JP2001068424A - Material for semiconductor thermal process device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for a semiconductor thermal process device, together with its manufacturing method, which accompanies less contamination by impurity material. SOLUTION: The semiconductor thermal process material is an Si-SiC composite material comprising Si and SiC powder comprising an Si layer on at least one surface, with content of impurity metal in the Si layer of 2.5 ppm or less. When manufacturing it, an organic binder is added to the SiC powder for mixing before molding. Then at least one surface of the mold is allowed to contact an Si where the content of impurity metal is 2.5 ppm or less, which is heated to 1500-1700 deg.C in vacuum to provide a molten Si. This is allowed to penetrate into the mold while an Si layer is formed on its surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor heat treatment apparatus such as a diffusion furnace or a CVD furnace used in the steps of oxidizing a silicon wafer, diffusing a doping element, and forming a thin film in a semiconductor device manufacturing process. Used soaking tube,
In reaction tubes, boats, cantilevers, susceptors, etc.
The present invention relates to a material used for the method and a method for manufacturing the material.

[0002]

2. Description of the Related Art In a material for a heat treatment apparatus used in a semiconductor element manufacturing process, impurity metal contained in the material contaminates a silicon wafer or a semiconductor element to be processed to cause defects, thereby lowering a product yield. Cause. In order to prevent the contamination of the impurity metal, a high-purity quartz glass material or a high-purity silicon carbide material is used.

[0003] Of these, quartz glass materials have been widely used since they can be easily produced with high purity. However, when the heat treatment temperature is increased to 1100 ° C or more, the material is softened and deformed or devitrified (crystallized). In addition to the above, there is a possibility that a crack is generated and the bending strength is as small as about 6 kg / mm ² , so that it is easily broken and has a short service life.

On the other hand, a silicon carbide-based material cannot be as high in purity as a quartz glass-based material, but is stable even at a high temperature of 1200 ° C. or more, and has a flexural strength of 20 kg / cm not only at room temperature but also at high temperature. Since a material as high as ² mm2 or more can be obtained, there is an advantage that there is no fear of deformation, damage is less likely, and durability is long.

Therefore, it is used as a material for a diffusion furnace. As the material, silicon carbide powder (hereinafter referred to as S
A sintered body sintered with iC powder) and Si is used, and a method for producing the silicon carbide sintered body is disclosed, for example, in Japanese Patent Publication No. 54-10825.

[0006] SiC which is a raw material of this silicon carbide sintered body
Since powders are widely used as abrasives, powders classified in a narrow particle size range are commercially available, and are classified according to purity. We choose and use.

The SiC powder is a substance which is particularly excellent in corrosion resistance to corrosive substances such as acids, and has sufficient corrosion resistance to hydrofluoric acid, hydrochloric acid, nitric acid, and also to these mixed acids. Therefore, utilizing this property,
As disclosed in JP-A-158622,
The iC powder is washed with a mixed acid of hydrofluoric acid and nitric acid and pure water to remove impurities and to use a highly purified powder.

According to this method, it is possible to obtain a raw material powder of SiC containing impurities at a level of 15 ppm.
It is used, for example, in the production of high-purity silicon carbide materials for diffusion furnaces.

However, as the degree of integration of semiconductor devices such as LSIs and VLSIs increases, contamination of the element to be processed by the impurity metal further affects the yield of the product, so that there is a concern about the contamination by the impurity metal. There is a strong demand to use heat treatment equipment materials of even higher purity.

Therefore, as one measure, Japanese Patent Laid-Open No.
No. 282152 discloses that CV is added to the surface of a silicon carbide material.
A method is disclosed in which a dense film with high purity is formed by the method D, and this film is used as a barrier for preventing diffusion of the impurity metal to prevent contamination of the product by the impurity metal.

[0011]

However, although this method is an effective method, it is not easy to form a film without pinholes, and the film may be peeled off. There is a problem that it is extremely difficult to completely prevent diffusion of the impurity metal contained in the material.

Further, since an impurity metal is present in the inside of the CVD apparatus, the impurity metal may be taken in during the film formation, which causes a problem of lowering the yield.

