JPH01115888A - Production of jig for producing semiconductor - Google Patents

Abstract

PURPOSE:To obtain a jig for producing a semiconductor without exudation of metallic silicon, by forming a carbonaceous film on the surface of a calcined body member of porous silicon carbide before filling metallic silicon in filling thereof into open cells of the calcined body member of porous silicon carbide. CONSTITUTION:Silicon carbide powder having <=5mum average particle diameter is formed into a desired shape and the resultant green compact is calcined in a nonoxidizing atmosphere (e.g. nitrogen gas) to afford a porous silicon carbide member having a three-dimensional network skeleton. At least one surface of the resultant porous silicon carbide member is then coated with a carbonaceous material (e.g. phenolic resin), which is then carbonized in a nonoxidizing atmosphere to form a carbonaceous film. Thermally melted metallic silicon is subsequently filled in open cells of the porous compact and the carbonaceous film is heated and removed in an oxidizing atmosphere to provide a jig for producing semiconductors.

Description

Detailed Description of the Invention (Field of Application in the Je Industry) The present invention is applied to semiconductor manufacturing, which is housed in a high-temperature furnace and used as a support for silicon wafers, etc., for manufacturing semiconductor elements for the electronic industry. This article relates to the manufacturing method of jigs for the electronics industry, especially for applications that require gas impermeability, such as process pipes used for semiconductor diffusion and oxidation, and wafers. The present invention relates to a method for producing a silicon carbide G1 composite material that can easily produce a silicon carbide composite material free from silicon exudation and suitable for applications requiring strength such as ports.

(Prior Art) Conventionally, this type of semiconductor manufacturing jig for the electronic industry has been made of, for example, quartz, carbon with silicon carbide waves formed on the surface of a graphite base material, silicon carbide composite, or carbide. Composites made of a silicon molded body filled with metallic silicon are known, and are used depending on their respective uses.

However, the quartz-based semiconductor manufacturing jig described above has poor heat resistance and is susceptible to softening and deformation during use.

In addition, carbon with a silicon carbide coating formed on the surface of the graphite base material,
Since the silicon carbide composite is produced by a method such as subjecting a graphite base material to a high temperature treatment in a halogen gas atmosphere in advance, a large amount of treatment cost is required and it is not economical.

Recently, a silicon carbide composite material in which metallic silicon is filled into the open pores of a porous silicon carbide sintered body member has been developed and used as a material that can solve these drawbacks.

The silicon carbide composite material described above is generally filled with metallic silicon by being immersed in a molten state into the open pores of a porous silicon carbide sintered body member. However, since the metal silicon undergoes physical expansion during solidification, a part of the metal silicon once impregnated oozes out from the porous silicon carbide sintered body member during cooling and curing after impregnation, resulting in a metal silicon layer on the surface layer. There was a drawback that it generated and adhered.

Methods for producing a silicon carbide composite material without a metal silicon layer on the surface layer as shown in L include, for example, a method of mechanically removing the metal silicon layer on the surface layer, or a method of boiling and dissolving it in an aqueous sodium hydroxide solution. There are known methods for removing it.

A method of manufacturing such a semiconductor manufacturing jig is, for example, disclosed in Japanese Patent Application Laid-open No. 51-85374, which includes an r process tube, a paddle having a size and shape that can be inserted into the tube, and at least one paddle that is supported by the paddle. a boat-shaped container, the process tube, paddle and boat are mainly composed of a sintered silicon carbide matrix containing 5-30% by weight of high purity silicon metal, and the silicon metal is connected to the tube, paddle and boat. A semiconductor diffusion furnace made of a container that is made gas impermeable. ” is disclosed.

However, in the case of JP-A-51-85374, the sintered silicon carbide matrix described in the publication is recrystallized silicon carbide, and since relatively coarse silicon carbide particles are used as the starting material, the surface roughness is low. It has been difficult to produce large sintered bodies that require complicated shapes and dimensional accuracy without special machining. Also,
It has been difficult to provide at a low cost a jig for manufacturing semiconductors, which is mainly made of high-purity semiconductors, is free from product contamination, has excellent heat resistance, and has excellent thermal conductivity and thermal shock resistance.

