JPH09129605A - Plasma etching single crystal silicon electrode plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plasma etching single crystal silicon electrode plate having less particle adhesion by a method wherein an electrode plate part and a retaining ring part are integrally formed by single crystal silicon. SOLUTION: A single crystal silicon electrode plate to be used for plasma etching is manuactured by cutting a single crystal silicon ingot, which is formed by a CZ method, into an electrode plate part 21 and an electrode plate form having a supporting ring part 22 by conducting a discharge machining, an ultrasonic wave machining, a laser processing and the like, and then by forming through holes 5 by machining and the like. To be more precise, a non-defective single crystal ingot is cut into round slices, a cutting work is conducted, and a flanged hat-like crystal silicon plate, having a flanged electrode part 21 as a supporting ring part 22, is manufactured. A number of small holes are perforated on said single crystal silicon plate by conducting an electrospark machining, a finish work is conducted using a supersonic wave drill, fine through holes 5 are formed, and the electrode plate 2 is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal silicon electrode plate used in a plasma etching apparatus.

[0002]

2. Description of the Related Art Generally, when manufacturing a semiconductor integrated circuit, it is necessary to etch a wafer. In recent years, a plasma etching apparatus has been used as an apparatus for etching this wafer. In this plasma etching apparatus, as shown in FIG. 2, for example, an electrode plate 2 and a pedestal 3 are provided at intervals in a vacuum container 1, a wafer 4 is placed on the pedestal 3, and an etching gas is used. 7
Flowing through the through pores 5 provided in the electrode plate 2 toward the wafer 4, the high frequency power source 6 causes the electrode plate 2 and the pedestal 3
A high frequency voltage can be applied between the two.

The etching gas 7 supplied by applying the high frequency voltage becomes plasma 10 in the space between the electrode plate 2 and the pedestal 3, and the plasma 10 hits the wafer 4 to etch the surface of the wafer 4. The electrode plate 2 used in this plasma etching apparatus has conventionally used a carbon electrode plate, but in recent years, as shown in FIG.
An electrode plate 2 formed by joining a single crystal silicon plate 8 and a carbon support ring 9 by brazing 11 is used.

[0004]

However, when a wafer is plasma-etched by using the electrode plate 2 formed by brazing 11 the conventional single crystal silicon plate 8 and the carbon support ring 9 to each other, conductivity is generated when a glow discharge occurs. Of abnormally generated electric discharge between the support ring 8 made of carbon and the wafer 4 having high property, and the carbon particles pass through the through holes 5 of the single crystal silicon plate 8.
Then, the wafer 4 is dropped onto the wafer 4 through the through holes to contaminate the wafer 4, and the yield of integrated circuits on the wafer is greatly reduced.

Contamination is particularly serious when plasma-etching SiO ₂ or the like on the wafer surface. It is Si
In the case of etching O ₂ , a plasma containing fluorine gas as a base is generally used. When sputtering is performed using the plasma containing fluorine gas as a base, carbon particles generated from the carbon-made support ring scraped by sputtering are used. Is not able to be volatilized, drops on the wafer as it is, and remains as particles.

In order to prevent the carbon particles from falling, a coating film of ceramics or the like is formed on the surface of the carbon support ring. However, if a large number of wafers are plasma-etched, the carbon particles will drop again. This is not enough because it starts, and the carbon support ring 9 is joined to the single crystal silicon electrode plate 8 by brazing 11. However, there is a problem that the brazing material protruding from this joining portion contaminates the wafer.

[0007]

Means for Solving the Problems Accordingly, the present inventors have
From this point of view, as a result of a study to prevent carbon particles from adhering to the surface of the plasma-etched wafer and further to prevent the wafer from being contaminated by the brazing material, as shown in FIG. Support ring portion 22
The single-crystal silicon electrode plate for plasma etching, which is composed of monocrystalline silicon integrated with each other, eliminates the conventional contamination of the wafer by the carbon particles generated from the carbon support ring and the contamination by the brazing material. The result of the study was that it was possible.

The present invention has been made based on the results of such research, and is characterized by an electrode plate made of single crystal silicon for plasma etching in which the electrode plate part and the support ring part are made of single crystal silicon. I have.

