JP2003071555A - MANUFACTURING METHOD FOR Si-SiC COMPOSITE MATERIAL - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a dense Si-SiC composite material without using a complicated mechanism or an expensive device and by a simple and easy method, and a manufacturing method capable of easily controlling a supply speed for Si. SOLUTION: On the upper part of a burnt body Si containing SiC as a main component, a crucible filled with Si is set, the crucible is heated to become a melted state, and a molten Si of the Si is supplied to the surface of the burnt body through the holes that the crucible has, to impregnate the Si in the burnt body. The crucible is made to have density in the range 1.30 g/cm<3> -3.02 g/cm<3> , a density ratio in the range of 40-92TD%, mean pore size (mean fine pore diameter) measured by a mercury porosimeter in the range of 50 nm-30 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing silicon-silicon carbide ceramics (hereinafter referred to as Si-SiC), and more particularly to a method for impregnating voids in a SiC fired body with Si.

[0002]

2. Description of the Related Art Conventionally, Si-S composed of Si and SiC
Since the iC-based material is excellent in denseness, high thermal conductivity and strength, it is used for a heat treatment member such as a silicon single crystal wafer, for example, a semiconductor heat treatment wafer boat, a semiconductor furnace core tube and the like.

The Si-SiC composite material is usually obtained by mixing SiC powder alone or a powder in which coarse particles and fine particles are mixed with a binder, and molding the mixture by isostatic pressing, casting method or the like. After firing, the fired body is manufactured by impregnating Si or the like.

The following method has been proposed as a typical method for impregnating a SiC sintered body with Si.

(A) A method in which porous SiC is placed in a molten Si bath, and the molten Si is impregnated by utilizing a capillary phenomenon generated by pores (open pores penetrating inside) of the SiC.

(B) Si is put in the crucible, carbon fiber or the like is placed between the crucible and the SiC calcined body, and the molten Si is guided to the calcined body by utilizing the capillary phenomenon of the carbon fiber, and S is added to the calcined body.
Method of impregnating with i (JP-A-7-89778, JP-A-2000-119079).

(C) A method in which Si is mixed with SiC powder and disposed around the impregnated body, and high-frequency heating is performed to melt and impregnate Si while moving the impregnated body (Japanese Patent Publication No. 53-53-
29319).

(D) A method of thermally decomposing silicon nitride (Si ₃ N ₄ ) to impregnate Si vapor into the pores of the SiC fired body (Japanese Patent Publication No. 36-15163).

The problems of the above Si impregnation method are as follows: (a) The impregnation method utilizing the capillary phenomenon cannot be impregnated when the height exceeds a certain level, and cannot meet the demands associated with the increase in size of today's members. Absent. In addition, the remaining S
Since i remains, a complicated and troublesome post-processing is left.

(B) When a plurality of carbon fibers (yarns) are arranged and impregnated at the same time, the labor and preparation in advance are complicated. Further, in addition to the material to be impregnated, a crucible for inserting Si, a carbon fiber, and other devices are required, which is complicated and the entire device must be expensive. In addition, the carbon fiber adheres to the impregnated body and requires subsequent treatment.

(C) Careful preparation is required for impregnation, and efficiency is poor. Furthermore, after cooling and solidification, S placed in the periphery
It is difficult to remove the iC powder.

(D) The decomposition temperature of Si ₃ N ₄ is high, which causes inefficiency because it decomposes Si more than necessary for impregnation, and excess Si is deposited around the furnace to impair the life of the furnace.

[0013]

[Problems to be Solved by the Invention] Porous S having open pores
In the method of impregnating Si into iC, a method for producing a dense Si-SiC composite material by a simple, easy, and reliable method without using a complicated impregnation mechanism or an expensive device, and supplying the molten Si at a supply rate It is an object to provide an easily controllable method and a Si crucible necessary for that purpose.

[0014]

The inventor of the present invention has reached the present invention as a result of intensive studies to solve the above problems. That is, the present invention relates to the following.

(1) A crucible containing Si is set on the upper portion of a fired body containing SiC as a main component, the crucible is heated to bring Si into a molten state, and a melt of Si is passed through a hole in the crucible to give a fired body. It is supplied to the surface and Si is impregnated into the fired body to form Si-S.
A manufacturing method of Si-SiC composite material which manufactures iC composite material.

(2) The method for producing an Si-SiC composite material according to (1), characterized in that two or more crucibles containing Si are provided on the upper part of the fired body containing SiC as a main component.

[0017] (3) crucible, the SiC as a main component, the density is in the range of ^{1.30g / cm 3 ~3.02g / cm 3} , in the range density ratio of 40～92TD%, mercury The average pore size (average pore size) measured with a porosimeter is 5
Within the range of 0 nm to 30 μm, the method for producing a Si—SiC composite material according to (1) or (2).

[0018] (4) crucible, the SiC as a main component, the density is in the range of ^{1.70g / cm 3 ~2.90g / cm 3} , in the range density ratio of 53TD% ~90TD%,
Average pore diameter measured by mercury porosimeter is 300 nm
Is in the range of up to 4000 nm (1)
Alternatively, the method for producing the Si-SiC composite material according to (2).

(5) The crucible has a particle size of 0.1 μm to 300 μm.
A binder is added to the SiC powder within the range of m, and the mixture is cast-molded, rubber-press molded, or mold-molded,
Thereafter, it is a crucible containing SiC as a main component, which is heated and baked in a temperature range of 1200 ° C to 2300 ° C, and the Si-S described in any one of (1) to (4).
Method for manufacturing iC composite material.

(6) The crucible is mainly composed of graphite, has a density in the range of 1.50 g / cm ^{3 to} 2.05 g / cm ³ , and has an opening at the bottom or side of the crucible. The manufacturing method of the Si-SiC composite material as described in (1).

(7) The opening has a hole shape and the hole diameter is 0.
It is in the range of 25 to 2.0 mmφ and the number density of holes in the region having the opening is 0.001 / cm ³ to 1 / c.
S in (6), which is within the range of m ^3.
Method for manufacturing i-SiC composite material.

[0022] (8) fired material mainly composed of SiC is, the density is in the range of ^{1.3g / cm 3 ~3.0g / cm 3} , in the range density ratio of 40TD% ~92TD% ,
Si-SiC according to any one of (1) to (7), characterized in that the average pore diameter (average pore diameter) measured by a mercury porosimeter is in the range of 50 nm to 30 μm.
Manufacturing method of composite material.

