JPS61214424A - Heat-resisting jig and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the heat-resisting jig effectively applicable to use in which heating and cooling are frequently repeated, by specifying the average diameter of particles of silicon carbide crystal constituting the sintered body, the volume of metal silicon in the sintered body, the sum of the volume of permeable voids, and the weight of metal silicon existing in the jig. CONSTITUTION:In case that the average diameter of particle of silicon carbide crystal is larger than 10mum, combination parts between particles in the porous material inevitably decrease, so that it is difficult to obtain the porous material of high permeable void and of excellence in respect of handling. The permeable void of this porous material is 38-65vol%. In case of the permeable void lower than 38vol%, the existing amount of metal silicon inevitably decreases so that the desired heat-resisting jig of high thermal conductivity can not be obtained. On the contrary, in case of the permeable void higher than 65vol%, the strength of porous material is small and the handeability is inferior. As to the weight of metal silicon existing in the heat-resisting jig, the most preferable value needs to be 55-135pts.wt. for 100pts.wt. of silicon carbide constituting the jig.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a heat-resistant jig and a method for manufacturing the same, and in particular, the present invention relates to a heat-resistant jig for the electronic industry, such as diffusion and oxidation treatment of semiconductors, and a method for manufacturing diodes. The present invention relates to corrosion-resistant and heat-resistant jigs suitable for bonding, glass sealing, brazing of package lead frames, etc., and a method for manufacturing the same.

[Conventional technology]

Conventionally, heat-resistant jigs for the electronics industry include, for example, carbon/carbide composites made by forming a silicon carbide film on the surface of a graphite base material, and composites made by filling quartz glass and silicon carbide molded bodies with metallic silicon. Incidentally, the carbon/silicon carbide composite in which a silicon carbide film is formed on the surface of the graphite base material is prepared by preparing the graphite base material in advance in a halogen gas atmosphere. It is necessary to perform purification treatment by a method such as high-temperature heat treatment, which is not economical because it requires a large amount of cost. Furthermore, although the quartz glass is preferable in terms of purity, it has rather low heat resistance and is susceptible to softening and deformation. Further, a composite body in which the silicon carbide molded body is filled with metallic silicon is disclosed in Japanese Patent Application Laid-open No. 51-85374, for example, which describes a process tube, a paddle having a size and shape that can be inserted into the process tube, and at least one paddle that can be supported by the paddle. 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; ``Semiconductor diffusion furnace which is made gas impermeable to gas.'' and JP-A-53-142183, ``A gas-impermeable silicon containing 35 to 70% silicon carbide* and 65 to 30% silicon metal by weight. An invention related to "Jig for Quever" is disclosed.

(Problems to be Solved by the Invention) However, the sintered silicon carbide matrix described in the former Japanese Unexamined Patent Publication No. 51-85374 is recrystallized silicon carbide, and relatively coarse silicon carbide particles are used as the starting material. In addition, it is difficult to produce a sintered body that has a large surface roughness and requires particularly high dimensional accuracy without special machining. The amount of metallic silicon contained was relatively small at 5 to 30% by weight.

On the other hand, the latter silicon quaver jig described in JP-A-53-142183 contains 30 to 65% of metallic silicon by weight.
However, the examples in the specification include a jig in which a molded body mainly composed of carbon fibers is silicified and a special porous silicon carbide body is impregnated with metallic silicon. It describes a manufacturing method and a method for manufacturing a jig using a reaction sintering method obtained by heating a mixture consisting of silicon carbide powder, metal silicon powder, phenol resin, etc., and the jig obtained by these manufacturing methods is economical. It is considered difficult to satisfy both properties and strength.

By the way, heat-resistant jigs for the electronics industry are mainly used for handling high-purity products such as semiconductors, so it is important that they be of high purity, free from product contamination, and have excellent wear resistance. In addition to this, since it is used in applications where heating and cooling are frequently repeated, it is preferable that it has excellent thermal conductivity and thermal shock resistance. It has been difficult to provide a heat-resistant jig with excellent properties at a particularly low cost.

[Means for solving problems]

Therefore, the present inventor provides a heat-resistant jig that has particularly excellent thermal conductivity compared to the conventionally known heat-resistant jig as described above, and is capable of obtaining good heat uniformity and quick thermal response. As a result of various research aimed at this purpose, we have obtained a porous silicon carbide sintered body with particularly high open porosity and high strength. Upon impregnation, we discovered a new silicon carbide composite that has extremely high thermal conductivity and can satisfy the above objectives, and we have completed the present invention.

