JPH01235344A - Semiconductor inspection apparatus and inspection of semiconductor wafer - Google Patents

Abstract

PURPOSE:To finely adjust the contact between an electrode pad and a probe pin by a method wherein fine positioning and control mechanisms by means of an electrical and mechanical conversion element are installed in three positions on an identical plane in a freely moving and close contact manner and a prescribed direct-current voltage is applied. CONSTITUTION:Displacement parts 16 (16-1, 16-2) of piezoelements 15 (15-1, 15-2) are brought into contact with contact faces 12 (12-1, 12-2) installed on the surface of a support sheet 13; a probe head is driven in the upward and downward z axis direction. Four pieces of the piezoelements 15 are installed to be symmetrical with respect to a central axis of the support sheet 13. A position sensor 36 is used in a coarse positioning operation in order to shift a drive stage 2 to a position where a probe pin 5 can be brought sufficiently into contact with an electrode pad 4 by using the piezoelements 15. The piezoelements 15 are driven while a direct-current voltage is applied from a drive terminal 31; probe pins 5, 5' are brought into contact with electrode pads 4, 4'. During this process, a conductivity sensor is used to control the overdrive of the electrode pads 4, 4'.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor inspection device, and particularly to a semiconductor inspection device equipped with a positioning mechanism suitable for highly reliable contact between a probe head and a semiconductor wafer, and a semiconductor inspection device using the same. The present invention relates to a method for inspecting semiconductor wafers.

[Conventional technology]

Conventional semiconductor testing equipment controls positioning by driving a wafer stage with a stepping motor in order to bring electrode pads formed on a wafer into contact with probe pins of a probe head fixed to the equipment. At this time, the structure of the probe pin provided in the probe head has spring properties. This type of probe pin with spring properties has a flexible contact with the electrode pad and has some excellent characteristics, but since it uses a spring such as a coil spring, it occupies a certain amount of space around the probe pin. High-density, multi-pin probes have limitations. Incidentally, related devices of this type include, for example, Tokyo Electron's product catalog: Full automatic prober N0DEL19S, Japanese Patent Application Laid-Open No. 61-80067, and the like.

[Problem to be solved by the invention]

In the above conventional technology, when the probe pin uses a fixed pin that does not have spring properties, no consideration is given to the point of highly reliable contact with the electrode pad on the wafer, especially the solder bump, and the above-mentioned electrode pad There was a problem of unstable contact due to the properties of the probe pin (including solder bumps) and the probe pin.

In other words, since conventional equipment moves the wafer stage up and down in the Z-axis direction using a stepping motor, an overshoot of about 10 - occurs even at one step level, but this can be absorbed by the spring properties of the probe pins. There were no particular problems. When a positioning mechanism that causes such an overshoot is used for the above-mentioned fixing pin, even if the fixing pin is brought into contact with the electrode pad, the fixing pin immediately separates due to reaction, resulting in poor contact and instability.

In the case of solder bumps, plastic deformation occurs when they come into contact with fixing pins, so there is a problem in that they exhibit a particularly remarkable tendency.

The purpose of the present invention is to solve the above-mentioned conventional technical problems, and in order to ensure contact stability between the fixing pin and the electrode pad, an improved positioning mechanism that is less likely to cause overshoot during contact is provided. An object of the present invention is to provide a semiconductor inspection device and a semiconductor wafer inspection method using the same.

[Means to solve the problem]

The above purpose is to move the wafer stage or probe head without mechanically moving parts when bringing the probe pins provided on the probe head into contact with the electrode pads of the semiconductor wafer.
This is achieved by driving using a vertically moving element that changes continuously with submicron precision. As the vertical movement element, an electromechanical conversion element (piezo actuator) is used that utilizes the so-called piezo effect in which an object mechanically expands and contracts by applying a voltage. As is well known, when a voltage is applied to a piezoelectric body made of a single crystal or polycrystalline sintered body of barium titanate, lead zirconate, etc., the amount of expansion and contraction of the object can be accurately controlled in accordance with the applied voltage. This electromechanical transducer is used for fine movement control for position determination. At this time, the amount of pushing of the probe pin into the electrode pad is detected and controlled by a position sensor or the like. In addition, deformation of the structure, warping,
An initial load is applied to the vertical movement element in order to improve positioning accuracy when pushing in due to looseness, etc.

