JPH10265976A - Production of plasma etching electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of particles and to prevent the defect at the time of processing of a silicon wafer by plasma etching by forming the gas blow-off holes of a plasma etching electrode, then further removing the inside surfaces of these holes to a prescribed extent or above by chemical etching. SOLUTION: A silicon single crystal is preferably used for the plasma etching electrode material. The formation of the gas blow-off holes may be executed by ultrasonic machining, etc. The diameter of the holes is preferably specified to 0.5 to 1.5 mm and the number of the holes to 300 to 1800 pieces. The inside surfaces of the gas blow-off holes are required to be removed further by >=4 μm by chemical etching. If the amt. of the etching is below 4 μm, the perfect removal of small chipping and the chips penetrating into flaws is not possible. The chemical etching is executed by immersing the plasma etching electrode into a strongly acidic etching liquid, etc., such as mixed acids composed of hydrofluoric acid and nitric acid, having pH around 0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plasma etching electrode used in a parallel plate type plasma etching apparatus used for processing a semiconductor wafer.

[0002]

2. Description of the Related Art In a plasma etching apparatus in which a plasma etching electrode is provided in a reaction chamber and a high-frequency discharge is used, fine particles (foreign matter) generated from the plasma etching electrode itself exposed to plasma during discharge.
Is required to be reduced as much as possible.

Conventionally, particles generated from a plasma etching electrode have been controlled for particles having a size of 0.3 μm or more. However, with the recent high integration of semiconductor integrated circuits,
It is expected that particles smaller than 0.3 μm will also be managed. Under these circumstances, at present, amorphous carbon is used as a material for plasma etching from
The mainstream has shifted to a silicon single crystal as disclosed in Japanese Patent No. 73936.

A plasma etching electrode made of silicon single crystal (hereinafter referred to as a silicon plasma etching electrode) is also provided with a gas blowing hole for discharging a plasma etching gas for plasma etching a material to be processed in a shower shape. . By using this silicon plasma etching electrode, the number of generated particles was reduced as compared with the plasma etching electrode made of amorphous carbon, but it did not mean that it did not disappear yet and did not affect the quality of the semiconductor integrated circuit, The production yield has not been significantly improved. In order not to affect the quality of the semiconductor integrated circuit, the number of particles of 0.3 μm or more adhering on a 6-inch wafer during one plasma etching is set to 10 or less.

[0005] As a cause of the generation of particles from the silicon plasma etching electrode, a large number of chips and scratches are generated on the inner surface of the gas blowing hole of the silicon plasma etching electrode due to the impact during the processing of the gas blowing hole. At the same time, fine cutting powder enters the chipping or flaw and digs in firmly due to the pressure of the gas blowing hole cutting process. When plasma etching of a silicon wafer is performed, the inside of the gas blowout hole is also consumed by the plasma that has entered the gas blowout hole, but the cutting powder that has been chipped or damaged at that time drops off and adheres to the wafer to become particles. . Ultrasonic cleaning and RCA cleaning were performed in order to remove the cutting powder, but it was impossible to completely remove it by any of the methods because it was mechanically firmly penetrated.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a plasma etching electrode for suppressing the generation of particles and preventing a plasma etching defect at the time of plasma etching a silicon wafer.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a plasma etching electrode having a gas blowing hole used in a parallel plate type plasma etching apparatus.
The present invention relates to a method for manufacturing a plasma etching electrode, wherein after forming a gas blowing hole, the inner surface of the gas blowing hole is further removed by 4 μm or more by chemical etching.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is preferable to use a silicon single crystal as a plasma etching electrode material. As the silicon single crystal, a silicon single crystal produced by a CZ method or an FZ method can be used. The plane orientation of the silicon single crystal is (100), the conductivity type is P type, and the resistivity is 0.1 to 0.1.
It is preferable to use one of 30 Ω-cm. There is no particular limitation on the method of forming the gas blowing holes, but it is preferable to form them by ultrasonic processing or drill cutting. There is no particular limitation on the diameter and the number of the gas blowing holes, for example, the diameter is preferably 0.5 to 1.5 mm,
0.8 to 1.0 mm is more preferable. The number is 300-1
800 pieces are preferable, and 500 to 1000 pieces are more preferable.

According to the present invention, the inner surface of the gas blowing hole is further etched by 4 μm or more, preferably 10 μm by chemical etching.
μm or more, more preferably 20 to 40 μm is required to be removed. If the etching amount is less than 4 μm, it is not possible to completely remove the cutting powder that has firmly bitten into small chips and scratches. Cannot be achieved. The etching amount can be calculated, for example, by measuring the diameter of the gas blowing hole before and after etching with a tool microscope. As a chemical solution used for chemical etching, it is preferable to use a strong acid etching solution having a pH of about 0, such as a mixed acid of hydrofluoric acid and nitric acid, or a strong alkaline etching solution having a pH of 14, such as caustic soda and potassium hydroxide. The target etching amount can be appropriately selected depending on the etching solution, etching time, and the like. The etching method is not particularly limited. For example, a method in which a plasma etching electrode is immersed in an etching solution to perform etching is preferable.

