JPH0410904A - Mold and molding method - Google Patents

Abstract

PURPOSE:To mold a piece easily with a high purity, by providing a heat- resistant layer on a surface of the mold, and removing the heat-resistant layer after molding. CONSTITUTION:A mold 2 comprising a heat-resistant base material is enclosed in a reactor 4, which is evacuated down to a predetermined pressure by a vacuum pump 5. Then, the mold 2 is heated by a heater 6 to a predetermined temperature, and a gas for forming a heat-resistant layer 3 is supplied from a gas supply port 7, thereby forming the heat-resistant layer 3 by a CVD method. A gas for forming an objective molded piece is then introduced into the reactor 4 to deposit a molded piece layer 8 on the heat-resistant layer 3 by a vacuum deposition method or a CVD method. The mold 2 is immersed in water 9 contained in a thermostat 10, and is filled with a wet-etching agent 11. The etching agent permeates the mold 2 to make contact with the heat- resistant layer 3, thereby etching away the layer 3. When the mold 2 is pulled up, therefore, the objective molded piece 8 can be easily obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a mold material for producing a molded body, a method for producing a molded body,
In particular, the present invention relates to a mold material for obtaining high-purity molded bodies of metals, ceramics, etc., and a method for manufacturing molded products using the molded material.

(Prior art) Conventionally, semiconductor processing jigs and melting crucibles have been manufactured by coating various metals and ceramics on a mold made of heat-resistant material such as carbon along the shape of the mold by vapor deposition or CVD. For example, pyrolytic boron nitride (PBN)
PBN is formed on a carbon family crucible-shaped mold material by low-pressure thermal CVD method, and PBN is produced from this mold material.
This is done by separating the molded bodies, and in this case, since the adhesion between carbon and PBN is small,
The molded body can be separated from the mold material relatively easily.

(Problems to be Solved by the Invention) However, when producing a molded body using the method described above, it is often difficult to separate the mold material from the molded body. When a silicon carbide (SiC) film, which is widely used in various fields, is formed on a carbon group mold material by the CVD method, carbon and S
Separation is difficult due to the strong adhesion between iC and SiC, and in order to obtain the desired SiC molded product, the carbon group mold material must be mechanically destroyed and removed, or the carbon group mold material must be burned in an oxygen atmosphere. This has the disadvantage that the mold material cannot be reused due to the need to remove it, and that the carbon diffuses during combustion of the mold material and contaminates the molded body as this carbon gets mixed in with the SiC molded body. be.

(Means for Solving the Problems) The present invention relates to a mold material for manufacturing a molded object that solves the above-mentioned disadvantages, and a method for manufacturing a molded object using the same. A molding material for producing a molded body, which is provided with a heat-resistant layer that can be wet-etched, and a vapor deposition method or C
The present invention relates to a method for manufacturing a molded body, which comprises forming a molded body by a VD method, removing a heat-resistant layer by wet etching, and then separating the molded body from a mold material.

That is, as a result of various studies conducted by the present inventors on methods for easily obtaining a molded article with high purity using a molding material, the inventors found that although there are various problems in separating the molding material and the molded object, According to this method, the mold material and the molded body can be easily separated by using a molded body provided with a heat-resistant layer that can be removed after forming the molded body, and by removing only this heat-resistant layer after forming the molded body. It has been discovered that the mold material can be reused and that contamination of the molded body due to processing of the mold material can be avoided, and this heat-resistant layer can be wet-etched, for example, using silicon (Si), By using silicon oxide (SiO2) and removing it by wet etching after forming the molded object, it was confirmed that the desired molded object could be easily obtained with high purity. The present invention was completed by conducting research on the types of layers, forming methods, and methods for removing heat-resistant layers.

This will be explained in more detail below.

(Function) The present invention relates to a mold material for producing a molded body and a method of manufacturing a high-purity molded body made of metal, ceramics, etc. using this mold material.

The mold material of the present invention must be made of a heat-resistant base material because a molded body is formed thereon by a vapor deposition method, a CVD method, or the like. Therefore, it is carbon, a mixture of carbon and silicon (Si), and silicon (Si) and silicon carbide (S).
iC), but when the molded body is made of silicon carbide (SiC), it is preferably of the carbon group.

The shape of this mold material can be arbitrary depending on the shape of the intended molded product, but for example, it can be boat-shaped, plate-shaped, or disc-shaped for semiconductor process jigs, and crucible-shaped for metal melting. And it is sufficient. As will be described later, this mold material has a heat-resistant layer formed on its surface that can be wet-etched, and this heat-resistant layer must be removed by wet etching afterward, so it is assumed that the wet etching solution will penetrate. For this purpose, it is preferable to use a material with a high porosity, so it is preferable to use a material with a porosity of at least 1% or more.

