JPH05234944A - Wafer temperature control method and equipment - Google Patents

Abstract

PURPOSE:To uniform the temperature distribution of a wafer which is etched by using plasma. CONSTITUTION:Ring type trenches 18, 19 and radial trenches 20 connecting the trenches 18, 19 are formed on the surface of an electrostatic attraction electrode 2 for retaining a wafer to be etched by using plasma. A ring type part 22 where a trench is not formed is arranged between an He gas introducing hole 21 at the center of the electrostatic attraction electrode 2 and the ring type trench 18. Thereby the pressure of the He gas on the rear of the wafer can be made high at the central part as compared with the outer periphery of the wafer, so that ununiformity of temperature distribution caused by the gap between the wafer and a pushing-up mechanism and the temperature difference between the electrostatic attraction electrode 2 and the push-up mechanism is corrected, and the temperature distribution of the wafer during etching can be made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer temperature control method and apparatus such as a microwave plasma etching apparatus,
The present invention relates to a wafer temperature control method and apparatus suitable for uniforming processing of a sample such as a semiconductor element substrate (wafer).

[0002]

2. Description of the Related Art A conventional wafer temperature control technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 62-120931, in which a wafer is placed on an electrode in a vacuum and a cooling gas is passed between the wafer and the electrode. It is designed to control the temperature of. Further, the push-up mechanism for transferring the wafer is not provided with the cooling means.

[0003]

In the above prior art, the gap in the center of the electrode into which the pushing-up mechanism is inserted is wide, and a temperature difference occurs between the electrode and the electrode during processing. There is a problem that the cost becomes high and the uniformity of the treatment is insufficient.

An object of the present invention is to provide a wafer temperature control method and apparatus for making a wafer processing temperature more uniform.

[0005]

To achieve the above object, a plurality of ring-shaped grooves and radial grooves connecting the grooves to each other are provided on the surface of the electrode, and further, the innermost ring-shaped groove is formed. A portion in which no groove is formed is provided between the cooling gas introduction holes at the center of the electrode.

[0006]

Since the pressure of the cooling gas on the back surface of the wafer, which is related to the heat transfer rate, can be distributed from the center of the wafer to the outer circumference, the temperature distribution in the wafer becomes uneven due to the difference in the gap and the temperature. Can be corrected.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a so-called magnetic field microwave etching apparatus to which an embodiment of the present invention is applied will be described below with reference to FIGS.
Will be explained. 1 shows the overall structure of the apparatus, FIGS. 2 and 3 show the shape of the electrostatic adsorption electrode, and FIG. 4 shows the pressure distribution of He gas on the back surface of the wafer.

The wafer 1 to be etched is placed on the electrostatic attraction electrode 2 in the etching chamber by a transfer device (not shown). After that, in the etching process of the wafer 1, the process gas 4 introduced into the discharge tube 3 is introduced into the microwave 5
Plasma 7 is formed by the interaction of the solenoid 6 and the solenoid 6, and a high frequency power is applied to the lower electrode 8 fixing the electrostatic attraction electrode 2 by a high frequency power source 9 to control the energy of the ions incident on the wafer 1.

On the other hand, the wafer 1 to be etched is cooled by applying a DC voltage from the DC power supply 12 to the insulating film 11 provided on the surface of the electrostatic attraction electrode 2 by turning on the switch 10 and then plasma 7 by the method described above. Is generated and the wafer 1 is grounded via the plasma 7,
1 and the wafer 1 is supported by the electrostatic attraction force generated between the wafer 1 and the wafer 1, and the mass flow controller 13 is opened to move the H
This is performed by introducing the e-gas 14 into the back surface of the wafer 1. The temperature of the lower electrode 8 is adjusted by circulating the coolant 16 by the circulator 15.

After the etching process is completed, the wafer 1 is removed from the electrostatic attraction electrode 2 by turning off the switch 10 and raising the push-up mechanism 17, and then transferred to another processing chamber or the like by a transfer device (not shown). Be transported.

