JP2000252260A - Plasma process equipment member and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve yield in manufacturing a semiconductor and to manufacture a semiconductor element of high quality by, in a high-density plasma wherein problem of occurrence of impurity contamination or particles exists and, preventing contamination or particles from occurring and providing a plasma- corrosion-resistance of longer period than a conventional material. SOLUTION: A high-purity SiO2 powder with purity 99.9% or above, content of hydroxyl group 5 ppm or below, and average particle size 5 μm or below is added with an organic binder to form a mold, which is oxidized in an oxidizing atmosphere at 600-900 deg.C, then sintered in vacuum or non-oxidizing atmosphere at 1300-1600 deg.C. Thus an SiO2 sintered body with content of hydroxyl group 5 ppm or below, 2.15 g/cm3 density or above, and 200 ppm carbon content or below is provided, which is used as a plasma process equipment member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a member for a semiconductor manufacturing apparatus, and more particularly to a member for a plasma processing apparatus such as a focus ring, a clamp ring, a bell jar, and a dome in a plasma process, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the use of plasma, such as a dry process and plasma coating, used for forming highly integrated circuits such as semiconductor elements and liquid crystals has been rapidly progressing. As a plasma process in a semiconductor, a halogen-based corrosive gas such as a fluorine-based gas is used for vapor phase growth, etching and cleaning due to its high reactivity.

[0003] The members which come into contact with these corrosive gases are required to have high corrosion resistance and contain as little impurities as possible which contaminate non-processed materials or cause particles. In the past, members other than the object to be treated that come into contact with the plasma generally use metals such as stainless steel and Monel in addition to materials mainly containing SiO ₂ such as glass and quartz.

In the manufacture of semiconductors, as a susceptor material for supporting and fixing a wafer, a sintered body of alumina, sapphire, or a sintered body of AlN, or a surface-coated body thereof by a CVD method or the like has been used as having excellent corrosion resistance. I have. Further, a heater coated with graphite or boron nitride is also used.

On the other hand, the use of high-density plasma has been advanced in order to increase the degree of integration of semiconductor elements. In particular, in the process of processing an insulating film, these members are required to have higher purity and non-particles.

[0006]

The sintered body and coating material of alumina and AlN have excellent corrosion resistance to fluorine-based gas, but when they come into contact with plasma at high temperature, the corrosion gradually progresses and the surface of the sintered body is coated. There is a problem that crystal grains are dislodged from the particles, and a reaction product with plasma precipitates and separates, causing particles to be generated.

[0007] The generation of such particles is caused by ion bombardment or breakage of metal wiring due to extremely fine particles produced by reaction in the gas phase due to higher integration of semiconductors and further cleanliness of the process. In addition, there is a possibility that problems such as deterioration of element characteristics and yield may occur.

In comparison with these materials, conventionally used silicon compound materials such as quartz glass are
Although corrosion resistance in plasma is insufficient, contamination and particles are hardly generated, so that it is attracting attention as a structural material for semiconductor manufacturing equipment. In particular, quartz materials are relatively easy to reduce impurities that cause defects, and materials having various characteristics are widely used depending on applications.

In particular, SiO ₂ -based materials as heat-resistant structural materials have long been used in a wide range of applications as materials having both heat resistance and high purity. In particular, the following inventions have been proposed for the core tube and bell jar in order to prevent deformation at high temperature and increase mechanical strength. Patent No. 167868
In Japanese Patent Application Laid-Open No. 1-126238, a mixed molded product of crystalline quartz powder and amorphous quartz powder can be sintered without vitrification to obtain a crystalline quartz sintered body. A method is described in which a nucleating agent is applied to the surface of a glass member, heat-treated, and the surface is coated with cristobalite crystals.

[0010] However, the above-mentioned conventional quartz glass material has a problem that corrosion resistance to plasma is reduced.
On the other hand, cristobalite formation progresses in these quartz glass materials, cristobalite crystals are randomly generated in the amorphous phase, and cracks are generated due to the difference in thermal expansion from the amorphous phase, resulting in fluorine or chlorine. And the like, there is a problem that the etching proceeds rapidly from this crack as a starting point.

[0011]

Means for Solving the Problems The present inventors have studied the improvement of the corrosion resistance of a SiO ₂ -based material used in a semiconductor plasma process to fluorine-based and chlorine-based corrosive gases, plasma and oxygen plasma. . As a result, the corrosion resistance to plasma is improved by reducing the number of hydroxyl groups, and the generation of disordered cristobalite crystals can be suppressed by reducing the amount of carbon in the material. Was found to be improved.