The present invention provides a heat-resistant jig in which metallic silicon is interposed in the open pores of a porous sintered silicon carbide body having open pores, the average grain size of silicon carbide crystals constituting the porous sintered silicon carbide body. The diameter is less than IOP, and the total volume of the intervening metal silicon and the volume of voids in the porous silicon carbide sintered body is 38 to 6
A heat-resistant jig and its This is the manufacturing method.

The present invention will be explained in detail below.

The heat-resistant jig of the present invention includes a porous silicon carbide sintered body (hereinafter simply referred to as a porous body)'5c base material composed of silicon carbide crystals having an average grain size of 10 Ptf or less. is necessary. The heat-resistant jig of the present invention is mainly used for applications requiring good heat uniformity and quick thermal response, and heat conduction is achieved through the open pores of the porous body constituting the heat-resistant jig. It is a composite material that has high thermal conductivity and gas impermeability by impregnating it with paulownia silicone, which has excellent properties. Therefore, it is desirable that the porous body has as high an open porosity as possible, but if the average grain size of the silicon carbide crystals constituting the porous body is larger than 10 tones, the particles within the porous body will inevitably Since the number of bonding points with grains is reduced, it is difficult to obtain a porous body with particularly high open porosity and excellent handling properties.

The porous body of the present invention needs to have open pores of 38 to 65 volumes. The open porosity is 38
The reason for limiting the range to 65 to 65 volume is that if the open porosity is lower than 38 volume, the amount of metal silicon will inevitably be reduced.

This is because it is not possible to obtain a heat-resistant jig with a high thermal conductivity as desired, and on the other hand, if the volume is higher than 65 cm, the strength of the porous body itself is weak and the handleability is poor.

The weight of the metal silicon interposed in the heat-resistant jig of the present invention is 45 parts by weight based on 100 parts by weight of silicon carbide constituting the jig.
~135 parts by weight is required.

The reason for this is that if the amount of metallic silicon is less than 45 parts by weight, it is not only difficult to obtain a heat-resistant jig with high thermal conductivity, which is the object of the present invention, but also gas-impermeable. On the other hand, the upper limit of the amount of intervening metal silicon is determined by the upper limit of the open porosity of the porous body. In addition, the amount of the gold maple silicon to be included is more preferably within the range of 55 to 135 parts by weight.

The porous body of the present invention has 30 layers of β-type crystal silicon carbide! #
It is preferable that it contains at least - or more.

The reason for this is that it is important that the porous body has a three-dimensional network structure in which crystal grains are strongly bonded to each other.

This is because by setting the content of silicon carbide in the β-type crystal to 30% by weight or more, it is possible to obtain a porous body having a three-dimensional network structure in which the bonds between the crystal grains are strong. Advantageously, it is greater than or equal to t.

The porous body of the present invention is a sintered body that is sintered without substantially shrinking, and it is advantageous that the shrinkage rate due to sintering is 2% or less. The reason for this is that silicon carbide sintered bodies produced by the normal pressureless sintering method, which undergoes shrinkage during sintering, are desirable in terms of strength and wear resistance, but shrinkage during sintering reduces open porosity and causes pores to form. Since the pores tend to become independent, it is not only difficult to fill with metallic silicon, but also difficult to manufacture a porous body with a large open porosity of 40 to 56%, which is the objective of the present invention. Because it becomes a pheasant.

It is advantageous for the porous body of the present invention to have an average bending strength of 5 KF/#'' or more. This is because it is easy to crack or crack, making it difficult to manufacture heat-resistant jigs.

Next, a method for manufacturing the heat-resistant jig of the present invention will be explained.

According to the present invention, silicon carbide powder is molded into a formed body, sintered in a non-oxidizing atmosphere, and after death, metallic silicon is filled into the open pores of the porous body obtained by the sintering. In the method for manufacturing a heat-resistant jig, a powder having an average particle size of 5 μm or less is used as the silicon carbide, the bulk specific gravity of the formed body is 1.12 to 2.0, and the bulk specific gravity is 1.12 to 2.0. A heat-resistant jig is manufactured by setting the sintering temperature of the compact to 1400 to 2100 C, and filling 45 to 136 parts by weight of the metal silicon with respect to 100 parts by weight of silicon carbide constituting the jig. Can be done.

According to the present invention, it is necessary to use a powder having an average particle size of 5 μm or less as silicon carbide. The reason for this is that if silicon carbide powder with an average particle size larger than 5 μm is used, there will be fewer bonding points between grains within the sintered body, making it difficult to obtain a high-strength porous body. be.

