JPH10194876A - Production of jig for semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jig for a semiconductor made of a silicon carbide-metallic silicon composite material, metallic silicon, etc., and used in a process of producing a semiconductor device without contaminating a silicon wafer. SOLUTION: A compact having a shape necessary for a jig for a semiconductor and made of a silicon carbide-silicon composite material, metallic silicon, etc., is washed with hydrofluoric acid or a mixture of hydrofluoric acid with hydrochloric acid. The washed compact is heat-treated at 1,000-1,300 deg.C in an oxidizing atmosphere to form an oxidized film of 0.1-5μm thickness in the surface. The compact with the oxidized film is mechanically worked and washed with hydrofluoric acid or a mixture of hydrofluoric acid with hydrochloric acid to removed the oxidized film.

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 jig for a semiconductor, and more particularly, to a method for manufacturing a semiconductor device, which is useful for a process tube, a wafer boat, and the like used for thermal diffusion processing of a silicon wafer. For example, the present invention relates to a method for manufacturing a jig formed from a composite material of silicon carbide and metallic silicon, metallic silicon, and the like.

[0002]

2. Description of the Related Art Conventionally, as a jig for semiconductors requiring high heat resistance of 1100 ° C. or higher, a jig made of metal silicon and silicon carbide (hereinafter referred to as “silicon carbide composite material”) has been formed. Things have been developed. However, at the beginning of development, it was difficult to obtain a high-purity silicon carbide composite material required for manufacturing semiconductor devices. Therefore, as a method of reducing contamination on a silicon wafer or the like, a method of forming a film of silicon carbide or the like on the surface of a substrate made of a silicon carbide composite material has been proposed (Japanese Patent Application Laid-Open No. 63-56700). Gazette).

On the other hand, with recent advances in material technology and high-purity technology, jigs made of metallic silicon and high-purity materials comparable to quartz glass have been developed, and their applications have been developed (Japanese Patent Application Laid-Open No. Hei 6-1994). No. 211574). However, these materials have a problem that cleaning is more difficult than a silicon carbide composite material or quartz glass provided with a silicon carbide film.

With the recent increase in the degree of integration and miniaturization of semiconductor devices, micro-contamination due to particles, metal impurities, and the like has greatly affected product yield and reliability. For this reason, the importance of cleaning in the VLSI process has been further increased. However, although attention has been paid to silicon wafer cleaning technology, there is still interest in jigs, especially jigs made of high-purity heat-resistant materials for heat-treating wafers, despite the great influence of contamination. Low (SEMI
Technology Symposium 1993 Proceedings Semicond
uctor Equipment and Materials International 199
3 years December, p. 450-453).

Conventionally, a quartz glass jig which has been used for semiconductor heat treatment is uniformly dissolved in a cleaning liquid such as hydrofluoric acid, and its surface is very smooth, so that cleaning is relatively easy. However, there were problems such as heat resistance.

On the other hand, for a silicon carbide composite material having higher heat resistance and higher strength than quartz, a high-purity material comparable to quartz glass has been developed, and its use has been developed. The silicon carbide composite material is a composite material formed by impregnating a molded body made of silicon carbide with metal silicon, so that the metal silicon is exposed on the surface thereof. If the surface is treated with a hydrogen halide gas, strong acid, etc. to clean such a composite material, metallic silicon will be eroded, and holes will be formed on the surface of the jig, causing contamination. This causes problems such as a shortened life. Similar problems also occur with jigs formed of metal silicon. That is, when the metal silicon jig is treated with a halogenated gas or a strong acid, the metal silicon itself is eroded. The erosion is not always performed uniformly, so that the grain boundaries of the polysilicon are eroded first and the surface roughness increases. When the surface is roughened, impurities remain during cleaning, which causes contamination. In addition, since the metal silicon itself forming the jig elutes, the jig becomes smaller each time washing is performed, and the dimensions become irregular.

On the other hand, in order to improve such disadvantages,
A method has been proposed in which a dense silicon carbide film or silica film is deposited on the surface to suppress diffusion of impurities and fill the surface voids (JP-A-57-58771, JP-A-57-58771).
4-61376, JP-A-64-14914). However, such a method has problems such as generation of pinholes in the silicon carbide film or silica film on the surface, low adhesion strength of the film, and cracking due to mechanical and thermal shocks. Further, the addition of the CVD film causes a cost increase.