A material having such characteristics can be obtained by molding a high-purity fine-particle raw material having a small number of hydroxyl groups, and then forming the raw material in air at 600 to 90%.
After oxidizing at 0 ° C. and firing at 1300 to 1600 ° C. in a vacuum or a non-oxidizing atmosphere without melting, a dense SiO ₂ sintered body having excellent plasma corrosion resistance was found to be obtained.

That is, the member for a plasma processing apparatus of the present invention has a density of 2.15 having a hydroxyl group content of 5 ppm or less.
consists g / cm ³ or more SiO ₂ sintered body, the carbon content is characterized by comprising the following SiO ₂ sintered body 200 ppm. Further, such a sintered body is desirably substantially composed of only an amorphous phase.

Further, as a method for producing the above-mentioned member, a molded product obtained by adding an organic binder to SiO ₂ powder having a purity of 99.9% or more, a hydroxyl group content of 5 ppm or less, and an average particle size of 5 μm or less is formed by oxidizing. 600-900 in atmosphere
After oxidizing at 1300C, firing at 1300 to 1600C in a vacuum or non-oxidizing atmosphere provides
An iO ₂ -based sintered body is obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A member for a plasma processing apparatus according to the present invention includes a halogen-based corrosive gas or plasma such as a fluorine-based or chlorine-based gas used in a semiconductor plasma process.
The member is exposed to O ₂ and Ar plasma, and the fluorine-based gas includes SF ₆ , CF ₄ , CHF ₃ , ClF ₃ , H
F, etc., and chlorine-based gases such as Cl ₂ , BCl ₃ ,
HCl and the like. When a microwave, a high frequency, or the like is introduced into an atmosphere in which these gases are introduced, these gases are turned into plasma.

In the present invention, at least a portion of the surface exposed to such a halogen-based corrosive gas or its plasma, O ₂ , or Ar plasma is formed of a SiO ₂ sintered body.

According to the present invention, the corrosion resistance to plasma can be improved by setting the content of the hydroxyl group contained in the sintered body to 5 ppm or less, particularly 1 ppm or less. Therefore, when the hydroxyl group content exceeds 5 ppm,
Corrosion resistance to plasma is sharply reduced. In addition, 1p
Up to pm, although the corrosion resistance to plasma gradually increases, no significant difference is seen in the etching rate even if the hydroxyl group is reduced to less than 1 ppm.

Incidentally, the content (X) of the hydroxyl group is calculated at a wavelength of 2.
The transmittance of infrared rays of 60 μm and 2.73 μm was measured, and based on the Lambert-Beer equation,
Can be calculated by

[0019]

(Equation 1)

The hydroxyl group content referred to in the present invention is the OH group concentration in a solid calculated from the above measurement, and indicates the average concentration of OH groups distributed throughout the bulk.

Further, according to the present invention, it is important to reduce the occurrence of fine cracks due to cristobalite crystals randomly generated in the sintered body. This is because, in the case of ordinary quartz glass members, when plasma, particularly highly corrosive halogen-based plasma comes into contact with the surface, radicals having high reactivity are concentrated on such fine defects, so that etching starting from this is started. And the corrosion resistance deteriorates.

According to the present invention, the occurrence of such fine cracks is reduced by reducing the amount of carbon contained in the sintered body to 200 pp.
By controlling the concentration to not more than m, particularly not more than 100 ppm, and more preferably not more than 80 ppm, crystallization to cristobalite can be suppressed. This carbon amount is 200p
If it is more than pm, the amount of fine cracks due to the formation of cristobalite crystals increases, and the corrosion resistance decreases.

Further, according to the present invention, the density of the SiO ₂ sintered body is not less than 2.15 g / cm ³ , especially 2.20 g / c 3.
It is also important that it is at least m ³ . This means that the density is 2.
If it is lower than 15 g / cm ^3, the corrosion resistance is reduced due to corrosion originating from the existing void due to insufficient densification.

As a method for producing the above-mentioned SiO ₂ sintered body, high-purity SiO ₂ powder having a hydroxyl group content of 5 ppm or less and an average particle size of 5 μm or less is used. Such SiO ₂
Powders are not obtained naturally, but are almost industrially synthesized. Since it is difficult to remove the hydroxyl groups in the raw material by a post-synthesis treatment, it is necessary to minimize the amount of hydroxyl groups in the raw material in order to obtain a sintered body having a low hydroxyl group content.

In order to reduce the hydroxyl group content, for example, a method of reacting an oxidizable silicon compound with oxygen gas by laser heating (Japanese Patent Publication No. 53-2443) or a method of performing heat treatment in a hydrogen atmosphere (Japanese Patent Laid-Open No. No. 254859).