According to the present invention, it is important to produce a porous body with low density, excellent handling properties, and high strength compared to conventionally known porous silicon carbide sintered bodies. When molding a formed body, it is advantageous to use as a starting material a silicon carbide powder obtained by homogeneously dispersing silicon carbide powder together with a deflocculant in a dispersion medium and then freeze-drying it.
When molding a product by the two-cast molding method, it is advantageous to use as a starting material a suspension in which silicon carbide powder is homogeneously dispersed together with a peptizer in a dispersion medium.

The reason for this is that silicon carbide powder has strong cohesiveness and tends to form secondary particles in which a large number of individual particles are closely aggregated. When used as a porous material, coarsening of crystal grains occurs in units of secondary particles, resulting in a relatively coarse three-dimensional network structure of the porous material, making it difficult to obtain a porous material with low density and high strength. It was difficult. However, there are two types of molded products, which are formed by pressure molding using silicon carbide powder that is homogeneously dispersed with a deflocculant in a dispersion medium as described above and freeze-dried, and molded products by casting and molding using a suspension. In all forms, it is possible to produce a formed form in which the individual particles of silicon carbide powder are extremely uniformly dispersed and exist in their original state, making it possible to develop an extremely fine and uniform three-dimensional network structure of the crystals. This is because a porous body having low density and high strength can be manufactured.

According to the present invention, various types of dispersion medium can be used, but those with a melting point in the range of 15 to 15C are advantageously used, especially when freeze-drying. Among them, it is advantageous to use at least one selected from benzene and cyclohexane or water.

According to the present invention, as a means for uniformly dispersing the silicon carbide powder in the dispersion medium, a dispersion means capable of applying a strong shearing force such as a vibration mill, an attritor 9-ball mill, a colloid mill, and a high-speed mixer is used. It is advantageous to use

According to the present invention, when the dispersion medium is organic, the deflocculant used when uniformly dispersing the silicon carbide powder in the dispersion medium includes fatty acid amine salts, aromatic amine salts, heterocyclic amine salts, etc. Cationic surfactants such as amine salts and polyalkylene polyamine conductors.

Ester type, ester ether type, ether type.

Nitrogen-containing nonionic surfactants are effective, and when the dispersion medium is water, for example, inorganic peptizers such as ammonium oxalate and aqueous ammonia, diethylamine, monoethylamine, pyridine ethylamine, and hydroxyl. Organic peptizers such as NW methyl ammonium and monoethanolamine are effective.

According to the present invention, when freeze-drying a suspension in which the silicon carbide powder is uniformly dispersed in a dispersion medium, the suspension is sprayed into an atmosphere maintained at a temperature lower than the melting point of the dispersion medium. It is advantageous to freeze it quickly.

By the way, there are α-type, β-type, and amorphous types of crystal systems of silicon carbide, but among them, the 4β-type is easy to obtain fine powder with an average particle size of 5μ2 or less, and is relatively easy to obtain. It can be advantageously used because a high-strength porous body can be easily produced, and it is particularly preferable to use a silicon carbide powder containing 50% by weight or more of β-type silicon carbide l/l.

According to the present invention, the bulk specific gravity of the formed body is 1.12 to 2.
．． 09/cIL3. The reason for this is that if the bulk specific gravity is smaller than 1.129/(
This is because if it is larger than gβ-, it is difficult to produce a porous body with a large open porosity, which is the object of the present invention, and it becomes difficult to produce a heat-resistant jig with high thermal conductivity.

According to the present invention, the sintering temperature is 1400 to 2100C.
It is necessary to do so. The reason is that the temperature is 14
If the temperature is lower than 21001:', it is difficult to sufficiently develop the neck that fully bonds the grains, and a porous material with high strength cannot be obtained.On the other hand, if the temperature is higher than 21001, the neck once grown This is because necks that are smaller than a certain size become constricted and become halo-like, 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 that the green body is fired in a non-oxidizing atmosphere without substantial shrinkage. The reason is that shrinkage during sintering is desirable for improving the strength of the porous body.

Firing shrinkage reduces open porosity and pores tend to become independent pores, making it difficult to fill with silicone, and it is also difficult to manufacture porous bodies with high dimensional accuracy by causing firing shrinkage. Because there is.

According to the present invention, in order to obtain a porous body that is easy to fill with metal silicon and has high dimensional accuracy, the firing shrinkage rate when sintering without substantially shrinking can be set to 2% or less. Preferably, especially.

More preferably, it is 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 product form. This is because the volatilization of silicon carbide from the formed body is suppressed.

This is because the neck that connects the silicon carbide grains can be sufficiently developed, especially when producing a porous body with high strength and excellent handling properties.

It is advantageous to control the volatilization rate of silicon carbide to 5% by weight or less.