(9) The supply rate of Si from the crucible to the fired body containing SiC as a main component is in the range of 1 g / min to 200 g / min. (1) to (8) The method for manufacturing the Si-SiC composite material according to any one of claims.

(10) The supply rate of Si from the crucible to the fired body containing SiC as a main component is from 0.005 g / (cm ³ · min) to the Si supply rate per unit volume of the fired body.
The method for producing a Si-SiC composite material according to any one of (1) to (9), characterized in that it is within a range of 5 g / (cm ³ · min).

(11) The Si supply rate of Si per crucible is in the range of 2 g / min to 200 g / min. (1) to (10) -S
Method for manufacturing iC composite material.

(12) The method for producing a Si-SiC composite material according to any one of (1) to (11), wherein the total amount of metallic impurities of SiC constituting the fired body is 50 ppm or less. .

(13) The Si according to any one of (3) to (5) and (8) to (11), characterized in that the total amount of metallic impurities of SiC constituting the crucible is 50 ppm or less. -The manufacturing method of a SiC composite material.

(14) The main component is SiC, and the density is 1.
In the range of ^{30g / cm 3 ~3.02g / cm 3} , in the range density ratio of 40TD% ~92TD%, an average pore diameter measured by a mercury porosimeter (average pore diameter) of 5
A crucible for melt impregnation of a fired body, which is in the range of 0 nm to 30 μm.

(15) The main component is graphite and the density is 1.5.
0 g / cm ³ in the range of ~2.05g / cm ^3, melt impregnation crucible to sintered body characterized by having an opening at the bottom or side of the crucible.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is mainly applied to a method for producing a heat treatment member for a semiconductor, for example, by impregnating a sintered body containing SiC as a main component with molten Si to obtain a Si—SiC composite material. A crucible containing Si is set on the upper part of a fired body as a component, the crucible is heated to bring Si into a molten state, and a melt of Si is supplied to the surface of the fired body through a hole provided in the crucible, and the Si is fired. S to produce composite material
It is a method of manufacturing an i-SiC composite material. At this time, it is preferable to control the density (void amount), the amount of open pores, and the diameter of the pores of the crucible into which Si is preliminarily controlled to control the amount of molten Si supplied to the impregnated body.

Conventionally, porous SiC is obtained by melting molten Si.
Put it in the bath and use the capillary phenomenon to make thin continuous pores Si
Was impregnated. In the present invention, simultaneously with this capillary phenomenon, gravity is used to drop and supply Si from the upper portion of the fired body to fill the voids of the fired body with Si. As a result, a distance, a large volume, and a high impregnation speed, which cannot be obtained only by the capillary phenomenon, can be obtained. As a result, it has become possible to easily impregnate a product with a complicated shape without being restricted by the shape and the size.

In the present invention, it is preferable that the crucible to be installed on the upper portion of the fired body is installed in several places according to the shape of the body to be impregnated. As a result, an efficient impregnation process can be performed in the minimum necessary space. The material for the crucible can be selected, for example, from a highly purified SiC porous body or graphite, or a Si-SiC composite material of the same quality. By using each material that has been subjected to high-purity treatment in this way, it is possible to manufacture boats and furnace core tubes suitable for semiconductor applications.

The amount of Si supplied is related to the amount of open pores in the crucible and its pore diameter. To increase the supply amount of Si, the amount of pores, the diameter of pores, or both are increased. On the other hand, the Si supply amount can be limited by reducing the pore amount and the pore diameter of the crucible. Further, in the case of a graphite crucible, it can be adjusted by the pore diameter, the number thereof and the density of the pores. In order to control the amount of open pores and the pore size of SiC or Si-SiC crucible, it is possible to operate by adjusting the particle size of the SiC powder as the raw material, the molding method thereof, the firing conditions, and the like.

It is necessary to suppress the supply rate of Si from the crucible containing Si to the body to be impregnated so as not to exceed the impregnation ability (speed) to the body to be impregnated. If the amount supplied from the crucible is too large, the Si melt will spill outside the impregnated body, and the amount of Si to be supplied to the impregnated body will be insufficient.

On the other hand, graphite usually has many pores of 10 to 40% by volume. When Si is supplied through the open pores, a part of graphite reacts to generate SiC. This reaction causes a decrease in the strength of the crucible and also causes a volume expansion to break the crucible. Therefore, when using a graphite crucible,
The use of relatively dense high-purity graphite having a porosity of 10 to 20% by volume can suppress Si intrusion and reaction. An arbitrary opening, for example, a hole is formed in the lower portion or side surface of such a crucible, and a necessary number of holes is formed at a position corresponding to the shape of the impregnated body, and S
It is preferable to adjust the supply amount of i.

As described above, according to the present invention, the upper part of the body to be impregnated,
Alternatively, a crucible containing Si is arranged in contact with the upper part of the impregnated body. For example, set a crucible containing Si on the body to be impregnated in a furnace heated under vacuum, and set the entire furnace to S
It is preferable that the Si, which has been heated to a temperature not lower than the melt temperature and becomes a melt, is supplied to the surface of the impregnated body through the open pores and the openings of the crucible to perform the impregnation treatment.

Generally, a member for heat treatment for semiconductors is required to have high strength, high purity and high thermal conductivity. Therefore, the sintered body whose main component is SiC, which is its precursor, has a high density,
And sufficient interparticle bonding force is required. For that purpose, it is desirable to obtain a high-density molded product and then fire it at a predetermined temperature. At this time, the pore size also increases in conjunction with the firing temperature. By setting these conditions, it is preferable to set the density, density ratio, and average pore diameter of the fired body so as to maximize the strength and the capillary attraction.

Si-impregnated by the method of the present invention
The SiC composite material has a remarkably small amount of pores and can have a dense structure. Further, the present invention provides an extremely efficient manufacturing method which does not require a post-treatment such as removing adhered Si and carbon fibers wound around an object to be impregnated by selecting an appropriate Si supply amount.

The present invention will be described in more detail below.

The production of a fired body containing SiC as the main component, which is the impregnated body, will be exemplified. The SiC sintered body is formed by using SiC powder and an organic binder, is debindered, and is then formed with continuous open pores suitable for Si impregnation treatment.
To obtain a SiC precursor sufficient to obtain a high strength impregnated body,
These are fired at a predetermined temperature.