Further, there is a method for further purifying the SiC powder used as a raw material with acid and pure water to further purify the SiC powder. In such a method, the impurity metal present on the powder surface can be removed by washing. If the inside of the SiC particles is newly exposed by machining or the like, there is a problem that the exposed portion may cause contamination by the impurity metal inherent in the inside of the particles.

The present invention has been made in view of the above-mentioned problems of the material for a semiconductor heat treatment apparatus, and has as its object to provide a material for a semiconductor heat treatment apparatus that is less contaminated by an impurity metal, and to provide a method for manufacturing the same. To provide.

[0015]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have penetrated high-purity Si into a compact made of SiC powder, and formed a surface of the Si layer. The present inventors have obtained the knowledge that a material for a semiconductor heat treatment apparatus with less contamination by impurity metals can be obtained if they are covered by the above, and have completed the present invention.

That is, the present invention relates to (1) Si-S comprising Si and SiC powder having a Si layer on at least one surface.
An iC composite material, wherein the content of the impurity metal in the Si layer is 2.5 ppm or less (claim 1).
After adding an organic binder to the C powder, mixing and shaping the same, at least one surface of the formed body is brought into contact with Si having an impurity metal content of 2.5 ppm or less, and it is heated in a vacuum to 1500 to 1500 ppm. The gist of the present invention is to provide a method for manufacturing a material for a semiconductor heat treatment apparatus, wherein a Si layer is formed on a surface while Si is heated and melted at a temperature of 1700 ° C. and penetrates into a molded body. I do. This will be described in more detail below.

As described above, the material for a semiconductor heat treatment apparatus according to the present invention is a Si—SiC composite material composed of Si and SiC powder having at least one Si layer on the surface, and an impurity in the Si layer. 2.5 metal content
It is a material for a semiconductor heat treatment apparatus to be less than ppm (claim 1).

This material is obtained by converting extremely high-purity Si into SiC
A Si layer is formed on the surface to be infiltrated at the same time as the Si layer is infiltrated into the molded body made of powder.
The layer suppresses the diffusion of impurities in the internal SiC powder, and becomes a material for a semiconductor heat treatment apparatus with extremely little contamination by impurity metals. And the formed Si layer is
Since it is formed continuously and connected to Si in the molded body, it does not peel off.

The content of the impurity metal in the Si layer is preferably 2.5 ppm or less in consideration of a decrease in yield due to contamination of the impurity metal in the manufacture of LSI.
It is still more preferable that the content is not more than ppm. The surface of the Si layer may be machined as long as the lower SiC powder is not exposed.

As a method for producing the material, an organic binder is added to the SiC powder, mixed, molded, and then, on at least one surface of the molded body, a Si metal powder having an impurity metal content of 2.5 ppm or less is formed. And heated in a vacuum at a temperature of 1500 to 1700 ° C. to melt S
A method of manufacturing a material for a semiconductor heat treatment apparatus, wherein i is penetrated into a molded body and a Si layer is formed on the surface at the same time (claim 2).

As described above, this manufacturing method allows extremely high purity, that is, molten Si having an impurity metal content of 2.5 ppm or less to penetrate into a compact made of SiC powder in a vacuum, and at the same time, to impregnate the surface with high purity. It forms a pure Si layer, and its permeation temperature is preferably 1500 to 1700 ° C., and if it is lower than 1500 ° C., a dense material cannot be obtained. A dense material cannot be obtained. Then, the evaporation of the Si remains as pores, that is, pinholes, in the Si layer on the molten surface, but does not remain as pinholes in the Si layer unless the Si is evaporated.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The production method of the present invention will be described in more detail. First, an SiC powder is prepared, an organic binder such as a phenol resin is added thereto, mixed, and molded by pressing or the like. A molded article is obtained by debinding. In order to make this compact into an appropriate shape,
It can be machined, which is also included in the present invention.

