide a predetermined pressurized fluid to the additional chamber.

In operation, the polishing platen 109 to which the polishing pad 135 is attached rotates, the carousel 102 rotates, and each head 103 rotates about their axis. In one embodiment of the CMP tool of the present invention, the axis of rotation 108 of the carousel is offset approximately one inch from the axis of rotation 110 of the platen. However, this is not necessary or desirable in every situation. In another embodiment, the speed at which each component rotates moves each part on the wafer 113 substantially the same distance at the same average speed as all other points on the wafer to provide uniform polishing or planarization of the substrate. To be selected. Since polishing pads are generally somewhat compressible, the manner and speed of the pads interaction with the wafer are important determinants of the amount of material removed from the edge of the wafer and the uniformity of the polished wafer surface.

In order to define the difference between the CMP head of the present invention and the CMP method related to the use of embodiments of the head, attention is first drawn to the simplified model head with the conventional design of FIG.

In the embodiment of Figure 2, mechanical coil springs are used to illustrate the application of different forces to different parts of the head. Indeed, although springs have been used to theoretically practice the present invention, pneumatic or hydraulic pressure in the form of pneumatic pressure is generally used to provide a more uniform pressure on a given area. The use of springs in this figure is essentially to avoid obscuring the present invention by providing a clear description and explaining unnecessary prior details.

The conventional CMP head 152 of FIG. 2 includes a shaft connecting the housing top 204 and the housing, in fact the remainder of the CMP head, to a motor or other source of rotation, as is known in the art. 206). In general, the housing 204 provides protection from the polishing slurry, protects the internal elements from unnecessary exposure and abrasion, and serves as a mechanical guide for other internal elements such as, for example, the retaining ring 214. An annular housing side portion 205 surrounding other components in the head to perform. In summary, the retaining ring 214 and the sub on a flat horizontal housing plate having an upper surface 208 to which the shaft 206 is attached and a retaining ring 214 and a lower surface 210 on which the subcarrier 212 hangs. The carrier 212 may be considered to be hanging.

The subcarrier 212 is fixedly connected to the upper surface 218 of the subcarrier and via a shaft 216 extending toward the spherical tooling ball 220 captured by the cylindrical bore 222 in the lower surface 210. It is connected to the lower surface 210 of the housing 204. Tooling ball 220 may move or slide vertically within bore 222 to protect housing 204 against vertical motion. The bore 222 is provided with respect to the housing 204 and polishing pad 226 when a plurality of tooling balls and bores are in place, such that the tooling ball 220 can be moved and a controlled amount of motion without binding. It is desirable to be slightly larger so that some angular movement or tilt of the subcarrier can occur. However, it must fit close enough not to cause any excessive movement, i.e., not to move to a degree that impairs the precision of the head. The tooling ball 220 provides a torque transfer connection between the housing and the subcarrier 212 so that rotational motion from the shaft 206 can be transferred to the wafer 230 being flattened through the subcarrier 212. In order to avoid unnecessary complexity that may obscure the present invention, retaining ring tooling balls may similarly be used to join the housing, although not shown in the figures.

One or more springs 232 are disposed between the bottom surface 210 of the housing and the top surface 234 of the retaining ring 214 and act to separate the retaining ring 214 from the top housing 204. Since the movement of the housing is constrained during polishing or planarization, the net effect is to press the retaining ring 214 downward against the top surface of the polishing pad 226. In this particular embodiment, the type of spring 232 and the number of springs 232 can be adjusted to provide a predetermined retaining ring force FRR or retaining pressure PRR. However, if pneumatics are used to propel the retaining ring against the polishing pad 226, the downward pressure on the retaining ring is the downward force of the retaining ring 214 relative to the polishing pad 226. Will be adjusted to achieve this.

In a similar manner, one or more subcarrier springs 238 are disposed between the lower surface 210 of the housing and the upper surface 218 of the subcarrier 212, separating the subcarrier from the housing, and pushing the subcarrier toward the polishing pad. Act to make it work. Movement of the housing 208 is constrained during the polishing operation, and the net effect is to press the subcarrier 212 downward toward the top surface of the polishing pad 226. Typically, a separate pneumatic cylinder is used to move and position the head 152 relative to the polishing pad 226. This movement is used, for example, to place the head lower closer to the polishing pad after the wafer or other substrate is loaded for planarization and to lift the head away from the pad 226 after the planarization is complete. It is advantageous to provide a mechanical interruption as a reference for the lower limits of motion to ensure reasonable repeatability and not to physically damage the head or wafer.

In this conventional configuration, the bottom surface of the subcarrier is mounted to the back surface 244 of the semiconductor wafer 230 either directly or through the optical polymer insert 160.

The conventional CMP head of FIG. 2 has a single subcarrier uniform between the retaining pressure (PRR) of the retaining ring 214 relative to the polishing pad 226 and at least theoretically between the front surface of the wafer 230 and the surface of the polishing pad. It can be appreciated that the pressure PSC is provided. As will be appreciated by those skilled in the art, the wafer will not actually be subjected to uniform pressure across its entire surface due to the dynamics associated with the rotating head and the rotating pad, local pad compression, polishing slurry distribution, and various other factors. Those skilled in the art will also appreciate that, in view of the description provided herein, a uniform planarization pressure may not yield a uniform planarization result, and certain controlled planarization pressure variations may be desirable. However, such control cannot be achieved with the CMP head or the planarization method of FIG.

The present invention provides several embodiments of CMP heads and novel polishing and planarization methods suitable for use with the heads of the present invention and the like. Each embodiment provides a structure for individually adjusting the downward force of the retaining ring relative to the polishing pad, as well as controllably changing the planarization pressure across at least two regions of the semiconductor wafer. Control of the retaining ring pressure is known to affect wafer leveling edge characteristics as it affects the interaction of the wafer and the polishing pad at the edges of the wafer. Since the influence of the retaining ring pressure can only be extended for a limited distance within the wafer, this effect is indirect.

Figure 3 illustrates three embodiments associated with the head of the present invention each having a membrane and a sealed pressure chamber formed between the subcarrier and the membrane. FIG. 3A illustrates an embodiment with a substantially solid membrane support plate 26, and FIG. 3B transfers the subcarrier force from the subcarrier plate 212 to the membrane 250 by annular cornering 260 only on the outer circumferential surface. An embodiment without the membrane support plate 261 is illustrated. 3C is similar to the embodiment of FIG. 3B, but has been replaced by a thick portion 263 of the membrane 250 that removes the annular cornering 260 and transmits the subcarrier force. It should be noted that in some embodiments, the membrane may be formed of synthetic material, and cornering 260 or other structures may be integrally formed within the edge of the membrane.

The structure of an embodiment of a CMP head according to the present invention of FIG. 3A is now described in more detail. Mechanical coil springs 232 and 238 are used to illustrate the application of different forces to different portions of the head 202. Indeed, although springs have been used to theoretically practice the present invention, pneumatic or hydraulic pressure, in the form of air pressure, can be distributed evenly over a given area, and these pressures do not change over time and mostly require mechanical springs. As pressure can be monitored that does not require frequent maintenance adjustments, it can generally be expected to provide better flattening results. The use of springs in this figure is primarily to provide a clear description and to avoid the need for conventional structures not related to the present invention.

The head 202 of the present invention of FIG. 3 includes a housing top 204 and a shaft 206 connecting the housing, ie, the remainder of the head, to a motor or other source of rotation, as is well known in the art. The housing 204 generally encloses other components in the head to provide protection from the polishing slurry, protect the internals from unnecessary exposure and wear, and serve as mechanical guides for other internals. Side portion, that is, skirt 205. Retaining ring 214 and subcarrier 212 generally form a housing having a top surface 208 to which shaft 206 is attached and a bottom surface 210 on which retaining ring 214 and subcarrier 212 are suspended. Hangs on a horizontal plate.

The subcarrier 212 is fixedly connected to the upper surface 218 of the subcarrier 212, and is connected to the spherical tooling ball 220 captured by the cylindrical bore 222 in the lower surface 210 of the housing top 204. It is connected to the lower surface 210 of the housing 204 via a shaft 216 extending toward. The tooling ball 220 can move or slide vertically within the bore 222 to provide relative vertical movement (up and down movement relative to the pad) to the housing 204. Bore 222 moves housing tool 204 when a plurality of tooling balls and bores (eg, three sets) are in place to move tooling ball 220 and perform some controlled amount of motion without binding. And a mechanical tolerance such that a predetermined angular movement or tilt of the subcarrier relative to the polishing pad 226 can be generated. The tooling ball 220 provides a torque transfer connection between the housing 204 and the subcarrier 212 so that rotational motion from the shaft 206 can be transferred to the wafer 230 which is planarized through the subcarrier 212. do. To avoid unnecessary complexity that may obscure the present invention, although not shown in the figures, the retaining ring may similarly be connected to the housing using a tooling ball in the same manner as described for the subcarrier. Other types of torque or rotational motion coupling structures and methods that are well known in the art may also be used.

One or more springs 232 are disposed between the lower surface 210 of the housing and the upper surface 234 of the retaining ring 214 to separate the retaining ring from the housing and propel the retaining ring against the pad 226. To act. Since the movement of the housing is constrained during polishing or planarization, the net effect is to press the retaining ring 214 downward against the top surface of the polishing pad 226. In this particular embodiment, the type and / or number of springs 232 can be adjusted to provide a predetermined retaining ring force FRR or retaining pressure PRR. However, in a preferred embodiment using pneumatics, the air pressure applied downwards (directly or indirectly) on the retaining ring will be adjusted to achieve the downward force of the retaining ring 214 relative to the polishing pad 226.                 

In a similar manner, one or more subcarrier springs 238 are disposed between the bottom surface 210 of the housing and the top surface 218 of the subcarrier 212 and act to separate the subcarriers from the housing top 204. Movement of the housing 208 is constrained during the polishing operation, and the net effect is to press the subcarrier 212 downward toward the top surface of the polishing pad 226. Unlike the retaining ring 214 having a lower surface 240 that directly presses the polishing pad 226, the subcarrier of the present invention does not directly contact the polishing pad, and in a preferred embodiment of the present invention, the wafer 230 It is also not in direct contact with the back wafer surface 244. Rather, most of the contact is made through a membrane, diaphragm or other flexible elastic material, and in other embodiments, the contact is made, in part or in whole, through a layer of pressurized air or gas.

In the structure of the present invention, the subcarrier 212 serves primarily to provide a stable platform for the attachment of the flexible film, diaphragm or membrane 250. In one embodiment (see FIGS. 3B and 3C), the chamber 251 is formed between the lower surface 252 of the subcarrier 218 and the inner or upper surface 254 of the membrane 250. The opposite or outer surface 256 of the membrane 250 is in contact with the backside 244 of the semiconductor wafer 230. In another embodiment (see FIG. 3A), a chamber 251 is formed between the lower surface of the membrane support plate 261 and the inner surface 254 of the membrane 250. The source and vacuum of air or gas pressurized by force (FBS) or pressure (PBS) is coupled to fitting 267 at the head surface or through a rotary union and is connected to chamber 251 by a pipe, tube or other conduit. Combined.

In the alternative embodiment of FIG. 4, the membrane only partially covers or extends over the wafer backside 244, and an orifice 265 or other opening is provided in the membrane 250. In this alternative embodiment, no chamber is formed by the structure of the head itself, but rather the backside of the wafer backside 244 only when the wafer 230 or other substrate is loaded onto the (chucked) head for polishing. Pressure PBS is formed.

In yet another alternative embodiment of FIG. 6, a large amount of air 280 or other gas flowing to the backside of the wafer is adjusted through an orifice to allow the wafer 250 to float on the cushion 280 of air. Air leaks between the back of the wafer.