On the other hand, a method for producing a clean semiconductor jig by purifying a porous silicon carbide molded body with a halogen-containing gas or a strong acid and then impregnating silicon as secondary baking (Japanese Patent Application Laid-Open No. 55-158622). ) And a method of obtaining a jig for a semiconductor by subjecting a porous silicon carbide molded body to a purification treatment at a temperature of 1600 ° C. to 2000 ° C. in an atmosphere of a halogen gas and then performing silicon impregnation as a secondary baking (Japanese Patent Laid-Open No. No. 60-138913) is also disclosed. However, these techniques do not provide any means for removing impurities adhering to the surface in a step of further processing after the silicon impregnation because the cleaning treatment is performed before the silicon impregnation.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a semiconductor jig which is more suitable for use without contaminating a silicon wafer during a semiconductor device manufacturing process, particularly a heat treatment step. Is to provide.

[0010]

According to the present invention, there is provided a method for manufacturing a jig for a semiconductor wherein at least the surface layer contains metallic silicon or at least the surface layer is composed of metallic silicon, comprising the following steps. Features.

(A) A molded article having a shape required for a semiconductor jig and containing at least a surface layer of metal silicon or at least a surface layer of a material made of metal silicon is formed by hydrofluoric acid or fluoridation. A step of washing with a mixture of hydrochloric acid and hydrochloric acid.

(B) heat-treating the washed molded body in an oxidizing atmosphere so that the surface of the molded body has a thickness of 0.1 to 5 μm;
forming an oxide film having a thickness of μm;

(C) a step of machining a molded body having an oxide film; (D) washing the machined molded body with hydrofluoric acid or a mixture of hydrofluoric acid and hydrochloric acid;

In the present invention, the heat treatment for forming the oxide film is preferably performed at a temperature of, for example, 1000 ° C. to 1300 ° C.

In the present invention, after the above-mentioned step (d), a new oxide film may be formed on the surface of the molded body by further heat-treating the machined molded body in an oxidizing atmosphere.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Semiconductor jigs manufactured according to the present invention include, for example, process tubes and wafer boats used for heat treatment of silicon wafers. The present invention is applied to manufacture a jig among these semiconductors that contains metal silicon at least in the surface layer portion or that at least the surface layer portion is made of metal silicon. For example, the jig manufactured according to the present invention includes a composite material composed of silicon carbide and metal silicon or a jig formed of metal silicon. The jig formed from the composite material is manufactured by, for example, performing a process of impregnating a molded body made of a porous silicon carbide sintered body with metallic silicon and then performing necessary machining on the obtained molded body. There are things to be done. Further, the jig formed of metal silicon can be obtained by machining a molded body of metal silicon.

According to the conventional method, a jig molded body obtained through steps such as molding and baking is subjected to machining such as cutting and grooving to obtain a jig having a predetermined shape and structure. can get. At this time, impurities from the grinding fluid, the grindstone, the fixture and the environment adhere to the active metallic silicon exposed on the surface. The impurities include organic substances such as resin and oil and metal impurities such as Na, K, Al, Fe, Ni, Cr, and Cu. Of these, organic impurities could be relatively easily removed with a solvent or an alkaline cleaning solution. On the other hand, acid cleaning should have been effective for metal impurities.
However, the present inventor believes that an element having a smaller ionization tendency than silicon, such as Cu, is reduced on the Si surface and adheres as a metal instead of an ion. (HF-HNO ₃ , HF-H
₂ O ₂ ) was required, and the problem of eroding Si on the surface of the metallic silicon or silicon carbide composite material was noticed. Therefore, as described in detail below, the inventor actively forms an oxide film on the jig molded body before performing necessary machining, and forms a jig molded body protected by the oxide film. The present inventors have found that a cleaner jig can be obtained by subsequent acid washing if machining is performed, and have completed the present invention.