Next, this mold material is provided with a heat-resistant layer that can be wet-etched in order to facilitate separation from the molded product formed on it. Since the body is formed by vapor deposition or CVD, it must be highly heat resistant to withstand this process. can be anything.

However, it itself has excellent heat resistance, and potassium hydroxide (KOH) and sodium hydroxide (NaO)
Silicon metal (Si) is easily etched when it comes into contact with an aqueous alkaline solution such as 1), and this etching rate increases as the temperature increases.Also, it has excellent heat resistance and can be easily etched even at room temperature when it comes into contact with an aqueous hydrofluoric acid solution. Preferred examples include silicon oxide (S402) etched by etching. Note that the heat-resistant layer that can be wet-etched may be formed by a known CVD method, plasma CVD method, sputtering method, etc., but the thickness of this heat-resistant layer is determined by uniformly coating the surface of the mold made of the heat-resistant base material. There is no particular limit as long as you have - 5 to 100μ for boat fishing.
It may be within the range of −.

The production of the molded body according to the present invention uses the mold material for manufacturing the molded body provided with the heat-resistant layer that can be wet-etched as described above, and metal or ceramic is deposited on the heat-resistant layer by vapor deposition or CVD. For example, metal products such as aluminum and copper can be formed using a vapor deposition method, and silicon carbide (SiC) can be formed using a CVD method.
Ceramic products such as silicon nitride (Sf3N4), boron nitride (BN), and carbon (C) can be molded, but silicon carbide (SiC) can be used for semiconductor process jigs and metal melting crucibles. good.

The molded body thus produced is then peeled off from the mold material and used as the desired molded body, but in the present invention, since the molded body is formed on the heat-resistant layer that can be wet-etched as described above, First, it is necessary to remove this heat-resistant layer by wet etching. If this heat-resistant layer is removed by wet etching, the mold material and the molded object are not in direct contact with each other, so the molded object can be easily peeled off from the mold material. In this case, the mold material is not subjected to any treatment, so that the molded product will not be contaminated due to the treatment of the mold material and its high purity will not be impaired.

Next, this will be explained based on the attached drawings. FIG. 1 is a longitudinal cross-sectional view of a mold material for producing a molded article according to the present invention, in which a wet-etchable heat-resistant layer is provided on the mold material. FIG. 2 is a longitudinal cross-sectional view of an apparatus for forming a molded product on this mold material. FIG. 3 shows a vertical cross-sectional view of an apparatus for wet etching a heat-resistant layer. The mold material 1 for producing a molded body in FIG. 1 is made of conventionally known carbon, a mixture of carbon and silicon, A wet-etchable heat-resistant layer 3 made of silicon metal or silicon oxide is coated on a crucible-shaped mold material 2 made of a heat-resistant base material such as a mixture with silicon carbide by CVD or the like. It is formed by attaching it to the surface.

The reaction device 4 in FIG. 2 is made of quartz, for example, and a mold material 2 is installed therein, and in order to form a heat-resistant layer 3 on the mold material 2 that can be wet-etched, it is heated in a predetermined manner by a vacuum pump 5. After reducing the pressure to a certain pressure, it is heated to a predetermined temperature by the heater 6, and a gas body for forming the heat-resistant layer 3 is supplied from the gas supply lower, and this CV
A heat-resistant layer 3 is formed by the D method, and then a gas body for forming the desired molded body is introduced therein, and the vapor deposition method or the C method is applied.
The molded body layer 8 may be formed on the heat-resistant layer 3 by the VD method.

Further, the molded material 2 obtained in this manner with the heat-resistant layer 3 and the molded body layer 8 provided thereon is then placed in water 9 contained in a constant temperature bath 10 as shown in FIG. When the wet etching agent 11 is filled into the mold material 2, this etching agent permeates through the mold material 2 and comes into contact with the heat-resistant layer 3, thereby etching and dissolving the heat-resistant layer 3.
By pulling up the molded body 8, the desired molded body 8 can be easily obtained.

(Example) Next, examples of the present invention will be given.

Example A hollow carbon base material IG-11 [manufactured by Tokai Carbon Co., Ltd., trade name] was placed in the quartz reactor 4 shown in FIG.
A crucible-shaped mold material 2 made of
The temperature inside the apparatus was raised to 1,100°C.

Next, hydrogen gas for dilution was supplied into the apparatus for 3 minutes, and then trichlorosilane (H5iCJ2s) gas was supplied for 0.5127 minutes through a bubbler together with hydrogen gas as a carrier gas at 1.21 t/minute. 3
When the reaction was allowed to proceed for 0 minutes and diluted hydrogen gas was supplied for 10 minutes after the reaction was completed, a molded body as shown in Fig. 1 was obtained, in which a metal silicon film was deposited as the heat-resistant layer 3 to a thickness of 10 μm on the mold material. Manufacturing mold material 1 was obtained.