If the average particle size of the SiO ₂ powder is larger than 5 μm, it is necessary to raise the firing temperature required for densification to near the melting point. In this case, the powder melts and the whole becomes vitrified. Therefore, the sintered body of the present invention cannot be obtained. If a raw material having an average particle size of 1 μm or less is used as the SiO ₂ powder, a dense sintered body can be produced without melting at a temperature lower than the melting point by 100 ° C. or more.

Examples of the synthesis of SiO ₂ raw material powder, that although it may be any method as long as obtain a SiO ₂ powder having a characteristic as described above as a result, a less fine powder having a hydroxyl group content From the point of view, Si
Desirable are a high-temperature hydrolysis method of Cl ₄ , a plasma method in which oxygen or a mixture of oxygen and Ar is reacted in a plasma, a method of burning high-purity metal Si powder in an oxidizing gas stream, and a sol-gel method using silicate alkoxide as a raw material.

Next, the powder is molded into a predetermined shape. As the molding method, an appropriate molding method may be selected according to the shape of the target member. Further, an organic binder may be added as needed. Specifically, any of dry molding methods such as mold press molding and isotropic isostatic press molding, and wet molding methods such as cast molding, extrusion molding and injection molding can be used. In the case of performing crushing, pulverization, and the like in a wet manner, the solvent is not particularly limited, but, for example, the use of water does not affect the hydroxyl group content of the sintered body at all.

The SiO ₂ compact thus formed is placed in an oxidizing atmosphere such as the air at 600 to 900
° C, preferably 650-850 ° C, more preferably 70 ° C.
At a temperature of 0 to 800 ° C., residual carbon generated by thermal decomposition of the organic binder is oxidatively removed to a level of 200 ppm or less. If the temperature at this time is lower than 600 ° C., the residual carbon is insufficiently oxidized and removed, and the amount of carbon is reduced to 2%.
It cannot be reduced to less than 00 ppm. On the other hand, when the temperature exceeds 800 ° C., the content of the hydroxyl group exceeds 5 ppm.

Then, the compact having the reduced amount of carbon as described above is placed in a vacuum or in a non-oxidizing atmosphere at 1300-1000.
1600 ° C., more preferably by firing at a temperature of 1350 to 1450 ° C., density 2.15 g / cm ³ or more, in particular to produce 2.20 g / cm ³ or more sintered body.

In order to reduce the hydroxyl group content in the sintered body,
It is effective to bake in a vacuum of 0.2 torr or less, but a hydroxyl group content of 5 ppm or less can be achieved even in a non-oxidizing atmosphere such as a mixed gas of Ar, N ₂ , H ₂ and Ar.

On the other hand, when firing is performed in an oxidizing atmosphere such as air, the content of hydroxyl groups in the sintered body exceeds 5 ppm, and it is impossible to produce a target SiO ₂ -based sintered body. It is.

If the sintering temperature is lower than 1300 ° C., the desired sinterability is deteriorated, and the desired SiO ₂ sintered body cannot be obtained. On the other hand, if the temperature is higher than 1600 ° C., the material is melted and vitrified as a whole, and the shape cannot be maintained. Therefore, the firing temperature is set to 1
By limiting the temperature range to 300 to 1600 ° C,
A dense SiO ₂ sintered body can be obtained.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. Synthetic Si with different hydroxyl content, average particle size and purity
A sintered body was prepared using the O ₂ powder raw material, and the physical properties were evaluated.

First, the raw material was wet-crushed with a ball mill using ultrapure water as a solvent, and paraffin wax was added as an organic binder to prepare a slurry. High-purity SiO ₂ balls were used as media.
The raw material powder obtained by granulating this slurry by spray drying is molded with a mold press under a load of 0.8 ton / cm ² ,
This molded body was degreased in the air for 5 hours under the conditions shown in Table 1.

The degreased body thus produced was baked in a vacuum at a degree of vacuum of 0.1 torr and a temperature range of 1400 to 1580 ° C., and various characteristics of the obtained SiO ₂ sintered body were measured. Further, these degreased bodies were baked at 1400 ° C. in an H ₂ + Ar atmosphere or in the air, and the same measurement was performed on the obtained sintered bodies.

The characteristics were evaluated for the following items.
The sintered body density was determined by measuring the bulk density by the Archimedes method.
The hydroxyl group content in the sintered body was in accordance with the above equation (1).

The crystal phase of the sintered body was measured by X-ray diffraction and judged based on the intensity ratio between the amorphous phase and the cristobalite crystal phase. The crystal phase on the outermost surface of the sintered body was measured by a thin-film X-ray diffraction method applied to the surface of the sintered body, and the center of the sintered body was cut out and ground for the inside of the sintered body, and measured by a powder X-ray method. . Further, the fracture surface of the sintered body was observed with a scanning electron microscope to determine the average particle size.