In the present invention, prior to active formation of an oxide film and machining, a molded body having a shape required for a semiconductor jig is washed with an acid. This molded body can be said to be a semi-finished product of a semiconductor jig, and is prepared by an ordinary method. For example, in the case of a jig made of metal silicon, a molded body is prepared by poly-Si-CVD or the like. In the case of a jig of a silicon carbide composite material composed of silicon carbide and metal silicon, for example, a mold having a shape required for the jig through a process of forming a molded body from silicon carbide particles, a sintering process, and a metal silicon impregnation process The body is prepared. The present invention can be applied as a part of a manufacturing process of a jig for a semiconductor including a step of preparing the molded body, and, for a molded body already prepared in another place,
This can be applied as a method of processing to obtain a clean semiconductor jig. Impurities adhere to the surface of this molded body during handling and the like. In the acid cleaning, the jig molding is cleaned so as not to contaminate the furnace used in the subsequent oxide film forming step with such impurities.
In the manufacture of a jig molded body made of a silicon carbide composite material, the silicon impregnation step is performed by converting a porous silicon carbide sintered body (main body) having a required shape as a jig into a porous silicon carbide sintered body. It is carried out in a state of being mounted on a pedestal made of and housed in a carbon crucible. Silicon melted by heating at a temperature equal to or higher than the silicon melting point is impregnated into pores of the main body through the pedestal by capillary action. Since silicon is stored in the carbon crucible in excess of that required to fill the pores, the silicon remains in the crucible after cooling, and the pedestal is fixed to the crucible by the remaining silicon. Therefore, it is necessary to separate the jig body fixed to the crucible via the pedestal by mechanical means. In some cases, it may be desirable to remove excess silicon present on the surface of the molded body obtained after the silicon impregnation step by mechanical means such as sandblasting or grinding. Impurities are generated in such a mechanical separation or a step of removing excess silicon. Such impurities are also removed by acid cleaning. In acid cleaning, it is necessary not to elute the surface silicon. Therefore, as an acid for cleaning, H
F or HF-HCl is used. These aqueous solutions,
That is, HF aqueous solution (hydrofluoric acid) or HF-HC
An aqueous solution (a mixture of hydrofluoric acid and hydrochloric acid) is used as an acid solution for washing. The concentration of hydrofluoric acid or a mixture of hydrofluoric acid and hydrochloric acid can be appropriately set. If an acid containing HF is used, a natural oxide film containing impurities formed on the surface of the metal silicon or silicon carbide composite material can be removed. However,
Among acids containing HF, HF-HNO ₃ and HF-H ₂ O ₂
An acid having a strong oxidizing power such as the above dissolves metallic silicon contained in the jig material, and is not preferred. It is preferable that the jig molded body that has been subjected to the acid cleaning be rinsed with ultrapure water and sufficiently dried in an environment with a high degree of cleanliness where there is no possibility of impurities being attached.

Next, the jig molded body subjected to acid cleaning is
It is set in a heat treatment furnace such as a semiconductor diffusion furnace or an oxidation furnace, and heat-treated in an oxidizing atmosphere to give an oxide film of 0.1 μm to 5 μm on the surface. A diffusion furnace or oxidation furnace having a high purity level that does not contaminate the molded jig is used. For example,
An oxide film (SiO ₂ ) is formed on the surface by heat-treating a jig molded body made of metal silicon or a silicon carbide composite material in an oxidizing atmosphere. As the oxidizing atmosphere, an atmosphere composed of oxygen and an inert gas (rare gas) and the like can be used in addition to an atmosphere composed of oxygen (oxygen atmosphere). The growth rate of the oxide film depends on the diffusion rate of oxygen in the formed oxide film, does not depend on the ratio of the metal silicon and silicon carbide phases of the jig material, and is constant with the heat treatment temperature and the oxidizing atmosphere. Therefore, an oxide film having a uniform thickness is formed even in a composite material of metal silicon and silicon carbide.

