JPH11278919A - Plasma-resistant member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma-resistant member scarcely wearing out even by exposure to a plasma in a halogen-based corrosive gas. SOLUTION: At least the surface exposed to a plasma in a halogen-based corrosive gas is formed of an alumina sintered compact having >=99.9% alumina content and containing Mg and Si as components other than the alumina in a weight ratio of the Mg to Si of >=1 MgO/SiO2 expressed in term of oxides and having <=10 μm average crystal grain diameter of the alumina in the sintered compact in an inner wall material of a reactional treating chamber, a wafer holding member 1 such as a susceptor or an electrostatic chuck and a plasma-resistant member such as a clamp member. The porosity of open pares present on the surface is <=0.3%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a susceptor for supporting an object to be processed such as a semiconductor wafer or an inner wall material of a reaction processing chamber exposed to plasma under a halogen-based corrosive gas in a film forming apparatus or an etching apparatus. The present invention relates to a wafer holding member such as an electrostatic chuck or a plasma-resistant member such as a clamp member for fixing the object to be processed on the wafer holding member.

[0002]

2. Description of the Related Art Conventionally, in a process of manufacturing a semiconductor device, a film forming device such as a CVD device or a PVD device for forming a thin film on a semiconductor wafer by converting a reaction gas into plasma, and an etching device for performing fine processing have been used. In addition, the reaction gas has the advantage that it can be processed at a relatively low temperature without requiring a high temperature.

[0005] For example, as shown in a schematic view of an etching apparatus in FIG. 5, a disk-shaped wafer holding member 21 for supporting a semiconductor wafer as a processing object 11 is installed in a bell-shaped reaction processing chamber 27. An upper electrode plate 9 and a lower electrode plate 10 for generating plasma are disposed above and below the reaction processing chamber 27 with the wafer holding member 21 interposed therebetween.
A ring-shaped clamp member 24 is installed on the wafer holding member 21 so as to be able to move up and down. When a semiconductor wafer is placed on the wafer holding member 21, the clamp member 24 is lowered, and It is designed to be fixed while holding down the periphery.

Then, HB, HCl, and Cl are supplied through a gas introduction pipe 28 integrally formed at the top of the reaction processing chamber 27.
_2. A halogen-based corrosive gas such as SF ₆ is introduced into the reaction chamber 27 as a reaction gas, and plasma is generated by applying high-frequency power between the upper electrode plate 9 and the lower electrode plate 10 to generate plasma. The etching is performed by turning gas into plasma and colliding halogen ions against the semiconductor wafer.

Since the plasma-resistant members such as the reaction processing chamber 27, the wafer holding member 21, and the clamp member 24 are also exposed to plasma under a halogen-based corrosive gas similarly to a semiconductor wafer, they are made of fluorine-based or chlorine-based. It has been proposed to improve the durability by forming an alumina sintered body having a plasma-resistant alumina content of about 99.5%, which is strong against plasma under a halogen-based corrosive gas.

[0006]

[SUMMARY OF THE INVENTION However, the alumina sintered body in which alumina content of about 99.5% is included in the large amount of sintering aid and the like, halogen, in particular SiO ₂ is fluorine Very easily reacts with system corrosive gas.
Since the reaction product was easily sublimated, abrasion could not be sufficiently suppressed. In addition, when a large amount of components other than alumina was contained, the components were easily worn by plasma. If these abrasion powders and the like adhere to the semiconductor wafer, they contaminate the wafer and cause wiring defects. Therefore, it is impossible to provide a high-quality semiconductor device, and the yield is poor. Was.

Therefore, it has been proposed to use a high-purity alumina sintered body whose alumina content has been increased to 99.9% as the plasma-resistant member (Japanese Patent Laid-Open No. 5-217).
946).