Referring to the embodiment of FIG. 3, the structure of the present invention forces different portions of the outer surface 256 of the membrane to be pressed at different pressures at the center portion 281 against the edge portion 282 on the wafer backside 244 ( 3a). In the embodiment of the invention illustrated in FIG. 3B, an annular or ring shaped edge or corner piece 260 is disposed at or near the periphery 262 of the wafer. At least a portion of the subcarrier force (FSC) or subcarrier pressure (PSC) may be applied to the backside of the wafer, even if a portion of the membrane 250 extends over the corner piece 260 to provide a substantially continuous membrane to the wafer contact area. Cornerpiece 260 is formed of a rather rigid material for delivery to 256. For example, the corner piece 260 may be made of an incompressible or substantially incompressible material, such as a metal, a hard polymer material, or the like, or a compressible or elastic material of soft plastic, rubber, silicone, or the like. Cornerpiece 260 may alternatively be in the form of a tubular bladder comprising air, gas, fluid, gel, or other material, and may have a certain planarization process with a constant volume and pressure, or characteristics such as rigidity, compressibility, etc. It may be coupled to a mechanism for changing the volume and / or pressure of air, gas, fluid, gel or other material so that it can be adjusted to perform properly. Overall, the characteristics of the cornerpiece 260 determine how much subcarrier force FSC is transmitted to the backside 244 of the wafer 230. The purpose of this corner piece 260 is to provide a means for adjusting the polishing pressure at the peripheral edge 262 of the wafer 230 apart from the polishing pressure applied on the remainder of the wafer so that material removal and edge effects can be controlled. It is.

If a substantially incompressible material is used for the cornerpiece 260, in fact a portion of the membrane 250 is provided with some compressibility and elasticity that is advantageous to minimize any edge transitions that may occur at the boundary between the cornerpiece and the interior of the wafer. It should be noted that. The thickness of the membrane 250 may be selected to provide the desired firmness and elasticity. Even different processes can be obtained from different properties. Although the cornerpiece 260 illustrated in the embodiment of FIG. 3B is shown to have a rectangular cross section, the cross section may alternatively be tapered or rounded to provide a smooth transition of surface contour and pressure.

In the embodiment of FIG. 3A, the membrane backing plate 261 provides the functional characteristics of the annular cornerpiece at the perimeter edge 283 of the wafer 230, and also when held on the head 202 by vacuum force. An additional support for wafers is provided. Membrane backing plate 261 limits the amount of bowing that can occur on the wafer during holding or chucking operations, and cracks are formed in traces and other structures formed on the wafer front surface 245. To prevent                 

The air pressure (eg, air pressure) interposed between the lower surface 261 (see FIG. 3A) or the subcarrier lower surface 264 (see FIGS. 3B and 3C) and the upper surface of the membrane 254 of the membrane support plate is the membrane 250. Provides a downward force on the back side 244 of the wafer. In one embodiment of the invention, the wafer back downward force (FBS) is passed through the fittings 267 to the cavity 251 through the bore, orifice, tube, conduit, pipe or other communication channel 272 and And / or by rotary unions to external sources. This back pressure is uniformly distributed across the surface of the wafer within the annular cornerpiece 260 of the embodiment of FIG. 3B and inside the thick membrane portion 263 of the embodiment of FIG. 3C and having the membrane backing plate in the embodiment of FIG. 3A. In the example, it is uniformly distributed over the wafer surface in the cavity 251 formed between the recessed portion 279 of the lower membrane support plate 261 and the membrane top surface 254.

As a result of the effective mechanical coupling between the annular portion 285 of the membrane 250 and the subcarrier lower surface 252 extending over and in contact with the cornering piece 260 or the periphery of the membrane support plate, the wafer ( It will be appreciated that 230 is subjected to pressure associated with the subcarrier pressure PSC near its perimeter 283. It should be noted that the membrane backing plate 261 does not transmit mechanical force from the subcarrier in its inner region due to the recessed recess 279 formed in its lower surface. Wafer 230 is under pressure associated with back pressure PBS that extends from the center of the wafer toward the edge. In the region adjacent the inner radius of the corner piece 260 and at the edge of the concave circular recess of the membrane support plate 261, a predetermined transition typically occurs between the two pressures PSC and PBS.                 

In general, the polishing pressure around the wafer can be adjusted to be greater than, less than or equal to the polishing pressure at the backside of the wafer. The retaining ring pressure PRR may also be greater than, less than or equal to the polishing pressure at the wafer center or the polishing pressure at the peripheral edge. In one particular embodiment of the present invention, the retaining ring pressure is generally in the range between about 5 psi and 6 psi, but about 5.5 psi is more common and the subcarrier pressure is generally in the range between about 3 psi and about 4 psi. However, approximately 3.5 psi is more common, and wafer back pressure is generally in the range between 4.5 psi and 5.5 psi, but more typically around 5 psi. However, these ranges are exemplary only, as pressures may be adjusted to achieve a desired polishing or planarization effect over a range between approximately 2 psi and approximately 8 psi. In some embodiments of the invention, the physical weight of the mechanical elements, such as the weight of the retaining ring assembly and the weight of the subcarrier assembly, may provide an effective pressure.

The structure of an alternative embodiment is illustrated in FIG. 3C. In this alternative embodiment, the cornerpiece 260 is removed and replaced with a thicker portion of the membrane 250 that effectively acts as a cornering or cornerpiece. The material properties of the membrane and the thickness (t) and width (w) of the thick portion generally determine which portion of the subcarrier force will be distributed over which portion of the backside of the wafer. Also, although generally a cross-sectional rectangular cross section of a thick membrane wall is illustrated in the embodiment of FIG. 3C, other cross-sectional shapes or profiles of thick portions may be advantageously selected to provide the desired magnitude and distribution of subcarrier forces. If the shape is appropriately selected, forces can be distributed non-uniformly from the peripheral edges, i.e. as a function of radial distance, to obtain the desired material removal properties. If justified by cost or other considerations, the material properties of the membrane as a function of the radial distance from the center (especially in the region of the thick wall 263) to obtain different force transfer properties through the thick wall This may change.

In the embodiment of FIG. 3 (as well as in each of the other embodiments described below), the area of the wafer 230 where the subcarrier forces are transferred directly or substantially directly to the wafer can be adjusted over a fairly wide range. For example, the location of the membrane backing material and / or membrane backing recess 279 (FIG. 3A), corner portion (FIG. 3B), or thick membrane wall portion is generally between about 1 mm and about 30 mm from the peripheral edge 262. And, more generally, between about 2 mm and about 15 mm, even more generally between about 2 mm and about 10 mm. In general, however, the width and size of the recess, corner or thick membrane wall portion is determined by the desired result rather than any absolute limit on the physical distance. These dimensions will preferably be determined experimentally at the time of setting and testing the process parameters. In one embodiment of a 200 mm wafer CMP machine, the recess has a diameter of approximately 198 mm, while in another embodiment the recess has a diameter of approximately 180 mm. In general, the required dimensions are specially processed and / or processed and determined experimentally in the development and design of the machine and in the tuning of the CMP process.

Finally, although the spring is illustrated as a means for generating the force generating elements, namely retaining ring force FRR and subcarrier force FSC, it should be understood that the spring generally cannot be used for various reasons. For example, by providing matching spring characteristics, many springs can be problematic in practical terms, especially where replacement is needed after months or years after initial manufacture. In addition, the structure of the spring will be physically coupled to the housing, retaining ring and subcarrier, inevitably impairing the independence of motion. Rather, an air or fluid tight chamber or pneumatic or hydraulic cylinder is provided so that the force or pressure of the pneumatic or hydraulic pressure that drives the retaining ring, subcarrier and membrane is developed. The manner in which the pressure chamber is used and the physical coupling between the members is reduced is referred to in the description of the preferred embodiment of the invention in FIGS. 10, 16 and other figures related to these embodiments.

Several alternative embodiments are now described that provide separate retaining ring polishing forces, waferedge polishing forces, and wafer-centric polishing forces. Since the general structure of the embodiment of the invention illustrated in FIGS. 4 to 9 is similar to that of the embodiment of FIG. 3, only the main differences are described below.

In the embodiment of FIG. 4, the membrane 250 includes at least one opening or orifice 265, and no closed chamber is formed by the structure of the head itself. Rather, after the wafer is chucked (mounted) to the head and pneumatic is introduced through the orifice 265 behind the wafer, only the wafer back pressure is created to propel the wafer against the polishing pad. Although embodiments have been illustrated with membrane support plates 261, these embodiments may alternatively be implemented with corner pieces 260 or thick membrane edge portions 263 already described with reference to FIGS. 3B and 3C. have. If a membrane backing plate is used, the membrane backing plate is a reservoir 291 that collects any polishing slurry or debris that can be sucked or pulled into the line 272 when vacuum is applied to mount and maintain the wafer. Optional but advantageously included. This reservoir 291 prevents this accumulation from clogging the line. Further benefits are realized by providing a downwardly inclined side 292 and optionally an opening 293 of the reservoir smaller than the largest size of the reservoir. This feature allows for relatively large reservoir capacities, while maintaining maximum backside support and helping liquids or slurries to exit the line.

In the embodiment of FIG. 5, the outward side of the membrane backing plate 261 is provided with grooves 294 processed or otherwise formed on a surface to transfer vacuum to different portions of the wafer and to assist in testing or sensing proper wafer positioning. Have The raised portion 295 is held to support the wafer and prevents excessive boeing. Because of the orifices, vacuuming and holding of the wafer may be impaired, so this modification is desirable. In one embodiment, a combination of radius and peripheral grooves 294 is provided. Wafer presence detection hole 296 is optionally provided to determine whether the wafer is properly mounted on the head. If a vacuum pressure is formed behind the wafer, the wafer is properly mounted, but if no vacuum is formed, the wafer does not exist or the wafer is not properly loaded. Details of such grooved membrane support plates have the details of the particular membrane support plates illustrated in FIGS. 17 and 18, and are described in more detail with respect to the embodiment of FIG. 16.                 

The embodiment of FIG. 6 also utilizes a membrane 250 having at least one opening or orifice 265, and in addition to controlling pressure to remove certain material from the wafer front, wafer back 244 and membrane outer surface. In order to maintain a layer of air (or gas) between the 256, the flow of air or other gas is regulated. In this embodiment, the wafer floats on a layer of air. Although only a single orifice is illustrated in the figures, multiple or multiple orifices may be used. Excess air 280 escapes between the wafer and the membrane at the wafer edge. Additional conduits for collecting and returning air may be provided at the retaining ring interface. The arrow indicates the flow of air exiting the periphery of the wafer over the backside of the wafer.

The embodiment of FIG. 7 is a variation of the embodiment of FIG. 3 and provides a plurality of pressure chambers (two pressure chambers in this example with forces FBS1 and FBS2 and corresponding pressures) on the backside of the wafer. In the embodiment of FIG. 7A, the embodiment of FIG. 3A is modified by providing a similar second support plate 261-2 and a second membrane 250-2 coupled to the interior of the first membrane 250-1. In addition to the control of the edge and retaining ring pressures, the two structures overlap at the center so that uniform pressure can be individually controlled over the center of the wafer. The center chamber 251-2 and the membrane 250-2 portions are illustrated as having a base plate 261-2 similar to the base plate 261-1 provided for the larger outer membrane 250-1. Different support plate structures may be used or support plates may not be used. For example, a simple membrane forming the chamber may be used. One or two membranes may be very thin so that the thickness and separation of the membranes 250-1 and 250-2 relative to the wafer backside 244 may be significantly smaller, and may be somewhat exaggerated to show the structure in FIG. 7A. I can understand that. In one embodiment, the thickness of the two membranes combined may be approximately 0.5 mm to 2 mm, although thinner or thicker combinations may be used. In other embodiments, membranes from different pressure chambers abut rather than overlay, and the partitioning partition or wall divides a plurality of chambers that are generally annular. In such a multichamber embodiment, the partition walls between adjacent annular pressure chambers will be very thin so that the partition walls do not readily introduce pressure discontinuities at the zone boundary.