Further details of the features of the semiconductor inspection apparatus of the present invention are as follows.

That is, the semiconductor inspection apparatus of the present invention includes a drive stage on which a semiconductor wafer is mounted and movable in three-dimensional free space;
A semiconductor testing device comprising at least a probe head in which probe pins inelastically fixed to the probe head contact electrode pads formed on the semiconductor wafer to transmit electrical signals, wherein the probe head A fine movement positioning control mechanism using an electromechanical transducer is provided on at least one of the support plate supporting the drive stage and the back surface of the drive stage, and the fine movement positioning control mechanism is provided in at least three places on the same plane in a loose and close manner. The present invention is characterized in that the contact between the electrode pad and the probe pin can be finely adjusted by applying a predetermined DC voltage.

Preferably, at least one of the probe head and the drive stage is supported by a support body using a spring structure so as to apply a predetermined initial load to the electromechanical transducer.

This makes it possible to prevent the occurrence of errors due to deformation, warping, rattling, etc. of the positioning control mechanism as described above.

Further, it is more preferable to provide means for superimposing an alternating current voltage on a direct current voltage as a driving power source applied to the electromechanical conversion element of the fine positioning control mechanism.

That is, the first purpose of this alternating current superimposition is to further prevent errors from occurring by vibrating the fine positioning control mechanism with alternating current as a break-in operation during a short blanking period prior to fine positioning. The second purpose is to apply AC voltage again while the probe pin is in contact with the electrode pad, vibrate the tip of the probe pin on the electrode pad, remove foreign objects on the electrode pad, and reduce the contact resistance. The goal is to reduce

Furthermore, the spring structure that presses and supports the electro-mechanical transducer is preferably constructed of a disk-shaped spring body that is hollow, circular, and has concentric pleats. Although it is possible to use a band-shaped spring, a disk-shaped spring body is preferable from the viewpoint of reliability.

The device mechanism constituted by the electromechanical transducer may be provided only on the probe head side, only on the drive stage side, or on both. When provided on both sides, extremely high precision positioning becomes possible, which is even more desirable. Further, this fine positioning mechanism is provided at at least three points, preferably four points, on the same plane. Two points will result in unstable positioning, which is not preferable.

It is necessary to know the distance between the probe head and the surface of the semiconductor wafer, and it is desirable to provide a position detecting means for optically measuring the surface position of the semiconductor wafer on the support of the probe head.

Next, the invention of a method for inspecting a semiconductor wafer using the semiconductor inspection apparatus described above will be described in detail. In other words, this wafer inspection method is a method for inspecting the electrical characteristics of semiconductor circuit elements provided within the wafer by press-contacting probe pins to electrode pads provided on the wafer. A dummy electrode pad is formed in advance, and when the probe pin comes into contact with the dummy electrode pad, a closed circuit is formed and a contact state between the electrode pad and the probe pin is detected.

More preferably, when electrically connecting the probe pin and the electrode pad by press-contacting the probe pin to the electrode pad, a DC voltage is applied to the electromechanical conversion element to cause the element to expand and contract. In order to extend and contract the tip of the probe pin by driving, as an initial operation, the probe head is vibrated by superimposing an AC voltage, and after the operation is stable, the probe pin is driven to a predetermined position by a DC voltage. After the probe pin is brought into contact with the electrode pad, an alternating voltage is again applied while the probe pin is in contact with the electrode pad, thereby causing the tip of the probe pin to vibrate on the electrode pad.

In actual use of the device of the present invention, until the probe pin approaches the semiconductor wafer to some extent, the probe pin is moved at high speed by a stepping motor provided on the drive stage side, and the probe pin is moved at high speed until it approaches the semiconductor wafer to a certain extent. At the contact stage,
This fine positioning mechanism will operate.