However, even if a high-purity alumina sintered body is used, it is not sufficient, and it has been required to further suppress abrasion.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides at least a halogen-based material among inner wall materials of a reaction processing chamber, a wafer holding member such as a susceptor and an electrostatic chuck, and a plasma-resistant member such as a clamp member. The surface exposed to the plasma under the corrosive gas has an alumina content of 99.9% by weight or more and contains Mg and Si as components other than the alumina, and the weight ratio of the Mg and Si is calculated as oxide. In M
It is formed of an alumina sintered body having gO / SiO ₂ ≧ 1 and having an average crystal grain size of alumina of 10 μm or less in the sintered body, and has an open porosity existing on the surface of 0.3% or less. It is characterized by having done.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is a perspective view showing an example in which the plasma-resistant member of the present invention is used for a wafer holding member 1. The disk-shaped member 2 has substantially the same diameter as an object to be processed, and has an alumina content of 99.9% by weight or more. And Mg and Si as components other than the above-mentioned alumina, and the weight ratio of the above-mentioned Mg and Si is M
It is formed of an alumina sintered body having gO / SiO ₂ ≧ 1 and having an average crystal particle diameter of alumina of 10 μm or less in the sintered body. In FIG. 1, the upper surface of the disc-shaped body 2 is a mounting surface 3 for the object to be processed, and the mounting surface 3 has a center line average roughness (Ra) of 1 μm or less, and is located on the mounting surface 3. The open porosity is 0.3% or less.

Although not shown, the disk-shaped body 2
An internal electrode can be buried inside.For example, if a resistance heating element is buried as an internal electrode, the object to be processed on the mounting surface can be directly heated, so that the heat uniformity of the object to be processed can be improved. If an electrode for electrostatic adsorption is buried as an internal electrode, an object to be processed can be accurately attracted and held on a mounting surface by electrostatic force, and an electrode for plasma generation can be embedded as an internal electrode. This eliminates the need for a lower electrode plate for generating plasma, so that the structure of the device can be simplified. In addition, two or more internal electrodes of the resistance heating element, the electrode for electrostatic attraction, and the electrode for plasma generation can be selectively embedded in the disc-shaped body, and three internal electrodes can be embedded therein. May be.

Next, FIG. 2 is a perspective view showing an example in which the plasma-resistant member of the present invention is used for the clamp member 4 and has an alumina content of 99.9% by weight or more, and Mg and Si as components other than the above-mentioned alumina. And the weight ratio of Mg to Si is MgO / SiO ₂ ≧ 1 in terms of oxide, and the average crystal particle diameter of alumina in the sintered body is 10%.
A ring-shaped body 5 made of an alumina sintered body having a diameter of not more than μm, and a step portion 6 having a diameter slightly larger than that of an object to be processed is provided on one main surface side of the ring-shaped body 5. The outer surface exposed to the plasma has a center line average roughness (R
a) is 1 μm or less, and the inner surface in contact with the object is 0.8 μm or less in center line average roughness (Ra).
The open porosity existing on the inner and outer surfaces is set to 0.3% or less.

FIG. 3 is a perspective view showing an example in which the plasma-resistant member of the present invention is used in the reaction processing chamber 7. The bell-shaped alumina content is 99.9% by weight or more, and components other than the above-mentioned alumina are used. Containing Mg and Si as
And the weight ratio of Si and Si is MgO / SiO ₂ ≧ 1 in terms of oxide, and the sintered body has an average crystal grain size of alumina of 10 μm or less. The thickness (Ra) is 1 μm or less, and the open porosity present on the inner wall surface is 0.3% or less. Note that a gas introduction pipe 8 for introducing a reaction gas is integrally formed at the top of the reaction processing chamber 7.

Next, FIG. 4 shows an etching apparatus using a plasma-resistant member such as the wafer holding member 1, the clamp member 4, and the reaction processing chamber 7.

In the etching apparatus shown in FIG. 4, a disk-shaped wafer holding member 1 shown in FIG. 1 for supporting an object to be processed 11 is installed in a bell-shaped reaction processing chamber 7 shown in FIG. An upper electrode plate 9 and a lower electrode plate 10 for generating plasma are arranged above and below the reaction processing chamber with the holding member 1 interposed therebetween. Further, a ring-shaped clamp member 4 shown in FIG. 2 is installed on the mounting surface 3 of the wafer support member 1 so as to be able to move up and down, and after the workpiece 11 is mounted on the wafer holding member 1. The clamp member 4 is lowered and fixed while suppressing the peripheral edge of the processing target 11.

