KR101601282B1 - Furnace for manufacturing silicon carbide and silicon carbide manufacturing method using same - Google Patents

Abstract

The present invention relates to a semiconductor device comprising: a side portion integral with a bottom portion; A lid part covering the upper part of the side part to seal the inside part; And at least one exhaust port formed at a height of 90% or more and 100% or less from the bottom portion of the side surface portion. The present invention also relates to a crucible for manufacturing silicon carbide powder and a method of manufacturing silicon carbide using the same. As a result, the impurity gas is easily discharged to reduce the source of contamination, thereby obtaining a high-purity silicon carbide powder and controlling the gas pressure inside the crucible to improve the product recovery rate.

High purity silicon carbide powder, crucible, vacuum degree

Description

FIELD OF THE INVENTION [0001] The present invention relates to a crucible for producing a silicon carbide powder and a method for producing the same,

The present invention relates to a crucible for producing a silicon carbide powder and a method for producing the pyroelectric silicon powder using the same.

Silicon carbide (SiC) is the most important carbide in the field of ceramics as a synthesis material. Silicon carbide has a β-phase having a cubic crystal structure and an α-phase having a hexagonal crystal structure. The? phase is stable in the temperature range of 1400-1800 占 폚, and the? phase is formed in 2000 占 폚 or more.

The molecular weight of SiC is 40.1, the specific gravity is 3.21, and decomposed at 2500 ℃ or higher.

Since SiC first succeeded in pressureless sintering by the addition of boron and carbon by GE Prochazka of USA in the 1970s, SiC has high temperature strength, excellent abrasion resistance, oxidation resistance, corrosion resistance and creep resistance, It is a high-grade ceramic material widely used for mechanical seals, bearings, various nozzles, hot cutting tools, fireproof plates, abrasive materials, reducing materials for steelmaking, lightning arresters and so on.

Conventional techniques for producing such SiC powder include an acheson method, a direct reaction method, a liquid phase polymer thermal decomposition method, and a high temperature self-combustion synthesis method.

Particularly, in order to obtain high-purity SiC powder, it is important to prepare SiC powder by synthesizing by adding heat and pressure to the mixed carbon source and the silicon source. Depending on the structure of the so-called crucible, the apparatus for synthesizing such SiC powder affects the recovery rate and high purity of SiC.

However, in the conventional crucible structure, the structure for controlling the discharge of the gas and the pressure management incidentally generated in the SiC synthesis has not been specifically developed. Therefore, a crucible shape capable of obtaining a high purity SiC powder at a high recovery rate is required.

It is an object of the present invention to provide a crucible for the production of silicon carbide powder and a method for manufacturing silicon carbide powder using the same to improve the recovery rate and high purity of SiC.

The crucible for producing a silicon carbide powder according to the present invention comprises: a side part integrally formed with a bottom part; A lid part covering the upper part of the side part to seal the inside part; And at least one exhaust port formed at a height of 90% or more and 100% or less from the bottom portion of the side portion, thereby improving the SiC recovery rate and high purity.

Here, each of the one or more exhaust ports is preferably a rectangle, an inverted triangle, a semicircle, an inverted trapezoid, a circular shape, a geometric shape, and the like, but is not limited thereto and includes all shapes that perform an exhaust- .

Particularly, the exhaust port is formed at a portion of 100% height from the bottom portion of the side portion, and the connecting portion between the exhaust port and the upper surface of the side portion is in an elongated shape. The risk of breakage can be reduced.

Also, a method for producing a silicon carbide powder according to the present invention comprises the steps of: (a) producing a mixture composed of a silicon source and a carbon source in a mixer; And (b) synthesizing the mixture as a silicon carbide (SiC) powder in a crucible, wherein the crucible is a crucible for silicon carbide production as described above.

The mass ratio of the silicon source to the carbon source in the step (a) is 1: 1 or more and 4: 1 or less.

In particular, the silicon source of step (a) may be selected from at least one of fumed silica, silica sol, silica gel, silica, and quartz powder, The carbon nanotubes may be carbon black, carbon nanotubes, fullerene, phenol resin, franc resin, xylene resin, polyimide, polyurethane, polyacrylonitrile at least one of polyacrylonitrile, polyvinyl alcohol, monomer containing polyvinyl acetate, prepolymer, cellulose, sugar, pitch, and tar is selected .

In the step (b), the mixture is heated at a degree of vacuum of more than 0.1 torr to 0.5 torr and at a temperature of 1300 to 1900 ° C to synthesize SiC powder.