[Effect]

The above-mentioned vertical movement element has a precision of submicron or less and is
The displacement of 0- can be changed continuously. This provides a positioning mechanism that brings the springless probe pin into contact with the electrode pad of the semiconductor wafer with high accuracy and with no or negligible overshoot, thereby achieving highly reliable contact.

In other words, the fine positioning mechanism using the electromechanical transducer can determine the position with high precision within a limited range by changing the DC applied voltage using the piezo actuator. Particularly in the initial state (during the blanking period), superimposing alternating current not only removes errors by applying an initial load to the element using a spring mechanism, but also prevents mechanical deformation, warping, rattling, etc. It has the effect of removing the based error. Further, when the probe pin is positioned on the electrode pad, if alternating current is applied again, foreign matter on the pad is removed, thereby reducing the contact resistance.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

Embodiment 1 FIG. 1 shows a drive stage 2 on which a semiconductor wafer 1 is mounted, which can be moved in XY force directions in the front, rear, left, and right directions, and a probe head 6 mounted on an electrode pad 4 on one chip area 3 of the semiconductor wafer 1.
FIG. 6 is a new view showing a Z-axis direction positioning mechanism for the top and bottom of the probe head 6 which transmits electrical signals by contacting the probe pin 5 implanted therein. The probe head 6 is electrically connected to the probe pin electrode pitch expansion substrates 7, 8, 8! Connected mechanically, and further connected to the connector part 9 (9-1, 9-2)
A power line, a signal line, and a ground line are led out by coaxial cables 10 (10-1, 10-2) and 11 and connected to a tester section (not shown) and a control section (not shown), respectively. The probe head 6 is mounted on a pitch expansion substrate 7.
, 8 are mechanically reinforced and supported by two rigid upper and lower support plates 13 and 14.

A contact surface 12 (12
-1, 12-2) on the piezo element 15 (15-1,
The displacement portions 16 (16-1, 16-2) of the probe head 6 (15-2) are brought into contact with each other to enable the probe head 6 to be driven in the upper and lower Z-axis directions. In this figure, piezo element 1
Although two pieces (15-1, 15-2) of 5 are shown, in reality, as described later, four pieces are provided symmetrically about the central axis of the support plate 13, and each can expand and contract in the vertical direction independently. However, the probe head has a structure in which the position of the pin 5 of the probe head can be moved upward and downward via the displacement section 6. The displacement portion 6 is made of a metal block, is adhesively fixed to the piezoelectric element, and is in close contact with the support plate 13 in a loose manner. Furthermore, the displacement portion 1 of the piezo element 15
In order to apply an initial load to the piezo element 6, a support plate system 17 (6+7 +8 +13+14) including the probe head 6 is pressed against the piezo element 15 using an annular spring structure 18, which will be described later in FIG. And 40a, 41
A denotes bolts for fixing the support plate system 17 to the spring structure 18, respectively.

Showing Natsuto. The spring structure 18 includes the piezo element 1
5 is fixed via a connecting part 16'(16'-1,16'-2) together with a support 19, each at an outer periphery 20.21 via a space ring 22 to the device body (not shown).
Bolts 40. It is fixed with a nut 41.

FIG. 2(a) is a plan view of the spring structure 18, FIG. 2(b)
shows a sectional view taken along line A-AM in FIG. 2(a).

The spring structure 18 is a hollow annular plate spring.

A rigid support plate system 17 connected to the inner ring surface 24
In order to push the inner ring surface 24 upward, the inner ring surface 24
It receives a force in the direction of , and is displaced to the state shown by the broken line 26. By adjusting the displacement amount 27 at this time, the support plate system 17
A predetermined initial load can be applied to the displacement portion 16 of the piezo element 15 that is in contact with the piezo element 15 . The amount of initial load required to push all the probe pins 5 into the electrode pads 4 is suitable.