[0016] Then, HB from the gas introduction pipe 8 which is integrally formed on top of the reaction chamber 7, HCl, Cl _2,
The reaction gas is introduced by introducing a halogen-based corrosive gas such as SF ₆ into the reaction processing chamber 7 as a reaction gas, and applying high frequency power between the upper electrode plate 9 and the lower electrode plate 10 to generate plasma. Plasma is generated, and etching is performed by colliding halogen ions with the workpiece 11.

In this etching apparatus, the surfaces of the plasma-resistant members such as the wafer holding member 1, the clamp member 4, and the reaction processing chamber 7, which are exposed to the plasma under the halogen-based corrosive gas, have an alumina content of 99%. 0.9 wt% or more, containing Si and Mg as components other than the alumina,
The weight ratio of Mg to Si is MgO / SiO in terms of oxide.
_{2 Since} it is made of a high-purity alumina sintered body with ≧ 1, there is almost no SiO ₂ which reacts easily with the halogen-based edible gas, especially SiO ₂ which strongly reacts with the fluorine-based gas. Since a large amount of Mg for forming an Mg spinel having excellent corrosion resistance to corrosive gas is contained, corrosive wear can be suppressed.

Further, since the average crystal grain diameter of alumina in the alumina sintered body is set to 10 μm or less, the sintered body can be further densified and the number of pores easily affected by plasma can be reduced.

When the open porosity existing on the surface exposed to the plasma under the halogen-based corrosive gas is larger than 0.3%, the plasma energy is concentrated on the edges of the pores, and the pores are easily worn. The open porosity is preferably 0.3% or less.

Incidentally, in order to obtain such an alumina sintered body, MgO and SiO 2 as auxiliary components are added to alumina powder having a purity of 99.9% or more and an average particle diameter of 0.8 μ or less as necessary. While adding and mixing ₂ , a solvent and a binder are added. After sintering, it is necessary to mix MgO and SiO _{2 so} that MgO / SiO ₂ ≧ 1 in terms of oxide.

[0021] These materials are kneaded to produce a slurry, which is molded into a predetermined shape by a tape molding method such as a casting method or a doctor blade method, or by drying the above-mentioned slurry to form a granulated material. The granules are filled in a mold and molded into a predetermined shape by a uniaxial pressure molding method, an equal pressure molding method, or the like. In addition, the part which cannot be formed at the time of molding may be subjected to cutting after molding.

Then, after the obtained molded body is fired in the air, an oxidizing atmosphere, or a vacuum atmosphere, a hot isostatic pressing (HIP) is performed for densification. It is important that the temperature be 1500-1650 ° C. That is, since high-purity alumina is difficult to be sintered, it is usually 1670 to 175 when it is densified.
It is fired in a temperature range of 0 ° C. However, even if the material fired at a temperature higher than 1650 ° C. is further densified by HIP treatment, the densification does not proceed, so that it is present on the surface of the alumina sintered body. The porosity of the resulting alumina sintered body cannot be reduced to 0.3% or less, and if fired at a temperature of less than 1500 ° C., the sinterability is poor, and the alumina sintered body obtained cannot be densified even when subjected to HIP treatment. .

The alumina sintered body thus obtained has an alumina content of 99.9% by weight or more and contains Mg and Si as components other than alumina, and the weight ratio of Mg to Si is MgO / oxide in terms of oxide. SiO ₂ ≧ 1 and
The average crystal grain size of alumina in the sintered body is 10 μm
Or less, and an alumina sintered body having an open porosity present on the surface of 0.3% or less can be obtained.

(Embodiment) A clamp member shown in FIG. 2 as a plasma-resistant member made of an alumina sintered body in which the alumina content, the average crystal grain diameter of alumina in the sintered body, and the open porosity present on the surface are different from each other. 4 was manufactured, and an experiment was performed to measure the degree of wear when exposed to plasma under a fluorine-based gas.