An effective method for suppressing volatilization of silicon carbide from the formed body is to charge the formed body into a heat-resistant container that can block the intrusion of outside air, and as the heat-resistant container, 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 fill 45 to 136 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 filling the open pores of the porous body with metal silicon can improve the strength. Because it has excellent thermal conductivity, by filling the open pores of a porous body with metallic silicon, it can be made into a heat-resistant jig that has high thermal conductivity and gas impermeability. . The reason why the filling amount of the metallic silicon is limited to 45 to 136 parts by weight is that if the optical filler of the metallic silicon is less than 45 parts by weight, the heat-resistant jig having thermal conductivity, which is the object of the present invention, cannot be obtained. 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.

The method of filling the open pores of the porous body with the Kinara silicon is a method of heating and melting metallic silicon to impregnate it, or a method of dispersing finely powdered Kinara silicon in a dispersion medium and dispersing the dispersion liquid into the porous body. A method such as impregnating a mass, drying it, and then heating it to a temperature higher than the melting temperature of gold parrot silicon can be applied.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 Silicon carbide powder used as starting material was 97.5% by weight
is a silicon carbide powder consisting of β-type crystals and the remainder is substantially 2H-type crystals, 0.12% by weight of free carbon, 0.3
7 wt% oxygen, 1.2 x 10-'wt% iron, 1
．． 4 x 10-4 doublet (l tD Cal7 UA,
8 X 10-' heavy sodium, I X 10-'
It contained 5xtS of potassium and traces of aluminum and had an average particle size of 1.1 μm. ``To 100 parts by weight of the silicon carbide powder, 5 parts by weight of polyvinyl alcohol, 0.3 parts by weight of monoethanolamine, and 100 parts by weight of water were blended, mixed in a ball mill for 5 hours, and then freeze-dried.

An appropriate amount of this dry mixture was taken and granulated, and then a formed body was molded using a hydrostatic press at a pressure of 1300 ψ-. The shape of the generated body is a disc with a diameter of 200 gm and a thickness of 10111 mm, and the density is 1,73 f/m3 (54 gm).
The volume was

The formed body was placed in a graphite crucible, and sintered in a Tammann-type sintering furnace in a stream of mainly argon gas at 1 atm. In the temperature raising process, the temperature was raised to zoOor: at a rate of 450 C/hour, and the temperature was maintained at a maximum temperature of 2000 C for 15 minutes. The CO gas partial pressure during sintering was controlled by appropriately adjusting the argon gas flow rate so that the partial pressure of the CO gas was 80 Pa or less in the chamber m to 1700C, and within the range of 300 to 50 Pa in the higher temperature range than 1700C.

The obtained sintered body has a density of 1 near 0? A porous body with a Δ-1 open porosity of 47 volume and a β-type silicon carbide content of 92
The balance in weight t% was mainly α-type silicon carbide of 4H type and 6H type. Furthermore, when this crystal structure was observed using a scanning electron microscope, it was found to have a three-dimensional structure in which block-shaped silicon carbide crystals were intricately intertwined and bonded by relatively thick necks, and the linear shrinkage rate for the formed shape was Also in the direction of 0.3±0.1% iI! Within the range, the average bending strength of this sintered body is 13. It has a high elasticity of gKg/m2 and contains 3XIO weight% aluminum, 6
It contained 10-' weight percent iron and 4×10 weight percent nickel. Note that the contents of chromium, calcium, and copper were all in trace amounts, and the contents of sodium and potassium were both less than I x to''% by weight.

Next, on the surface of the porous body, apply a slurry in which 100 parts by weight of Kinmen silicon powder with an average particle size of 20 μm and a purity of 99.99991111% or more and 60 parts by weight of a 5% acrylic acid ester benzene solution are mixed, The surface was coated with metal silicon 3809. This porous body coated with metallic silicon was heated at a temperature increase rate of 450C/hour in an argon gas stream to a maximum temperature of 1450C/hour.
G- for about 1 hour to allow the metal silicon applied to the surface of the porous body to permeate into the porous body to obtain a silicon carbide composite.

The resulting silicon carbide composite had a porosity of 2%, was gas impermeable, and its dimensions were only 0.03 m larger than before filling with metallic silicon, with an average The bending strength was as strong as 32.1 KP/fe112, and the thermal conductivity was extremely good as 0.23 cal/cm·see C, making it extremely suitable for use as a heat-resistant jig.

Comparative Example 1 Same as Example 1, except that the silicon carbide powder used in Example 1 and commercially available α-type silicon carbide (GC Su24) were used as starting materials.
A porous body was prepared using a mixed powder of 0.0 μm, average particle size: 80 μm′) mixed at a weight ratio of 3.0 μm, and then impregnated with metallic silicon to obtain a silicon carbide composite.