Therefore, the present inventor has developed a tool that can be made into a more complex shape than the previously known semiconductor jigs as described above, has particularly excellent thermal conductivity, good thermal uniformity, and fast thermal response. As a result of various research efforts to develop semiconductor manufacturing jigs with excellent chemical resistance, we have succeeded in manufacturing the necessary semiconductor manufacturing jigs by forming a coating layer made of silicon on the surface. It was completed after discovering new things that could be done.

Note that various methods can be applied to form a coating layer made of silicon on the surface. For example, (a) chemical vapor deposition method in which a film is formed by reducing silicon tetrachloride with hydrogen; (b) physical vapor deposition method in which a film is formed by heating metal silicon in vacuum with an electron beam; (C) molten metal silicon (d) A method in which metal silicon and a carbonaceous substance that remains in the carbon state when heated are dispersed in an organic solvent are applied and heat fused by applying a slurry. be.

When using the dip method in (c) above, a carbonaceous substance that can be left in the carbon state during impregnation is applied in advance to the surface of the porous silicon carbide sintered body member in order to facilitate the adhesion of molten silicon. A method is disclosed. The semiconductor manufacturing jig obtained by the L-length method in the dip method is
After being appropriately fired under predetermined conditions, the contact surface with the silicon wafer is polished with abrasive grains to adjust the surface roughness to a predetermined value.

In this case, when dipping the metal silicon, it is important to be able to process the immersed metal silicon uniformly and accurately on the silicon carbide member even when dipping either the upper or lower part, especially when the part is complex and large. It is very difficult to

In order to satisfactorily impregnate metallic silicon, it is necessary to perform the treatment under uniform temperature distribution. However, for the complex and large materials mentioned above, it is impossible to reduce the temperature distribution in the furnace in a uniform state during impregnation with metallic silicon, especially during the cooling process, and precipitation is particularly observed on the inner surface. Furthermore, it is also very difficult to control the process using atmospheric gas and feed gas. If metal silicon is impregnated too much, it will precipitate and fuse unevenly and excessively on the surface of the porous silicon carbide sintered body, requiring a great deal of effort in polishing the surface roughness after firing, and making it difficult to use semiconductor manufacturing jigs. This seems to be inappropriate from an economic point of view as a manufacturing method. Furthermore, since more polishing is required, it becomes difficult to ensure purity as a jig for semiconductor manufacturing.

(Problems to be Solved by the Invention) However, all of the above-mentioned methods require a step for removing the metal silicon layer once formed, and are not only as complicated as 2R, but also The latter method of mechanically grinding away is particularly difficult in manufacturing jigs with complex shapes, while the latter method of boiling in an aqueous sodium hydroxide solution tends to leave sodium in the jigs, especially when This method is not suitable for use in jigs that require high purity.

As a result of various studies to solve the above-mentioned problems, the present invention has been developed to extremely easily remove metallic silicon equivalent to the amount that oozes out from a porous silicon carbide sintered body member during cooling from a silicon carbide composite material during the solidification process. The object of the present invention is to provide a method for manufacturing a semiconductor manufacturing jig that can obtain a silicon carbide composite material without oozing of metal silicon.

(Means for solving the problem) According to the present invention, silicon carbide powder is molded into a green body, and after sintering the green body in a non-oxidizing atmosphere, the resulting porous A method for manufacturing a silicon carbide-based composite material by filling open pores of a silicon carbide sintered body member with metallic silicon, which comprises melting and impregnating at least the open pores of the porous silicon carbide sintered body member. By coating the surface of the porous silicon carbide sintered body member with a carbonaceous material in advance before filling, it is possible to produce a silicon carbide-based composite material that does not seep out of metallic silicon.