The structural modification of FIG. 7A is illustrated in FIG. 7B where only the retaining ring 214 and subcarrier 212 portions are shown, without any other portion of the CMP head 202. In this embodiment, the outer or edge transition chamber 251-1 receives the first pressure, and the inner or back pressure chamber 251-2 receives the second pressure. Retaining ring 214 receives a third pressure (not shown). As already described above in connection with other embodiments of the present invention, one or both of the edge transition chamber 251-1 and the back chamber 251-2 can include an opening or orifice. When the edge transition chamber 251-1 includes an opening, this opening can be conveniently provided as an annular ring (not shown) adjacent to the inner rear chamber 251-2, and is understood in this particular embodiment. As can be seen, the circular inner membrane and the annular outer membranes 250-1 and 250-2 surrounding the inner membrane need not necessarily overlap.

The embodiment illustrated in FIG. 8 provides for a different change in differential pressure or a differential pressure control concept, wherein the substantially tubular annular pressure ring or bladder 255 is a portion of the membrane support plate 261. Disposed between or within the subcarrier 212, ie generally the groove 257 in the subcarrier, the pressurized tube or bladder 257 is used to provide additional pressure to certain areas where additional material is required to be removed. . Channel 259 connects pressurized air FBS2 or other fluid from an external source to tubular bladder 257. When pressurized, the tube is pressed against the inner surface 254 of the membrane to partially increase the planarization pressure PBS1 present by the chamber 251.

9 further expands the above concept to provide a plurality of abutted or substantially abutted concentric pressure rings or bladders 255 to be polished or planarized to a higher or lower pressure than the surrounding area. . Although a tubular ring or bladder having a substantially circular cross section is illustrated, in the embodiments of FIGS. 8 and 9, the tubular shape may be conveniently selected to have a predetermined pressure or force profile relative to the membrane, ie, wafer 230. Can be understood. Pressurized gases or fluids FBS1, FBS2, FBS3, FBS4, FBS5 are adjusted to provide a desired polishing pressure profile across the wafer surface. In one embodiment, the tube generally has a circular cross section, while in a preferred embodiment, the tube has a rectangular cross section and the face of the substantially flat tube is pressed against the membrane. In the embodiment of Figure 9, the annular tube may have a different radius or width between the inner and outer diameters.

While each of these several embodiments has been described individually, in view of the description provided herein, those skilled in the art will appreciate that elements and features in one embodiment may be modified from elements and features in other embodiments without departing from the scope of the invention. It can be combined with features.

These embodiments illustrate some of the important features of some CMP heads whose ambiguity has been eliminated by special individual means. Once the structure in operation of these embodiments is understood, the structure, planarization method and advantages of the embodiment of FIGS. 10 and 16 will be more readily understood.

Looking back at the conventional design of FIG. 2, a similar head design using a conventional polymer insert 160 is interposed between the lower subcarrier 264 and the wafer backside 244. In this structure, the pressure on the backside 244 of the wafer 230 is uniform (at least to be uniform). Structures and mechanisms are not provided to vary the pressure at or near the wafer's periphery with respect to either the pressure at the center of the wafer or the pressure applied to the top surface of the polishing pad 226 by the retaining ring 214. Do not.

Further embodiments of two preferred embodiments of the present invention are described, describing alternative embodiments of the structures of the present invention with respect to FIGS. 3-9 and comparing these structures and planarization methods with conventional structures such as the structure of FIG. Attention is directed to a first embodiment using a thin membrane and a sealed pressure chamber (Fig. 10) and a second embodiment having a membrane with an open orifice, similar to the embodiment described with respect to Figs. Examples (FIG. 16) each provide additional features and advantages over these embodiments. In view of the description provided herein, those skilled in the art will appreciate that alternatives described with respect to these embodiments of FIGS. 5-9 have been made with respect to the embodiments of FIGS. 10 and 16.

By providing a ring of relatively rigid rubber to the outer edge of the wafer and applying subcarrier pressure, the amount of material removed at the edge is controlled with respect to the amount of material removed in the inner zone relative to the edge, such as relative to the center of the substrate. Can be.

The subcarrier pressure presses the rubber ring against the backside of the wafer while forming a compression seal. Pressing the wafer down through the rubber ring at the edges allows the wafer edge removal rate to be controlled relative to the removal rate within or at the center of the wafer so that edge nonuniformity can be controlled and defined.

In some head designs that use a diaphragm to provide wafer back pressure, there is no known conventional CMP head that provides a structure to apply differential pressure to the edge and the inner zone. In the structure of the present invention, a higher subcarrier pressure relative to the backside pressure increases the amount of material removed relative to the center of the wafer, and a lower subcarrier pressure relative to the wafer backside pressure results in an amount of material removed from the edge relative to the centerside. Decreases. These two pressures can be used to achieve uniform or substantially uniform material removal or, if any nonuniformity is introduced in a previous manufacturing process, to compensate for previously introduced nonuniformity from edge to center. It can be adjusted to achieve a profile of.

In these embodiments of the present invention, the subcarrier is primarily maintained to provide a stable element that communicates to the area near the edge of the wafer as the subcarrier pressure chamber is in uniform communication with the rubber ring (pressure at the edges is maintained). An embodiment of the present invention is provided for the purpose of adjustment, recalling that absolute uniform pressure may be undesirable or may not be provided). The flatness and smoothness of the subcarrier surface are not critical, except for the proper flatness requirements at the peripheral edges where downward pressure is applied to the wafer through the rubber ring. Thus, the subcarrier can be a low precision and less expensive part.

These structures provide tools (CMP tools) for polishing substrates or other workpieces, such as polishing (or planarizing) devices, machines or semiconductor wafers. The apparatus includes a rotatable polishing pad, a wafer subcarrier that itself includes a wafer or substrate receiving portion to receive the substrate and position the substrate relative to the polishing pad; And a wafer processing member comprising a first processing member and a second processing member, wherein the first processing member exerts a first load pressure against the polishing pad at the edge of the wafer, and the second processing member is at the center of the wafer. A second load pressure is applied to the pad, where the first and second load pressures are different. Although such a wafer subcarrier and a wafer processing member can be used separately, in a preferred embodiment of the present invention, the polishing apparatus applies a third load pressure against the polishing pad in the retaining ring and the retaining ring surrounding the wafer subcarrier. It further comprises an ining ring pressing member. The first, second and third load pressures can be adjusted independently.

The head 302 of the present invention of FIG. 10 includes a housing including an upper housing plate 308, a lower housing skirt 310, and an inner housing plate 312. The upper housing plate 308 is attached to the shaft 306 via the shaft attachment collar 316 by means of a screw or other fastener. Although a simple shaft 306 is illustrated, the shaft 306 is generally of conventional design, for example, bearings (not shown) and rotatable mounting of the shaft to the remainder of the polishing machine and such gases or fluids. One or more rotary unions 305 that communicate gas and / or fluid from the stationary source from the head to the lower head. One example of a shaft and rotary union type that can be used as the head structure of the present invention is illustrated in US Patent Application No. 5,443,416 entitled Rotary Union for Coupling Fluids in a Wafer Polishing Apparatus by Volodarsky et al., Assigned to Mitsubishi Materials Corporation.

In the embodiment described above, the upper housing plate 308 provides a stable mechanical platform to suspend or mount the retaining ring assembly 320 and the subcarrier assembly 350. The lower housing skirt 310 provides protection, such as preventing polishing slurry from entering the interior of the head, over the outer circumference of the retaining ring assembly 320, and controls or restricts the horizontal movement of the retaining ring assembly 320. And an outer radius edge 324 of the flexible retaining ring assembly mounting ring 323 to the upper housing plate 308.

The inner housing plate 312 is attached to the lower surface of the upper housing plate 308 and is operated to clamp the inner radius edge 326 of the flexible retaining ring assembly mounting ring 323 to the upper housing plate 308. The inner housing plate 328 is also operated to clamp the inner radius edge 328 of the flexible subcarrier assembly mounting ring 327 to the inner housing plate 312, and its direct to the upper load housing plate 308. The same applies to the upper housing plate 308 by connection.

Although the embodiments of FIGS. 3 and 4 have been described with respect to one simple subcarrier and retaining ring, generally cylindrical and annular, this embodiment provides a rather complex assembly comprising a plurality of components to perform these functions. to provide. Therefore, it is preferable to refer to the retaining ring assembly rather than the retaining ring and the subcarrier assembly rather than the subcarrier. The structural and functional principles described above are appropriate for these further embodiments, and features of the invention relating to the embodiments illustrated in FIGS. 3-9 are enhanced with particular implementation details described with respect to the embodiments of FIGS. 10 and 16. Can be configured precisely.

The retaining ring assembly 320 forms a wafer pocket 334 along the inner radius edge 335, so that the polishing pad on the lower ring wear surface 322 is constrained by the wafer 230 in the horizontal plane of the pad 226. And retaining ring 321 in contact with 226. Retaining ring assembly 320 also includes a generally annular suspension plate 336 having a lower surface 337 and an upper surface 338. The lower surface 337 is attached to the upper surface of the retaining ring 338, and the suspension plate passes from the lower surface through the retaining ring suspension coupling element 325 which is generally annular. Extends upwardly to an upper surface 338 cooperating with a lower surface 339 of the clamp 340 that is movably attached to 308.

In one embodiment of the invention, the retaining ring pressure is compensated for the retaining ring wear. In the case of non-rectangular retaining ring wear, the surface area contacted by the pad changes over time and wear. Thus, the pressure set for the process would not have the intended effect and would be desirable to be modified to accommodate large surfaces. A non-rectangular retaining ring shape, such as a retaining ring shape that provides a beveled outer edge, is preferred because it improves the distribution of polishing slurry for the wafer and the pads immediately below the wafer. With this angle, the slurry can be easily obtained. Thus, the retaining ring pressure can be independently controlled for both the subcarrier pressure at the edge of the wafer and the back pressure at the center region of the wafer. The retaining ring wear pressure compensation is preferably automated under computer control, for example based on any one of the sensors that detect the number of wafers processed, working time, manual measurement or the actual amount of retaining ring wear.

In one embodiment, the retaining ring suspension element 325 is molded of a flexible rubber material (EPDM material) to include two annular channels 341 and 342 on both sides of the clamp 340. These two channels have a cross section of curved loops (see detail in FIG. 12) and provide a relatively frictionless vertical retaining ring assembly relative to the housing 304 and the subcarrier assembly 350. do. In addition, the suspension elements 325 of this type retain retaining ring assembly 320 and subcarrier assembly 350 so as to be capable of independent or substantially independent movement except for friction that may be created on their sliding surfaces. To relieve your movement.

Suspension of the retaining ring assembly 320 relative to the housing 304 by clamping the radially outer edge portion 324 between the upper housing 308 portion to the lower housing skirt 310 with a screw 344 or other fastener or the like. This at least some degree can be achieved. In a similar manner, the radially inner edge portion 326 is clamped between the other portion of the upper housing 308 and the lower housing skirt 310 by screws 345 or other fasteners or the like. The central portion 343 of the suspension element 325 is clamped between the top of the retaining ring suspension plate 336 and the clamp 339 using a screw 346 or other fastener. Preferably, the edges and corners of the housing 304, the retaining ring suspension plate 336 and the clamp 339 are retaining ring suspension elements at their contacts to reduce stress on the suspension elements and to prevent wear and extend the life of the elements. Circularly approximates to the nominal curvature of 325. Channels or loops 341 and 342 are sized to provide a range of vertical motion (up and down relative to the polishing pad) with respect to retaining assembly 320.

The movement of retaining ring assembly 320 is advantageously limited to a predetermined range of motion sufficient for wafer loading, wafer unloading and polishing operations. The embodiment of FIG. 10 illustrates a variation of the interfering mechanical structure utilized to limit the range of motion, and notches in the retaining ring suspension plate 336 to limit movement beyond a predetermined limit of the retaining ring assembly. A 348 is provided in contact with the mating protrusion 349 extending from the inner housing plate 312. It is desirable to provide such out of range protection to protect internal components, in particular retaining ring suspension elements 325, from damage or premature wear. For example, if the total weight of the retaining ring assembly is supported by the retaining ring suspension element 325, the retaining ring suspension element 325 is susceptible to breakage or at least premature wear.

One embodiment of the retaining ring suspension element 325 is a perspective and bisected portion of the element showing the intermediate portion 343, the inner and outer loops or channel portions 342, 343, and the inner and outer radial edge portions 324, 326. Illustrated in FIG. 11 illustrating a cross section.

Subcarrier assembly 350 includes a subcarrier plate 351, a membrane support plate 352, a membrane attached to support plate 351 by screws or other fasteners, and in one embodiment, back pressure chamber 354. Is generally formed between the bottom or outer side 355 of the membrane support plate 352 and the inner side 356 of the membrane 350. Other embodiments of the back pressure chamber 354 provided by the present invention are described in more detail later.

In addition, the subcarrier assembly 350 is attached to the support plate 351 and the inner housing plate 312 to prevent the subcarrier assembly from extending excessively from the housing when the head is lifted away from the polishing pad 226. It is preferred to include a mechanical stop 358 in the form of a stop screw or stop bolt 358 that cooperatively interacts with the stop surface 359 of the inner housing plate 312 through the aperture. The stop bolts 358 are provided to impart an appropriate range of motion of the subcarrier within the head, but not an overly large range of motion where the internal elements of the head may be damaged by excessive extension during loading, unloading and polishing. For example, in the retaining ring assembly, if the total weight of the subcarrier assembly 350 must be supported by the subcarrier assembly suspension element 360, the subcarrier suspension element 360 is susceptible to damage or at least premature wear. .                 

As described with respect to the embodiment of FIGS. 3 and 4, a tool ball or key, spline, seam to couple the housing 208 to the retaining ring assembly 320 and the subcarrier assembly 350 for rotational motion. Comparable mechanical structures such as diaphragms, diaphragms and the like may also be used.

In one alternative embodiment, a thin sheet 329 of a material such as metal (eg, thin stainless steel) is used to transfer torque to the retaining ring assembly and the subcarrier assembly as illustrated in FIG. 12. . This structure allows vertical relative movement between the housing and the attached retaining ring assembly or subcarrier assembly while simultaneously transmitting rotational motion and torque between the joined members. Although the design of the metal coupling 339 is intended to be transmitted in only one direction of rotation, this limitation is not a problem when the head is rotated in only one direction. Alternatively, other diaphragm type couplings may be used to couple the housing to the retaining ring assembly and / or the subcarrier assembly. The features of the invention described herein are not limited to any particular retaining ring or subcarrier suspension system.

The mechanical structure of the housing, retaining ring assembly and subcarrier assembly is designed to reduce the footprint of the CMP head. For example, part of the ring suspension plate is overlaid with part of the subcarrier support plate. These and other forms of mechanical structure preferably make it possible to reduce the size of the head and generally make the CMP machine smaller.

The radially outer portion 361 of the subcarrier assembly suspension element 360 is attached to the top surface 366 of the subcarrier support plate 351 by the first clamp 367. The clamp 367 includes, for example, an annular ring 368 that is overlaid with the radially outer portion 361 and secured with a screw 369 to the subcarrier support plate 351 through the opening of the suspension element 360. You may. The radially inner portion 362 of the subcarrier assembly suspension element 360 is attached to the bottom surface 370 by a second clamp 371. The second clamp 371 is, for example, an annular ring that is overlaid with the radially inner portion 362 and secured with a screw 372 to the subcarrier support plate 351 through the hole 364 of the suspension element 360. 337 may be included.

A detailed portion of the CMP head of the present invention is illustrated in FIG. 13, which shows an exemplary structure of the subcarrier assembly suspension element 360, among other features. This element is also illustrated in FIG. 14, a perspective view and a partial bisection. In particular, FIG. 14 shows an element 360 having an intermediate portion 363 in the form of an annular loop or channel portion and radially outer and inner edge portions 361 and 362. Annular channels 363 appearing in the form of curved loops in cross-section provide relatively frictionless vertical movement to the subcarrier assembly relative to housing 304 and retaining ring assembly 320. In addition, this type of suspension element 360 desirably mitigates the impact of the movement of the retaining ring assembly 320 and the subcarrier assembly 350, i.e., negligible frictional interference that may occur in the sliding surface. Except for this, the movement is independent. Suspension element 360 may be formed of EPDM, also known as EPR, which is a general purpose rubber material having excellent chemical resistance and dynamic properties. One variation of EPDM has a tensile strength of 800 psi and a nominal durometer between 55 and 65.                 

The upper surface 380 of the membrane support plate 352 is attached to the lower surface 381 of the subcarrier support plate 351 by screws 353 or other fasteners. In one embodiment, the bottom or outer side 382 (the side facing the membrane 350) of the backing plate comprises a recess or cavity 383, so that when the membrane 350 is attached to the membrane backing plate 352, The membrane is allowed to contact the support plate only at the outer radial periphery near the edge of the support plate. In the embodiment of FIG. 10, the separation or cavity 383 between the membrane 350 and the membrane backing plate forms a chamber in which gas or air pressure (static and negative pressure or vacuum) can be introduced to perform certain operations of the head. .

In an alternative embodiment described with respect to FIG. 16, the membrane includes at least one hole or orifice 265 so that no enclosure or chamber is formed but rather pressure is applied directly to the backside of the wafer. The membrane 350 of the latter embodiment is used to limit contamination of the slurry into the head and to seal or partially seal the wafer to the head.

Referring again to the simplified descriptions of FIGS. 3 and 4, it is used to transfer a predetermined force from a corner portion 260 with predetermined material properties, a membrane backing plate 261 with a recess 279 or a subcarrier. Any one of the thickened portions 263 of the membrane itself is close to the periphery. A similar result is that the membrane support plate 351 alone or advantageously extends across the membrane support plate 252 (in the form of a drum skin over a somewhat cylindrical frame), and the membrane support plate 351 and the subcarrier support plate, which are clamping elements. It is provided in conjunction with the membrane 250 to be attached utilizing the bottom surface.                 

In one embodiment, the membrane 250 is molded from a material of EPDM or other rubbers. However, other materials can also be used. For example, silicon rubber may also be used, but may sometimes stick to the silicon wafer in some circumstances. The membrane material should generally have a durometer of between about 20 and 80, preferably between about 30 and 50 and more preferably between about 35 and 45, of which, among other examples, a durometer of 40 provides the best results. Durometer is a unit of hardness for polymer materials. Low durometers represent materials that are softer than high durometer materials. The material must be elastic and have consistently good chemical resistance and other physical and chemical properties in operation in a CMP flattening environment.

In one embodiment, the membranes 250 and 350 are made approximately 0% to 5% in diameter, preferably approximately 2% to 3% smaller in diameter than the predetermined installed size, especially for lower durometer materials. To full size (100%). Therefore, the manufactured membrane is stretched and tamed when installed because it is smaller than the diameter when installed.

15 illustrates one embodiment of a circular membrane 250. Membrane 250 has a nominal thickness made to a thickness of approximately 0.2-2 mm, preferably approximately 0.5-1.5 mm, and in certain embodiments approximately 1 mm. These dimensions are for the central portion of the membrane of constant thickness and do not include thickened portions at or near the periphery of some embodiments described above. The membrane is fitted over either the corner ring or the outer edge of the membrane support plate 261.                 

In practice, the size of the membrane in contact with the backside of the wafer may vary depending on the edge exclusion, the uniformity of the incoming wafer, the nonuniformity of polishing of the CMP process when operated without edge pressure differences and other factors. Under normal circumstances, the size of the membrane in contact with the backside of the wafer varies between approximately 0.5-20 mm, preferably approximately 1-10 mm, more preferably 1-5 mm. However, these ranges arise from the need to correct for non-uniformity of the process, and the structure or method of the present invention does not limit these ranges. For example, if there is a reason to provide direct subcarrier pressure to the outer 50 mm area of the wafer, the structure and method of the present invention may be suitable for this situation.

In an embodiment of the head of the present invention that utilizes an annular or ring shaped corner insert to deliver the pressure of the subcarrier to the edge of the wafer, the membrane has a substantially uniform bottom and sidewall wall thickness. However, if the thickened membrane sidewall itself is used as the force transmission means, the sidewall thickness should be equal to the distance the subcarrier force is applied directly to the wafer. In short, if it is desired that a subcarrier force be exerted on the outer 3mm of the wafer, the thickness of the membrane sidewalls should be 3mm. The relationship between the thickness of the membrane sidewall and the predetermined area or zone to which the subcarrier force is to be applied may not be exactly one to one. Between adjacent regions some transfer of force or transfer of pressure is anticipated and, in some situations, may be desirable to avoid sudden pressure discontinuities. Also, but not always, in this case, it is desirable to provide a membrane sidewall thickness that is slightly less than or greater than the distance the subcarrier force is applied to provide a predetermined pressure transition between the subcarrier pressure and the pressure on the backside of the wafer. There is. For example, in some examples for the outer peripheral region of a nominal 3mm wafer subjected to direct subcarrier pressure, the membrane sidewall thickness may be in the range of approximately 2-4 mm. The values of these specific values are only examples and the best dimensions depend on factors such as membrane material, planarization pressure, polishing pad properties, type of slurry, etc. and are generally determined empirically during the development of CMP machines and processes. .

It is a general idea that the theory is not supported. For FCS> FBS, the subcarrier pressure (FSC) overwhelms the pressure at the edge of the wafer, resulting in the subcarrier pressure (FSC) at the wafer edge, and the back pressure (FBS) at the center of the wafer. ) Appears. If FSC <FBS, the subcarrier pressure (FSC) can be governed if the backside membrane pressure (FBS) is large enough. However, CMP heads typically operate with FSC <FBS so that the removal of material at the wafer peripheral edge is reduced relative to the amount of material removed at the center. Relative pressure, diameter and material properties are adjusted to achieve the desired planarization result.

Now, the pressure applied to the pressure zone, the pressure chamber and the various parts of the system will be described. In summary, the retaining ring pressure is applied to push the lower wear surface of the retaining ring against the polishing pad, the subcarrier pressure is applied mainly around the radial periphery outside the wafer, and the backside wafer pressure (or vacuum) is It is applied against the back center of the wafer. One more pressurized line or chamber is advantageously used for head cleaning to clean polishing slurries and debris that can move if not washed. One or more additional pressure zones may optionally be applied as a circular region in the center of the backside of the wafer or in an annular region interposed between the center region and the outer peripheral region of the backside of the wafer. Embodiments utilizing a generally annular expandable tube or ring bladder having a rotary union for communicating pressurized fluid with these and other areas of the head are described in some of the specification herein.

In the embodiment just described, the back pressure chamber 354 is generally formed between the outer surface 355 of the membrane support plate 352 and the inner surface 356 of the membrane 350.

