JP2001220243A - Corrosion-resistant composite member and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a corrosion-resistant composite member having excellent heat resistance, composed of a composite material of silicon nitride and silicon oxynitride, capable of controlling occurrence of particle and to provide a method for producing the corrosion-resistant composite member. SOLUTION: This corrosion-resistant composite member comprises silicon nitride and silicon oxynitride as a main phase, contains 0.5-3 mol% of oxide of element of the group 2a or the group 3a of the periodic table and 20-60 mol% of silicon dioxide in the molar ratio of silicon dioxide to the oxides of >=10 and has >=70% relative density and <=0.01 wt.% of the total of cation impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has high corrosion resistance to chlorine-based corrosive gas or its plasma, and is suitably used as an inner wall material or a jig in a plasma processing apparatus or a plasma apparatus for semiconductor / liquid crystal production. The present invention relates to a corrosion-resistant member used, a corrosion-resistant member used for a target material sputtered on the surface of a component thereof, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the use of plasma in processes such as a dry process and a plasma coating process for manufacturing semiconductors and liquid crystals has been rapidly progressing. As a plasma process in semiconductor / liquid crystal production, a halogen-based corrosive gas such as a chlorine-based gas is used for vapor-phase growth deposition, etching and cleaning because of its high reactivity. Members that come into contact with these corrosive gases and plasma are required to have high corrosion resistance.

[0003] Conventionally, members that come into contact with these corrosive gases other than the object to be treated and the plasma thereof are generally
Materials mainly composed of silicon dioxide such as glass and quartz,
Corrosion-resistant metals such as stainless steel and Monel are frequently used.

In a semiconductor manufacturing process, as a susceptor material for supporting and fixing a Si wafer, alumina, sapphire, aluminum nitride, or a material coated with a surface thereof by a CVD method or the like is used because of its excellent corrosion resistance. Further, a heater or the like coated with graphite or boron nitride is also used.

[0005]

However, conventionally used glass and quartz have inadequate corrosion resistance in plasma and are intensely depleted. In particular, when they come into contact with chlorine-based plasma, the contact surface is etched and the surface properties change. Thus, problems such as affecting the etching conditions have occurred.

[0006] Further, even members made of metal such as stainless steel have insufficient corrosion resistance, causing problems such as generation of particles due to corrosion. Particularly, in semiconductor manufacturing, one of the major causes for increasing the defective product generation rate is one. Had one.

[0007] Alumina, sapphire, aluminum nitride or those obtained by surface-coating them by CVD or the like,
Compared to the above materials, it has excellent corrosion resistance to chlorine-based corrosive gas and its plasma, but when it comes in contact with plasma at high temperature, corrosion gradually progresses, and reaction product particles and crystal particles with the gas from the surface This causes a problem that the particles are shed and cause the generation of particles.

In order to solve such a problem, it is also proposed to use a material mainly composed of an element of Groups 2a and 3a of the periodic table, which forms a stable chlorinated material on the surface of the material with respect to chlorine-based plasma. However, with the further increase in the degree of integration of semiconductors and the further cleanliness of the process, there is a risk that extremely fine particles generated by reaction in the ion bombardment or gas phase may cause defects.

Accordingly, an object of the present invention is to provide a corrosion-resistant member made of a composite material of silicon nitride and silicon oxynitride having excellent heat resistance and capable of suppressing generation of particles, and a method of manufacturing the same.

[0010]

According to the present invention, a composite material of silicon nitride and silicon oxynitride is excellent in electric insulation and thermal shock resistance and can suppress the generation of particles. It is based on the finding that it is suitable for a corrosion-resistant member. The grain boundary phase of the sintered body composed of a composite material of silicon nitride and silicon oxynitride is selectively corroded, and the generation of particles and the corrosion resistance vary greatly depending on the composition of the auxiliary agent, so that the structure of the sintered body is controlled. This is very important.

Therefore, according to the present invention, in the auxiliary composition of a sintered body made of a composite material of silicon nitride and silicon oxynitride, the sintering auxiliary is an essential component for achieving densification by sintering. However, the corrosion resistance greatly differs depending on the auxiliary component. Among them, by adding a predetermined amount of a Group 2a element or a Group 3a element of the periodic table, the corrosion resistance of the composite material is not impaired. And generation of particles can be suppressed.