The fired body containing SiC as a main component means a fired body containing carbon as a main component, carbon from a binder, Si to be impregnated, and other unavoidable impurities.

High-purity SiC powder is used alone, or several kinds of powders having different particle diameters are mixed, and a binder is mixed therein to produce a dense compact.

It is desirable to use high-purity powder as the SiC raw material. Fe and N, which are easily mixed as metal impurities
It is preferable to use a powder containing few elements such as i, Cr, Ca, and Cu. The amount of metal impurities can be generally reduced by repeatedly pickling with hydrofluoric acid or a mixed acid of hydrofluoric acid and nitric acid.
Further heat treatment in a halogen-based gas results in further purification. A powder in which the total amount of these metal impurities is at least 50 ppm is preferable.

The particle diameter of the SiC powder is 0.1 μm to 300 μm.
The range of μm is preferred. In the case of molding with only a single particle size, if the particles having an average particle size within the range of 0.3 to 20 μm are used, a molded product excellent in moldability and filling property can be obtained.

When two or more particle sizes are mixed for densification, coarse particles have an average particle size of 50 to 300 μm, and fine particles have an average particle size of 0.1 to 30 μm. It is preferably used. The mixing ratio of the coarse particles and the fine particles is preferably 3 to 7: 7 to 3. More preferably, by selecting the ratio of coarse particles to fine particles within the range of 4 to 6: 6 to 4, a high filling property can be obtained. Further, the powder is preferably a monodispersed powder without aggregation.

The crystal system of SiC may be hexagonal (hereinafter α), cubic (hereinafter β), amorphous or a mixture thereof. The αSiC powder obtained by the Acheson method can be preferably used because various particle sizes can be easily obtained at low cost.

High purification of this SiC powder is generally obtained by pickling the powder. As the type of acid, hydrochloric acid, hydrofluoric acid, nitric acid, or a mixed acid thereof is used.

The distribution of metal impurities in SiC synthesized by the Acheson method is disclosed in Japanese Patent Application Laid-Open No. 5-32458. Generally, the finer the particle size, the easier the impurities can be removed.

A dispersant and an organic binder are added to the SiC powder, and the mixture is stirred and mixed for granulation, and then a metal mold, rubber press molding (CIP), or the mixed slurry is molded by cast molding using a gypsum mold. The cast molding method is excellent for obtaining various shapes and thin tubes, long-sized molded products and the like as semiconductor heat treatment members.

As the organic binder, it is preferable to use a water-soluble phenol resin, polyacetic acid emulsion, silicone resin, acrylic resin emulsion or the like. The compounding ratio of the binder varies depending on the particle size of the SiC powder within the range of 0.2% by mass to 15% by mass. Add a small amount for coarse particles and a large amount for fine particles. When phenolic resin is used as a binder, carbon remains in the molded body. This carbon changes to SiC when impregnated with Si.

The method for measuring the open pore diameter is a mercury porosimeter.
By. That is, mercury is pressed into a molded body and the pore diameter or pore diameter converted from the pressure is obtained.

A liquid having a wetting angle of 90 ° or more cannot enter the pores by itself due to surface tension. Therefore, in order to put the liquid into the pores, it is necessary to apply pressure from the outside, and the required pressure is related to the pore diameter.

The relationship between the applied pressure and the pore size that can be entered at that time is expressed by the following formula.

Pr = 2σ cos θ P: Applied pressure r: Pore radius θ: Contact angle (wetting angle) (The average value for mercury is 14
1.3 degree) σ: Surface tension of mercury (480 mN / m ² ).

This relational expression is known as the Fochborn expression. Although the pore size of most porous materials is not cylindrical, this formula is commonly used to calculate the pore size distribution from mercury intrusion data.

When the above pores are assumed to be cylinders and mercury is permeated, the following equation is obtained by substituting the above values.

R = 7500 / P r: Pore radius P: Absolute pressure applied

The measuring method is to measure the mass of a rectangular parallelepiped having a length of about 30 mm and a size of several mm. Five sides of the rectangular parallelepiped are coated with an organic resin. Put the sample in a glass container (dilatometer) and set it in the mercury press-in device. After degassing in vacuum, fill with mercury. Remove the diradometer from the mercury injection method and set it in the autoclave. Mercury is sequentially injected into the system and the amount of injection at each pressure is recorded. After the measurement, the pressure and the pore diameter are converted to obtain the pore diameter distribution.

In order to impregnate Si, a large capillary attraction is applied to the SiC sintered body as a precursor. Generally, the capillary attraction is represented by the following formula. When the pull-up height of the impregnated Si is h, h = (2σ) / r · ρ · cos α σ: surface tension (Si (1500 ° C.) 800 mN /
m ² ) r: radius of capillary tube (pore diameter) ρ: specific gravity of liquid (2.5 g / cm ³ ) cos α: contact angle (less than 40 degrees)

As described above, generally, the smaller the pore size, the larger the capillary force will be. However, the actual pore morphology is a three-dimensionally intricate, indeterminate-shaped continuous pore in which thick and thin pores intersect.

The pore size of the compact is related to the particle size of the SiC powder used. That is, the smaller the particle size of the SiC powder, the smaller the pore size, and the larger the particle size of the SiC powder, the larger the pore size. For example,
A powder having an average particle diameter of 0.4 μm was added to the above binder, and the close-packed compact had an average pore diameter of about 20 nm.
Is about 30 nm, about 50 nm when the average particle size is 0.6 μm, and about 70 nm to 100 nm when the average particle size is 3 μm.
Also, coarse particles having an average particle diameter of 50 μm to 100 μm and 10 μm
The average particle size of the powder obtained by mixing fine particles of m or less is 15 μm.
A molded body having a pore size of 100 to 200 nm is obtained in the range of up to 40 μm. In small pores of 50 nm or less, the melted Si has a higher resistance due to the pore morphology of the pores than the capillary force (suction force) of the molded body, and only the vicinity of the surface is impregnated. Therefore, it is necessary to adjust the pore size so that Si can easily enter by firing.

First, the molded body is processed into a predetermined shape, and then debinding is performed in a vacuum or a non-oxidizing atmosphere. The degreasing temperature is in the range of 700 ° C. to 1100 ° C. and is maintained at a predetermined temperature for 1 hour to 3 hours. As the non-oxidizing gas, it is preferable to use nitrogen, argon, helium gas or the like.