Attention is now directed to the embodiment according to the invention of FIG. 16 having a membrane with an orifice similar to that already described with respect to FIG. 4. Since the membrane 250 is provided with a membrane pressure hole or orifice, back pressure is directly applied to the wafer without the need to contact the membrane with the wafer backside, except near the outer periphery of the wafer where direct subcarrier pressure will be applied. In this embodiment, the membrane overlying the center portion of the wafer during polishing is mainly used to form a pressure / vacuum seal. This is the case when the wafer is held against the head during the loading and unloading of the wafer. The size of the membrane orifice varies from a few millimeters to a diameter close to the outer diameter of the subcarrier plate.

As described with respect to FIG. 4, the reservoir during wafer loading prevents the polishing slurry from being sucked into the pressure / vacuum line. Inclination of the edge of the reservoir facilitates the discharge of the slurry from the head again. Note that the amount of slurry sucked into the reservoir is expected to be small and only needs to be cleaned from time to time. The cleaning is accomplished by manually or by blowing off steam or pressurized air, water or a mixture of air and water to clean the lines and reservoirs.

The presence of the membrane orifices makes it difficult to communicate vacuum to the back side of the wafer and makes it difficult to properly sense wafer mounting when sensing is accomplished by sensing for vacuum pressure accumulation. If the recess of the membrane backing plate is shallow, withdrawing the vacuum from the central pressure line results in sealing of the membrane at the center with respect to the backing plate but no vacuum is communicated to other areas of the wafer. The membrane itself does not draw out the vacuum as there is no orifice. On the other hand, this problem can be solved by increasing the thickness or membrane backing recess, or by using the corner insert or the implementation of the thickened membrane edge. However, this lowers the wafer holding capacity.

A better solution is provided by the embodiment of the membrane support plate illustrated in FIGS. 17 and 18, where FIG. 18 is a perspective view of the plate illustrated in FIG. 17. It is desirable to provide additional support to prevent flexing, bowing or wrapping of the wafer. The wafer substrate itself is typically not permanently deformed, cracked or damaged, but metals, oxides and / or other structures and lines on the front of the wafer may crack when stressed. Therefore, it is desirable to fully support the back side, especially when the wafer is pulled against the diaphragm during loading before and after polishing before removing the wafer.

At least one orifice is provided near the outer edge of the membrane support plate. They serve as bolt holes to clamp the membrane between them while attaching the membrane backing plate to the subcarrier plate. The first and second radial channels extend from a central orifice that is in communication with an external pressure / vacuum that provides back pressure during polishing and that is joined to be in vacuum communication during loading of the wafer before and after polishing. The concentric first and second annular channels intersect the radial channels. The purpose is to transfer pressure and vacuum to the wafer and to preferably support the wafer.

In addition, the physical structure of the head facilitates an access to remove the membrane 250 from the subcarrier support plate on the outside of the head without the need to disassemble the head as in many conventional head structures. Recall that the bolt holes in the membrane support plate secure the membrane to the subcarrier plate and are accessible from outside the head. One or a set of holes is used to access a screw or other fastener that attaches the membrane to the head. Since the membrane is an abrasive item, it sometimes needs to be replaced, and therefore the ability to replace the membrane from the outside of the head without having to disassemble the head is good.

Further embodiments are now described with respect to FIGS. 19-27. Each of these CMP head and tool designs are somewhat similar to those already described with respect to FIGS. 7A, 7B, 8 and 9.

19 illustrates a first zone, or Zone I, in which the polishing head 300 has two chambers for providing an edge zone and a central zone. In the embodiment of FIG. 19, the portion partially shown in cross-sectional view shows a head 300 having an outer chamber, ie, an edge transition chamber 302 and an inner, ie, back pressure chamber 304. The partial cross-sectional view of the head 300 shown includes a subcarrier plate 306 having an outer side 308, a retaining ring 310 and a backing plate, ie an adapter retaining ring 312. The flexible membranes 314 and 316 (indicated by irregular lines to emphasize their flexible or elastic properties) are formed on the outer surface 312 of the subcarrier plate 306 and the spacers 313, i.e., the supports, to form the chambers 302 and 304. Used in conjunction with The outer membrane 314 has a receiving surface 317 suitable for receiving a substrate or wafer 318 thereon. Fluid pressurized from an external pressurization source (not shown) is introduced into the edge transition chamber 302 at a first pressure and into the back pressure chamber 304 at a second pressure. Pressurized fluids are typically air or other gases, but alternatively liquids may be used. The fluid acts to press the entire wafer 318, including the edge of the substrate, onto a polishing pad (not shown), while the back pressure chamber 304 acts to apply a loading force to the center region of the wafer. Only the edge transition pressure of the edge transition chamber 302 in the edge region or region loads or presses the wafer 318 against the pad. However, in the central region where the two membranes 314 and 316 are overlaid with each other, the polishing pressure is combined with the two pressures, which are not necessarily added. The purpose of overlapping two zones is to create various pressures or load forces across two zones or zones. These two pressures are preferably determined during process arrangement to achieve the result of the desired planarization. Generally, though not necessarily, the pressure of the fluid introduced into the back pressure chamber 304 is higher than the pressure of the fluid introduced into the edge transition chamber 302. This embodiment is useful when a polishing process with a fast removal rate at the center is desired, for example, when the wafer 318 has a convex surface due to a material such as copper deposited thereon. Alternatively, higher pressure in the central region may be desirable to compensate for processes that have a fast removal rate of the edge due to the polishing pad, the particular slurry used, or the so-called edge effect, if not compensated for.

20 is a schematic diagram of a second zone or Zone II in which the polishing head 300 has an edge zone and a central zone. The embodiment of FIG. 20 is provided in a similar structure except that the outer membrane 314 is in the form of an open annular membrane, and the inner membrane 316 is circular or disk shaped and the two membranes do not overlap. In this embodiment, the annular outer membrane 314 has a receiving surface 317 suitable for receiving the wafer 318 thereon and a lip portion 320 to help seal the wafer with the head 300. ). The pressurized fluid introduced into the first chamber 302 formed by the outer membrane 314, the back side of the wafer 318, and the outer side 308 of the subcarrier plate 306 directly forces against a portion of the back side of the wafer. Add to The outer membrane 314 also helps to apply edge pressure or force against the edges of the wafer 318.

21 is a schematic diagram of a third zone or Zone III in which the polishing head 300 has an edge zone and a central zone. 21 and 20 except that the outer and inner membranes 314 and 316 have been replaced with a single membrane 322 having an inner wall 324 separating the non-overlapping edge zone chamber and back pressure chamber. Similar to the embodiments shown. Accordingly, only the edge transition pressure introduced into the outer chamber 302 acts on the outer annular zone, and the edges introduced into the outer annular zone and the inner chamber 304 of the wafer 318 for the inner circular portion of the wafer. Only the transition pressure acts.

22 is a schematic diagram of a fourth zone or Zone IV in which the polishing head 300 has an edge zone and a central zone. The embodiment of FIG. 22 is similar to the embodiment already described with respect to FIG. 21, but the outer chamber includes or is formed of an expandable inner tube 326 or bladder. In one form of this embodiment, the head 300 is combined with an inner tube 326 previously expanded and sealed to a predetermined pressure to simplify the connection to the head of pressurized fluid. Accordingly, the force applied to the edge portion of the wafer 318 is mainly determined by the force applied by the subcarrier 306, while the force applied to the center portion of the wafer 318 is the pressure of the fluid introduced into the central chamber. And the force exerted on the subcarrier. Thus, varying the pressure of the fluid introduced into the central chamber can change the division of the force exerted by the subcarrier 306, which is transmitted to the central and edge regions of the wafer 318. That is, fluid introduced into the central chamber 304 at a pressure greater than the pressure in the expandable tube 326 causes most or all of the force exerted by the subcarrier 306 to be delivered to the central region of the wafer 318. On the other hand, a pressure less than the pressure in the expandable tube results in most or all of the force exerted by the subcarrier 306 delivered to the edge region.

FIG. 23 is a schematic diagram of a fifth zone or Zone V in which the polishing head 300 has a single annular membrane 328 for creating an edge zone and a central zone. The embodiment of FIG. 23 includes an outer annular chamber 330 formed by the annular membrane 328 described above. The edge transition chamber 302 is formed by the annular membrane 328, the outer surface 308 of the subcarrier plate 306, and the spacer 313. The back pressure chamber 304 that imposes a polishing pressure on the interior of the wafer does not include a separate membrane or distinct chamber. Instead, the back pressure chamber 304 is held on the outer surface 308 of the subcarrier 306, the inner circumferential edge 332 of the annular membrane 328 and the receiving surface 317 of the annular membrane 318. It is formed by the back of the. Thus, the back pressure chamber 304 is formed only when the wafer 318 or other substrate is mounted to the head 300, in particular when it is mounted to be sealed together with the annular membrane 328. This embodiment has the advantage that defects that may be present in the membrane (or prior art contact subcarriers) do not cause a flattening change in the center of the wafer 318 where pressure can be applied directly.

24 is a schematic diagram of a polishing head 300 having a plurality of membranes or a single membrane having an inner wall for providing a central zone and a plurality of annular zones. The embodiment shown in FIG. 24 is a single membrane 334 substantially covering the bottom surface 308 of the subcarrier plate 306 and the four annular membranes 336a-d creating the annular zones 338a-d. And a central zone 340 formed by the bottom surface of the subcarrier plate, a single membrane 334 and an inner circumferential wall of the annular membrane 336d. Alternatively, a single membrane (not shown) with four inner annular walls forming five zones can be used. In either embodiment, five zones may be controlled simultaneously or substantially independently. If fewer or more zones are desired, the number of inner walls and / or membranes can be adjusted appropriately to provide a predetermined number of chambers.

25 illustrates an embodiment of a double membrane head, wherein the outer membrane is in the form of an open annular membrane, and the pressure applied to the inner circular membrane can be varied to change the area of the substrate center where the force is applied. have. Referring to FIG. 25, a polishing head 350 is generally a housing or carrier having a subcarrier plate 354 that holds and positions a substrate 356 on a polishing surface (not shown) during polishing or planarization operations. 352 and a retaining ring 358 disposed circumferentially relative to a portion of the subcarrier plate. Retaining rings 358 through subcarrier plate 354 and backing ring 360 allow them to hang from carrier 352 and move vertically with little restraint and little friction. A small mechanical tolerance is provided between the subcarrier plate 354 and retaining ring 358 and the elements adjacent thereto to float on the polishing surface in such a way that it can accommodate both small vertical movements and small angular changes during polishing operations. it can be floated. The flange 361 is attached to the inner bottom 362 of the housing 352 by screws (not shown) or other fasteners. The flange 361 is first flexible to the inner support ring 366 attached to the subcarrier plate 354 to flexibly support the subcarrier plate and form a closed chamber or cavity 368 on the subcarrier plate. Joined via member or gasket 370. The retaining ring 358 is supported by a second flexible member or gasket 370 extending between the subcarrier plate 354 and the skirt portion of the carrier 352. The retaining ring 358 may be coupled to the second gasket 370 via a backing ring 360 attached to a backing plate (not shown) on the opposite side of the gasket using an adhesive, screw or other fastener (not shown). . The flange 361, the lower skirt 372, the inner support ring 366, and the first and second gaskets 366 and 370 form a second closing cavity 374 over the retaining ring 358. As described above, pressurized fluid, such as gas or liquid, may be introduced into the cavities 368 and 374 during operation to provide a force to push each of the subcarrier plate 354 and retaining ring 358 relative to the polishing surface. Can be.