That is, in the corrosion-resistant composite member of the present invention, the surface directly in contact with a corrosive gas or plasma has a main phase of a composite material of silicon nitride and silicon oxynitride, and a group 2a element (A) of the periodic table. Alternatively, the group 3a element (RE) is 0.5 to 3 mol% in total as oxide (AO or RE ₂ O ₃ ), and excess oxygen is 20 to 6 mol as silicon dioxide (SiO ₂ ).
0 mol% each, and SiO ₂ / (AO
+ RE ₂ O ₃ ) and a sintered body having a total amount of cationic impurities of 0.1% by weight or less and a relative density of 70% or more. Excellent corrosion resistance in gas and its plasma. In particular, the Group 3a element of the periodic table is converted to oxide in an amount of 0.5%.
Preferably, it is contained in an amount of 3 mol%.

[0013] The manufacturing method is a method for manufacturing a corrosion-resistant composite member having a surface which is in direct contact with a corrosive gas or plasma. The method includes manufacturing a silicon nitride raw material powder having a total amount of cationic impurities of 0.1% by weight or less. On the other hand, Periodic Table 2a
Group oxides (AO) or group 3a element oxides (RE ₂ O ₃ ) in total of 0.5 to 3 mol%, and silicon dioxide (0.1% by weight or less in total amount of cationic impurities) Si
O ₂₎ and includes a 20 to 60 mol%, and the molar with an oxide of a Group 2a element periodic table and silicon dioxide (AO) and the periodic table oxides of Group 3a element (RE ₂ O ₃₎ Specific SiO ₂
The method is characterized in that a molded body of a mixed powder having / (AO + RE ₂ O ₃ ) of 10 or more is fired. In particular, it is preferable to contain a Group 3a element of the periodic table in an amount of 0.5 to 3 mol% in terms of oxide, because of excellent sinterability. The firing is preferably carried out at normal pressure from the viewpoint of cost reduction.

[0014]

Corrosion resistant composite member of the embodiment of the present invention is a member in direct contact with the corrosive gas or plasma thereof, chlorine gas, as the chlorine-based gas, Cl _2, SiC
_{l 4, BCl 3, HCl,} ClF 3 and the like. When microwaves or high frequencies are introduced into the atmosphere in which these gases are introduced, these gases are turned into plasma.

According to the present invention, the surface of such a chlorine-based corrosive gas or the surface thereof which comes into direct contact with the plasma is made of a composite material mainly composed of a silicon nitride phase and a silicon oxynitride phase. Is what you do. In this composite material, Si and the element of Group 2a or 3a of the periodic table are present at the grain boundaries between the phases.
Form a composite material with a group III element. For example, at least one selected from the group consisting of disilicate, monosilicate, and RE ₂ Si ₃ N ₂ O ₅ is formed as a grain boundary phase. Since these grain boundary phases have high corrosion resistance and do not easily react with chlorine gas or plasma, they exhibit excellent corrosion resistance to chlorine gas.

From the viewpoint of gas permeation, it is necessary that at least the inside of the sintered body has a relative density of 70% or more and closed pores are generated. When the relative density is less than 70%, the pores are formed of open pores, and particles are easily generated. In addition, dust enters the pores during manufacturing, causing impurities to be generated. In addition, when exhausted from the atmosphere to a vacuum, large degassing occurs, which causes a problem of lowering the operation rate of the apparatus. In particular, the relative density is preferably 80% or more, and when strength is required, it is preferably 95% or more.

It has been conventionally known that a composite material of silicon nitride and silicon oxynitride does not sinter alone.
Densification can be achieved by adding a sintering aid such as a Group 3a element of the periodic table such as b ₂ O ₃ or a Group 2a element of the periodic table such as MgO. This sintered body is composed of a main crystal phase composed of silicon nitride and silicon oxynitride, and a grain boundary phase formed mainly by a component added as a sintering aid and an impurity component. It is.

From the viewpoint of corrosion resistance to chlorine-based gas,
Silicon nitride and silicon oxynitride have excellent corrosion resistance because they are composed of chemically stable compounds having a covalent bond per se, but the components mixed as the sintering aid and impurities are inferior in corrosion resistance depending on the composition. The grain boundary phase is locally etched or easily reacts with the gas.

Therefore, according to the present invention, corrosion resistance is impaired.
In order to improve the sinterability, the periodic table 2
Group a element or Group 3a element of the periodic table, and silicon dioxide
Element (SiO_Two) Is added. That is, the periodic table 2a
Group element (A) or group 3a element (RE) of the periodic table is an acid
Compound conversion (AO or RE_TwoO_Three) At 0.5-3 mol%,
Silicon dioxide (SiO_Two) Of 20 to 60 mol%, silicon dioxide
Element and Group 2a element (A) or Periodic table 3a
Molar ratio of SiO with group element (RE)_Two/ (AO + RE
_TwoO_ThreeIs important to be 10 or more. In particular, AO
And / or RE _TwoO is 1 to 2.5 mol% in total,
It is preferable that silicon oxide be contained in an amount of 30 to 50 mol%.