Next, the present invention will be explained in detail.

According to the present invention, before melting and impregnating and filling the open pores of the porous silicon carbide sintered body member with metal silicon, the porous I! It is necessary to coat the silicon carbide sintered body member with an R1 substance.

The reason for this is that when the porous silicon carbide sintered body member is impregnated with metal silicon, the metal silicon exists in a molten state in the open pores of the sintered body, but when it is cooled, the sintered body surface By forming a dense carbon film with the carbonaceous material coated in the! This is because it is possible to prevent seepage from the porous silicon carbide sintered body member due to hardening.

Incidentally, the surface carbonized film of the porous silicon carbide sintered body member after solidifying the metallic silicon can be easily removed without using special means by heating in an oxidizing atmosphere.

According to the present invention, compared to the conventionally known porous silicon carbide sintered body member that uses silicon carbide powder with an average particle size of 5 pm or less to form a formed body, it has a lower density and is easier to handle. It is important to produce a porous body with high strength, and when molding is performed by pressure molding, silicon carbide powder as a starting material is uniformly dispersed in a dispersion medium together with a deflocculant, and then
It is advantageous to use freeze-dried silicon carbide powder, and when molding the resulting body by casting, the silicon carbide powder as a starting material is uniformly dispersed in a dispersion medium together with a deflocculant. It is advantageous to use solid suspensions, as it is possible to produce a product form in which the individual particles of the powder are present in a very homogeneous distribution, so that the three-dimensional network structure of the crystals can be very fine and This is because it can be developed uniformly, and a porous body with low density and high strength can be manufactured. Furthermore, as a specific means for uniformly dispersing the silicon carbide powder in the dispersion medium, it is advantageous to use a dispersion means that can sharpen strong shearing force, such as a vibration mill, attritor, ball mill, colloid mill, and high-speed mixer. It is.

According to the present invention, the silicon carbide powder is uniformly dispersed in the dispersion medium.
It is advantageous to quickly freeze the suspension by spraying it into an atmosphere maintained at a temperature below the melting point of the dispersion medium.

According to the present invention, the sintering temperature is set at 1400 to 2100°C.
It is necessary to do so. The reason is that the temperature is 14
If the temperature is lower than 2100°C, it is difficult to sufficiently develop the neck that connects each grain, making it impossible to obtain a porous body with high strength. This is because necks smaller than a certain size may become constricted or, in severe cases, disappear, resulting in a decrease in strength.

According to the present invention, the formed body is made of at least one selected from argon, helium, neon, nitrogen, hydrogen, and carbon oxide in a non-oxidizing atmosphere that does not oxidize silicon carbide. It is fired in a gas atmosphere or in a vacuum.

According to the invention, it is advantageous for the green body to be fired in a non-oxidizing atmosphere without substantial shrinkage.

The reason for this is that shrinkage during sintering is desirable for improving the strength of the porous body, and shrinkage during sintering reduces open porosity and tends to cause pores to become independent, making it difficult to fill with metallic silicon. This is because it is difficult to produce a porous body with high dimensional accuracy by causing firing shrinkage.

According to the present invention, in order to obtain a porous body that is easy to fill with metallic silicon and has high dimensional accuracy, the firing shrinkage rate when sintering without substantially shrinking is 2% or less. is preferable, and more preferably 1% or less.

Further, according to the present invention, when firing the green body, it is advantageous to suppress volatilization of silicon carbide from the green body. The reason for this is that by suppressing the volatilization of silicon carbide from the formed body, necks that connect silicon carbide grains can be sufficiently developed, resulting in particularly high strength and excellent handling properties. When manufacturing a porous body, it is advantageous to control the volatilization rate of silicon carbide to 5% by weight or less.

An effective method for suppressing the volatilization of silicon carbide from the formed body is to insert the formed body into a heat-resistant container that can block the intrusion of outside air, and the heat-resistant container includes: It is preferable to use a heat-resistant container made of a material such as graphite or silicon carbide.