Next, the degreased compact is fired. The firing temperature is 1200 ° C to 2300 ° C. The atmosphere is a vacuum or a non-oxidizing atmosphere. As the non-oxidizing gas, it is preferable to use nitrogen, argon, helium gas or the like. When firing in a vacuum atmosphere, it is preferable to perform firing at 2000 ° C. or lower in consideration of heat resistance of the constituent materials of the furnace and decomposition of SiC. The degree of vacuum is 133 Pa (1 T
orr) or less is preferable, and more desirably 13 Pa
(0.1 Torr) or less is excellent. When firing under vacuum, impurities are easier to remove than under normal pressure.
That is, the content of impurities such as Ca, Fe and Cu in the compact can be reduced by 50% to 80% by firing under vacuum.

The holding time at each firing temperature is 1 to 5 hours. Grain growth ends halfway if it is less than 1 hour,
The target pore size cannot be adjusted stably. Even if it is held for 5 hours or more, it has no meaning because the pore diameter does not increase.

By firing the compact, the grain growth in the compact progresses and the pore size increases. As a result of earnest research, it was found that Si is most easily sucked when the pore size in the fired body is in the range of 50 nm to 30 μm, and more preferably in the range of 300 nm to 5 μm.

The other main element, the impregnated body, contains S
In the crucible for supplying i, the supply rate of Si can be controlled by the pore diameter or the size and density of the openings.

The shape and size of the crucible are determined from the viewpoint of the geometrical balance with the body to be impregnated and effective utilization of the furnace space.
The shape of the crucible is preferably a cylinder. The wall thickness should be the thickness required to maintain the minimum shape. If you want to increase the surface area of the crucible, prepare multiple small crucibles. The pore diameter of the crucible is preferably about the same as that of the impregnated body. When the pore diameter is small, the supply amount is small with respect to the impregnated body, and when the pore diameter is large, the supply amount is large with respect to the impregnated body. If the pore size is smaller than 50 nm, Si will not be supplied through the open pores. Also, 3
If it is larger than 0 μm, the supply of Si may be too fast and the target object to be impregnated may not be completely impregnated and may spill outside.

A crucible containing SiC as a main component means SiC as a main component, carbon from a binder, and S to be impregnated.
i means a crucible containing other unavoidable elements.

The density of the crucible containing SiC as a main component is a minimum density of 1.30 g / cm ³ or more, more preferably 1.70 g / cm ³ or more, and a density ratio of 40 TD% or more for maintaining the shape during molding. , More preferably 53 TD% or more, 3.02 g / as the upper limit of the density capable of maintaining the shape of open pores.
It is preferably not more than cm ³ . Further, as the density becomes higher, the amount of pores becomes smaller and the pore size becomes smaller, resulting in Si
Supply of less. Therefore, the density is more preferably 2.90 g / cm ³ or less, and the density ratio is 92TD% or less,
More preferably, a SiC sintered body of 90TD% or less is desirable.

The density ratio TD% means the true density of the substance forming the crucible (3.21 g / cm ^{3 in} the case of 100% SiC).
Is. It represents the ratio of the density (bulk density) of the actual crucible to (). The Archimedes method can be exemplified as the measuring method, but in the case of a porous material, the surface is covered with paraffin or the like to determine the bulk density. In addition, it is possible to obtain the bulk density and the porosity from the air weight (W ₁ ), the water weight (W ₂ ), and the included water weight (W ₃ ) after vacuum deaeration in water. The density and porosity are calculated according to the following formulas.

Bulk density (ρ) ρ = W ₁ / (W ₃ −W ₂ ) Porosity (Po) Po = (W ₃ −W ₁ ) / (W ₃ −W ₂ ) × 100 (according to JIS R2205)

Next, a method for adjusting the pore diameter of the crucible and the fired body containing SiC as a main component will be described. The firing temperature of the formed body containing SiC as a main component differs for each SiC powder particle size. About 0.4μ
Fine powder such as m has already started grain growth at 1000 ° C., and 1
200nm at 200 ° C, 500nm at 1400 ° C, 16
It grows up to about 1 μm at 00 ° C. and about 2 μm at 2000 ° C. Further, when the coarse particles and the fine powder are blended, the fine powder diffuses into the coarse particles, so that remarkable grain growth occurs, and as a result, the pore diameter reaches 20 μm. Therefore, the firing temperature is preferably 1200 ° C to 1800 ° C. On the other hand, when the particle size is large, the change in pore size is small even if the firing temperature is changed, and when the particle size is 15 μm, the pore size shows a constant value of about 3 μm. As described above, the pore size is appropriately selected for each particle size at a preferable firing temperature. Table 1 shows the particle size, the pore size of the molded product, and the change in the pore size at each firing temperature.

[0073]

[Table 1]

Next, the crucible containing graphite as a main component will be described. The crucible containing graphite as a main component means a crucible containing inevitable impurities and other additive elements in addition to graphite as a main component, and a crucible containing graphite whose surface has been modified as a main component.

When attempting to supply Si through the open pores of the graphite crucible, a part of the graphite is converted into SiC due to the reaction between the graphite particles and the melted Si, and the crucible swells, causing cracking or damage to the crucible. Therefore, the graphite crucible has a porosity of 10 to 20.
% High density products are preferred. The density at this time is 1.50 g
/ Cm ³ be in the range of ～2.05G / cm ^3. When the density is high, the pore diameter becomes small, and Si does not penetrate into the pores, and the surface is coated with Si.

From the viewpoint of repeatedly using the graphite crucible, the thickness of the crucible is preferably 20 mm or more. An arbitrary hole is formed on the side surface or bottom of the crucible, and molten Si is supplied to the impregnated body from the hole. Pore diameter is 0.25mmφ ~
The range of 2.0 mmφ is preferable.