In the electrode plate made of single crystal silicon for plasma etching according to the present invention, the electrode plate portion and the support ring portion are formed by cutting, discharging, ultrasonic machining, laser machining or the like of the single crystal silicon ingot manufactured by the CZ method. It is manufactured by cutting into the shape of the electrode plate that it has and then forming through-pores by drilling, ultrasonic processing, or the like.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Diameter of straight body part: 250 mm, length:
A defect-free single crystal silicon ingot having a length of 400 mm and a total length of 700 mm is prepared, the ingot is sliced into a thickness of 28 mm with a diamond hand saw, and the sliced sliced single crystal silicon plate is cut and processed as shown in FIG. Outer diameter a of the collar portion of the support ring portion 22 as shown: 240 mm,
Inner diameter of collar b: 205 mm, thickness of collar c: 9 mm, electrode plate 2
A cap-shaped single crystal silicon plate with a collar having an outer diameter d of 224 mm, an electrode plate thickness e of 6 mm, and an overall height f of 26 mm was manufactured.

This cap-shaped single crystal silicon plate with a collar was subjected to electrical discharge machining to form pores having a diameter of 0.5 mm at intervals of 2.8 mm and 33.
The electrode plate of the present invention was prepared by opening 00 holes and further finishing by ultrasonic drilling to form the through pores 5 having a diameter of 0.8 mm.

For comparison, a single crystal silicon plate 8 having an outer diameter d: 224 mm and a thickness e: 6 mm as shown in FIG. Similar to the electrode plate of the present invention, a single crystal silicon plate 8 was prepared by opening 3300 pieces at 2.8 mm intervals, and further, the outer diameter a: 2 of the collar portion.
A carbon support ring 9 having dimensions of 40 mm, flange inner diameter b: 205 mm, flange thickness c: 9 mm, and support ring height g: 17 mm was prepared, and the carbon support ring 9 had a thickness of 0. After forming a 1 mm alumina film, the single crystal silicon plate 8 and the carbon support ring 9 were brazed to produce a conventional electrode plate.

The electrode plate of the present invention and the conventional electrode plate are set in a plasma etching apparatus, the chamber pressure: 10 ^-1 Torr, the gas flow rate ratio: 90 sccm CHF ³ +4 sccmO ² +150 sc
CmHe, RF power: 300 W, etching time:. 1.0 min, at conditions was subjected to SiO ₂ layer by CVD diameter: 15
Wafers of 2 mm in total: 5000 pieces were subjected to plasma etching, and the number of carbon particles (pieces / wafer) adhering to the surface of the 250th, 1000th, 2500th and 5000th wafers was measured, and the wax at that time was also measured. Whether or not the material was contaminated was observed, and the results are shown in Table 1.

[0014]

[Table 1]

From the results shown in Table 1, the electrode plate of the present invention can perform plasma etching up to 5000 sheets without contamination by carbon particles and brazing material.
It can be seen that the conventional electrode plate is contaminated with carbon particles when it is 1000 sheets, and further, the contamination is due to brazing material when it is 2500 sheets.

[0016]

As described above, since the electrode plate made of single crystal silicon for plasma etching in which the electrode plate portion and the support ring portion of the present invention are made of integral single crystal silicon, the service life is remarkably extended, Since the number of replacements can be reduced, production efficiency can be significantly improved, and since there is no carbon particle adhesion or contamination by brazing material, the occurrence of defective semiconductor integrated circuits due to plasma etching is greatly reduced. Therefore, it can greatly contribute to the development of the semiconductor device industry.

[Brief description of the drawings]

FIG. 1 is a sectional view of a single crystal silicon electrode plate for plasma etching according to the present invention.

FIG. 2 is a cross-sectional explanatory diagram of a plasma etching apparatus.

FIG. 3 is a cross-sectional view of a conventional electrode plate made of single crystal silicon for plasma etching.

[Explanation of symbols]

 1 Vacuum Container 2 Electrode Plate 3 Stand 4 Wafer 5 Through Hole 6 High Frequency Power Supply 7 Plasma Etching Gas 8 Single Crystal Silicon Plate 9 Carbon Support Ring 10 Brasma 11 Brazing 21 Electrode Plate Part 22 Support Ring Part

Claims (1)

[Claims] 1. An electrode plate made of single crystal silicon for plasma etching, characterized in that the electrode plate part and the support ring part are made of integral single crystal silicon.