According to the present invention, it is necessary to impregnate or coat a carbonaceous material in order to efficiently impregnate a low-density, high-strength porous body without precipitating excess metallic silicon. Conventionally, the purpose of impregnating or coating with a carbonaceous material was to facilitate the adhesion of molten silicon to the surface of a porous sintered body as a silicon carbide member. However, according to the present invention, the carbonaceous material is used not only for the above purpose but also for preventing the precipitation of excessive metallic silicon according to the present invention. In particular, when used as a jig for semiconductor manufacturing such as a wafer port, the surface of the jig that can come into contact with the wafer boat should preferably have a surface roughness of Rm.
It is necessary to satisfy a x≦154m. For this purpose, it is necessary to prevent precipitation even in metal silicon impregnation, and to manufacture the product without impairing purity during polishing.

Specifically, it is necessary to impregnate or coat the surface of the silicon carbide sintered body member with a carbonaceous material so as to form a carbonized film of 0.4 to 1.0 mm.

According to the present invention, 0.4 to 1.0 mm is required, and increasing the thickness beyond this not only increases the effort of impregnating and coating the carbonaceous material, but also increases the amount of carbonaceous material used when impregnating the carbonized film and silicon. Alternatively, the carbonized film may fall off, inhibiting the formation of a uniform carbonized film.

Examples of carbonaceous substances include phenolic resin.

Various organic substances such as lignin sulfonate, polyvinyl alcohol, corn starch, molasses, coal tar pitch, alginates, etc., or car, bomb black, etc.
Pyrolytic carbons such as acetylene black and the like can be advantageously used. Furthermore, the above organic substances and pyrolytic carbon may be used in combination.

The silicon carbide sintered body member impregnated with or coated with the carbonaceous material is dried at 60 to 80°C. This is to dry and remove the solvent used to adjust the carbonization rate and viscosity in order to form a properly specified carbonized film depending on each material during impregnation or coating with a carbonaceous material. Further, there is no problem even if the entire surface of the silicon carbide sintered member is coated. However, when impregnating with metallic silicon by the dip method, it is necessary to provide an uncoated portion as an impregnation opening for molten silicon.

According to the present invention, the dried silicon carbide sintered member is fired and carbonized in a non-oxidizing atmosphere. The firing temperature is
It is preferable to maintain the temperature at around 200 to 300°C and then raise the temperature to 950°C or higher. This is because, in order to sufficiently carbonize the carbonaceous material, a carbonized film can be formed uniformly by maintaining the temperature sufficiently near the thermal decomposition temperature of the carbonaceous material. Further, it is preferable that the temperature increase rate up to 300°C be relatively slow. This is because if the temperature increase rate is increased, foaming occurs during carbonization of the carbonaceous material, making it impossible to obtain a uniform carbonized film, and the foaming becomes noticeable in softening materials. The carbonized film formed by carbonization of the carbonaceous material prevents the metal silicon impregnated on the porous surface of the silicon carbide member from precipitating from the surface of the molten silicon, so it is necessary to sufficiently fill the surface pores. The effect cannot be demonstrated.

According to the present invention, it is necessary to fill 45 to 135 parts by weight of the metal silicon with respect to 100 parts by weight of silicon carbide constituting the jig. The reason for filling the metal silicon is that metal silicon has good compatibility with silicon carbide, and by filling the open pores of the porous body with metal silicon, the strength can be improved. Because it has excellent conductivity, by filling the open pores of a porous body with metal silicon, it can be used as a semiconductor manufacturing jig that provides high thermal conductivity and gas impermeability. . Further, the reason why it is advantageous to set the filling amount of the metal silicon to 45 to 135 parts by weight is that if the filling amount of the metal silicon is less than 45 parts by weight, the semiconductor manufacturing jig has high thermal conductivity. However, the upper limit of the filling amount is determined by the open porosity of the porous body.

More preferably, the filling amount of the metal silicon is 55 parts by weight or more.