The reason why the composition is limited to the above range is that if the content of AO and / or RE ₂ O ₃ is less than 0.5 mol%, the sinterability is poor, and if it exceeds 3 mol%, particles are likely to be generated. is there. Further, when the content of SiO ₂ is in the range of 20 to 60 mol%, the sinterability is improved, and the molar ratio of SiO ₂ is improved.
This is because the sinterability deteriorates even if / (AO + RE ₂ O ₃ ) is less than 10.

In the present invention, at least one element selected from the group consisting of Mg, Ca, Sr, Ba, and Ra as a Group 2a element of the periodic table, or Y, Ce, La, or Yb, Er, Lu, Dy, Nd, S
It is important to contain at least one selected from the group consisting of m and Gd. In particular, it is preferable to contain a Group 3a element of the periodic table, and among them, Yb, Lu, E
containing at least one of r, Ce and Y,
It is preferable in order to densify with a small amount. And among these, Yb is the most suitable.

If the total amount of cationic impurities in the sintered body exceeds 0.1% by weight, a low-melting grain boundary phase containing a high concentration of impurities is generated and exposed to chlorine-based corrosive gas or plasma. When used for a long time in an environment where the sintered body is used, the grain boundary phase component inside the sintered body easily diffuses and moves toward the surface of the member, so that erosion proceeds to the inside and the corrosion resistance deteriorates, A negative effect may occur. Therefore, the content of cationic impurities is 0.1% by weight or less,
In particular, it must be 0.05% by weight or less, and more preferably 0.01% by weight or less.

The cation impurity is defined in the second part of the periodic table.
It refers to all elements that can be cations other than group a elements, group 3a elements of the periodic table, and silicon. Particularly, among the cationic impurities, Na, K, and F are used to adversely affect the semiconductor and promote erosion of the grain boundary during semiconductor manufacturing.
As for e, Cr, and Ni, the total amount in terms of metal is preferably 0.05% by weight or less, particularly preferably 0.01% by weight or less.

The corrosion-resistant composite member of the present invention is manufactured by the following method.

First, a silicon nitride powder having a total amount of cationic impurities of 0.1% by weight or less is prepared as a starting material. Since most of the cationic impurities remain even after firing, it is important to reduce the amount of the cationic impurities in the raw material to 0.1% by weight or less. In particular, the content is preferably 0.05% by weight or less. This raw material powder preferably has an average particle size of 1 μm or less in terms of sinterability, and may be any of α-type and β-type with an oxygen content of 0.5 to 2.0% by weight.

Next, an oxide of a Group 2a element or a Group 3a element of the periodic table is added to the silicon nitride raw material powder in an amount of 0.5 to 3%.
Mol%, the total amount of impurities is 0.1% by weight or less, silicon dioxide in the range of 20 to 60 mol%, and the molar ratio of silicon dioxide to the group 2a element and the group 3a element of the periodic table is SiO _2.
/ (AO + RE ₂ O ₃ ) is added so as to be 10 or more. Note that these raw material compositions do not involve scattering or the like in normal firing, and thus substantially become a sintered body composition. Therefore, it is important to set the composition in the above range.

These powders are pulverized by a ball mill or the like to an average particle size of 3 μm or less, preferably 2 μm or less. If the raw material powder is larger than 3 μm, the sinterability tends to deteriorate. Therefore, the conditions for pulverization or crushing are set so as to be 3 μm or less. Thereafter, the mixed powder is formed into a desired shape of a corrosion-resistant composite member by a desired forming means, for example, a mold press, a cold isostatic press, an injection molding, an extrusion molding and the like, and then fired.

The firing is performed in a non-oxidizing atmosphere such as nitrogen.
00 ° C to 1850 ° C, preferably 1750 ° C to 1800
Firing is performed in an atmosphere containing SiO gas in a temperature range of ° C. Thereby, a sintered body having a relative density of 70% or more can be obtained.

As the sintering method, normal pressure firing, hot pressing, nitrogen gas pressure firing, hot isostatic pressure firing, and the like can be employed, but normal pressure firing is preferred from the viewpoint of cost and firing of large products. Then, as described above, the relative density 70
% Of the sintered body is subjected to a grinding process to finish the product in a predetermined size.

According to such a heat treatment method, it can be easily applied to a large member having a complicated shape, and a member having high corrosion resistance can be efficiently manufactured.

