JPH10284471A - Dry etching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the adhesion of particles to wafers so as to eliminate the occurrence of defective products due to the particles by capturing floating particles with electrode plates by impressing a larger potential difference than that of an electrostatic chuck stage to the earth upon the electrode plates. SOLUTION: After a wafer 8 is carried in a vacuum chamber 7 and placed on an electrostatic chuck(FSC) stage 3, a voltage having an absolute value larger than that of the voltage applied across the FSC stage 3 is applied across electrode plates 1 by operating a DC power source 4a with the signal of a sequence control section 2 several seconds before starting etching. When the voltage is applied across the electrode plates 1, charged particles floating in the chamber 7 are attracted to the electrode plates 1. After the floating particles are completely removed, the wafer 8 is chucked by the ESC stage 3 and etched by generating plasma by making an introduced gas to cause glow discharge by operating a high-frequency power source 6 and a DC power source 4 with the signal of a sequence control section 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus for etching a semiconductor substrate, and more particularly to a dry etching apparatus having an electrostatic suction stage for holding a semiconductor substrate (hereinafter, referred to as a wafer) by coulomb force.

[0002]

2. Description of the Related Art An electrostatic suction stage (Electric)
In Static Chuck, a voltage is applied to the electrode side of the stage main body to hold the wafer by electrostatic attraction. This electrostatic chuck stage (hereinafter referred to as ESC stage) has better adhesion between the wafer and the stage surface than a normal mechanical clamp type stage, so the heat transfer efficiency between the wafer and the stage body is good and the wafer cooling effect is improved. Can be enhanced. For this reason, there is an advantage that in-plane uniformity such as an etching rate of a wafer is improved,
It is used in many semiconductor substrate processing apparatuses.

FIG. 3 is a schematic sectional view showing an example of a conventional dry etching apparatus. As shown in FIG. 3, this dry etching apparatus is disposed opposite to a disk-shaped upper electrode 5 of a vacuum chamber 7 and has an ESC stage 3 as a lower electrode on which a wafer 8 is placed, and an upper electrode 5 And E
High frequency power supply 6 for applying a high frequency voltage to SC stage 3
And a DC power supply 4 for applying a DC voltage between the ESC stage 3 and the ground.

A high frequency voltage is applied between the ESC stage 3 and the upper electrode 4 facing the same by a high frequency power supply 6, an etching gas is introduced into a vacuum chamber 7 to generate plasma, and the wafer 8 is etched. I have. Further, when performing this etching, a voltage of, for example, about -1000 V is applied to the ESC stage 2 side by the DC power supply 4 to electrostatically attract the wafer 8 and the stage surface to hold the wafer 8 during the etching. It is a mechanism.

[0005]

In the above-described conventional dry etching apparatus, the application of the voltage to the stage electrode is faster than the application of the high-frequency voltage, and the charged particles floating in the vacuum chamber adhere to the charged wafer surface. There has been the problem of being attracted and sticking, causing serious defects in the quality of the etched wafer.

A dry etching apparatus having a stage of a normal mechanical clamp system without using an ESC stage and having means for suppressing particles is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 4-370929.
In this apparatus, a film heater is attached to the inner wall of the chamber, and the reaction product is volatilized by heating to prevent deposition on the inner wall of the chamber. Further, the flow of ions is directed to the stage electrode by making it the most positive potential in the chamber.

[0007] However, in this dry etching apparatus, although ions from the plasma can be prevented from adhering to the inner wall of the chamber during the processing, charged particles floating in the vacuum chamber adhere to the wafer surface before the wafer is etched. Is inevitable. In particular, when an ESC stage to which a voltage is applied before processing is used, adhesion of the particles is promoted.

Therefore, an object of the present invention is to prevent charged particles in a vacuum chamber from being attracted to a stage electrode side even when an ESC stage is used to hold a wafer, and to prevent particles from adhering to the wafer. An object of the present invention is to provide a dry etching apparatus capable of performing etching.