According to the present invention, the impurity gas is easily discharged to reduce the source of contamination, thereby obtaining a high-purity silicon carbide powder and controlling the gas pressure inside the crucible, thereby improving the product recovery rate.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a crucible for manufacturing a silicon carbide powder according to an embodiment and a method for producing silicon carbide powder using the same will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid unnecessarily obscuring the subject matter of the present invention.

1 is a three-dimensional perspective view of a crucible for silicon carbide production according to an embodiment of the present invention.

1, a crucible for manufacturing silicon carbide according to the present invention includes a bottom 110, a side 120, an exhaust 140, and a lid 130. More specifically, the bottom portion 110 and the side portion 120 are integrally formed, and the exhaust port 140 is located at a portion of the side portion 120 that is 90% or more and 100% or less in height from the bottom portion 110.

Here, the shape of the crucible may be a rectangular shape or a cylindrical shape, and in particular, a cylindrical shape is preferable in order to improve the synthesis uniformity.

Particularly, FIG. 1 shows a case in which the exhaust port 140 is formed at a position of a 100% portion of a side portion. It is preferable that the position of the exhaust port 140 is located at the uppermost position as shown in the figure for the increase of the amount of the raw material and the easy discharge of the impurity gas.

The exhaust port 140 thus formed is preferably composed of a plurality of exhaust ports for discharging the incidental water and the impure gas. Here, the shape of the exhaust port 140 is preferably a rectangular shape, an inverted triangle shape, a semicircular shape, an inverted trapezoidal shape, a circular shape, and a geometric shape, but is not limited thereto and includes all shapes that perform a function of a passageway .

2 is a cross-sectional view of a crucible for the production of silicon carbide according to the present invention. This drawing shows a state in which the lid is closed. Generally, since one or more crucibles are stacked and heated, the risk of damaging the exhaust port due to the lid during the synthesis process increases as the furnace is stacked on the lower crucible. Therefore, as shown in FIG. 3, when the exhaust port 140 is located at the uppermost portion of the side surface portion, it is preferable that the connection portion between the uppermost surface and the exhaust port has a curved shape. Such a tortuous portion reduces the frictional force between the lid and the exhaust port, thereby reducing the risk of damage to the exhaust port 140. [ (Also, it is preferable that the size of the exhaust port 140 is set to 1/4 of the separation distance between the exhaust ports 140. For example, as shown in the figures of FIG. 3, ', The separation distance of the exhaust section may be implemented as' 40. 00'),

A method of producing silicon carbide using such a crucible for silicon carbide production will be described below.

4 is a flowchart showing the procedure of a method for producing silicon carbide powder using the crucible for silicon carbide powder according to the present invention. Referring to Fig. 4, first, a carbon source and a silicon source are prepared. (S1) Here, although carbon black is used as the carbon source, it is not limited thereto. For example, a solid carbon such as carbon nanotubes or fullerene, or an organic compound having a high residual carbon ratio, such as phenol resin, franc resin, xylene resin, polyimide, poly A monomer or prepolymer of a resin such as polyurethane, polyacrylonitrile, polyvinyl alcohol or polyvinyl acetate, a cellulose, a sugar, a pitch, Tar, and mixtures thereof may also be used.

The silicon source may also be selected from one or more of fumed silica, silica sol, silica gel, silica, and quartz powder.

Thereafter, such a silicon source is mixed with a carbon source. (S2) Specifically, 40 g of dry silica as a silicon source and 18 g of carbon black as a carbon source are mixed (S2). When a solid carbon source is used, the mass ratio of the silicon source to the carbon source is preferably 1: 1 or more and 4: 1 or less. When a carbon source of an organic material is used, a carbon source of about twice as much as that of a solid carbon source is required. However, there may be a slight difference depending on a carbon production amount generated in a subsequent carbonization process. Next, the mixture of the silicon source and the carbon source is heated to carbonize the carbon source contained in the mixture (S3). The temperature of the carbonization process is preferably 700 ° C to 1200 ° C, more preferably 900 ° C to 1100 ° C. However, if the carbon source is not an organic carbon material, the carbonization process may be omitted.

Thereafter, heat is applied to the mixture in a crucible having an exhaust port at the uppermost portion thereof, thereby synthesizing silicon carbide powder (S4). More specifically, it can be produced in an argon (Ar) atmosphere or a vacuum atmosphere, but a vacuum atmosphere is more preferable. The silicon carbide (SiC) is synthesized by heating at a degree of vacuum of more than 0.03 torr but not more than 0.5 torr and a temperature of 1300 to 1900 ° C (S4). Here, the heating time is preferably about 3 hours, but is not limited thereto. It is more preferable that the heating temperature is 1600 DEG C or more and 1900 DEG C or less. Here, the vacuum degree is preferably a heat treatment in a vacuum atmosphere of 0.1 torr or less, but when the degree of vacuum is 0.03 torr or less, the mass production equipment requires a lot of mechanical load, It is not desirable for a lot.