As a method for filling the open pores of the porous body with the metal silicon, a method of heating and melting the metal silicon to impregnate the porous body can be used.

According to the invention, it is necessary to remove residual carbonized substances from the metal-silicon impregnated body. In the silicon impregnation, carbide to prevent excessive silicon precipitation remains on the impregnated body surface. During impregnation, a portion of the interface between the carbide and the porous body is converted into silicon carbide, but most of the carbide remains as a residue.

According to the present invention, as a method for removing carbides, a method of oxidation removal in an oxidizing atmosphere or an applied oxidation temperature is as follows:
Advantageously, the temperature is between 800 and 950'C. The reason for this is that if the treatment is performed at temperatures below 800°C, the oxidation rate of the carbide film will decrease, resulting in a longer oxidation time.
If the temperature is 50° C. or higher, silicon carbide, which is a member, will be oxidized, which is not preferable.

When the porous silicon carbide sintered body member is impregnated or coated with a carbonaceous material and the dried member is carbonized and impregnated with metallic silicon, the heat treatment may be performed in the same container.

The present invention will be explained below with reference to Examples and Comparative Examples.

(Example) The silicon carbide powder used as the starting material was a silicon carbide powder consisting of 97.5% by weight β-type crystals and the remainder substantially 2H-type crystals, and had a mass of 0.12% by weight. % free carbon, 0.3
7% oxygen.

1.2XlO-'wt% iron, 1.4xlO-'wt%
of calcium, s x l 0-13% sodium, 1X10-' weight % potassium, and trace amounts of aluminum, and had an average particle size of 1.1 gm.

5 parts by weight of polyvinyl alcohol, 0.3 parts by weight of monoethanolamine, and 100 parts by weight of water were blended with 100 parts by weight of the silicon carbide powder, mixed in a ball mill for 5 hours, and then freeze-dried.

An appropriate amount of this dry mixture was taken, granulated, and then formed into a green body using an isostatic press at a pressure of 1300 kg/c rn'. The shape of this generated form is 18
It had a cylindrical shape of 0Φ×160Φ and a length of 1700L, and the density was 1.73g/crn' (54% by volume).

The formed body was inserted into a graphite crucible and sintered in a Tamman type sintering furnace in an atmosphere of mainly argon gas at 1 atm. The temperature was raised to 700°C at a rate of 600°C/hour, then to 1950°C at a rate of 300°C/hour, and the maximum temperature was maintained at 1950°C for 10 hours. The CO gas partial pressure during sintering was at room temperature. ~1700℃ is 80Pa or less, 1700℃
The argon gas flow rate was appropriately adjusted and controlled so that the temperature was within the range of 300±50 Pa in the higher temperature range than ℃.

The obtained sintered body is a porous body with a density of 1.70 g/crn', an open porosity of 47% by volume, and a content of β-type silicon carbide of 92% by weight, with the remainder being mainly 4H-type. 6H type α
It was silicon carbide. In addition, this crystal structure was observed using a scanning electronic time mirror and was found to have a three-dimensional structure in which block-shaped silicon carbide crystals or relatively thick necks are connected in a complex manner. The linear shrinkage rate for the shape is 0.3±0.1% in either direction.
Within the range, the average bending strength of this sintered body is 13.8 kg
/'mrrT' and has a high strength of 3xlO-'
It contained by weight % aluminum, 6 x 10-' weight % iron, and 4 x lO-' weight % nickel. In addition,
The contents of chromium, calcium, and copper were all in trace amounts, and both sodium and potassium were less than 1xlO-'% by weight.

Then, a silicon carbide member made of one or more porous silicon carbide sintered bodies is prepared.

Next, the inner surface of the porous silicon carbide sintered body member was coated with a hardening phenol resin (solid content 45%) using a brush, and then dried in a dryer at 60° C. for 10 hours to obtain a coating after drying. The thickness was 1 mm.