[0009]

A feature of the present invention is to provide an electrostatic attraction stage for holding a semiconductor substrate housed in a vacuum chamber with an electrostatic attraction force and mounting the semiconductor substrate thereon. A high frequency voltage is applied between the electrostatic chuck stage and the upper electrode facing the electrostatic chuck stage to etch the surface of the semiconductor substrate, wherein the static electricity is provided between the inner wall of the vacuum chamber and the electrostatic chuck stage. A cylindrical electrode plate disposed so as to surround the electroadsorption stage, and a voltage having an absolute value larger than the voltage applied to the electrostatic adsorption stage is applied to the electrode plate, and after a predetermined time elapses, the electrode plate is applied to the electrode plate. The dry etching apparatus includes a sequence control unit that cuts off the applied voltage and applies the high-frequency voltage. Preferably, the electrode plate is equally divided into a plurality.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIGS. 1 (a) and 1 (b) are a schematic cross-sectional view and a top view of an electrode plate for illustrating a dry etching apparatus according to an embodiment of the present invention. This dry etching apparatus, as shown in FIG.
A cylindrical electrode plate 1 disposed between the inner wall of the vacuum chamber 7 and the ESC stage 3 so as to surround the ESC stage 3, and a DC power supply 4a for applying a negative potential to the electrode plate 1;
And a sequence controller 2 for controlling the timing of application and cutoff of the DC power supply 4 for applying a negative potential to the DC power supply and the ESC stage and the high-frequency power supply 6.
Otherwise, it is the same as the conventional example.

When the wafer 8 is etched by the dry etching apparatus, a negative voltage of, for example, about -1000 V is applied to the electrode side of the ESC stage 3 by the DC power supply 4 so that the wafer 8 and the ESC stage 3 are connected to each other. The gap is electrostatically attracted to hold the wafer 8 during etching. On the other hand, the conductive electrode plate 1 is installed inside the vacuum chamber 7. The material of the electrode plate 1 may be any material as long as it is conductive. However, in order to facilitate handling for maintenance and replacement, the electrode plate 1 is preferably divided into a plurality of equal parts and lightweight aluminum. This electrode plate 1 has a DC power supply 4
By a, a negative voltage having an absolute value larger than the voltage of the ESC stage 3 is applied. For example, if the ESC voltage is -1000V
Then, a voltage of about -1100 V may be applied to the electrode plate 1.

FIG. 2 is a time chart for explaining the operation of the dry etching apparatus of FIG. Next, the operation of the dry etching apparatus will be described with reference to FIGS. First, the wafer 8 is loaded into the vacuum chamber 7 and placed on the ESC stage 3, and a few seconds before the start of etching, the DC power supply 4 a is operated by the signal of the sequence control unit 2, and the electrode plate 1 is transferred to the ESC stage 3. A voltage having an absolute value larger than the voltage to be applied is applied. Thus, the charged particles floating in the vacuum chamber 7 are attracted to the electrode plate 1.

After a lapse of time when it is considered that the floating particles are completely eliminated, the high frequency power supply 6 and the DC power supply 4 are operated by the signal of the sequence control unit 2, and the wafer 8 is attracted and held on the ESC stage 3, and the high frequency voltage The gas introduced by the application of glow discharges glow to generate plasma and etch the wafer 8. Then, the switch of the high frequency power supply 6 and the DC power supply 4
Is turned off, and E is simultaneously
The suction of the wafer 8 by the SC stage 3 is released.

By controlling as described above, the particles do not move toward the ESC stage 3 at all, and the particles do not adhere to the surface of the wafer 8.

[0016]

As described above, according to the present invention, an electrode plate is arranged so as to surround the periphery of an ESC stage, a potential difference larger than the potential difference of the ESC stage with respect to the ground is applied to the electrode plate, and floating particles are removed from the electrode plate. Thus, it is possible to prevent particles from adhering to the wafer, and it is possible to eliminate a product defect due to particle adhesion.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration of an apparatus for explaining a dry etching apparatus according to an embodiment of the present invention, and a top view of an electrode plate.

FIG. 2 is a time chart for explaining the operation of the dry etching apparatus of FIG. 1;

FIG. 3 is a schematic sectional view showing an example of a conventional dry etching apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode plate 2 Sequence control part 3 ESC stage 4, 4a DC power supply 5 Upper electrode 6 High frequency power supply 7 Vacuum chamber 8 Wafer

Claims (2)

[Claims] 1. An electrostatic attraction stage for holding a semiconductor substrate housed in a vacuum chamber with an electrostatic attraction force and mounting the semiconductor substrate thereon, and the electrostatic attraction stage and an upper portion facing the electrostatic attraction stage In a dry etching apparatus for applying a high-frequency voltage between electrodes and etching the semiconductor substrate surface, the dry etching apparatus is disposed between an inner wall of the vacuum chamber and the electrostatic suction stage so as to surround the electrostatic suction stage. A cylindrical electrode plate, and a voltage having an absolute value greater than the voltage applied to the electrostatic suction stage is applied to the electrode plate and the voltage applied to the electrode plate is cut off after a predetermined time, and the voltage is cut off. A dry etching apparatus comprising a sequence control unit for applying a high-frequency voltage. 2. The dry etching apparatus according to claim 1, wherein said electrode plate is divided into a plurality of equal parts.