The recoverability and purity of the recovered silicon carbide powder using the crucible for producing silicon carbide powder according to the present invention are shown in Table 1 below in comparison with the prior art.

Comparative Example Example 1 Example 2 Recovery (g / l) 20.7 25.5 25.2 impurities
content
(ppm) Ca One 0.5 0.01 Na 0.5 0.01 0.01 K 0.5 0.01 0.01 Al One 0.5 0.2 Cr 0.1 0.1 0.1 Fe 0.1 0.1 0.1 Ni 0.5 0.1 0.1 Cu 0.1 0.1 0.1

Referring to Table 1, the comparative example shows a case where a hydrocarbon powder is synthesized using a crucible having an exhaust shape and position in a conventional manner. In Examples 1 and 2, a hydrocarbon powder was produced by using a crucible for the production of a silicon carbide powder according to the present invention.

Here, in all the conditions common to all cases, 40 g of fumed silica having an average particle diameter of 40 nm was selected as a silicon source, 18 g of carbon black having an average input of 20 nm as a carbon source was selected, and the mixing step was carried out and the carbonization step was omitted. In a 100? * 100h crucible composed of a graphite material, the degree of vacuum was 0.1 torr or more and 0.5 torr or less and the temperature was 1700 for 3 hours.

Specifically, the exhaust port of the crucible used in the comparative example is formed in a circular shape with a diameter of 3Φ at an 80% height of the crucible, and a total of 65 g of the raw material is injected.

On the contrary, in the crucible used in Example 1 according to the present invention, four crucibles are formed at the top (100%) height of the crucible in a semicircle of 3Φ, and a total of 80g of the raw material is charged.

In addition, the exhaust port of the crucible used in Example 2 according to the present invention is formed with 4 squares of 3 * 3 square at the top (100%) height of the crucible, and a total of 80 g of the raw material is injected.

As a result, the recovery rates of the silicon carbide powders recovered in the crucibles used in Examples 1 and 2 were 25.5 (g / l) and 25.2 (g / l), respectively, which were superior to Comparative Example 20.7 (g / l) . This is because a larger amount of material can be supplied as the height of the exhaust port increases.

In addition, it is understood that the contents of impurities, that is, Ca, Na, K, Al, and Ni are much smaller than those of the comparative example.

Referring to the following reaction formula for synthesizing silicon carbide powder,

SiO ₂ + C? SiO + CO

SiO2 + 2C? SiC + CO

  ---------------------

SiO ₂ + 3C → SiC + 2CO

This is because CO generated during the reaction can be released quickly. This rapid discharge is due to the position of the exhaust port being higher than in the prior art, and it is most preferable that the position of the exhaust port is the topmost position.

Further, the gas pressure can be controlled by adjusting the position and shape of the exhaust port, and it is most preferable that the gas pressure is formed in the rectangular shape at the top in consideration of the exhaust efficiency and the raw material input efficiency.

As a result, the recovery rate of the silicon carbide powder can be improved and the manufacturing cost can be reduced. In addition, it is possible to produce a silicon carbide powder of higher purity, and when used in a semiconductor or the like, the reliability of the product is improved.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical spirit of the present invention should not be limited to the above-described embodiments of the present invention, but should be determined by the claims and equivalents thereof.

1 is a perspective view of a crucible for producing silicon carbide according to an embodiment of the present invention.

2 and 3 are cross-sectional views of a crucible for the production of silicon carbide according to the present invention

4 is a flow chart of a process for producing a silicon carbide powder using a crucible for silicon carbide powder according to the present invention

Description of the Related Art [0002]

110: bottom part 120: side part

130: lid part 140: exhaust port

Claims (7)

A side portion integrally formed with the bottom portion; A lid part covering the upper part of the side part to seal the inside part; And a plurality of exhaust ports disposed on the uppermost surface of the side surface portion and configured to penetrate from the outside to the inside of the side surface portion and having an upper surface opened and disposed at regular intervals from each other, The exhaust port And a crucible for producing silicon carbide powder, the height of which is 90% or more and 100% or less from the bottom of the side surface portion. The method according to claim 1, Wherein the connecting portion between the uppermost surface and the exhaust port has a curved shape with a constant curvature. The method according to claim 1 or 2, Wherein the crucible for producing the silicon carbide powder has the same cross-sectional shape as the plurality of exhaust ports. The method of claim 3, Wherein the shape of a cross section of the exhaust port is a square or a rectangle. The method of claim 4, In the crucible, Due to the shape of the horizontal cross section Cylindrical crucible for the production of silicon carbide powders. delete delete

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