According to an embodiment of the present invention, the polishing head 350 is coupled to the outer surface 378 of the subcarrier plate 354 by a spacer 379, the receiving surface suitable for receiving the substrate 356 thereon ( 380, an annular first membrane 376 having a lip or lip 382 suitable for being sealed to the back side of the substrate to form a first chamber 384 between the back side of the substrate and the outer side of the subcarrier plate, and It further includes a second membrane 386 positioned on the first membrane. The second membrane 386 is coupled to the subcarrier plate 354 to form a second chamber 388 between the inner side 390 of the second membrane and the outer side 378 of the subcarrier plate. Pressurized fluid introduced into the second chamber 388 through the passage 391 during the polishing operation causes the membrane to bend or expand outward to exert a force on the backside of the substrate 356 so that the arrow 356 on the substrate surface The predetermined area indicated by the shape is pressed against the polishing pad. This predetermined area is proportional to the pressure of the fluid introduced into the second chamber. In one embodiment, the predetermined area is directly proportional to the pressure of the fluid.

In one embodiment, a pressurized fluid of lower pressure than the fluid introduced into the second chamber 388 to press the surface of the substrate 356 against the polishing pad is also introduced into the first chamber 384 through the passage 393. Is introduced. In this embodiment, the predetermined area 392 is proportional to the difference between the pressure of the fluid introduced into the first chamber and the second chamber.

In another embodiment, the second membrane 386 includes a skirt portion 394 and a lower surface portion 396, wherein the skirt portion has a bottom surface of the second membrane between the first chamber 384 and the second chamber 388. It has a hardness less than the hardness of the lower surface portion in order to be expanded, bent or deformed in a regular and controlled manner by pressure changes. Preferably, the skirt portion 394 has a hardness that is at least approximately 50% higher than the lower surface portion 396. More preferably, when the lower surface portion 396 has a durometer of approximately 30A to 60A, the skirt portion 394 has a durometer of approximately 60A to approximately 90A. Most preferably, when the lower surface portion 396 has a hardness of a durometer smaller than approximately 50A, the skirt portion 394 has a hardness of at least approximately 70A durometer.

Alternatively, the lower surface portion 396 has a thickness thinner than the thickness of the skirt portion 394. Preferably, the skirt portion 394 has a thickness that is approximately 20 to 70% thicker than the thickness of the lower surface portion 396. More preferably, the skirt portion 394 has a thickness that is at least 50% thicker than the thickness of the lower surface portion 396. Thus, for the second or inner membrane 386 with the underside portion 396 having a thickness of approximately 0.3 mm to 3 mm, the skirt portion 394 generally has a thickness of approximately 1 mm to 30 mm. It should be understood that the exact thickness depends, in particular, on the overall diameter of the inner membrane 386. That is, the inner membrane 386 sized to accommodate a substrate 356 having a diameter of 100 mm is typically thinner than that designed for a 200 mm to 300 mm substrate.

In another embodiment shown in FIG. 26, the first membrane 376 extends substantially across the outer side 378 of the subcarrier plate 354 surrounding the second or inner membrane 386. The pressurized fluid introduced into the second chamber causes the second membrane to exert a force on the first or outer membrane to press a portion of the surface of the substrate 356 with the desired area 392 against the polishing pad. . Optionally, the first or outer membrane 376 may have a thickness of the outer membrane 376 such that pressurized fluid is supplied at least somewhat directly to the backside of the substrate 356 to press the substrate directly against the polishing surface. It may further include a plurality of openings or holes (not shown) extending through. In general, the pressure applied is in the range of approximately 2 to 8 psi, more preferably approximately 5 psi. Preferably, the number and size of the holes maximizes the area of the substrate 356 that is directly exposed to the pressurized fluid, while providing a sufficient area of the receiving surface 380 that engages or contacts the substrate to provide a polishing head ( 350 to provide torque or rotational energy to the substrate.

FIG. 27 illustrates another embodiment of a head 350 having a single membrane in the form of a closed annular membrane 400 suitable for sealing with an edge on the backside of the substrate 356 to form two chambers. . The first annular chamber 402 is formed by the annular membrane 400, the spacer 379 and the outer surface 378 of the subcarrier plate 354. The second or central chamber 404 is formed by the back surface of the substrate 356 held on the annular membrane 400, the outer side 378 of the subcarrier plate 354 and the receiving surface 380 of the annular membrane. do. By varying the pressure exerted on the annular membrane 400, the relative size of the area of the edge of the substrate 356 or the chambers 402 and 404 to which the force is applied can be varied.

In one embodiment, pressurized fluid at a pressure lower than the pressure introduced into the annular chamber 402 is introduced into the central chamber 404 to press the surface of the substrate 356 against the polishing pad. In this embodiment, the predetermined area 392 is proportional to the difference between the pressure of the fluid introduced into the annular chamber 402 and the central chamber 404.

In another embodiment, the annular membrane 400 has a skirt portion 406 and a bottom portion 408, which pressurizes the bottom portion 408 of the annular membrane 400 to the chambers 402, 404. It has a hardness lower than the hardness of the lower surface portion in order to be able to bend or deform in a regular and controlled manner due to the pressure change of the fluid. Preferably, skirt portion 406 has a hardness that is at least approximately 50% higher than lower surface portion 408. More preferably, when the lower surface portion 408 has a durometer of approximately 30A to 60A, the skirt portion 406 has a durometer of approximately 60A to approximately 90A. Most preferably, when the lower surface portion 408 has a hardness of less than approximately 50 A, the skirt portion 406 has a hardness of at least approximately 70 A durometer.                 

Alternatively, the lower surface portion 408 has a thickness thinner than the thickness of the skirt portion 406. Preferably, the skirt portion 406 has a thickness that is approximately 20 to 70% thicker than the thickness of the lower surface portion 408. More preferably, the skirt portion 406 has a thickness that is at least 50% thicker than the thickness of the lower surface portion 408. Thus, for the annular membrane 400 with the bottom surface 408 having a thickness of approximately 0.3 mm to 3 mm, the skirt portion 406 generally has a thickness of approximately 1 mm to 30 mm. It should be understood that the exact thickness depends, in particular, on the overall diameter of the annular membrane 400. That is, the annular membrane 386 sized to accommodate a substrate 356 having a diameter of 100 mm is typically thinner than that designed for a 200 mm to 300 mm substrate.

Those skilled in the art to which the description provided herein may be provided may have other chambers of mixed circular and annular shapes, each chamber may be in sealed form or sealed only when the substrate is mounted to the head. Should understand.

It is also to be understood that as the number of zones increases, it is necessary to provide different pressures for each zone. To date, rotary unions have been used for this purpose. However, as the number of zones has increased, it has become more complicated to provide rotary unions or the number of rotary unions to deliver certain kinds of different pressures. Thus, in some embodiments of the CMP head, CMP tool and polishing and planarization methods of the present invention, pressure regulating means are provided on or within the head. The pressure regulating means may, for example, comprise a plurality of pressure regulators coupled to a common manifold for receiving pressurized gas from a common source. Then, a single source of pressurized gas is distributed to the different zones at a regulated predetermined pressure. The pressure regulation may include sensors and feedback to maintain a fixed or constant level of pressure for each zone.

In the following, some of the important aspects of the present invention will be repeated to further emphasize their structure, function and advantages.

In one aspect, a carrier for a substrate polishing apparatus for polishing a substrate such as a semiconductor wafer is provided. The carrier includes a housing; A retaining ring fixedly coupled to the housing; A first pressure chamber applying a first force for pushing the retaining ring in a predetermined first direction with respect to the housing; A subcarrier plate having an outer surface and fixedly coupled to the housing; A second pressure chamber for applying a second force for pushing the subcarrier plate in a predetermined second direction with respect to the housing; A retaining ring surrounding a portion of the subcarrier plate and forming a circular recess; A spacer coupled to an outer circumferential edge of the outer surface of the subcarrier plate inside the circular recess of the retaining ring; A membrane comprising a flexible elastic material coupled to the subcarrier plate via a spacer, the membrane being separated from the subcarrier outer surface by the thickness of the spacer; And a third pressure chamber formed between the membrane and the outer subcarrier plate surface to apply a third force for pushing the membrane in a predetermined third direction with respect to the housing. In general, since no insert is provided between the membrane and the substrate, the process for handling changes caused by changes in insert properties can be reduced.

The spacer may comprise a ring of rings, a circular disk, or a thickened portion of the membrane near the periphery of the membrane. Generally, the spacer has a ring shape and annular width, and the edge polishing pressure is applied against the peripheral edge of the substrate by a second force acting through the annular spacer, where the central polishing pressure is applied to the substrate. Applied against the center part. Preferably, the spacer has a annular width between approximately 1 mm and 20 mm. More preferably, the spacer has a annular width of between about 2 mm and 10 mm, most preferably between about 1 mm and 5 mm. Even more preferably, the spacer has a annular width between 1 mm and 2 mm, or approximately 2 mm and 5 mm.

The spacer is made of a material selected to provide a predetermined edge pressure to the central pressure transition. The spacer may be formed from an incompressible material, such as a metallic material, or a compressible material, such as a compressible polymer material or a viscous material.

Generally, the third pressure chamber formed between the membrane and the outer subcarrier plate surface is formed only when the substrate is mounted in the recess. Preferably, the membrane comprises an orifice between the third chamber and the recess. More preferably, pressurized fluid flows through the orifice into the recess during planarization of the substrate.

In one embodiment, the retaining ring is indirectly coupled to the housing by a subcarrier, and the subcarrier is flexibly coupled to the housing indirectly via a retaining ring. Alternatively, the retaining ring and the subcarrier are flexibly fixedly coupled directly to the housing.

In other embodiments, the carrier may be positioned relative to the polishing pad by a separate pneumatic system or mechanical motion system.                 

In another embodiment, the first, second and third pressures are each constructed independently of the other pressures.

In another embodiment, the retaining ring is flexibly coupled to the housing by the first diaphragm and the subcarrier plate is flexibly coupled to the housing by the second diaphragm. In one form of this embodiment, the retaining ring is flexibly coupled to the housing via a first ring formed of an adaptive material and the subcarrier plate is flexibly coupled to the housing via a second ring formed of an adaptive material. Preferably, the adaptive material is selected from the group consisting of EPDM, EPR and rubber.

In an alternative embodiment, the subcarrier plate is also coupled through a receptacle for receiving the rod and the rod transmitting the rotational force between the housing and the subcarrier plate. Generally, the rod includes a tooling ball at the distal end and the receiver includes a cylinder for slidably receiving the tooling ball. In one variation of the invention, a plurality of rods and receivers couple the subcarrier plate to the housing.

In another embodiment, the retaining ring is further coupled by a receptacle for receiving the rod and the rod transmitting the rotational force between the housing and the subcarrier plate. Generally, the rod includes a tooling ball at the distal end and the receiver includes a cylinder for slidably receiving the tooling ball. Preferably, the plurality of rods and receivers couple the retaining ring to the housing.

In one embodiment, the membrane comprises at least one hole and the third chamber is sealed only when mounting the substrate to the membrane. Alternatively, the membrane comprises at least one hole and the third chamber is formed only when mounting the substrate to the carrier.

In another embodiment, the pressure of the subcarrier plate is the pressure applied to the peripheral edge of the substrate. The subcarrier plate is not in contact with the substrate but provides stability. Alternatively, the membrane has a thickened portion at the edge to transmit mechanical force.

In another embodiment, the membrane comprises a hole, which hole is used to determine if the substrate is attached to the membrane based on the possibility to create a vacuum in a third chamber of a predetermined size. In one modification of this embodiment, the inspection hole with the substrate is disposed near the center of the membrane. In another variation, the membrane is sometimes a consumable item that needs to be replaced and multiple holes are provided so that the membrane can be removed without having to disassemble the carrier. The hole has a size between about 1 mm and about 10 mm.

In general, spacers in combination with the membrane transfer some elastic force without the need to seal the substrate to the membrane.