It is substantially difficult and uneconomical to form holes smaller than 0.25 mmφ in high density graphite. In addition, for the purpose of always supplying a fixed amount of molten Si by opening a large hole of 2.0 mmφ or more, the pressure of the Si bath changes between the initial stage and the final stage, and the supply amount of Si becomes unstable and impregnation. Would be inconvenient. Therefore, the hole diameter is preferably 0.25 mmφ to 2.0 mmφ. The amount of Si supplied when a graphite crucible is used is controlled by the pore diameter and the number of pores. In the graphite crucible of the present invention, the number density of holes in the region having the opening is 0.001 / cm ³ to 1 / c.
The range of m ³ is preferable, and the range of 0.01 / cm ^{3 to} 0.1 / cm ³ is more preferable. The number density of holes in a region having an opening means the calculation of the number density of holes in the outer surface of the graphite crucible except for the region where no opening is formed.

The positional relationship between the crucible and the impregnated body (calcined body containing SiC as a main component) is a positional relationship in which the crucible is arranged above the calcined body, and only the outer periphery of the crucible is in contact with the impregnated body. Is also good. Further, it is more preferable that the entire surface of the crucible is not in contact with the crucible but a groove is formed on the surface of the crucible like a comb blade to reduce the contact area. 1 for SiC crucible
If it is used for impregnation, the composition becomes Si-SiC, and it can be repeatedly used as a crucible for supplying Si. Similarly, the graphite crucible can be used any number of times.

The crucible and the fired body are preferably subjected to a purification treatment while circulating a halogen-based gas such as Cl ₂ or HCl. The purification temperature is preferably in the range of 1100 ° C to 1700 ° C. When the heating temperature is 1100 ° C. or lower, purification is insufficient and it is difficult to sufficiently remove impurities diffused on the SiC surface. Also, if the temperature rises above 1700 ° C, Si
The formation of chloride due to the reaction between C particles and chlorine is remarkable, which is not preferable. Purification with a halogen-based gas reduces the amount of impurities such as Fe, Na and Cu in the crucible and the compact. In addition to this, wet pickling is performed, for example, by immersing the crucible or the fired body in hydrofluoric acid or a mixed acid of hydrofluoric acid and nitric acid, hydrofluoric acid and hydrochloric acid, etc. to dissolve metal impurities in the acid, and then using an acid group with pure water or the like. It is preferable to remove the same because the same purification can be obtained.

It is also possible to assemble a boat, a tube, etc. by combining the fired and purified members. In this case,
Care must be taken to ensure good adhesion between the members and familiarity with the base material.

The joining process may be performed on either the molded body or the fired body. It is preferable to use a slurry having the same composition as the adhesive, but it is not always necessary to use the same slurry.
A SiC slurry or the like to which a phenolic binder that causes SiC reaction formation during the impregnation is added can be suitably used as the bonding agent.

In the impregnation of Si into the fired body, the amount of Si required for impregnation is calculated from the density of the fired body, and the Si amount corrected for the amount of Si volatilized during heating is put in the crucible. At this time, in the case of a crucible containing SiC as a main component, the amount of Si necessary for the amount of voids is also added. The crucible containing Si is placed on the body to be impregnated and set in the furnace. The body to be impregnated is placed on, for example, a purified graphite plate, carbon felt, or purified graphite particles. Further, it is preferable to put the entire contents in the furnace in a highly pure closed graphite container. After depressurizing, 1500 ℃ ~
Heat to 1800 ° C. After keeping at the same temperature for 1 to 3 hours, it is cooled.

The degree of vacuum in the furnace is 133 Pa (1 Torr)
The following is preferable, and more preferably 1 Pa (0.01 To
rr) or less is desirable. The impregnation temperature may be higher than the melting point of Si, but is preferably 1500 ° C. or higher at which the viscosity of Si is sufficiently lowered. On the other hand, if the temperature is 1800 ° C. or higher, vaporization of Si into the furnace increases and the furnace is unnecessarily soiled, which is not preferable. The holding time depends on the supply rate of Si from the crucible containing Si, but it is preferably 1 to 3 hours for the Si to be sufficiently spread over the entire impregnated body.

At this time, the supply amount of Si is 1 g / min to 20
It is preferably within the range of 0 g / min. When it is 1 g / min or less, impregnation takes too much time and the amount of Si volatilized increases, which is uneconomical. On the other hand, if it exceeds 200 g / min, the amount of Si supplied to the object to be impregnated is too large and a part of Si is not impregnated and falls.

The flow rate of Si supplied is influenced by the shape of the body to be impregnated and the amount of voids. Suction by capillary force and gravity,
Unit volume of the impregnated body (cm ³ )
When converted to per hit, 0.005 g / (cm ³ · min)
Within the range of ⁵ g / (cm ³ · min), more preferably 0.
It is preferable to supply within the range of 01 g / (cm ³ · min) to 1 g / (cm ³ · min). Supply amount is 0.005g /
If it is less than (cm ³ · min), the impregnation takes too long and becomes inefficient. Also, if it is faster than 5 g / (cm ³ · min), the Si absorption capacity of the impregnated body is exceeded, and Si flows out from the impregnated body.

The impregnated body from which the crucible has been removed is subjected to a blast treatment to remove the protruding Si adhered to a part thereof. Further, the groove and the like is subjected to groove cutting using a diamond blade or the like. Then, the surface is cleaned with hydrofluoric acid or a mixed acid of hydrofluoric acid and hydrochloric acid. The acid concentration is 1:10 for HF: H ₂ O.
It is preferably within the range of 1: 5. Next, high-pressure water cleaning using pure water and ultrasonic cleaning are performed to completely remove acid components and impurities adhering to the surface. Then, it is dried at about 500 ° C.

The impregnated body after drying is heated at 1100 ° C to 1600 ° C.
It is placed in an atmosphere containing silane-based gas and methane-based gas as main components within a temperature range of ° C, and a SiC film is formed on the surface by a CVD method to manufacture a Si-SiC composite material.

[0088]

Example 1 An αSiC powder (# 150) and an αSiC powder having an average particle size of 2 μm were mixed with hydrofluoric acid and nitric acid (1:
Pickled with mixed acid of 1), Fe is 2.1 ppm each
And 1.2 ppm of powder was obtained. αSiC (# 150) and 2 μm αSiC particles were mixed at a ratio of 1: 1 (mass ratio), and pure water and a water-soluble phenol resin were added and mixed therein to obtain a slurry having a solid content concentration of 80% by mass. Next, this slurry was poured into a plaster mold (square rod having a length of 30 mm, a length of 40 mm, and a length of 1 m) to perform solid casting. Similarly, the slurry was poured into a plaster mold having a diameter of 230 mm and molded into a disk shape having a wall thickness of 10 mm.