[0031]

EXAMPLE First, α-type silicon nitride powder having an amount of cationic metal impurities other than silicon of 0.006% by weight and an average particle diameter of 0.7 μm was used.
% And 0.1% by weight of Yb having an average particle size of 1.2 μm
₂ O ₃ , Y ₂ O ₃ , Er ₂ O ₃ , Lu ₂ O ₃ , Lu ₂ O ₃ and C
powder eO ₂ powder and SrCO ₃ or MgCO ₃ were formulated as shown in Table 1, was pulverized for 20 hours in a vibrating mill,
It was formed by a mold press. Then, the formed body was fired at 1750 ° C. for 5 hours in a nitrogen atmosphere. However, the sample No. 27 was baked at 1800 ° C. for 5 hours.

The amount of impurities in the obtained sintered body was measured by ICP emission analysis. The cation impurities are elements that are not included in the composition and are all elements that can be cations. In 2, Si and Y
All elements other than b were treated as impurities. In addition, relative density measures the bulk specific gravity and true specific gravity by Archimedes method,
Bulk specific gravity / true specific gravity was defined as relative density.

Next, for the measurement of the amount of particles, the above-mentioned sintered body having a size of 8 inches was prepared, the surface was processed into a mirror surface state, and BCl ₃ (1
(00 sccm) in a chlorine plasma at room temperature. The etching conditions were a pressure of 4 Pa, an RF output of 1.8 kW, and a plasma irradiation time of 240 hours. Then, the wafer was brought into contact with an 8-inch wafer, and the number of particles on the wafer was measured to be 0.3 μm using a particle counter by a laser scattering method.
The above particles were measured. Table 1 shows the results.

[0034]

[Table 1]

Sample No. of the present invention 2-5, 8-10, 1
3 to 20 and 22 to 27 have a particle amount of 500
Or less.

On the other hand, the sample No. in which the SiO ₂ content did not reach 20 mol%. Sample No. 1 and more than 60 mol%
Sample No. 6 had a relative density of less than 70%, out of the range of the present invention, and a particle amount of 1600 or more.

In the case of Sample No. in which AO + RE ₂ O ₃ was less than 0.5 mol%. Sample No. 7 and more than 3 mol%
11 is out of the range of the present invention, and the particle amount is 12
The number was 00 or more.

Further, the sample No. having an SiO ₂ / (AO + RE ₂ O ₃ ) ratio of less than 10 was used. 12 means that the particle amount is 12
There were 00 pieces.

Further, the sample No. having a cationic impurity amount exceeding 0.1% by weight was used. 21 is 18 particles
There were 00 pieces.

[0040]

As described in detail above, according to the present invention,
By using a composite material including silicon nitride and silicon oxynitride, a corrosion-resistant composite member with less generation of particles can be realized.

Claims (5)

[Claims] A surface which is in direct contact with a corrosive gas or plasma is mainly composed of a composite material of silicon nitride and silicon oxynitride, and is a Group 2a element (A) or a Group 3a element (RE) of the periodic table. In terms of oxide (AO or RE ₂ O ₃ ) in total of 0.5 to 3 mol%, and excess oxygen in terms of silicon dioxide (SiO
₂ ) containing 20 to 60 mol% in each case, and
A corrosion-resistant composite member comprising a sintered body having iO ₂ / (AO + RE ₂ O ₃ ) of 10 or more, a total amount of cationic impurities of 0.1% by weight or less, and a relative density of 70% or more. 2. An element of Group 3a of the periodic table in an amount of 0.
The corrosion-resistant composite member according to claim 1, wherein the content is 5 to 3 mol%. 3. A method for producing a corrosion-resistant composite member having a surface directly in contact with a corrosive gas or plasma, wherein the silicon nitride raw material powder having a total amount of cationic impurities of 0.1% by weight or less is subjected to a periodic rule. Table 2a Group Oxides (AO)
Alternatively, an oxide of a Group 3a element (RE ₂ O ₃ ) may be added in a total amount of 0.
5 to 3 mol% and 0.1% by weight of cationic impurities in the total amount
The following silicon dioxide (SiO ₂ ) is contained in an amount of 20 to 60 mol%, and silicon oxide and an oxide of a group 2a element of the periodic table (AO) and an oxide of a group 3a element of the periodic table (RE ₂₎
O ₃₎ molar ratio _{SiO 2 / (AO + RE 2} O 3) are provided methods for producing corrosion-resistant composite member and firing the shaped body of the mixed powder is 10 or more. 4. An element of Group 3a of the periodic table which is contained in an amount of 0.
The method for producing a corrosion-resistant composite member according to claim 3, wherein the content is 5 to 3 mol%. 5. The method for producing a corrosion-resistant composite member according to claim 3, wherein the firing is normal pressure firing.