In yet another embodiment, the subcarrier plate further comprises a passage for transmitting a third pressure from an external source into the third chamber. Preferably, the subcarrier plate comprises a cavity disposed around the passageway to provide a reservoir for the polishing slurry and to prevent the polishing slurry from being drawn into the passageway when a vacuum is applied to attach the substrate to the membrane. More preferably, a vacuum is applied to the third chamber for holding the substrate with respect to the membrane before and after polishing. Most preferably, the cavity has a conical shape so that the polishing slurry is easily discharged from between the membrane and the subcarrier plate.                 

In another embodiment, a back substrate support is provided to support the substrate upon mounting, and a plurality of channels are provided on the support to check for the presence of the substrate.

In another form, a carrier for a substrate polishing apparatus is provided. The carrier includes a subcarrier plate; A first pressure chamber disposed to generate a first downward pressure on the subcarrier plate; A membrane having a substrate receiving surface and bonded to a subcarrier plate, wherein the annular outer circumference of the membrane is mounted to the subcarrier, the inner circular part of the membrane is separated from the subcarrier plate, and is adapted to generate a second pressure. A membrane forming a second pressure chamber; A substrate mountable to the membrane at both the annular outer circumference and the inner circular portion; And an annular outer circumferential portion for applying a first pressure to the outer circumferential edge of the substrate and an inner circular portion for applying a second pressure to the substrate.

In another aspect, a method of planarizing a semiconductor wafer is provided. Generally, the method includes pressing the retaining ring surrounding the wafer to a polishing pad at a first pressure; Pressing the first peripheral edge portion of the wafer against the polishing pad at a second pressure; And a method of pressing the second portion of the wafer that is inward with respect to the peripheral edge portion against the polishing pad at a third pressure.

In one embodiment, the second pressure is provided through mechanical means in contact with the outer edge portion, and the second pressure is pneumatic against the back side of the wafer. In one variation of this embodiment, pneumatic pressure is applied through the elastic membrane. Pneumatic pressure is applied by a gas that directly presses at least a portion of the backside of the wafer.                 

In another embodiment, the method further includes a method of pressing the annular portions inside the plurality of wafers that are inward with respect to the peripheral edge portion at various pressures against the polishing pad.

In another aspect, a subcarrier for a CMP apparatus is provided, the apparatus comprising: a plate having an outer surface; A first pressure chamber for applying a force for pushing the plate in a predetermined direction; A spacer coupled to the peripheral outer edge of the plate; A membrane coupled to the plate via the spacer and separated from the plate by the thickness of the spacer; And a second pressure chamber formed between the membrane and the plate surface to apply a second force for pushing the membrane in a predetermined third direction.

In another form, a polishing apparatus is provided for polishing a substrate surface. The polishing apparatus includes a rotary polishing pad and a substrate subcarrier. The substrate subcarrier includes a substrate receiving portion for receiving the substrate and positioning the substrate with respect to the polishing pad and a substrate pressing member including a first pressing member and a second pressing member, wherein the first pressing member is a polishing pad. A first load pressure is applied to the edge portion of the substrate with respect to the substrate, and the second pressing member applies a second load pressure different from the first load pressure to the center portion of the substrate with respect to the polishing pad.

In one embodiment, the polishing apparatus includes a retaining ring surrounding the wafer subcarrier and a retaining ring pressing member for applying a third load pressure to the retaining ring against the polishing pad. Preferably, the first, second and third load pressures can be adjusted separately.

In another form, a polishing apparatus for polishing the surface of a substrate is provided. The polishing apparatus includes a rotary polishing pad and a substrate subcarrier. The substrate subcarrier includes a substrate receiving portion for receiving the substrate and positioning the substrate relative to the polishing pad and a substrate pressing member including a first pressing member and a second pressing member, wherein the first pressing member is attached to the polishing pad. A first load pressure is applied to the edge portion of the substrate, and the second pressing member applies a second load pressure to the center portion of the substrate with respect to the polishing pad, wherein the first and second load pressures are different.

In one embodiment, the polishing apparatus further includes a retaining ring surrounding the wafer subcarrier and a retaining ring press member for applying a third load pressure to the retaining ring against the polishing pad. Preferably, the first, second and third load pressures are separately adjustable.

In another form, a polishing apparatus for polishing the surface of a substrate is provided. The polishing apparatus includes a rotary polishing pad and a substrate subcarrier. The substrate subcarrier includes a substrate receiving portion and a substrate pressing member for receiving the substrate and positioning the substrate with respect to the polishing pad, wherein the substrate pressing member applies a first load pressure to an edge portion of the substrate with respect to the polishing pad. And a second pressing member for applying a plurality of different load pressures to the central portion of the substrate with respect to the pressing member and the polishing pad.

In one embodiment, the second pressing member each comprises a plurality of substantially concentric pressing members which apply a load pressure to the localized area of the substrate with respect to the polishing pad. In one variation of this embodiment, each of the plurality of substantially concentric pressing members comprises a pressure chamber formed on at least one portion by an elastic surface, which elastic load is applied when the pressurized gas is introduced into the chamber. It is pressed against the substrate for hanging. In another variation, the polishing apparatus further includes a membrane interposed between each elastic pressing surface and the substrate. In general, the membrane is selected from the group of materials consisting of EPDM, EPR and rubber.

Preferably, the intervening membrane forms a surface portion of the outer pressure chamber that receives pressure from an external source of pressurized gas and exerts a load on the substrate against the polishing pad. More preferably, the intervening membrane forms a surface portion of the outer pressure chamber that receives pressure from an external source of pressurized gas and exerts a load on the substrate against the polishing pad, wherein each of the plurality of substantially concentric pressing members is external. It is included in the pressure chamber. Most preferably, the load pressure applied by the external pressure chamber is separately added to the load pressure of one of the plurality of pressure members so that the load pressures in different zones can be adjusted individually, and the external pressure chamber extends over the pressure zone boundary. Minimize pressure discontinuities.

In another embodiment, at least one of the plurality of substantially concentric pressing members comprises a substantially circular or annular member that exerts a load pressure on a substantially annular region of the substrate. Preferably, at least one of the plurality of substantially concentric pressing members comprises a substantially annular member for exerting a load pressure against a substantially annular region of the substrate, wherein one of the plurality of substantially concentric pressing members Includes a substantially circular member that exerts a load pressure on a substantially circular region of the substrate.

In another form, a substrate subcarrier is provided for polishing a substrate with respect to a polishing pad of a CMP tool. The substrate subcarrier includes a substrate receiving portion for receiving the substrate; And a substrate pressing member for pressing the substrate against the polishing pad, the substrate pressing member being different from the first pressing member for applying the first load pressure to the edge portion of the substrate with respect to the polishing pad and the polishing pad in the central region of the substrate. And a second pressing member for applying a load pressure.

In one embodiment, the second pressing members each comprise a plurality of substantially concentric pressing members that apply a load pressure to the localized area of the substrate with respect to the polishing pad. Each of the plurality of concentric pressing members may include a pressure chamber formed at least in part by an elastic surface, the elastic surface being pressed against the substrate to apply a load when the pressurized fluid is introduced into the chamber. .

In another aspect, a method of planarizing a semiconductor wafer is provided. In general, the present invention provides a method of pressing an edge region of a semiconductor wafer at a first load pressure against a polishing pad and a portion of a plurality of semiconductor wafers of concentric regions inside the edge region at various different load pressures against the polishing pad. It includes a method of pressurizing.

In one embodiment, the method includes pressing the retaining ring surrounding the wafer at a third load pressure against the polishing pad. In one variation of this embodiment, the load pressure includes pneumatic pressure applied through the elastic membrane.

Optionally, the pneumatic pressure is applied by a gas that directly presses at least a portion of the backside of the wafer.

According to one aspect of the present invention, there is provided a polishing head for positioning a substrate having a predetermined surface on a polishing surface of a polishing apparatus that presses the substrate to remove material from the substrate. The polishing head is a subcarrier plate having an outer surface, an annular first membrane coupled to the subcarrier plate, the receiving surface suitable for receiving the substrate thereon, and a first surface between the rear surface of the subcarrier substrate and the outer surface of the plate. A first membrane having a lip suitable for sealing to the back side of the substrate to form a chamber and a second membrane positioned over the first membrane, the second membrane being disposed between the inner side of the second membrane and the outer side of the subcarrier plate; And a second membrane coupled to the subcarrier plate to form the chamber. During the polishing operation, the pressurized fluid introduced into the second chamber presses a predetermined area of the substrate surface against the polishing pad by forcing it to bend outward and exerting a portion of the backside of the substrate. The predetermined area is proportional to the pressure of the fluid introduced into the second chamber.

In one embodiment, the fluid pressurized to a pressure lower than the pressure introduced into the second chamber is introduced into the first chamber to press the surface of the substrate against the polishing pad. In this embodiment, the predetermined area is proportional to the difference between the pressure of the fluid introduced into the first chamber and the second chamber.

In another embodiment, the second membrane comprises a skirt portion and a lower surface portion, wherein the skirt portion has a lower strength than the lower surface portion. Alternatively, the lower surface portion has a thickness thinner than the thickness of the skirt portion.

In another embodiment, the first membrane extends substantially across the outer surface of the subcarrier plate, and the pressurized fluid introduced into the second chamber causes the second membrane to apply a force on the first membrane to the polishing pad. A part of the surface of the substrate having a predetermined area is pressed against the surface.

Another aspect of the present invention relates to a method for polishing a surface of a substrate using the apparatus described above, and a semiconductor substrate polished according to the method. The method comprises the steps of: (i) providing an annular first membrane coupled to a subcarrier plate, the receiving surface suitable for receiving the substrate thereon and a back surface of the substrate and an outer surface of the subcarrier plate. And a lip suitable for sealing with the back side of the substrate to form a first chamber therebetween; (ii) providing a second membrane positioned over the first membrane, the second membrane being a sub Coupling a carrier plate to form a second chamber between an inner side surface of the second membrane and an outer side surface of the subcarrier plate; (iii) positioning the substrate on the receiving surface of the first membrane; Iii) introducing a pressurized fluid into the second chamber to press the surface of the substrate against the polishing pad so that the second membrane exerts a force on a portion of the back side of the substrate. The step of pressing the predetermined region of the substrate surface; And (iii) providing relative movement between the subcarrier and the polishing pad to polish the surface of the substrate. In general, the pressurized fluid has a pressure selected to provide a predetermined predetermined area.

In one embodiment, pressing the surface of the substrate against the polishing pad comprises introducing a pressurized fluid into the first chamber at a lower pressure than the fluid introduced into the second chamber to press the surface of the substrate against the polishing pad. It further comprises a step. Thus, the predetermined region is proportional to the difference between the pressures of the fluid introduced into the first chamber and the second chamber, and the pressurized fluid has a pressure selected to provide a predetermined predetermined region.

In another form, a polishing head is provided for positioning a substrate having a predetermined surface on a polishing surface of a polishing apparatus for processing a substrate to remove material from the substrate. The polishing head includes a subcarrier plate having a peripheral outer edge and an outer surface having a central portion, a spacer coupled to the peripheral outer edge of the subcarrier, and an annular membrane having a receiving surface suitable for receiving a substrate thereon, the ring The shaped membrane has an outer edge coupled to the peripheral outer edge of the outer side of the subcarrier plate through a spacer and an inner edge coupled to the central portion of the outer side of the subcarrier plate, wherein the annular membrane is looped between the membrane and the outer side. It is separated from the outer side by the thickness of the spacer to form the shape chamber. During the polishing operation, the pressurized fluid introduced into the annular chamber presses a predetermined area of the substrate surface against the polishing pad by forcing it to bend outward and exert a force on a portion of the backside of the substrate. The predetermined area is proportional to the pressure of the fluid introduced into the second chamber.

In one embodiment the receiving surface of the annular membrane is sealed with the backside of the substrate to form a central chamber between the backside of the substrate, the receiving surface of the annular membrane and the outer side of the subcarrier plate, wherein the substrate Pressurized fluid at a lower pressure than the pressurized fluid introduced into the annular chamber to pressurize the surface is introduced into the central chamber. In this embodiment, the predetermined area is proportional to the difference between the pressure of the fluid introduced into the annular chamber and the central chamber.