Similarly, the diameter is 140 mmφ and the height is 100 mm.
The slurry was poured into the cylindrical gypsum mold of No. 1 and molded into a cylindrical container having a wall thickness of 4 mm to prepare a crucible.

After the molded body was dried and processed, it was degreased at 1100 ° C., and then baked in a vacuum atmosphere at 1800 ° C. for 2 hours. At this time, the porosity of the fired body was 19%, and the pore size of the fired body was about 800 nm. A rectangular rod and a disk were joined using a homogenous slurry containing a phenol resin to form a boat, and the boat was dried at 200 ° C.

A high-purity Si amount of 1.1 kg necessary for the porosity of the fired body and the SiC crucible was weighed and put in the SiC crucible. SiC with 20% porosity and 600 nm pore size
The crucible was placed on a boat and set in an impregnation furnace. A total of 5 sets of this combination were prepared and all were arranged in the furnace.

The whole was placed in a closed high-purity graphite container and kept in vacuum at 1650 ° C. for 1 hour to impregnate Si. The SiC crucible was removed from the impregnated boat, the impregnated body was blasted, and the protruding Si adhering to part of the surface was removed. The boat was grooved using a diamond blade to form a groove having a width of 2 mm. Next, it was washed with hydrofluoric acid and pure water. After that, high-pressure water cleaning and ultrasonic cleaning are performed using pure water to remove Si-
Wafer boats made of SiC composite were manufactured. The composite material had a dense structure in which voids were impregnated with Si and had no pores.

Example 2 αSiC powder (# 180) and αSiC powder having an average particle diameter of 2.5 μm were subjected to pickling treatment with a mixed acid of hydrofluoric acid and nitric acid, and Fe was 2.4 p
A powder with pm and 2 ppm was obtained. αSiC powder (# 18
0) and 2.5 μm αSiC particles 4: 6 (mass ratio)
And mixed with pure water and an acrylic resin emulsion to obtain a slurry having a solid content concentration of 82% by mass.
Next, pour this slurry into a cylindrical plaster mold, and
After confirming the wall thickness of m, the slurry was discharged. (This is called the sludge casting molding method.) As a result, the outer diameter is 350 m.
A cylindrical molded body having mφ, an inner diameter of 341 mmφ and a length of 1.5 m was obtained.

Similarly, a cap having a curvature of 500 mmφ was produced by a sludge casting method and joined to one end of a cylinder.

After degreasing the above molded body at 1100 ° C.,
In a vacuum atmosphere, the firing temperature was kept at 2000 ° C. for 2 hours for firing. At this time, the porosity of the fired body was 19%, and the pore size of the fired body was about 1 μm. A high-purity Si amount of 3.4 kg required for the porosity of the fired body and the SiC crucible was measured and put in the crucible. A SiC crucible having a porosity of 23% and a pore size of 900 nm was placed on a soaking tube, which was set in an impregnation furnace, and the whole was put in a highly purified graphite container to complete the preparation.

The inside of the impregnation furnace is evacuated to 2700 ° C.
It was kept for a period of time to impregnate Si. The SiC crucible was removed from the impregnated body, acid cleaning was performed with mixed acid and pure water, and then high pressure water cleaning and ultrasonic cleaning were performed to obtain a soaking tube for semiconductors. The composite material had a dense structure in which voids were impregnated with Si and had no pores.

Example 3 αSiC powder (# 240) and high-purity αSiC powder having an average particle size of 1 μm (Fe impurity concentration: 0.6 ppm) were mixed in a mass ratio of 3: 7, and pure water, Glycerin as a plasticizer and cellulose as a binder were added and mixed to obtain a kneaded product having a solid content of 77% by mass and having plasticity.

Using an extrusion molding machine having a cylinder and a plunger coated with Teflon (registered trademark) resin, a thin tube having an outer diameter of 6 mm and an inner diameter of 4 mm was obtained. A protective tube was manufactured by closing one end with the same material.

After the protective tube was dried and processed, it was degreased at 700 ° C. and then baked at 1600 ° C. for 1 hour in an argon atmosphere. The porosity of the fired body at this time is 21%,
The pore size of the fired body was about 700 nm.

Dozens of the above-mentioned fired bodies were arranged upright on a graphite plate so that one closed end faces down. A SiC crucible was placed thereon, and 230 g of high-purity Si required for impregnating the fired body and the pores of the crucible was weighed and put in the crucible. The porosity of the crucible was 20% and the pore size was 600 nm. In vacuum,
The sintered body was impregnated with Si by holding it at 1650 ° C. for 1 hour.
Then, the impregnated body was heated at 1200 ° C. in the atmosphere to form an oxide film on the surface of the impregnated body to manufacture a protection tube made of a Si—SiC composite material. The composite material had a dense structure in which voids were impregnated with Si and had no pores.

Example 4 The same αSiC powder as in Example 1 was mixed in a mass ratio of 4: 6, and pure water and polyvinyl alcohol were added thereto and mixed to obtain a slurry having a solid content concentration of 82 mass%. It was Next, this slurry is poured into a cylindrical plaster mold, and solid casting is performed so that the wall thickness becomes about 25 mm.
Outer diameter 350 mmφ, inner diameter 300 mmφ, length 300 mm
The molded body of was manufactured.

After the molded body was dried and processed, it was degreased at 1100 ° C., and kept at 1900 ° C. for 2 hours in an argon atmosphere and baked. At this time, the porosity of the fired body was 20%, and the pore size of the fired body was about 900 nm.

1 is attached to the lower part of the side surface of a crucible made of high-purity graphite and having an outer diameter of 200 mmφ, an inner diameter of 150 mmφ and a height of 100 mm.
Eight holes of mmφ were evenly formed. A graphite crucible was charged with 1.4 kg of high-purity Si corresponding to the amount of pores of the impregnated body.
Place the material to be impregnated on a high-density graphite plate, set the crucible on it, and put it in a highly-purified graphite container that is hermetically sealed.
It was kept at 750 ° C. for 2 hours to impregnate Si. The graphite crucible was removed from the impregnated body, the protruding Si was removed by blasting, and after grinding and acid cleaning, high-pressure water cleaning and ultrasonic cleaning were performed to manufacture a Si-SiC composite bell jar tube. did. The composite material had a dense structure in which voids were impregnated with Si and had no pores.