An ingot of Si having an impurity metal content of 2.5 ppm or less is brought into contact with the surface of the obtained molded body on the side on which it is used, and this is heat-treated at a temperature of 1500 to 1700 ° C. in a vacuum to a predetermined temperature. After holding for a time, the molten Si is allowed to penetrate into the molded body, and at the same time, a Si layer is formed on the surface, and then cooled to produce a material for a semiconductor heat treatment apparatus. A product made of a material for a semiconductor heat treatment apparatus can be manufactured by subjecting the formed Si layer to mechanical processing such as surface grinding and lapping. The thickness of the Si layer can be controlled to a desired thickness by controlling the Si penetration time.

When a material for a semiconductor heat treatment apparatus is manufactured by the above method, a material for a semiconductor heat treatment apparatus with less contamination by an impurity metal can be manufactured. .

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention and Comparative Examples.

(Example 1) (1) Preparation of material for semiconductor heat treatment apparatus SiC powder (GC # 800, manufactured by Shinano Electric Refining Co., Ltd.) 100
3 parts by weight of a phenol resin (BRL-101 manufactured by Showa Polymer Co., Ltd.) as an organic binder was added to the parts by weight, and mixed,
This was press-molded in a mold, and then debindered at 200 ° C. to obtain a 50 × 50 × 50 mm molded body.

On the upper surface of the obtained molded body, an ingot of Si having an impurity metal content of 1 ppm or less (manufactured by Nippon Denko KK)
And holding it in a vacuum at a temperature of 1600 ° C. for 3 hours, thereby infiltrating the molten Si into the molded body and simultaneously forming an Si layer on the surface, and then cooling it to produce a material for a semiconductor heat treatment apparatus. did.

(2) Evaluation The content of the impurity metal in the Si layer on the obtained material surface was analyzed. Further, the material was cut, and the state of the cross section was visually observed. Table 1 shows the results.

Comparative Examples 1 to 3 Comparative Examples 1 to 3
2, except that the permeation temperature of Si was outside the range of the present invention,
In Comparative Example 3, a material for a semiconductor heat treatment apparatus was produced in the same manner as in Example 1 except that the surface of Example 1 was ground to eliminate the Si layer. The analysis of the impurity metal was performed in Comparative Example 1,
2 was the same as in Example 1 and was not analyzed, and only the result of visual observation was evaluated. In Comparative Example 3, the evaluation was the same as in Example 1. The results are also shown in Table 1.

As is clear from Table 1, in Example 1,
The total amount of impurity metals in the Si layer on the surface was much less than 1 ppm. This indicates that if the surface of the composite material of Si and the SiC powder is covered with a Si layer containing an extremely small amount of impurity metal, the material can be used as a material for a semiconductor heat treatment apparatus with less contamination by the impurity metal.

On the other hand, in Comparative Example 1, many pores were generated in the material because the permeation temperature of Si was too low. Further, in Comparative Example 2, since the permeation temperature of Si was too high, many pores were also generated in this material. further,
In Comparative Example 3, a large amount of impurity metal was present on the surface.

[0032]

As described above, the material for a semiconductor heat treatment apparatus according to the present invention can be a material having a very low impurity metal content, so that contamination of the semiconductor element to be processed by the impurity metal is reduced. Now you can do it. This has made it possible to easily obtain a high-purity material for a heat treatment apparatus that does not reduce the product yield.

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/68 C04B 35/56 101S F-term (Reference) 4G001 BA22 BA62 BA71 BA78 BB22 BB62 BB71 BC17 BC33 BC46 BC47 BC52 BC54 BD38 BE11 5F031 CA02 DA13 EA01 HA02 HA03 HA62 HA63 MA28 PA26 5F045 AA03 AA20 BB14 EB03 EC05 EF11 EH08 EM09

Claims (2)

[Claims] An Si-SiC composite material comprising Si and SiC powder having at least one surface with a Si layer, wherein the content of the impurity metal in the Si layer is 2.5 ppm.
A material for a semiconductor heat treatment apparatus, comprising: 2. An organic binder is added to SiC powder,
After mixing and shaping the same, at least one surface of the shaped body has an impurity metal content of 2.5 ppm or less.
i. The material is heated at a temperature of 1500 to 1700 ° C. in a vacuum to infiltrate the molten Si into the molded body and simultaneously form a Si layer on the surface thereof. Method.