The heat treatment for forming the oxide film is 100
It is preferable to carry out at a temperature of 0 ° C or more and 1300 ° C or less. 10
If the temperature is lower than 00 ° C., the growth rate of the oxide film is small, and a long-time treatment is required. If the temperature exceeds 1300 ° C., the oxidation rate is too high, so that control becomes difficult. Also, it becomes difficult to prepare a heat treatment furnace such as a diffusion furnace capable of performing high-temperature and high-purity processing at a temperature exceeding 1300 ° C. The treatment time varies depending on the heat treatment temperature and atmosphere,
The time is preferably from 5 hours to 200 hours. If the heat treatment time is less than 0.5 hour, the oxide film thickness hardly reaches 0.1 μm even at the heat treatment at 1200 ° C., but from the viewpoint of processing efficiency, 200 hours or less is desirable. If the treatment time is too long, the oxide film becomes too thick, and the dimensions of the jig may be out of the tolerance range when the oxide film is removed by the subsequent acid cleaning.
A more preferable heat treatment temperature is 1100 ° C to 1250 ° C, and a more preferable heat treatment time is 2 hours to 60 hours.

In the present invention, the oxide film formed on the surface layer prevents impurities from adhering in the processing step. The oxide film can function as a barrier that prevents adhesion of impurities to a surface made of silicon or a surface containing silicon. The thickness of the oxide film to be formed is 0.1 μm to 5 μm
Is appropriate. When the thickness of the oxide film is less than 0.1 μm, the barrier effect against impurities is thin. Also, providing an oxide film having a thickness of more than 5 μm requires a long-time heat treatment at a high temperature and a surface oxidation due to a difference in expansion with a substrate. It is not preferable because the film is peeled off. If the oxide film is too thick as described above, the dimensions of the jig may be out of the tolerance range when the oxide film is removed by the subsequent acid cleaning. More preferred thickness of the oxide film is 0.2 μm to 2 μm
It is.

Next, a jig molded body having an oxide film includes:
Machined. For example, cutting,
There are grooving and plane polishing. For machining, grinding,
Polishing, cutting, or the like can be used. In cutting, grooving, and the like, partial machining is performed on necessary portions of the jig molded body. The shape, structure, and the like required as a jig are further provided by machining. When machining,
Impurities from the grinding fluid, the grindstone and the environment adhere to the surface of the jig. These impurities include organic substances such as resins and oils and metal impurities such as Na, K, Al, Fe, Ni, Cr, and Cu. Among them, the ionization tendency is Si
In the case where an oxide film is not formed and the surface of Si is exposed, an element such as Cu, which is lower than that, is reduced on the Si surface and adheres to the surface as a metal instead of as an ion. Therefore, when an oxide film is not provided on the surface of the jig, its removal becomes difficult. However, in the present invention, such a metal element can be prevented from adhering by protecting the surface of the jig molding to be machined with an oxide film. By machining the portion covered with the oxide film, a new surface is formed and metal silicon is exposed, but the peripheral portion that is not machined is covered with the oxide film. Therefore, the amount of impurities adhering to the exposed surface of the metal silicon is smaller than in the conventional case where impurities adhere to the entire surface of the jig without forming an oxide film. Further, since the processed surface is smoother than other surfaces of the jig, it is relatively easy to remove impurities.

After the machining is completed, further washing is performed. This cleaning can be final cleaning, and after the cleaning, a semiconductor jig as a final product can be provided. In the cleaning step, impurities generated in the machining are removed. Organic impurities such as resin and oil can be relatively easily removed with an organic solvent or an alkaline cleaning solution.
Metal impurities newly attached to the surface generated by machining, metal impurities attached to the surface of the oxide film previously applied, and the like are removed by acid cleaning. An HF aqueous solution (hydrofluoric acid) or an HF-HCl aqueous solution (a mixture of hydrofluoric acid and hydrochloric acid) is used for acid cleaning. With these acids, the formed oxide film can be removed, and together with the removal of the oxide film, metal impurities and the like attached to the surface can be easily removed. Fine particles such as grinding dust generated in the processing step adhere to the irregularities on the jig surface, but can be easily removed by removing the oxide film applied in advance with an acid. HF to remove oxide film
HF-HNO ₃ and HF-H ₂
O ₂ is not preferable because it dissolves metallic silicon contained in the jig material. It is preferable that the jig obtained after the acid cleaning be rinsed with ultrapure water and sufficiently dried in an environment with a high degree of cleanliness where there is no risk of impurities being attached.