The porous body has a density of 2.379/cIn'', an open porosity of 26% by volume, and an average bending strength of 5.2 Kp/w+
The intensity was relatively low as s2. Furthermore, the porosity of the silicon carbide composite obtained by impregnating metal silicon is 1. It had gas impermeability at 7%, but the metal silicon content was 24ffiM per 100 parts by weight of silicon carbide.
, and the N1 conductivity is 0.21 cal/cx-Be
(It wasn't as good as IC.

Example 2 Same as Example 1, except that the silicon carbide powder used in Example 1 and the commercially available α-type silicon carbide powder (GOS 6000) were ground as starting materials, and the silicon carbide powder was further purified and classified for particle size. (average particle size 1.2 μm) mixed in various proportions to produce a porous body, and then the porous body was placed in a graphite crucible, and the purity was 99.999.
After placing 9% by weight or more of bulk gold silicon around the porous body, Jjf! was applied at 1450C. A silicon carbide composite which becomes gas impermeable upon heating was produced.

The properties of the obtained porous IC body and silicon carbide composite were shown in the first test.

As can be seen from Table 1, the porous body using silicon carbide powder with a high mixing ratio of β-type silicon carbide powder as a starting material had excellent strength relative to its density.

Example 3 A silicon carbide composite was manufactured in the same manner as in Example 1, but by changing the molding pressure, formed bodies having different bulk specific gravity were manufactured. The properties of the obtained porous body and silicon carbide composite are shown in Table 2.

As can be seen from Table 2, the porous body of the present invention has excellent strength even at low density.

Example 4 To 100 parts by weight of the fc reconstituted silicon powder used in Example 1, 3 parts by weight of polyacrylic acid ester, 0.4 parts by weight of tetramethylammonium hydroxide and 60 parts by weight of water were blended, and the mixture was milled in a ball mill. After mixing for 10 hours in a mold, it was cast and molded, with an outer diameter of 60ml, an inner diameter of 45mm, and a length of 300m.
A cylindrical formed body with a density of 1.63/min was obtained.

Next, a silicon carbide composite was produced under the same conditions as in the example.

The properties of the obtained porous body and silicon carbide composite were as follows.
Shown in the table.

〔Effect of the invention〕

As described above, the heat-resistant jig of the present invention is a silicon carbide composite having a porous silicon carbide sintered body as a skeleton, and has excellent wear resistance, as well as thermal conductivity and thermal shock resistance. Therefore, it can be extremely advantageously applied to applications where heating and cooling are frequently repeated, and is extremely useful industrially.

Claims (1)

[Scope of Claims] 1. A heat-resistant jig in which metallic silicon is interposed in the open pores of a porous silicon carbide sintered body having open pores, comprising: silicon carbide constituting the porous silicon carbide sintered body; The average grain size of the crystals is 10 μm or less, and the total volume of intervening metallic silicon and the volume of voids in the porous silicon carbide sintered body is 38 to 65% by volume with respect to the volume of the jig. The weight of the metal silicon interposed in the jig is 45 parts by weight based on 100 parts by weight of silicon carbide constituting the jig.
135 parts by weight of a heat-resistant jig. 2. The heat-resistant jig according to claim 1, wherein the porous silicon carbide sintered body contains 30% by weight or more of β-type crystal silicon carbide. 3. The porous silicon carbide sintered body is made by molding silicon carbide powder with an average particle size of 5 μm or less, and has a bulk specific gravity of 1.12 to 2.
0g/cm^3 production form and none, 1400-2100
The heat-resistant jig according to claim 1 or 2, which is a porous silicon carbide sintered body obtained by sintering in a non-oxidizing atmosphere at ℃. 4. After shaping the silicon carbide powder into a formed body and sintering it in a non-oxidizing atmosphere, metal silicon is filled into the open pores of the porous silicon carbide sintered body obtained by the sintering. In the method for manufacturing a heat-resistant jig, the silicon carbide is a powder having an average particle size of 5 μm or less, and the bulk specific gravity of the formed body is 1.12 to 2.0 g/cm.
^3, and the sintering temperature of the sintered body was 1400 to 210.
0° C., and filling 45 to 136 parts by weight of the metal silicon with respect to 100 parts by weight of silicon carbide constituting the jig. 5. The manufacturing method according to claim 4, wherein the silicon carbide powder contains at least 50% by weight of β-type crystal silicon carbide. 6. The shrinkage rate due to sintering of the porous silicon carbide sintered body is 2.
% or less, the manufacturing method according to claim 4 or 5.