Next, the silicon carbide member coated with phenol was heated at a heating rate of 60°C/hour for 300°C in an argon gas flow.
'C and held for 1 hour, then heated to 500°C at a heating rate of 120°C/hour, then to 1000°C.
The phenol coated on the surface of the porous silicon carbide sintered member was carbonized by heating to a maximum of 950° C./hour. The thickness of the inner carbonized film after the carbonization treatment was approximately 0.5 mm.

Next, each silicon carbide member has a purity of 99.9999.
% or more by weight of metallic silicon is placed in a heating furnace, heated in an argon gas stream at a heating rate of 600°C/hour, and held at a maximum temperature of 1600°C for about 12 hours to sinter the porous silicon carbide. Metallic silicon was infiltrated into the body member to obtain a silicon carbide composite.

The obtained composite was heated at 950° C. for 10 hours in an oxidizing atmosphere to undergo oxidation treatment.

The obtained silicon carbide composite has extremely good surface properties, with no metal silicon being observed at all due to seepage of metal silicon into the inner surface layer.

The porosity is 2% and gas impermeable, the dimensions are only 0.3 mm larger than before filling with metal silicon, and the average bending strength is 32. It had a strong thermal conductivity of 1 kg/mrn' and an extremely good thermal conductivity of 0.23 cal/cm·sea°C, and was recognized to be extremely suitable for use as a semiconductor manufacturing jig.

Example 2 Same as Example 1, but by changing the thickness of the carbonized film made of phenol resin as shown in Table 1, metal silicon was allowed to penetrate into the open pores of the porous body.

Example 3 Same as Example 1, but metal silicon was allowed to penetrate into the open pores of the porous body by coating both sides with a carbonized film of phenol resin. The obtained silicon carbide composite material had extremely good surface properties, with no oozing of metallic silicon observed on either side.

The process is the same as in Example 1, but the surface of the sintered body member obtained by sintering the formed body using a Tammann furnace is infiltrated with metallic silicon without coating with phenol resin, and silicon carbide is formed. Obtained a complex. In the obtained silicon carbide composite, a metal silicon layer was formed on the inner surface due to seepage of metal silicon.

All of the silicon carbide composite materials obtained had extremely good surface shapes, with no oozing of metal silicon observed at all, except for those obtained in comparative examples.

(The following is a blank space) Table 1 (Effects of the invention) As detailed above, in the method for manufacturing a semiconductor manufacturing jig according to the present invention, a heat-resistant jig for electronics, for example, semiconductor diffusion, It is possible to easily manufacture silicon carbide semiconductor manufacturing jigs that do not bleed silicon and are suitable for uses such as process tubes and wafer boards used in acid treatments, etc., without requiring any special treatment. There are things that can be done that are extremely useful for industry.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a state in which a cylindrical porous silicon carbide body is erected and a carbon film is formed on the inner surface, and Fig. 2 is a state in which a rod-shaped porous silicon carbide body is erected. Fig. 3 is a vertical cross-sectional view showing a state in which a carbon film is formed on the surface of a silicon carbide porous material having a large number of cuts, and a longitudinal cross-sectional view showing a state in which a carbon film is formed in the cut portions of a porous silicon carbide material having a large number of cuts. It is. Explanation of symbols 10--Graphite crucible, 11--Carbon film, 12-...
Metallic silicon, 20... Porous body.

Claims (1)

[Claims] 1). Silicon carbide powder with an average particle size of 5 μm or less is molded into a formed body of a desired shape, and this formed body is sintered in a non-oxidizing atmosphere, and then the resulting porous material has a three-dimensional network skeleton. A semiconductor manufacturing treatment characterized by coating at least a part of a surface of a quality silicon carbide member with a carbonaceous substance, carbonizing the carbonaceous substance in a non-oxidizing atmosphere, and then filling it with metal silicon. Method of manufacturing ingredients. 2). 2. The method of manufacturing a semiconductor manufacturing jig according to claim 1, further comprising removing residual carbon substances from said metal silicon-impregnated body.