In the present invention, after the acid cleaning, it is more preferable to further apply an oxide film to the jig from which the oxide film has been removed. The oxide film can be formed by setting the jig in a heat treatment furnace such as a semiconductor diffusion furnace or an oxidation furnace and performing heat treatment in an oxidizing atmosphere, as described above. The heat treatment can be performed under the same conditions as described above. The thickness of the formed oxide film is preferably in the range of 0.1 μm to 5 μm, but is not limited thereto. Since the highly active metal silicon is exposed on the surface of the jig after the acid cleaning, impurities easily adhere to the jig. Thus, by forming the oxide film again on the surface in this way, the adhesion of impurities can be more effectively prevented.

By the above steps, a jig for a semiconductor which contains metal silicon at least in the surface layer portion or has at least the surface layer portion made of metal silicon and has a high purity level which does not contaminate the silicon wafer is manufactured. be able to. Hereinafter, the present invention will be described more specifically with reference to examples.

[0026]

【Example】

Example 1 A silicon carbide composite material having a Fe, Ni, and Cr content of less than 0.1 ppm, a Cu content of less than 0.2 ppm, and an Al content of less than 1 ppm (comprising a porous silicon carbide sintered body) The 6-inch wafer boat molded body formed by impregnating the molded body with metal silicon to impart gas impermeability) was first immersed in a 10% by weight semiconductor-grade HF aqueous solution and washed for 60 minutes. . Next, the step of immersing the acid-washed wafer boat in ultrapure water and washing for 60 minutes was performed three times. Ultrapure water was changed for each process.
The wafer boat molded body washed with pure water was sufficiently dried in a clean booth. Next, the dried wafer boat molded body was set in a diffusion furnace, and heat-treated at a temperature of 1200 ° C. in an oxygen atmosphere for 20 hours to give an oxide film having a thickness of about 1.1 μm on the surface. In this heat treatment, the gas flowing into the diffusion furnace was only oxygen, and the inside of the reaction tube was almost oxygen 1
00%.

The molded wafer boat having the oxide film formed thereon is:
Machined using a boat grooving machine. The wafer boat molded body was subjected to grooving with a resin bond diamond grindstone of 150 mmφ at a setting of 3,000 rpm. In the wafer boat molded body, a rectangular groove having a width of 2.5 mm and a depth of 7 mm and a pitch of 4.76 mm was formed in a portion where a silicon wafer was to be mounted. After the grooving is completed, cleaning with an alkaline cleaning solution is performed.
Acid cleaning was performed by immersing in a 60% by weight aqueous solution of semiconductor grade HF for 60 minutes. The step of immersing the acid-washed wafer boat in pure water and washing for 60 minutes was performed three times. Ultrapure water was changed for each process. Further, under the same conditions as above, washing with a 10 wt% HF aqueous solution and washing with ultrapure water were repeated. After drying sufficiently in a clean booth, a wafer boat product was obtained.

The following test was conducted on the purity of the obtained wafer boat product. A 6-inch silicon wafer was placed on the obtained wafer boat product, and heat-treated at 1200 ° C. for 2 hours in an oxygen atmosphere in a diffusion furnace. For the heat-treated wafer, the wafer lifetime was measured using TA-330A manufactured by Leo Giken with a laser current value of 20A. When there are a large number of impurities (such as transition metals) that form a deep level serving as a recombination center in a semiconductor, the lifetime is reduced. Therefore, it is relatively easy to evaluate the degree of contamination of a wafer by measuring the lifetime. Can do it. If the wafer lifetime is long,
This means that the degree of contamination from the wafer boat to the wafer is small, and therefore the purity of the wafer boat is higher.

Table 1 summarizes the cleaning conditions, the heat treatment conditions, the thickness of the formed oxide film, and the measured lifetimes of the heat-treated silicon wafer on the wafer boat product.

Example 2 The same as Example 1 except that a mixed acid obtained by mixing a 10% by weight aqueous HF solution and a 10% by weight aqueous HCl solution (semiconductor grade) at a volume ratio of 1: 1 was used as the acid used in the acid washing. A 6-inch wafer boat was manufactured under the following conditions. Washing conditions,
Table 1 shows the heat treatment conditions, the thickness of the formed oxide film, and the measured lifetime of the silicon wafer.

Example 3 The heat treatment conditions for forming an oxide film were 1000 ° C. and 50 ° C.
A 6-inch wafer boat was manufactured under the same conditions as in Example 1 except for the time. Table 1 shows cleaning conditions, heat treatment conditions, thickness of the formed oxide film, and measured lifetime values of the silicon wafer.

