JPH09321027A - Composite silicon electrode plate for plasma etching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly reduce generation of defects in semiconductor integrated circuits due to plasma etching by brazing a flanged single crystal Si-support ring to a single crystal Si-substrate having fine through-holes. SOLUTION: A flanged support ring 21 is composed of a single crystal Si, and it is brazed to a single crystal Si substrate 8 to form a composite Si electrode plate for plasma etching. This plate prevents a wafer from being contaminated by carbon grains produced from a flanged carbon support ring. Since contamination does not occur by deposited carbon, the defect of semiconductor integrated circuits due to plasma etching can be greatly reduced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composite 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. 3, 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.
A composite electrode plate 12 is used in which a single crystal silicon plate 8 having through holes 5 and a carbon support ring 9 with a collar are joined by brazing 11.

[0004]

However, the conventional single crystal silicon plate 8 and the carbon support ring 9 with a collar are used.
When the wafer is plasma-etched using the composite electrode plate 12 formed by brazing 11, the abnormal discharge occurs between the carbon support ring 9 with the collar having high conductivity and the wafer 4 when the glow discharge occurs, and the carbon particles are separated from each other. It has descended onto the wafer 4 through the through pores 5 of the crystalline silicon plate 8 to contaminate the wafer 4 and greatly reduce the yield of integrated circuits on the wafer.

Contamination is particularly serious when plasma-etching SiO ₂ or the like on the wafer surface. It is Si
Generally, when etching O ₂ , a plasma based on fluorine gas is used, but when the plasma based on fluorine gas is used for sputtering, it is generated from a carbon-made support ring with a collar scraped by sputtering. This is because the carbon particles cannot be volatilized, fall on the wafer as they are, and remain as particles.

In order to prevent the fall of these carbon particles, a film of ceramics or the like is formed on the surface of the carbon support ring with a collar. However, when a large number of wafers are plasma-etched, the carbon particles fall again. Is not enough because it starts.

[0007]

Means for Solving the Problems Accordingly, the present inventors have
From this point of view, as a result of research to prevent carbon particles from adhering to the plasma-etched wafer surface, (a) as shown in FIG. 1, the support ring with a collar is made of single crystal silicon, and Single crystal silicon plate 8
Brazing the single crystal silicon support ring 21 with a collar 11
The composite silicon electrode plate for plasma etching is
It is possible to eliminate the contamination of the wafer by the carbon particles generated from the conventional carbon support ring with a collar. (B) As shown in FIG. 2, the support ring with a collar is made of polycrystalline silicon, Single crystal silicon plate 8
And brazing polycrystalline silicon support ring 22 with collar 11
It has been found that the composite silicon electrode plate for plasma etching to be performed can also eliminate the contamination of the wafer with carbon particles.

The present invention has been made on the basis of the results of such research. (1) A composite silicon electrode plate for plasma etching, in which a single crystal silicon plate and a flanged single crystal silicon support ring are brazed, 2) It is characterized by a composite silicon electrode plate for plasma etching, in which a single crystal silicon plate and a polycrystalline silicon support ring with a collar are brazed.

The brazing of the single crystal silicon plate and the collared single crystal or polycrystal silicon support ring may be performed by using an ordinary brazing material, but especially a soft brazing material having a Brinell hardness of 1 to 50 is used for plasma etching. It is preferable because the composite silicon electrode plate is less likely to crack. The reason is
It is considered that the soft brazing material absorbs the difference in thermal expansion between the electrode plate and the collared support ring.

Therefore, the present invention provides (3) a composite silicon electrode plate for plasma etching, wherein a single crystal silicon plate and a flanged single crystal silicon support ring are brazed with a brazing material having a Brinell hardness of 1 to 50, ( 4) It is characterized by a composite silicon electrode plate for plasma etching in which a single crystal silicon plate and a polycrystalline silicon support ring with a collar are brazed with a brazing material having a Brinell hardness of 1 to 50.

The single crystal silicon plate 8 is manufactured by cutting and grinding a single crystal silicon ingot manufactured by the CZ method, and the single crystal silicon plate is drilled and ultrasonically processed. It is manufactured by forming through-pores by processing or the like. On the other hand, the collared single crystal silicon supporting ring 21 or the collared polycrystalline silicon supporting ring 22 is manufactured by grinding and electric discharge machining a single crystal silicon ingot or a polycrystalline silicon ingot, respectively. The composite silicon electrode plate for plasma etching of the present invention is manufactured by ordinary brazing the single crystal silicon plate 8 and the flanged single crystal silicon support ring 21 or the flanged polycrystalline silicon support ring 22.

[0012]

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 length of 700 mm is prepared, the ingot is sliced into a thickness of 7 mm with a diamond hand saw, and the sliced single crystal silicon plate is ground to have an outer diameter d. : 23
A single crystal silicon plate having a size of 0 mm and a plate thickness e: 6.4 mm was prepared, and 3300 pores having a diameter of 0.5 mm were opened at intervals of 2.8 mm by electric discharge machining. Further, finishing processing was performed by ultrasonic drilling to manufacture a single crystal silicon plate 8 in which the through pores 5 having a diameter of 0.8 mm were formed. Further, brazing materials having the compositions and Brinell hardness shown in Table 1 were prepared.

[0013]

[Table 1]

Example 1 A defect-free single crystal silicon ingot having a straight body diameter of 250 mm and a length of 400 mm and a total length of 700 mm was prepared, and this ingot was cut into 20 mm thick pieces with a diamond hand saw. By grinding a single crystal silicon plate that has been sliced into round pieces, as shown in FIG. 1, the outer diameter a of the flange is 240 mm, the inner diameter b is 203 mm, and the thickness c of the flange is 9 m.
m, the height g of the collared support ring g: A collared single crystal silicon support ring 21 having dimensions of 19 mm was prepared. The whole height f: by brazing the support ring 21 with the collar made of single crystal silicon with the previously prepared single crystal silicon plate 8 and any one of the brazing materials A to E shown in Table 1.
The composite silicon electrode plates of the present invention (hereinafter referred to as the electrode plate of the present invention) 1 to 5 having a size of 25.4 mm were produced.

The electrode plates 1 to 5 of the present invention are set in a plasma etching apparatus, the chamber pressure: 10 ^-1 Torr, 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
2mm wafers in total: 10,000 pieces Plasma-etched, the number of carbon particles adhering to the surface of the 250th, 1000th, 2500th, and 5000th wafers (pieces / wafer) was measured, and the results are displayed. Shown in 2.

[0016]

[Table 2]

Example 2 A polycrystalline silicon plate having a thickness of 20 mm was cut and processed, as shown in FIG.
Outer diameter a: 240 mm, inner diameter b: 20 as shown in
A polycrystalline silicon support ring 22 with a collar having dimensions of 3 mm, a collar thickness c: 9 mm, and a height g: 19 mm was produced. The supporting ring 22 with the collar and the single crystal silicon plate 8 prepared previously are brazed with any one of the brazing materials A to E shown in Table 1 to obtain the overall height f: 25.4 mm. The electrode plates 6 to 10 of the present invention were prepared. The electrode plates 6 to 10 of the present invention were set in a plasma etching apparatus, and under the same conditions as in Example 1, a total of 10000 wafers having a diameter of 152 mm and having a SiO ₂ layer formed by CVD were subjected to plasma etching. The number of carbon particles (particles / wafer) attached to the surface of the 1000th, 2500th and 5000th wafers was measured, and the results are shown in Table 3.

[0018]

[Table 3]

Conventional Example 1 For comparison, the outer diameter a of the collar portion is 240 mm and the inner diameter b of the collar portion is 2;
After preparing a carbon support ring 9 with a collar having dimensions of 03 mm, thickness c of the collar portion: 9 mm, and height g: 19 mm, after forming an alumina film having a thickness of 0.1 mm on the carbon support ring 9 with the collar portion. The single crystal silicon plate 8 produced in Example 1
The carbon support ring 9 with a collar was brazed with any of the brazing materials A to E shown in Table 1 to prepare conventional composite silicon electrode plates (hereinafter referred to as conventional electrode plates) 1 to 5.
The conventional electrode plates 1 to 5 were set in a plasma etching apparatus, and under the same conditions as in Example 1, a total of 10,000 wafers having a diameter of 152 mm and having a SiO ₂ layer formed by CVD were subjected to plasma etching. The number of carbon particles adhering to the surface of the 1000th, 2500th and 5000th wafers (particles / wafer) was measured, and the results are shown in Table 4.

[0020]

[Table 4]

From the results shown in Tables 2 to 4, the electrode plates 1 to 10 of the present invention can perform plasma etching up to 5000 sheets without contamination by carbon particles.
It can be seen that the conventional electrode plates 1 to 5 are contaminated by carbon particles when they are 1000 sheets.

[0022]

As described above, the composite silicon electrode plate for plasma etching of the present invention has a remarkably long service life and is free from contamination due to carbon particle adhesion. The generation can be greatly reduced, which can greatly contribute to the development of the semiconductor device industry.

[Brief description of drawings]

FIG. 1 is a sectional view of a composite silicon electrode plate for plasma etching of the present invention.

FIG. 2 is a sectional view of a composite silicon electrode plate for plasma etching according to the present invention.

FIG. 3 is a cross-sectional explanatory diagram of a plasma etching apparatus.

FIG. 4 is a cross-sectional view of a conventional composite silicon electrode plate for plasma etching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Electrode plate 3 Frame 4 Wafer 5 Through hole 6 High frequency power supply 7 Plasma etching gas 8 Single crystal silicon plate 9 Carbon support ring with flange 10 Brasma 11 Brazing 12 Composite electrode plate 20 Composite silicon electrode plate 21 Single with flange Crystal silicon support ring 22 Polycrystalline silicon support ring with collar

Claims (3)

[Claims] 1. A composite silicon electrode plate for plasma etching, comprising a single crystal silicon plate having through holes and a single crystal silicon support ring with a collar, which are brazed. 2. A composite silicon electrode plate for plasma etching, comprising a single crystal silicon plate having through holes and a polycrystalline silicon support ring with a collar, which are brazed. 3. The composite silicon electrode plate for plasma etching according to claim 1, wherein the brazing material used in the brazing is a brazing material having a Brinell hardness of 1 to 50.