Regarding the plasma resistance of the sintered body, a sintered body having a diameter of 220 mm was prepared and used as a sample, and CF ₄ + O ₂
At room temperature to examine the etching rate and the presence or absence of particles. Etching conditions are pressure 10
Pa, RF output was 1 kW, and plasma irradiation time was 3 hours. The etching rate is calculated from the weight change before and after the test,
For particles, after etching, an 8-inch Si wafer was placed on the plasma-irradiated surface of the sample, and the unevenness of the contact surface of the wafer was detected by laser scattering, and the number of particles of 0.3 μm or more was measured by a particle counter. . Table 1 shows the results.

[0040]

[Table 1]

According to the results shown in Table 1, of the samples Nos. 1 to 16 produced by vacuum firing, the sample No. In No. 6, the raw material had a hydroxyl group content of 50 ppm, and as a result of the presence of hydroxyl groups exceeding 5 ppm in the sintered body, the corrosion resistance to plasma was lowered.

Sample No. 7 is an oxidation treatment temperature of 600 ° C.
Therefore, the oxidative decomposition of the residual carbon component is insufficient, and the C content after firing is as large as 0.08% by weight. Therefore, many cristobalite crystals having carbon as a nucleus were generated in the sintered body, and microcracks occurred due to a difference in thermal expansion from the amorphous phase. For this reason, although the hydroxyl group content is low, the corrosion resistance is relatively low.

Sample No. 12 is an oxidation treatment temperature of 900
℃, the hydroxyl content in the sintered body is 20ppm
, The corrosion resistance decreased.

Sample No. Nos. 17 to 22 were fired at 1400 ° C. in an H ₂ + Ar gas stream. Sample No. Sample No. 22 had a raw material hydroxyl group content exceeding 20 ppm, and the presence of a hydroxyl group exceeding 5 ppm in the sintered body resulted in a decrease in corrosion resistance to plasma.

Sample No. 23. Baking at a temperature of 1400 ° C. in the atmosphere. In this case, although the hydroxyl group content in the raw material was low, hydroxyl groups exceeding 200 ppm were detected in the sintered body. As a result, the etching rate increased.

The sample Nos. 1-5, 8-1
1, 13 to 15 and 17 to 21 each have a density of 2.15.
g / cm ³ or more, a dense SiO ₂ sintered body having a hydroxyl group content of 5 ppm or less and a carbon content of 200 ppm or less.
Since the content is not more than ppm, disordered cristobalite formation with carbon as a nucleus in the sintered body is suppressed, and as a result, a structure accompanied by fine cracks can be eliminated. As a result, the corrosion resistance to plasma is greatly improved as compared with the conventional quartz glass material.

[0047]

As described above in detail, according to the present invention, by using a predetermined sintered body of SiO ₂ as a member for a semiconductor manufacturing apparatus, particularly a member for a plasma processing apparatus in a plasma process, contamination of impurities is particularly achieved. It does not generate contamination or particles in high-density plasma where the generation of particles and particles is a problem, and has a longer plasma corrosion resistance than conventional materials, thus improving the yield of semiconductor manufacturing and producing high-quality semiconductor devices. be able to.

Continued on the front page (72) Inventor Masahiro Nakahara 1-1, Yamashita-cho, Kokubu-shi, Kagoshima Inside the Kokubu Plant of Kyocera Corporation (72) Inventor Toshiyuki Hamada 1-1, Yamashita-cho, Kokubu-shi, Kagoshima Kyocera Corporation Kokubu F-term (reference) 5F004 AA00 BB11 BB23 BB29 BB30 BC08 DA00 DA01 DA16 DA18 DA20 DA23 DA26 5F045 AA08 AC02 AC05 AC11 AC16 AF01 AF02 AF03 BB14 BB15 EB03 EC05 EF11 EH08 EM09

Claims (3)

[Claims] (1) a hydroxyl group content of 5 ppm or less and a density of 2.1
S of 5 g / cm ³ or more and carbon amount of 200 ppm or less
A member for a plasma processing apparatus comprising an iO ₂ sintered body. 2. The member for a plasma processing apparatus according to claim 1, wherein the member is substantially composed of only an amorphous phase. 3. The purity is 99.9% or more, and the content of hydroxyl groups is 5%.
ppm or less, high-purity SiO ₂ powder having an average particle diameter of 5 μm or less, and an organic binder added thereto. The molded body is oxidized at 600 to 900 ° C. in an oxidizing atmosphere, and then in a vacuum or in a non-oxidizing atmosphere. A method for producing a member for a plasma processing apparatus, wherein the member is fired at 1300 to 1600 ° C.