A silicon plasma etching electrode is cut out of a silicon single crystal ingot into a predetermined shape, for example, a shape having a diameter of 203 mm, 208 mm, etc. and a thickness of 3 mm, 5 mm, etc., using a diamond cutting machine or the like. Is formed by forming a gas blowout hole having a size in the range shown in FIG. 1, removing the inner surface of the gas blowout hole by 4 μm or more by chemical etching, and polishing and cleaning both end surfaces as a final finish. Polishing and cleaning are not particularly limited as long as scratches (fine processing scratches), dirt and foreign matter do not adhere to both end surfaces.

[0011]

【Example】

Example 1 Using a diamond cutting machine or the like from a silicon single crystal ingot having a plane orientation of (100), a conductivity type of P type, and a resistivity of 0.7 Ω-cm manufactured by the CZ method, a diameter of 203 mm and a thickness of A 3 mm disk was made. Then, with a diamond-coated drill, 1000 gas ejection holes having a diameter of 0.8 mm are formed at equal intervals of 3 mm at a rotation speed of 5,000 min ^-1 and a feed rate of 20 mm / min to form a silicon plasma etching electrode A. Obtained.

Next, the silicon plasma etching electrode A obtained above is immersed in an etching solution (liquid temperature: 20 ° C.) containing 18% by weight of hydrofluoric acid, 24% by weight of nitric acid and 58% by weight of water for 5 minutes to perform chemical etching. After that, both ends of the silicon plasma etching electrode A were polished and subjected to ultrasonic cleaning with pure water to obtain a silicon plasma etching electrode B. The etching amount of the obtained silicon plasma etching electrode B was 4 μm. In addition, the etching amount was calculated by measuring the diameter of the gas blowing hole before and after etching with a tool microscope. same as below.

Example 2 The silicon plasma etching electrode A obtained in Example 1 was immersed in an etching solution (liquid temperature 20 ° C.) used in Example 1 for 25 minutes.
For 1 minute to perform chemical etching.
Through the same steps as described above, a silicon plasma etching electrode C was obtained. The etching amount of the obtained silicon plasma etching electrode C was 20 μm.

Example 3 The silicon plasma etching electrode A obtained in Example 1 was immersed in an etching solution (liquid temperature 90 ° C.) containing 50% by weight of caustic soda and 50% by weight of water for 3 minutes to perform chemical etching. Thereafter, a silicon plasma etching electrode D was obtained through the same steps as in Example 1. The etching amount of the obtained silicon plasma etching electrode D was 6 μm.

Example 4 The silicon plasma etching electrode A obtained in Example 1 was placed in an etching solution (liquid temperature 90 ° C.) used in Example 3 for 21 days.
For 1 minute to perform chemical etching.
Through the same steps as described above, a silicon plasma-etched electrode E was obtained. The etching amount of the obtained silicon plasma etching electrode E was 42 μm.

Comparative Example 1 The silicon plasma etching electrode A obtained in Example 1 was used as Comparative Example 1 (without chemical etching).

Comparative Example 2 The silicon plasma etching electrode A obtained in Example 1 was placed in the etching solution (liquid temperature 90 ° C.) used in Example 3 for 1.
Chemical etching was performed by immersion for 5 minutes, and a silicon plasma etching electrode F was obtained through the same steps as in Example 1 below. The etching amount of the obtained silicon plasma etching electrode F was 3 μm.

Next, each silicon plasma etching electrode obtained above was set in a plasma etching apparatus, and a reaction gas: trifluoromethane (CHF ₃ ) 40 cc / min, tetrafluorocarbon (CF ₄ ) 60 cc / min, argon (A)
r) 300 cc / min, gas pressure in the reaction chamber: 0.
5 Torr, power frequency: 400 KHz and applied power: 600
Under the condition of W, plasma etching of a silicon oxide film of a 6-inch diameter wafer was performed. After the plasma etching, the number of particles of 0.3 μm or more adhering on the silicon wafer was counted by a wafer foreign matter inspection device (LS-5000 manufactured by Hitachi Tokyo Electron Ltd.). Table 1 shows the results.

[0019]

[Table 1]

As shown in Table 1, the silicon plasma etching electrode obtained by the method of the present invention has a small number of particles of 9 or less.

[0021]

The plasma etching electrode obtained by the method according to the present invention can greatly suppress the generation of particles, and is industrially very suitable.

Claims (1)

[Claims] In a method of manufacturing a plasma etching electrode having a gas outlet used in a parallel plate type plasma etching apparatus, after forming the gas outlet, an inner surface of the gas outlet is further removed by 4 μm or more by chemical etching. A method for producing a plasma etching electrode, comprising: