JPH11279761A - Corrosion resistant materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the corrosion resistant member of long term reliability achieving excellent corrosion resistance by covering a boron carbide film, in which a density is higher than a specified value and a surface roughness is less than a specified value, on a surface of a substrate so as not to generate a particle. SOLUTION: This corrosion resistant member is made so that a surface of a substrate is covered with a boron carbide film having a density of >=2.40g/cm<3> and a surface roughness Ra of <=0.6 μm. The content of at least one of elements among boron, aluminum, iron in the boron carbide film is totally <=3,100 ppm (including 0). The corrosion resistant member, on the surface of which the boron carbide film of this constitution is covered is made plasmatic, under a fluorine group, a chlorine group, a halogen group corrosion gas, and by introducing a micro wave/high frequency voltage into the gas atmosphere, and excellent corrosion resistance can be attained under such plasma. Further, the substrate is constituted of a ceramic sintered body of boron carbide sintered body, AlN, Al2 O3 , Si3 N4 , SiC, etc., cermet and graphite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant member having excellent corrosion resistance to a corrosive gas such as a fluorine-based or chlorine-based gas, or to a fluorine-based or chlorine-based plasma. For example, it is used for a spacer ring of a semiconductor manufacturing apparatus, a support for supporting an inner wall member or an object to be processed, and various other jigs for manufacturing a semiconductor.

[0002]

2. Description of the Related Art In recent years, a plasma process such as a dry process and a plasma coating used for manufacturing a highly integrated circuit device such as a semiconductor device has been used. System gases are used for etching and cleaning.

[0003] The members that come into contact with these gases are required to have high corrosion resistance. For this reason, metals such as glass, quartz, stainless steel, and monel are frequently used.

[0004] On the other hand, a susceptor material for supporting and fixing a wafer in a semiconductor manufacturing apparatus includes an alumina sintered body, sapphire, aluminum nitride (AlN) sintered body, or a material obtained by surface-coating them by a CVD method or the like, and further comprises a carbonized material. A silicon (SiC) sintered body coated with a SiC film by a CVD method is also used.

[0005]

However, in the above-mentioned members made of glass or quartz,
There is a problem that corrosion resistance is inadequate, which leads to severe wear. Especially, when exposed to fluorine-based or chlorine-based plasma, the film is etched and its surface properties are deteriorated.

[0006] Metal members such as stainless steel also have insufficient corrosion resistance and are difficult to use for a long period of time. Further, in semiconductor manufacturing, defects may occur in the manufacturing equipment itself or wafers. Had become. Furthermore, members made of an alumina sintered body or an AlN sintered body are superior in corrosion resistance to fluorine-based gas as compared with the above materials, but when exposed to high-temperature plasma, corrosion gradually progresses. Crystal grains were shed from the body surface.

As described above, the generation of particles is also a problem. However, these particles are generated by a physical action such as ion bombardment, or are generated by a chemical vapor phase reaction, and become dust, thereby forming a vacuum container. Each member inside is adversely affected. That is, in a semiconductor manufacturing apparatus,
With the increase in the degree of integration of semiconductors and the further cleanliness of the process, such particles have caused disconnection of metal wiring, defects in patterns, and the like, thereby causing deterioration in device characteristics and reduction in yield.

In order to solve the above problems, it has been proposed to form a corrosion-resistant member by using a material containing a Group 3a element of the periodic table that is stable against fluorine-chlorine-based plasma as a main component (Japanese Patent Laid-Open No. Hei 9 (1998)). No. 295863).

However, even with such a corrosion-resistant member, a satisfactory corrosion resistance has not yet been achieved.
Particles were generated due to dropout of the halide formed on the surface or gas phase reaction.

In view of the above circumstances, the present inventor has found that an element (Cr, Fe, Zn, Na, K, N) that impairs the performance of a semiconductor against a fluorine-based or chlorine-based corrosive gas or plasma.
As a result of intensive studies on a high corrosion resistant material that does not contain i, Cu, Li, and Na) and does not generate particles, a boron carbide film can be easily densified in production and reacted with fluorine and chlorine. Even in this case, a reactant having a high vapor pressure is not formed into a solid due to generation of the reactant, and is released as a gas without generating particles, and reacts with a fluorine-based and chlorine-based corrosive gas or plasma. It has been found that it is difficult to perform, so it has excellent corrosion resistance.

Accordingly, the present invention has been completed based on the above findings, and an object of the present invention is to provide a long-term reliable corrosion-resistant member which does not generate particles and achieves excellent corrosion resistance.

Another object of the present invention is to provide a corrosion-resistant member for semiconductor production which prevents generation of particles by not reacting with fluorine-based and chlorine-based corrosive gas or plasma.

[0013]

The corrosion-resistant member of the present invention is characterized in that the surface of the substrate is coated with a boron carbide film having a density of 2.40 g / cm ³ or more and a surface roughness Ra of 0.6 μm or less. I do.

In another corrosion resistant member of the present invention, the total of at least one element of silicon, aluminum and iron in the boron carbide film is 3100 ppm or less (including 0).
It is characterized by being.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The corrosion-resistant member of the present invention has a substrate surface coated with a boron carbide film having the above-described structure. By introducing a microwave or a high-frequency voltage, a plasma is formed. Even with such a plasma, excellent corrosion resistance is achieved. SF ₆ , CF ₄ , CHF ₃ , ClF ₃ , HF
And chlorine-based gases include Cl ₂ , BCl ₃ , and HCl.

The substrate is made of a sintered boron carbide, AlN, Al
Ceramic sintered bodies such as ₂ O ₃ , Si ₃ N ₄ , SiC,
It is composed of cermet or graphite.

With respect to the above-mentioned boron carbide film, when the density becomes low, the number of pores increases, so that the contact area with a corrosive gas or plasma increases, and the consumption becomes faster, so that the density becomes 2.4.
0 g / cm ³ or more, preferably better to high density 2.45 g / cm ³ or more.

Further, as a constituent of the film, boron carbide is added to 96 parts.
If it is at least 98% by weight, preferably at least 98% by weight, a dense body is obtained, and a density of at least 2.40 g / cm ³ is achieved. In order to make the boron carbide 96% by weight or more, it is preferable not to contain free carbon and free boron, and it is also preferable not to contain other impurities.

In order to form such a boron carbide film, a known film forming technique, for example, a CVD method may be used. In this case, benzene (C ₆ H ₆ ) and boron trichloride (BCl ₃ ) are used. ) As the starting material gas,
A film is formed at a reaction temperature of 050 to 1100 ° C.

The thickness of the boron carbide film is desirably 0.5 μm or more, so that the corrosion resistance can be maintained for a long period of time.

Further, when the surface roughness Ra of the boron carbide film is 0.5 μm or less, preferably 0.2 μm or less, it is advantageous in that generation of particles is reduced and excellent corrosion resistance is obtained. The surface roughness Ra of 0.5 μm or less can be obtained by setting the surface roughness Ra of the substrate to 0.5 μm or less.

Further, according to the present invention, the inventors of the present invention have conducted intensive studies on impurities in the step of forming a boron carbide film, and have found that each atom of silicon, aluminum and iron is a factor that deteriorates corrosion resistance. And the total amount thereof is 3100 ppm or less, preferably 2000 ppm or less. Within this range, excellent corrosion resistance can be obtained even when exposed to fluorine-based or chlorine-based plasma for a long time. The present inventor considers that each atom of silicon, aluminum and iron floats in a gas atmosphere from various semiconductor manufacturing jigs such as a chamber when the boron carbide film is subjected to CVD coating and is contained by this.

[0023]

EXAMPLES (Example 1) First, a boron carbide sintered body as a substrate of the present invention was produced. This boron carbide sintered body has a firing temperature of 22.
It was produced by hot pressing at 00 ° C. and a molding pressure of 200 kgf / cm ² .

A boron carbide film having a thickness of 1.0 μm was formed on the surface of the substrate by a CVD method. In this CVD method, boron trichloride (BCl ₃ ) is used as a boron source, benzene (C ₆ H ₆ ) is used as a carbon source, and the reaction temperature is set to 1100 ° C.
_{A 4} C film was formed.

As shown in Table 1, the amount, density, and surface roughness of the boron carbide film (i.e., Si, Al, F
e has an impurity content of 3100 ppm or less in total)
Was changed in any number of ways to form a film. 1 to 6 were produced. Further, a sample which was not formed on the above-mentioned substrate was designated as Sample No. 7 was set.

[0026]

[Table 1]

When the evaluation of each of these samples was performed using both fluorine-based plasma and chlorine-based plasma, the results shown in Table 2 were obtained.

[0028]

[Table 2]

In the case of evaluation using fluorine-based plasma, each sample was placed in a RIE (Reactive Ion Etching) plasma etching apparatus, and then CF ₄ gas was introduced at a flow rate of 60 sccm, Ar gas was introduced at a flow rate of 60 sccm, and
By setting the Pa and the RF output to 1 kW and irradiating the plasma for 3 hours, a fluorine-based plasma was formed, and the plasma was evaluated at room temperature to check the etching rate and the generation of particles.

The etching rate is calculated based on the change in weight before and after the test using the specific gravity of the material and the time, and is expressed in units of Å / min. That is, the etching rate [Å /
Min) = [(weight of sample before etching−weight of sample after etching) / specific gravity of sample] / (plasma irradiation area × plasma irradiation time).

Further, the state of generation of particles was observed with an electron microscope on the surface of each sample, and the state of adhesion of particles to the surface was observed. The mark “○” indicates that almost no particles were generated, and the mark “X” indicates that particles were significantly generated.

On the other hand, in the case of evaluation using chlorine-based plasma, each sample was put into an RIE plasma etching apparatus, and B
Cl ₃ gas is introduced (flow rate 100 sccm), pressure 4P
a, RF output l. Plasma irradiation was carried out for 3 hours under the etching condition of 8 kW, and the chlorine plasma was evaluated at room temperature, and the etching rate and particles were similarly measured and evaluated.

As is clear from the results shown in Table 2, the sample No. of the present invention. With respect to Nos. 1 to 4, the etching rate was low and no particles were generated.

On the other hand, the sample No. In Sample No. 5, the density of the film was low. In No. 6, the surface roughness was large, thereby increasing the etching rate and generating particles. Sample No. As for No. 7, the etching rate was increased and particles were generated by not forming a boron carbide film.

Example 2 A boron carbide film is formed on the surface of a boron carbide sintered body as a substrate by a CVD method in the same manner as in Example 1, and as shown in Table 3, impurities of Si, Al and Fe are further added. And the total content was changed to change the sample No. 8-13
Was prepared. In each sample, the boron carbide content of the boron carbide film was 96% by weight, the density was 2.45 g / cm ³ , and the surface roughness was Ra.
Was set to 0.5 μm, and the others were formed exactly as in Example 1.

[0036]

[Table 3]

The evaluation of each sample was performed using both fluorine-based plasma and chlorine-based plasma, and the results shown in Table 3 were obtained. As is clear from the results, the sample No. For Nos. 8 to 10, the etching rate was low and no particles were generated. The sample no. In Nos. 11 to 13, no particles were generated, but the etching rate was high.

[0038]

As described above, according to the present invention, the substrate surface has a density of 2.40 g / cm ³ or more and a surface roughness Ra of 0.
By coating with a boron carbide film having a thickness of 6 μm or less, a long-term reliable corrosion-resistant member which did not generate particles and achieved excellent corrosion resistance could be provided.

Further, according to the present invention, a corrosion-resistant member for semiconductor production which does not react with fluorine-based and chlorine-based corrosive gas or fluorine-based / chlorine-based plasma and does not generate particles (for example, an inner wall member of a plasma processing apparatus, A jig member such as a support for supporting an object to be processed can be obtained. As a result, the yield of semiconductor manufacturing can be improved, the production cost can be reduced, and a high quality and highly reliable semiconductor element can be manufactured. Was.

Moreover, the corrosion-resistant member of the present invention
By setting at least one element of silicon, aluminum and iron in the boron carbide film to be 3100 ppm or less, no particles were generated, and more excellent corrosion resistance could be achieved.

Claims (2)

[Claims] 1. A corrosion-resistant member comprising a substrate having a surface coated with a boron carbide film having a density of at least 2.40 g / cm ³ and a surface roughness Ra of at most 0.6 μm. 2. The method according to claim 1, wherein at least one element selected from the group consisting of silicon, aluminum and iron in said boron carbide film has a total of 3100 pp.
The corrosion-resistant member according to claim 1, wherein m is equal to or less than 0 (including 0).