Example 4 A 6-inch wafer boat was manufactured under the same conditions as in Example 1 except that the heat treatment for forming an oxide film was performed at 1300 ° C. for 20 hours. Table 1 shows cleaning conditions, heat treatment conditions, thickness of the formed oxide film, and measured lifetime values of the silicon wafer.

Example 5 After a wafer boat product was obtained in the same manner as in Example 1, the obtained product was set in a diffusion furnace, and was placed under an oxygen atmosphere for 1200 hours.
Heat treatment was performed at 20 ° C. for 20 hours. As a result, an oxide film having a thickness of about 0.9 μm was formed. The wafer boat thus provided with the oxide film was used as a final product, and a test was performed in the same manner as in Example 1 to measure the lifetime value of the silicon wafer. Table 1 shows cleaning conditions, heat treatment conditions, thickness of the formed oxide film, and measured lifetime values of the silicon wafer.

Example 6 After a wafer boat product was obtained in the same manner as in Example 2, the obtained product was set in a diffusion furnace and heat-treated at 1200 ° C. for 20 hours in an oxygen atmosphere. By the heat treatment, an oxide film of about 1.0 μm was formed on the surface of the wafer boat.
The obtained final product was tested in the same manner as in Example 1, and the lifetime value of the silicon wafer was measured. Table 1 shows cleaning conditions, heat treatment conditions, thickness of the formed oxide film, and measured lifetime values of the silicon wafer.

Example 7 After a wafer boat product was obtained in the same manner as in Example 3, the obtained product was set in a diffusion furnace and kept at 1000 ° C. for 50 hours.
Heat treatment was performed in an oxygen atmosphere. A test was carried out in the same manner as in Example 1 by using a wafer boat on which an oxide film having a thickness of about 0.8 μm was formed by heat treatment as a final product. Table 1 shows cleaning conditions, heat treatment conditions, thickness of the formed oxide film, and measured lifetime values of the silicon wafer.

Example 8 After manufacturing a wafer boat product in the same manner as in Example 4,
This was set in a diffusion furnace and heat-treated at 1300 ° C. for 20 hours in an oxygen atmosphere. A wafer boat on which an oxide film having a thickness of about 2.1 μm was formed by heat treatment was used as a final product, and a test was performed in the same manner as in Example 1. Table 1 shows cleaning conditions, heat treatment conditions, oxide film thickness, and measured lifetime values of the silicon wafer.

Comparative Example 1 The same conditions as in Example 1 were used except that a mixed acid obtained by mixing a 10% by weight aqueous HF solution and a 10% by weight aqueous HNO ₃ solution (all of which were semiconductor grades) at a volume ratio of 1: 1 was used for acid cleaning. Produced a 6-inch wafer boat. Cleaning conditions, heat treatment conditions,
Table 1 shows the thickness of the formed oxide film and the measured lifetime value of the silicon wafer.

Comparative Example 2 Same as Example 1 except that a mixed acid obtained by mixing a 10% by weight aqueous solution of HF and a 10% by weight aqueous solution of H ₂ O ₂ (both semiconductor grades) at a volume ratio of 1: 1 was used for acid washing. Under these conditions, a 6-inch wafer boat was produced. Cleaning conditions, heat treatment conditions,
Table 1 shows the thickness of the formed oxide film and the measured lifetime value of the silicon wafer.

COMPARATIVE EXAMPLE 3 Heat treatment conditions for forming an oxide film were 800 ° C. and 100 ° C.
A 6-inch wafer boat was manufactured under the same conditions as in Example 1 except for the time. Table 1 shows the cleaning conditions, the heat treatment conditions, the thickness of the formed oxide film, and the measured lifetime of the silicon wafer.

Comparative Example 4 A 6-inch wafer boat was manufactured under the same conditions as in Example 1 except that the heat treatment temperature for forming an oxide film was 1350 ° C. Table 1 shows the cleaning conditions, the heat treatment conditions, the thickness of the formed oxide film, and the measured lifetime of the silicon wafer.