The shape of the electrostatic attraction electrode 2 used in the present invention will be described with reference to FIGS. On the surface of the electrostatic attraction electrode 2, two ring-shaped grooves 18 and 19 are provided in order to make the temperature distribution of the wafer 1 being processed uniform, and these grooves 18 and 19 are provided.
A radial groove 20 connecting the two is provided, and an annular portion 22 in which no groove is formed is provided between the introduction hole 21 of the He gas 14 and the ring-shaped groove 18. An insulating film 11 made of alumina or the like is coated on the surface to electrostatically attract the wafer 1.

Next, the effect of making the temperature distribution of the wafer 1 being processed uniform according to the present invention will be described. FIG. 4 shows a radial pressure distribution of the He gas 14 on the back surface of the wafer 1 related to the heat transfer rate between the wafer 1 and the electrostatic attraction electrode 2. He gas introduced to the back surface of the wafer 1 is shown in FIG. 14
Flows from the center of the wafer 1 toward the outer periphery. First, He
Between the introduction hole 21 of the gas 14 and the ring-shaped groove 18,
Since the groove is not formed, the conductance is very small and a pressure loss according to the flow rate of the He gas 14 is generated, and the back surface pressure is drastically lower than that in the center of the wafer 1. And
Since the ring-shaped grooves 18 to 19 are connected by the radial grooves 20, the conductance is extremely large, and the back surface pressure during this time is substantially constant. Then, outside the ring-shaped groove 19, the pressure is reduced to the same pressure as in the etching processing chamber.

From the above, in the region where the molecular flow condition is satisfied (the clearance between the wafer 1 and the electrostatic adsorption electrode 2 and the clearance between the wafer 1 and the pushing-up mechanism 17 are very small compared to the mean free path of the He gas 14), the wafer is 1 The pressure on the back surface and the heat transfer rate are almost proportional to each other, and the heat transfer rate at the central part of the wafer 1 can be made larger than that at the part attracted to the electrostatic adsorption electrode 2.
It is possible to correct the non-uniformity of the temperature distribution generated on the wafer 1 due to the gap between the push-up mechanism 17 and the wafer 1 and the temperature difference between the push-up mechanism 17 and the electrostatic attraction electrode 2.

Although the wafer 1 is supported by the electrostatic attraction force in the above embodiment, the present invention can be similarly applied to the case of supporting the apparatus by utilizing gravity.

[0015]

According to the present invention, the temperature distribution of the wafer to be etched can be made uniform.

[Brief description of drawings]

FIG. 1 is a front view showing the overall configuration of an etching apparatus to which the present invention is applied.

FIG. 2 is a plan view of an electrostatic attraction electrode used in the present invention.

FIG. 3 is a side view of FIG.

FIG. 4 is a diagram showing a pressure distribution on the back surface of a wafer according to the present invention.

[Explanation of symbols]

1 ... Wafer, 2 ... Electrostatic adsorption electrode, 18, 19 ... Ring-shaped groove, 20 ... Radial groove, 22 ... Annular part.

Claims (3)

[Claims] 1. A wafer temperature control method in which a wafer is placed and a cooling gas is supplied between the wafer and the wafer to control the temperature of the wafer being processed. A wafer temperature control method, characterized in that a difference in thermal resistance due to a difference in gap is corrected. 2. A wafer temperature control method in which a wafer is placed and a cooling gas is supplied between the wafer and the wafer to control the temperature of the wafer being processed. A wafer temperature control method, characterized in that a difference in thermal resistance due to a difference in temperature is corrected. 3. A wafer temperature controller for mounting a wafer and supplying a cooling gas between the wafer and the wafer to control the temperature of the wafer, in order to give a distribution of the pressure of the cooling gas on the back surface of the wafer. A wafer temperature control device characterized in that gas flow grooves having different conductances are provided in the electrostatic attraction electrode.