Example 5 αSiC powder (# 180) and high-purity αSiC powder having an average particle size of 15 μm were mixed in a mass ratio of 1: 1 and pure water and polyvinyl alcohol were added thereto and mixed to granulate. did. Next, the granulated powder was molded by a hydrostatic pressure molding method (CIP molding) at a pressure of 1.5 ton / cm ² to obtain a flat plate having a width of 350 mm, a length of 125 mm, and a thickness of 8 mm.

After degreasing the molded body at 1100 ° C.,
In an argon atmosphere, 2100 ° C. was maintained for 2 hours for firing. At this time, the porosity of the fired body was 18%, and the pore size of the fired body was about 3 μm. This fired body was erected so as to be horizontally long, and a plurality of sheets were lined up with a gap of about 10 mm from each fired body. Horizontal 200 made by casting into a square shape
mm, length 300 mm, height 50 mm, porosity 20
%, A rectangular SiC crucible having a pore diameter of 600 nm was placed.
High-purity Si amount required for the amount of pores in the SiC crucible and the molded body 7.
1 kg was measured and put in a SiC crucible. A total of 6 sets of this combination were prepared, all were lined up in the furnace, and the whole was placed in a closed high-purity graphite container.
It was kept for a period of time to impregnate Si. The crucible was removed from the impregnated flat plate, and the impregnated body was blasted to remove the protruding Si attached to a part thereof. The impregnated body was further ground to produce a tray of 4-inch wafers made of a Si-SiC composite. The composite material had a dense structure in which voids were impregnated with Si and had no pores.

(Example 6) αSiC fine particles (# 1200)
Was further pulverized, pickled, and clarified by circulating HCl gas. Fe was 0.2 ppmm and maximum particle size was 15 μm.
High-purity αSiC fine particles having a particle size of less than m and an average particle diameter of 1.8 μm were obtained. Pure water and an acrylic resin emulsion were added to and mixed with this powder to obtain a slurry having a solid content concentration of 78 mass%.
Next, this slurry was poured into a gypsum mold to obtain a fork-shaped compact for wafer boat transportation.

After this molded body was dried and degreased at 1100 ° C., it was held in a vacuum atmosphere at 1900 ° C. for 2 hours and baked. At this time, the porosity of the fired body was 21%, and the average pore diameter of the fired body was about 5 μm. For the impregnation, the Si-SiC crucible used once for the impregnation treatment was used, and the crucible was placed on the horizontally elongated fired bodies. A high-purity Si amount of 1.2 kg necessary for the amount of pores of the impregnated body was weighed and placed in a crucible, and the whole was placed in a closed high-purity graphite container.
It was kept at 2 ° C. for 2 hours to impregnate Si. The crucible was removed from the impregnated body, and the surface of the impregnated body was blasted to remove the protruding Si attached.

The impregnated body was further ground to produce a fork-shaped Si-SiC composite material for wafer transportation. The composite material had a dense structure in which voids were impregnated with Si and had no pores.

Example 7 βSiC from SiO ₂ and carbon
ΒS with an average particle diameter of 1.5 μm
iC powder was obtained. Pure water and dextrin were added to form a slurry, which was cast into the gypsum mold of Example 1. After solidification, it was demolded to obtain a disc and a square rod. Similarly, diameter 140mmφ, height 100
Pour the slurry into a mm plaster mold and have a thickness of 4 mm
After that, the crucible was manufactured by draining the slurry and adding Si.

The molded body was dried and processed, degreased, and then baked in a vacuum atmosphere at 1900 ° C. for 1 hour. At this time, the porosity of the fired body and the crucible was 21%, and the pore size of the fired body was about 4 μm. Weigh out 1.2 kg of high-purity Si required for the amount of pores between the fired body and the SiC crucible, and add S
It was placed in an iC crucible, placed on a boat to which a SiC crucible was joined, set in an impregnation furnace, placed in a closed high-purity graphite container, and held in vacuum at 1650 ° C. for 1 hour to impregnate Si. Remove the SiC crucible from the impregnated boat and remove the Si-
A boat-shaped product made of a SiC composite material was manufactured. The boat-shaped product had a dense structure in which voids were impregnated with Si and had no pores.

(Example 8) βSiC synthesized in Example 7
The powder was further water-classified to obtain a powder having an average particle size of 0.3 μm. After performing a purification treatment, polyvinyl alcohol was added and granulated. Molded body density of 1.5g / c
A square pot with m ³ , porosity of 53%, 100 mm square and 80 mm height was formed. This is fired at 1200 ° C. to have a pore size of 30.
A porous body having pores of 0 nm was obtained.

A high-purity Si amount required for the porosity of the SiC square bowl and the impregnated body separately fired under the same conditions as in Example 1 was 1.
3 kg was measured and put in a SiC square bowl. Place it on the material to be impregnated, set it in the impregnation furnace, put it in a closed high-purity graphite container, and hold it in vacuum at 1600 ° C. for 2 hours to obtain Si.
Was impregnated. The SiC crucible was removed from the impregnated boat to obtain a boat-shaped product. It was confirmed that the boat-shaped product was a dense Si-SiC composite material in which voids were impregnated with Si and had no pores.

Example 9 αSiC blended in Example 2
12% of a water-soluble phenolic resin as a carbon source was added to the powder, and pure water was added thereto to obtain a slurry having a solid content concentration of 80% by mass. This was poured into the gypsum mold used in Example 1 to form a SiC crucible. After processing this, it was dried, degreased, and held in a vacuum atmosphere at 1900 ° C. for 1 hour to be baked. At this time, the porosity of the SiC crucible was 21%, and the pore size of the fired body was about 900 nm. This fired body is impregnated with Si to convert the remaining carbon into SiC, and S
An i-SiC composite material was obtained. Its density is 3.1 g / cm ^3.
Became. A part of this was cut out and Si was removed with acid to obtain a SiC substrate having a density of 2.9 g / cm ³ and an open porosity of 10
%, And the pore size was 350 nm.

A high-purity Si amount of 0.8 kg necessary for the porosity of the fired body containing SiC as a main component was measured and put in a crucible,
Place the crucible on the joined boat and set it in the impregnation furnace, put it in a closed high-purity graphite container, and in vacuum 1650
It was kept at 2 ° C. for 2 hours to impregnate Si. It was confirmed from the weave observation that the composite material after impregnation was a dense body having no pores.