The etching conditions are as follows. With the degree of vacuum in the reaction processing chamber set to 1 torr, CF ₄ gas is introduced as a reaction gas, and high-frequency power of 100 W is applied between the upper electrode plate and the lower electrode plate to generate plasma. The generated clamp member was etched.

The inner and outer surfaces of the clamp member 4 each have a center line average roughness (Ra) of 1 μm.

The amount of wear was determined as follows: the reference sample had an alumina content of 99.5%, the average crystal grain size of alumina in the sintered body was 38 μm, and the open porosity existing on the surface was 3.5.
%, The wear amount of the clamp member made of the alumina sintered body was set to 100, and the value was calculated as a relative value to the reference sample.

The respective results are as shown in Table 1.

[0029]

[Table 1]

As a result, first, the alumina content is high,
It can be seen that the smaller the average crystal particle diameter of alumina and the smaller the open porosity, the smaller the amount of wear. And
It can be seen that when the alumina content is 99.9%, the average crystal particle diameter of alumina is 10 μm or less, and the open porosity is 0.3% or less, the wear amount can be reduced to 30 or less.

(Example 2) Therefore, the sample No. 9
An experiment was carried out to measure the amount of wear when the amounts of Mg and Si in the alumina sintered body were changed under the same conditions as in Example 1.

The results are shown in Table 2.

[0033]

[Table 2]

As a result, MgO / SiO _{2 in} terms of oxide
If ≧ 1, it can be seen that the wear amount can be further reduced to 25 or less. In particular, when MgO / SiO ₂ > 1, the abrasion amount could be reduced to less than 20, and the plasma resistance was excellent.

[0035]

As described above, according to the present invention, at least the halogen-based corrosive gas among the inner wall material of the reaction processing chamber, the wafer holding member such as a susceptor and an electrostatic chuck, and the plasma-resistant member such as a clamp member. The surface exposed to the plasma underneath has an alumina content of 99.9% or more and contains Mg and Si as components other than the alumina,
Is formed of an alumina sintered body having a weight ratio of MgO / SiO ₂ ≧ 1 in terms of oxide in terms of oxide, and having an average crystal particle diameter of alumina of 10 μm or less in the sintered body, and is present on the surface. Since the open porosity is 0.3% or less, it has excellent corrosion resistance to a halogen-based corrosive gas, and is hardly worn by plasma, so that it can be used for a long time.
In addition, when the object to be processed is a semiconductor wafer due to low abrasion, it is unlikely to contaminate the wafer or cause a wiring failure, so that a high-quality semiconductor device can be provided and the yield can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example in which a plasma-resistant member of the present invention is used as a wafer holding member.

FIG. 2A is a perspective view showing an example in which the plasma-resistant member of the present invention is used as a clamp member, and FIG. 2B is a cross-sectional view taken along line XX of FIG.

FIG. 3 is a perspective view showing an example in which the plasma-resistant member of the present invention is used as a reaction processing chamber.

FIG. 4 is a schematic view showing an etching apparatus using the plasma-resistant member shown in FIGS. 1 to 3;

FIG. 5 is a schematic view showing an example of a conventional etching apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer holding member 2 ... Disc-shaped body 3 ...
Mounting surface 4 ・ ・ ・ Clamp member 5 ・ ・ ・ Ring-shaped body 6 ・ ・ ・
Step portion 7: Reaction processing chamber 8: Gas introduction tube 9: Upper electrode plate 10: Lower electrode film 11: Workpiece

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumio Matsunaga 1-1, Yamashita-cho, Kokubu-shi, Kagoshima Inside the Kyocera Corporation Kagoshima Kokubu Plant

Claims (1)

[Claims] A surface exposed to plasma at least under a halogen-based corrosive gas has an alumina content of 99.9% by weight.
As described above, Mg and Si are contained as components other than the above-mentioned alumina, and the weight ratio of the above-mentioned Mg and Si is Mg in terms of oxide.
It is made of an alumina sintered body in which O / SiO ₂ ≧ 1 and the average crystal grain diameter of alumina in the sintered body is 10 μm or less, and the open porosity present on the surface is 0.3
% Or less.