This is to absorb positioning errors during pushing that occur due to deformation, warpage, and rattling of the support plate system 17 and the like.

In addition, 29 (29-1, 29-2, 29-3,
29-4) is a through hole for fixing the support plate system 17;
29a (29a-1, 29a-2, 29a-3
, 29a-4) indicates a through hole portion for bolting and fixing to the support body 23.

FIG. 3(a) is a plan view of the support plate 13 in contact with the displacement portion 16 of the piezo element 15, and FIG.
A sectional view taken along line B-B of FIG.

The support plate 13 prevents the pitch expansion substrate 8 from being deformed and has a rigidity that can withstand the pressure applied by the displacement portion 16 of the piezo element 15. In this example, high-strength, lightweight duralumin is used as the material.

On the surface of the support plate 13, contact surfaces 12 (12-1, 12-2,
12-3, 12-4) are provided.

In particular, the contact surface 12 is surface-treated with a material having a high hardness and subjected to chloride treatment in order to ensure contact stability.

By using four piezo elements 15, it has a structure that drives the support plate 13 in the Z-axis direction while keeping it horizontal. To ensure a horizontal surface, at least three piezo elements 15 may be used. Further, in the support plate 13, a through hole 28 (28-1,
28-2, 28-3, 28-4) and through-hole portions 29'(29'-1,29'-2) for forming the support plate system 17.
, 29'-3, 29'-4) are provided.

FIG. 4(a) shows one chip area 3 within a semiconductor wafer 1.
FIG. 4(b) is a plan view showing the arrangement of dummy electrode pads 4' forming the conduction sensor in FIG. 4(a).
- Dummy electrode pad 4' corresponding to the C-line cross section and probe pin 5 forming a continuity sensor provided on the probe head 6
4(c) is a sectional view showing the contact state when the probe head 6 is inclined with respect to the semiconductor wafer 1. FIG. The continuity sensor detects the contact position due to conduction between the probe pin 5' and the electrode pad 4', and the dummy electrode pad 4' provided at the four corners of one chip area and the probe pin 5' provided at the four corners of the probe head 6. probe pins 5 formed by and corresponding to each other.
' and the electrode pad 4' come into contact with each other, as shown in FIG.
) A closed circuit indicated by a broken line 32 is formed and a conductive state is established. Fourth
In the case of the state shown in FIG. 6(c), the parallelism between the probe head 6 and the semiconductor wafer 1 is adjusted, and then the probe head 6 and the semiconductor wafer 1 are brought into contact with each other again. In order to ensure the accuracy of the contact position by the continuity sensor, the probe pins 5 and 5' formed on the probe head 6 are
It is necessary to minimize the variation in the height of the tip and the variation in the height of the electrode pads 4, 4'. In particular, when the electrode pads 4 and 4' are thickly formed of soft material such as solder bumps, the probe pins 5 and 5' can be pushed into the electrode pads 4 and 4' by a certain amount, so that the height of both can be adjusted. Variation conditions are relaxed. In this example, three dummy electrode pads 4' are provided at each of the four corners of one chip area 3 and are electrically connected to each other within the chip, but it is not necessary to have such a dummy electrode structure. As shown in FIG. 4(d), the electrode pad 4 used for other inspections (not shown in the drawing) is made of the same material and has the same pad height as the probe pin. By providing individual dummy pads at the four corners of the chip surface that are large enough to form a closed circuit on the pads when they come in contact with each other, and by contacting the probe pin 5' that forms a continuity sensor with one of the dummy pads. A closed circuit may also be formed.

Returning to FIG. 1 again, the drive stage 2 can be moved in the Z-axis direction 35 by a stepping motor 34 via a main shaft 33. Further, the position sensor 36 disposed in the center of the support body 19 is a non-contact type using a laser beam and detects the surface position on the semiconductor wafer 1.
Measure the distance to. For this reason, a through hole 37 is formed near the center of the support plate system 17 to allow the laser beam to pass therethrough. Note that 30 indicates the optical path of the laser beam.

The conduction sensor and the position sensor 36 described above each function as follows in positioning in the Z-axis direction.

The position sensor 36 is used for coarse positioning, and is used to move the drive stage 2 to a position where the piezo element 15 allows the probe pin 5 and the electrode pad 4 to come into sufficient contact. The gap between the probe pin 5 and the electrode pad 4 at this time is made smaller than the maximum displacement amount of the piezo element 15. In particular, in the case of a solder bump in which the electrode pad 4 is thickly formed, a certain amount of pushing is required, so the gap described above needs to be set smaller by the amount of pushing.

Next, the piezo element 15 is driven by applying a DC voltage from the drive terminal 31 to connect the probe pins 5, 5' and the electrode pad 4.
, 4' are brought into contact. At this time, since overshoot does not occur, the electrode pads 4, 4' of the probe pin 5°5'
The contact resistance tends to stabilize in proportion to the amount of pushing into the electrode pads 4, 4', but if the pushing amount exceeds a certain amount, the lower portions of the electrode pads 4, 4' are destroyed. Therefore, a continuity sensor is used to control the amount of push. In other words, the maximum pushing amount is calculated in advance from the thickness of the electrode pads 4, 4', etc., the initial contact position is detected by a continuity sensor, and the subsequent pushing amount is controlled by the drive voltage applied to the piezo element 15. .

The piezo element 15 is normally driven by applying a DC voltage to both ends of the element and controlling the amount of displacement by adjusting the voltage. It is desirable to provide means for applying an alternating voltage of a predetermined frequency to the probe head, and to vibrate the probe head by superimposing the alternating voltage during the initial blanking period of driving and at the time of completion of positioning. By vibrating during the blanking period at the initial stage of driving, causes of mechanical errors such as residual strain and backlash in the head support system can be removed, and when positioning is complete, the probe pins will not come into contact with each other. Improve the contact condition on the electrode pad. In other words, if any foreign matter exists on the electrode pad, it can be removed, and the contact resistance between the probe pin and the electrode pad can be reduced.

Embodiment 2 FIG. 5 shows another embodiment of the present invention, in which both the drive stage 2 and the probe head 6 are each connected to a piezo element 15.
'(15' -1, 15' -2), 15 (15
-1, 15-2) is a sectional view showing a Z-axis direction positioning mechanism that can be driven using the Z-axis direction positioning mechanism.

The positioning mechanism of the probe head 6 using the piezo element 15 is structurally similar to that shown in FIG. 1, but is used to adjust the parallelism between the semiconductor wafer 1 and the probe head 6 using software. On the other hand, the piezo element 38 attached to the upper part of the main shaft 33 connected to the stepping motor 34 and moving in the Z-axis direction 35 is connected to the electrode pad 4 by the aforementioned continuity sensor.
．． After detecting the initial contact position by bringing the probe pin 5.5' into contact with the probe pin 4', the pushing amount is controlled by the DC drive voltage applied to the drive terminal 31'.

As described above, by controlling the parallelism between the probe head 6 and the semiconductor wafer 1 and at the same time controlling the amount of push of the probe pin 5 into the electrode pad 4, highly accurate and reliable positioning can be achieved and stable contact can be achieved. You can get the status. Furthermore, the parallelism control and the push amount control can be performed by the piezo element 15' and the piezo element 15, respectively.

The fine positioning mechanism provided on the drive stage 2 side is
The structure is basically the same as that provided on the probe head side described above. That is, the support plate 13', the spring structure 18', the stage support 19', and the bolt 40' that fixes the spring structure 18' to the stage support 19'.

a nut 41', a bolt 40'a that fixes the stage 2 to the spring structure 18 together with a support plate 13' which is a reinforcing material;
The nut 41'a and the like are almost the same as those on the probe head side. Reference numeral 38 in the figure is a support shaft for the stage 2, which is not necessarily necessary. Although it is provided in this example, its height is such that it touches the support plate 13' when an initial load is applied to the piezo element 15' by the spring structure 18'.

〔Effect of the invention〕

According to the present invention, a springless probe pin can be attached to an electrode pad of a semiconductor wafer with high precision and without overshoot by using a vertical movement element that continuously changes a displacement of several tens of degrees with an accuracy of submicron or less. , or contact can be made in a negligible state, which has the effect of realizing highly reliable contact.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a positioning mechanism of a semiconductor inspection device according to an embodiment of the present invention, FIG. 2(a) is a plan view of a spring structure 18, and FIG. AA line sectional view of
FIG. 3(a) is a plan view of the support 13, FIG. 3(b) is a sectional view taken along the line B-B in FIG. 3(a), and FIG. 4(a) shows a conduction sensor within one chip area. Dummy electrode pad 4'
FIG. 4(b) and FIG. 4(c) are respectively cross-sectional views, FIG. 4(d) is a cross-sectional view when using a different dummy electrode pad, and FIG. 5 is a plan view showing the arrangement. FIG. 3 is a sectional view of another embodiment of the invention. In the figure, 15, 15'... Piezo elements 18, 18'... Spring structure 36... Position sensors 13, 13', 14... Support plate attorney Junnosuke Nakamura 18... Huh? li! td shi, i4to (b) Fig. 2 (b) 13-・- Fig. 3 without husband Pr

Claims (1)

[Claims] 1. A drive stage on which a semiconductor wafer is mounted and movable in three-dimensional free space; a probe pin fixed inelastically to a probe head, and an electrode pad formed on the semiconductor wafer; A semiconductor inspection device comprising at least a probe head that transmits an electric signal by contacting the probe head,
At least one of the support plate that supports the probe head and the back surface of the drive stage is provided with a fine positioning control mechanism using an electromechanical transducer at at least three locations on the same plane in a loose and close manner, and the fine positioning is controlled by 1. A semiconductor inspection device characterized in that contact between the electrode pad and the probe pin can be finely adjusted by applying a predetermined DC voltage to a control mechanism. 2. The semiconductor according to claim 1, wherein at least one of the probe head and the drive stage is supported by a support body using a spring structure so as to apply a predetermined initial load to the electromechanical conversion element. Inspection equipment. 3. The semiconductor inspection apparatus according to claim 2, wherein the spring structure is a hollow circular disk-shaped spring body with concentric pleats. 4. According to claim 1, claim 2, or claim 3, the fine positioning control mechanism further comprises means for superimposing an alternating current voltage on a direct current voltage as a driving power source applied to the electro-mechanical conversion element of the fine positioning control mechanism. semiconductor inspection equipment. 5. The semiconductor according to claim 1, claim 2, claim 3, or claim 4, wherein the support of the probe head is provided with position detection means for optically measuring the surface position of the semiconductor wafer. Inspection equipment. 6. In a method for testing the electrical characteristics of a semiconductor circuit element provided in the wafer by press-contacting a probe pin to an electrode pad provided on the wafer, dummy electrode pads are formed at predetermined locations on the wafer. and, when the probe pin contacts the dummy electrode pad, a closed circuit is formed and a contact state between the electrode pad and the probe pin is detected.
A semiconductor wafer inspection method using the semiconductor inspection apparatus according to claim 3, claim 4, or claim 5. 7. When electrically connecting the probe pin and the electrode pad by press-contacting the probe pin to the electrode pad, applying a DC voltage to the electro-mechanical conversion element to drive the element to expand and contract. In order to extend and retract the tip of the probe pin, as an initial operation, the probe head is vibrated by superimposing an AC voltage, and after the operation is stable, the probe pin is driven to a predetermined position by a DC voltage, and the probe pin is moved to the electrode pad. 7. Inspection of a semiconductor wafer according to claim 6, wherein after the probe pin is brought into contact with the electrode pad, an alternating current voltage is again superimposed while the probe pin is in contact with the electrode pad, and the tip of the probe pin is vibrated on the electrode pad. Method.