Comparative Example 5 A 6-inch wafer boat was manufactured under the same conditions as in Example 1 except that the heat treatment time for forming an oxide film was changed to 0.3 hour. Table 1 shows cleaning conditions, heat treatment conditions, thickness of the formed oxide film, and measured lifetime values of the silicon wafer.

Comparative Example 6 A 6-inch wafer boat was manufactured under the same conditions as in Example 1 except that the heat treatment time for forming an oxide film was changed to 250 hours. Table 1 shows cleaning conditions, heat treatment conditions, thickness of the formed oxide film, and measured lifetime values of the silicon wafer.

Conventional Example 1 A silicon carbide composite material having a Fe, Ni, and Cr content of less than 0.1 ppm, a Cu content of less than 0.2 ppm, and an Al content of less than 1 ppm (porous silicon carbide sintered material) A 6 inch wafer boat molded body formed by impregnating metallic silicon into a molded body made of a sintered body to impart gas impermeability) was machined in the same manner as in Example 1 to form a groove. Next, the grooved wafer boat was washed with an alkaline cleaning solution, then immersed in a 10% by weight aqueous solution of semiconductor grade HF, and washed for 60 minutes. next,
The acid-washed wafer boat is immersed in ultrapure water for 60 minutes.
The step of washing for 3 minutes was performed three times. Ultrapure water was replaced for each process. Further, under the same conditions as above, 10% HF
Washing and ultrapure water washing were repeated. After drying sufficiently in a clean booth, a wafer boat product was obtained. The obtained wafer boat was tested in the same manner as in Example 1. Table 1 shows the cleaning conditions and the measured lifetime values of the silicon wafer.

Conventional Example 2 The same conditions as in Conventional Example 1 were used except that a mixed acid obtained by mixing a 10% by weight aqueous HF solution and a 10% by weight aqueous HCl solution (each of which was a semiconductor grade) at a volume ratio of 1: 1 was used for acid cleaning. A 6-inch wafer boat was manufactured. Table 1 shows the cleaning conditions and the measured lifetime values of the silicon wafer.

As is clear from Table 1, in Examples 1 to 8, the wafer lifetime value is remarkably large as compared with the conventional example, and it is understood that the wafer boat product is cleaner. On the other hand, in Comparative Examples 1 and 2, the product surface Si
Eluted and the surface flatness was impaired. In Comparative Examples 3 and 5, since an oxide film having a sufficient thickness was not obtained,
A cleaner wafer boat product could not be obtained. In Comparative Example 4, a decrease in furnace life was observed because the temperature of the oxygen heat treatment was high. In Comparative Example 6, although a cleaner wafer boat product was obtained than before, a thicker oxide film was formed and removed, so that an error occurred in the dimensions of the wafer boat groove, and no suitable product was obtained.

[0046]

[Table 1]

[0047]

As described above, according to the present invention, a cleaner jig for a semiconductor can be manufactured. The jig with high cleanliness obtained by the present invention greatly contributes to the improvement of the manufacturing yield and the reliability of the semiconductor device.

Claims (3)

[Claims] 1. A method for manufacturing a jig for a semiconductor, wherein at least a surface layer portion contains metallic silicon or at least a surface layer portion is made of a material made of metallic silicon, wherein the jig has a shape required for the semiconductor jig. And a step of washing the molded body made of the material with hydrofluoric acid or a mixture of hydrofluoric acid and hydrochloric acid; and performing a heat treatment on the washed molded body in an oxidizing atmosphere so that the surface of the molded body has 0%. Forming an oxide film having a thickness of 1 μm to 5 μm; machining the molded body having the oxide film; and hydrofluoric acid or hydrofluoric acid and hydrochloric acid for the machined molded body. Cleaning method with a mixture of the above. 2. The method according to claim 1, wherein the step of forming the oxide film comprises:
Characterized by being carried out at a temperature of from 1C to 1300C.
A method of manufacturing the semiconductor jig according to claim 1. 3. After the step of washing the machined molded body with hydrofluoric acid or a mixture of hydrofluoric acid and hydrochloric acid, the molded body is subjected to a heat treatment under an oxidizing atmosphere to thereby form the molded body. The method for manufacturing a jig for a semiconductor according to claim 1, further comprising a step of forming an oxide film on a surface.