In another embodiment, the annular membrane has a skirt portion and a lower surface portion, and the skirt portion has a hardness lower than the hardness of the lower surface portion. Alternatively, the lower surface portion has a thickness thinner than the thickness of the skirt portion.

Another aspect of the invention relates to a method of polishing a surface of a substrate using the apparatus described above and a semiconductor substrate polished according to the method. The method comprises the steps of: (i) providing an annular membrane having a receiving surface adapted to receive a substrate thereon, wherein the annular membrane is coupled to a peripheral outer edge of the outer surface of the subcarrier plate via a spacer. An inner edge coupled to the center portion of the outer side of the edge and subcarrier plates, the annular membrane being separated from the outer side by the thickness of the spacer to form an annular chamber between the membrane and the outer side. (Ii) positioning the substrate on the receiving surface of the annular membrane; (iii) introducing a pressurized fluid into the annular chamber to force the annular membrane against a portion of the substrate backside by Pressing a predetermined area of the substrate surface; And (iii) providing relative motion between the subcarrier and the polishing pad to polish the surface of the substrate. In general, the pressurized fluid has a pressure selected to provide a predetermined predetermined area.

In one embodiment, the receiving surface of the annular membrane is sealed with the backside of the substrate to form a central chamber between the backside of the substrate, the receiving surface of the annular membrane and the outer surface of the subcarrier plate, and the polishing pad is closed against the polishing pad. Pressing the surface further includes introducing a pressurized fluid of lower pressure into the central chamber than pressurized fluid introduced into the annular chamber to pressurize the surface of the substrate against the polishing pad. Thus, the predetermined area is proportional to the difference between the pressure of the fluid introduced into the annular chamber and the central chamber, and the pressurized fluid has a pressure selected to provide a predetermined predetermined area.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The above embodiments are selected and described in order to best explain the principles and practical application of the present invention, and various modifications can be made by considering whether they are suitable for a particular use in order that those skilled in the art can best use the present invention and various embodiments. . It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (144)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete In the carrier for substrate polishing apparatus, Subcarrier plates; A first pressing member arranged to generate a first downward pressure on the subcarrier plate; A membrane coupled to the subcarrier plate, having a substrate receiving surface receiving the substrate thereon, an annular outer circumference of the membrane mounted on the subcarrier plate, and an inner circular portion of the membrane separated from the subcarrier plate And the membrane forming a second pressure chamber for generating a second downward pressure that is distinct from the first downward pressure; The substrate is mountable to the membrane at both the annular outer circumference and the inner circular portion; The annular outer circumferential portion may apply the first downward pressure through the subcarrier plate in contact with the outer circumferential edge portion of the substrate during the polishing process, and the inner circular portion may be configured to provide the first circular pressure with respect to the substrate during the polishing process. And a second downward pressure, wherein the first downward pressure and the second downward pressure are controlled independently of each other. In the method of planarizing a semiconductor wafer, Pressing the retaining ring surrounding the wafer to a polishing pad at a first pressure; Pressing the first pressure member against the polishing pad at a second pressure against the polishing pad to pressurize the wafer against the polishing pad at a second pressure during the polishing step; And During the polishing step, pressing a portion of the wafer located inside the peripheral edge portion to a third pressure against the polishing pad, wherein the second pressure and the third pressure are controlled independently of each other. How to. The method of claim 60, The second pressure is provided through a mechanical member in contact with the peripheral edge portion, And said third pressure is an air pressure to the back surface of said wafer. 62. The method of claim 61, The air pressure is applied through an elastic membrane. 62. The method of claim 61, The air pressure is applied by a gas that directly presses at least a portion of the backside of the wafer. The method of claim 60, And pressing the plurality of annular portions of the wafer located within the peripheral edge portion at a plurality of pressures against the polishing pad. delete delete delete delete delete delete delete delete delete delete A polishing apparatus for polishing a surface of a substrate, Rotatable polishing pads; And A substrate subcarrier, wherein the substrate subcarrier, A substrate receiving portion for receiving the substrate and positioning the substrate with respect to the polishing pad; And A substrate pressing member, wherein the substrate pressing member comprises: During the polishing step, a first pressing member for applying a first downward load pressure at the edge portion of the substrate against the polishing pad; And And a second pressing member for applying a plurality of different load pressures to the pad in the central region of the substrate during the polishing step, wherein the first downward load pressure and the plurality of different load pressures are controlled independently of each other. Polishing apparatus. 76. The method of claim 75, And the second pressing member includes a plurality of substantially concentric pressing members each applying a load pressure in the local region of the substrate to the polishing pad. 77. The method of claim 76, Each of the plurality of substantially concentric pressing members comprises a pressure chamber formed on at least one portion by an elastic surface, the elastic surface being pressed against the substrate so that when pressurized gas is introduced into the chamber Polishing device, characterized in that to give the load. 78. The method of claim 77 wherein And a membrane interposed between each of said elastic pressing surfaces and said substrate. The method of claim 78, And the interposed membrane forms a surface portion of an outer pressure chamber that receives pressure from an external source of pressurized gas and exerts a loading force of the substrate against the polishing pad. The method of claim 78, The interposed membrane forms a surface portion of an outer pressure chamber that receives pressure from an external source of pressurized gas and exerts a load on the substrate against the polishing pad; And each of the plurality of substantially concentric pressing members is contained in the outer pressure chamber. The method of claim 80, The load pressure exerted by the outer pressure chamber is separately added to the load pressure of one of the plurality of pressure members, so that the load pressure in different zones is separately adjustable, and the outer pressure chamber has a pressure discontinuity across the pressure zone boundary. Polishing apparatus, characterized in that to minimize. 77. The method of claim 76, And at least one of the plurality of substantially concentric pressing members comprises a substantially annular member for applying a load pressure to a substantially annular region of the substrate. 77. The method of claim 76, Wherein said one of said plurality of substantially concentric pressing members comprises a substantially circular member for applying a load pressure to a substantially circular region of said substrate. 77. The method of claim 76, At least one of the plurality of substantially concentric pressing members includes a substantially annular member that exerts a load pressure on a substantially annular region of the substrate; Wherein said one of said plurality of substantially concentric pressing members comprises a substantially circular member for applying a load pressure to a substantially circular region of said substrate. The method of claim 78, And the membrane is selected from the group of materials consisting of EPDM, EPR and rubber. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete 1. A method of polishing a surface of a substrate using a device comprising a polishing pad and a polishing head having an outer surface subcarrier plate, the method comprising: Providing a ring-shaped first membrane coupled to the subcarrier plate, the receiving chamber being adapted to receive a substrate thereon, and forming a first chamber between a rear surface of the substrate and an outer surface of the subcarrier plate; Providing the first membrane having a lip adapted to seal with a back surface of the substrate; Providing a second membrane positioned above the first membrane, wherein the second membrane is coupled to the subcarrier plate to form a second chamber between an inner surface of the second membrane and an outer surface of the subcarrier plate; Providing; Positioning the substrate on a receiving surface of the first membrane; In order to force the second membrane on a portion of the back surface of the substrate, by introducing a pressurized fluid into the second chamber, by pressing the surface of the substrate against the polishing pad, the surface of the substrate Pressing a predetermined area of the pad against the polishing pad; And Providing a relative motion between the subcarrier and the polishing pad to polish the surface of the substrate. 103. The method of claim 102, Pressing the surface of the substrate against the polishing pad comprises providing a pressurized fluid having a pressure selected to provide a predetermined predetermined area. 103. The method of claim 102, Pressing a surface of the substrate against the polishing pad includes introducing a pressurized fluid into the first chamber at a pressure lower than that introduced into the second chamber to press the surface of the substrate against the polishing pad. Further comprising the step of: 105. The method of claim 104, The predetermined area is proportional to the pressure difference between the fluids introduced into the first chamber and the second chamber, and the step of pressing the surface of the substrate against the polishing pad provides a predetermined predetermined area. Selecting a pressure of the fluid introduced into the first chamber and the second chamber. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete Claim 134 was abandoned upon payment of a set-up fee. A polishing apparatus for polishing a substrate surface, Rotatable polishing pads; And A substrate subcarrier, wherein the substrate subcarrier, A substrate receiving portion for receiving the substrate and positioning the substrate with respect to the polishing pad; A flexible member connected to the subcarrier to enable the bottom surface of the flexible member to contact the substrate during operation; And Mechanically coupling the peripheral portion of the flexible member to the substrate subcarrier such that the first force applied to the annular member during operation becomes a first pressure acting on the substrate in contact with the peripheral portion of the flexible member including an annular member, And the flexible member is a membrane and the annular member is a thick portion of the membrane. Claim 135 was abandoned upon payment of a registration fee. 135. The method of claim 134, And a retaining ring external to the wafer subcarrier and capable of applying a load pressure to the polishing pad. Claim 136 was abandoned upon payment of a setup registration fee. 135. The method of claim 134, The flexible member is a membrane and the membrane is decoupled from the wafer subcarrier at one or more points by a chamber, And the chamber is pressurized to apply air pressure on the substrate at the point of contact with the decoupled portion of the flexible member during operation. Claim 137 was abandoned upon payment of a registration fee. 138. The method of claim 136, The substrate comprises a semiconductor wafer, the polishing apparatus, A retaining ring external to the wafer subcarrier and capable of applying a load pressure on the retaining ring to the polishing pad, And the first pressure, the air pressure, and the load pressure are independently adjustable. Claim 138 was abandoned upon payment of a set-up fee. A substrate subcarrier for polishing a substrate against a polishing pad in a CMP tool, comprising: A substrate accommodation portion accommodating the substrate; A membrane connected to the subcarrier, the bottom surface of the membrane being in contact with the substrate during operation; The membrane is decoupled from the subcarrier at one or more points by a chamber, The chamber may be pressurized to apply a first pressure on the substrate at the point of contact with the decoupled portion of the membrane during operation, The side wall of the membrane is thickened from the bottom to the top of the side wall such that the second force applied to the subcarrier during operation is in contact with the periphery of the membrane in contact with the thickened second pressure. Substrate subcarrier, characterized in that applied through the side wall. Claim 139 was abandoned upon payment of a setup registration fee. 138. The method of claim 138, wherein And said membrane comprises one or more openings and said first pressure is introduced through said openings. A substrate subcarrier for polishing a substrate against a polishing pad in a CMP tool, comprising: A substrate accommodation portion accommodating the substrate; A membrane connected to the subcarrier, the bottom surface of the membrane being in contact with the substrate during operation, the interior of the membrane being supplied by a first pressing member for pressing the substrate against the polishing pad during operation; Pressurized to a first pressure; And a second pressing member for applying a second pressure to the inner portion of the membrane to apply the second pressure to the substrate during operation. And the center of the substrate is pressed only by the first pressing member and not by the second pressing member. Claim 141 was abandoned upon payment of a registration fee. 141. The method of claim 140, And the second pressing member includes a plurality of pressing members that are substantially concentric, each of the pressing members applying a load pressure to a local region of the substrate with respect to the polishing pad. . Claim 142 was abandoned upon payment of a setup registration fee. 141. The method of claim 140, The second press member is a substrate subcarrier, characterized in that provided by a pressurized fluid. Claim 143 was abandoned upon payment of a setup registration fee. 141. The method of claim 140, And the second pressing member includes a bladder disposed between the membrane and the subcarrier. Claim 144 was abandoned upon payment of a setup registration fee. 141. The method of claim 140, And the membrane comprises one or more openings or orifices, and wherein the first pressure is introduced through the openings or orifices behind the substrate.

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