(Comparative Example 1) The flat plate produced in Example 5 was fired under the same conditions, and the fired bodies were arranged side by side with an interval of about 10 mm so that the fired body was horizontally long. In the meantime, a mixture of 7.4 kg of Si required for impregnation of the fired body, high-purity graphite of about 5 mmφ, and SiC of 3 mm in diameter was filled. The whole was placed in a closed high-purity graphite container and kept at 1600 ° C. for 2 hours in vacuum to impregnate Si. When the flat plate that is the impregnated body is peeled off, a mixed phase of excess Si, SiC particles, and graphite particles is deposited in the lower portion, so several flat plates are damaged and It took a lot of time to remove it.

(Comparative Example 2) Granular Si was uniformly applied and fixed with a phenol resin around the SiC fired body fired in Example 1, and the periphery thereof was covered with carbon fiber to prevent the granular Si from falling off. This was kept in vacuum at 1650 ° C. for 1 hour to impregnate Si. Excessive Si and carbon fibers adhered to the surface of the impregnated body, and it took a lot of time to isolate them. Also, the surface of the fired body had an unimpregnated phase, so the impregnation treatment was performed again. There was a need.

(Comparative Example 3) The fired body produced in Example 2 was placed in the center of the furnace, carbon fibers were wound around the fired body, and Si placed in the graphite crucible was arranged so as to be supplied by the capillary action of the carbon fibers. . These were placed in a closed high-purity graphite container and kept under vacuum at 1800 ° C. for 2 hours to impregnate Si.

The impregnated body had a structure in which some pores were left, and a uniform Si-SiC composite material could not be obtained.

[0119]

EFFECTS OF THE INVENTION According to the present invention, as compared with the conventional impregnation method, complicated and labor-intensive preparation such as winding of carbon fiber, coating and filling of Si is unnecessary, and an extremely simple and efficient manufacturing method is achieved. Available now. In particular, batch processing of a plurality of products with different product forms has become possible, resulting in a marked increase in production efficiency.

Further, the Si-SiC composite material produced by using the production method of the present invention has a high-purity and dense structure, and particularly in the field of semiconductor jigs, a highly reliable jig for increasing the yield of products. Can be provided.

Claims (15)

[Claims] 1. Si is formed on the upper portion of a fired body containing SiC as a main component.
The crucible containing the above is installed, and the crucible is heated to bring Si into a molten state, and a melt of Si is supplied to the surface of the fired body through the holes of the crucible, and the fired body is impregnated with Si to impregnate the Si-SiC composite material. The manufacturing method of Si-SiC composite material which manufactures. 2. S is formed on the upper part of a fired body containing SiC as a main component.
The method for producing a Si-SiC composite material according to claim 1, wherein two or more crucibles containing i are installed. 3. The crucible contains SiC as a main component and has a density of 1.
In the range of ^{30g / cm 3 ~3.02g / cm 3} , in the range density ratio of 40~92TD%, an average pore diameter measured by a mercury porosimeter (average pore diameter) is 50nm
It is in the range of -30 μm. 3. The method for producing a Si—SiC composite material according to claim 1, wherein 4. The crucible contains SiC as a main component and has a density of 1.
In the range of ^{70g / cm 3 ~2.90g / cm 3} , in the range density ratio of 53TD% ~90TD%, an average pore diameter measured by a mercury porosimeter 300nm~40
It is in the range of 00 nm, The manufacturing method of the Si-SiC composite material of Claim 1 or 2 characterized by the above-mentioned. 5. A crucible is cast-molded by adding a binder to SiC powder having a particle size of 0.1 μm to 300 μm, or rubber press-molded or die-molded, and thereafter,
5. A Si-SiC composite material according to any one of claims 1 to 4, which is a crucible containing SiC as a main component, the crucible being heated and fired within a temperature range of 1200 ° C to 2300 ° C. Method. 6. The crucible mainly contains graphite and has a density of 1.5.
In the range of ^{0g / cm 3 ~2.05g / cm 3} , the manufacturing method of the Si-SiC composite material according to claim 1, characterized in that it comprises an opening at the bottom or side of the crucible. 7. The opening has a hole shape and the hole diameter is 0.25 to 0.25.
It is within the range of 2.0 mmφ, and the number density of holes in the region having the opening is within the range of 0.001 / cm ³ to 1 / cm ^3. 7. Si-
Method for manufacturing SiC composite material. 8. A sintered body mainly composed of SiC is, the density is in the range of ^{1.30g / cm 3 ~3.02g / cm 3} , in the range density ratio of 40TD% ~92TD%,
The average pore diameter (average pore diameter) measured by a mercury porosimeter is within a range of 50 nm to 30 μm, The method for producing a Si—SiC composite material according to claim 1. 9. The supply rate of Si from the crucible to the fired body containing SiC as a main component is within the range of 1 g / min to 200 g / min. Item 6. A method for producing a Si-SiC composite material according to Item. 10. The feed rate of Si from the crucible to the fired body containing SiC as a main component is S per unit volume of the fired body.
i at a feed rate of 0.005 g / (cm ³ · min) to 5 g /
Method for producing a Si-SiC composite material according to any one of claims 1-9, characterized in that it is in the range of (cm ³ · min). 11. The supply rate of Si per crucible is 2
It is in the range of g / min to 200 g / min, The manufacturing method of Si-SiC composite material of any one of Claims 1-10 characterized by the above-mentioned. 12. The total amount of metal impurities of SiC constituting the fired body is 50 ppm or less.
12. The method for producing a Si-SiC composite material according to any one of 1 to 11. 13. The total amount of metallic impurities of SiC forming the crucible is 50 ppm or less.
The manufacturing method of the Si-SiC composite material of any one of 5 and 8-11. 14. Main component is SiC, and density is 1.30 g.
/ Cm ^{3 to} 3.02 g / cm ³ , the density ratio is in the range of 40TD% to 92TD%, and the average pore diameter (average pore diameter) measured by a mercury porosimeter is 50 nm.
A crucible for impregnating a fired body with a melt, characterized in that the crucible has a thickness within the range of -30 μm. 15. A graphite-based material having a density of 1.50 g /
A crucible for impregnating a melt into a fired body, characterized in that the crucible has an opening in a lower portion or a side portion of the crucible in a range of from cm ^{3 to} 2.05 g / cm ³ .