In addition, after raising the temperature of this reactor 4 to 1,300°C, diluted hydrogen gas 3J2/min was supplied for 3 minutes, and then methyltrichlorosilane (CHs
0.5j2/min of SiCf s) gas was supplied together with 1.2117 min of hydrogen gas as a carrier gas to react for 120 minutes, and after the reaction was completed, diluted hydrogen gas was supplied for 10 minutes and then cooled to room temperature. Body manufacturing mold material 1
A silicon carbide molded body layer 8 was molded to a thickness of 100 μm on the heat-resistant layer 3 . Next, the mold material 1 for producing a molded body on which the silicon carbide molded body layer 8 has been formed is taken out from the apparatus and placed in a constant temperature bath 10 as shown in FIG. When 500 g of a 25% by weight aqueous sodium hydroxide solution as the wet etching agent 11 was injected into the mold material 2 and held for 6 hours, the sodium hydroxide solution permeated the mold material and came into contact with the heat-resistant layer 3, dissolving it. Therefore, when only the mold material 2 was pulled up, it could be easily separated from the molded article 8, and a crucible-shaped silicon carbide molded article 8 could be obtained.

In addition, when the silicon carbide film crucible obtained in this way was quantitatively analyzed for the amount of impurity elements by ICP emission spectrometry, the amount of impurities was Fe, ^bu, Na, Mg.
, B, C%P, Cu%Y, Bi are all 0.
It was confirmed that the purity was 01ppa+ or less, and that the purity was extremely high.

(Effects of the Invention) The present invention relates to a mold material for producing a high-purity molded body made of metal, ceramics, etc., and a method for manufacturing a molded body using the same. A mold for producing a molded body, which is formed by providing a wet-etchable heat-resistant layer on a mold material, and a molded body is formed on the heat-resistant layer of this mold material by a vapor deposition method or a CVD method, and then wet-etched. This relates to a method for producing a molded body, which is characterized by removing the heat-resistant layer and then separating the molded body from the mold material. According to this method, the heat-resistant layer provided on the mold material for manufacturing the molded body is removed by wet etching. The molded body and mold material can be easily separated, and in this case, there is no need for post-treatment of the mold material, so the molded body is not contaminated by the IA coral of the mold material. In addition to being able to easily obtain the desired molded product with high purity, the mold material has the advantage of being able to be used repeatedly.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a mold material for producing a molded object according to the present invention, FIG. 2 is a longitudinal sectional view of an apparatus for forming a molded object on this mold material, and FIG.
The figure shows a longitudinal sectional view of a wet etching apparatus used in the method of the present invention. Top...Mold material for molded body production 2...Mold material 3...Heat-resistant layer 4...Reactor 5...Vacuum pump
6... Heater 7... Gas supply port 8.
...Molded body layer 9...Water -10...Thermostatic bath 11...Wet etching agent Patent applicant Shin-Etsu Chemical Co., Ltd. agent/patent attorney Ryo Yamamoto - 〃 〃 Kaneji Arai 7'Z No. h Section map

Claims (1)

[Scope of Claims] 1. A molding material for producing a molded body, characterized in that a heat-resistant layer that can be wet-etched is provided on a molding material made of a heat-resistant base material. 2. The mold material for producing a molded object according to claim 1, wherein the heat-resistant substrate is made of carbon, a mixture of carbon and silicon carbide, or a mixture of silicon and silicon carbide. 3. Heat-resistant layer that can be wet etched is silicon (Si)
or silicon oxide (SiO_2). 4. A heat-resistant layer that can be wet-etched is provided on a mold made of a heat-resistant substrate, a molded body is formed on this heat-resistant layer by vapor deposition or CVD, and then the heat-resistant layer is removed by wet etching. A method for producing a molded body, which comprises: then separating the molded body from the mold material. 5. Heat-resistant layer that can be wet etched is silicon (Si)
5. The method for manufacturing a molded body according to claim 4, wherein the Si layer is removed by etching with an alkaline aqueous solution. 6. The wet-etchable heat-resistant layer is made of silicon oxide (S).
iO_2), and this SiO_2 layer is removed by etching with an aqueous hydrofluoric acid solution. 7. The molded body is made of metals such as aluminum and copper by vapor deposition method, or silicon carbide (Si) by CVD method.
C), silicon nitride (Si_3N_4), boron nitride (B
5. The method for producing a molded body according to claim 4, wherein the molded body is made of ceramics such as N) and carbon (C).