KR20130020490A - Silicon carbide and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A silicon carbide and a manufacturing method thereof are provided to improve productivity and purity by limiting the mole ratio of carbon to silicon to 2.5-2.8 and to have high purity by manufacturing the silicon carbide to have a low content of remaining carbon and oxygen. CONSTITUTION: A silicon carbide and a manufacturing method thereof include following steps: A silicon source and a carbon source are mixed(ST10). Silicon carbide from heating mixed raw material is formed(ST20). In the mixing stage of raw material, the mole ratio included in the carbon source about silicon included in the silicon source is 2.5-2.8. The carbon source includes a solid carbon source or an organic carbon compound. The solid carbon source includes at least one material selected from a group comprised of graphite, carbon black, carbon nanotubes, and fullerene. The organic carbon compound includes at least one material selected from a group comprised of penol, franc, xylene, polyimide, polyunrethane, polyvinyl alcohol, polyacrylonitrile, and polyvinyl acetate. [Reference numerals] (ST10) Raw material mixing step; (ST20) Heating step

Description

Silicon carbide and its manufacturing method {SILICON CARBIDE AND METHOD FOR MANUFACTURING THE SAME}

The present disclosure relates to silicon carbide and methods of making the same.

Silicon carbide has recently been used as a semiconductor material for various electronic devices and purposes. Silicon carbide is particularly useful due to its physical strength and high resistance to chemical attack. Silicon carbide also has radiation hardness, high breakdown filed, relatively wide bandgap, high saturated electron drift velocity, high operating temperature, and spectral blue, violet has excellent electronic properties, including absorption and release of both high energy in the violet and ultraviolet regions.

Such silicon carbide may be produced by a method of mixing a raw material such as a silicon source and a carbon source, followed by heating. In the manufacturing method of silicon carbide, it is an important subject to raise the recovery rate of high purity silicon carbide by a simple process.

As a conventional method for producing silicon carbide powder, an Acheson method, a carbon thermal reduction method, a liquid polymer pyrolysis method, or a CVD method is used. Particularly, the high purity silicon carbide powder synthesis method used liquid phase pyrolysis method or carbon thermal reduction method.

That is, silicon carbide is synthesized by mixing a carbon source and a silicon source material and carrying out a carbonization process and a synthesis process.

The reaction scheme of the silicon carbide powder is as follows.

SiO ₂ (s) + 3C (s)-> SiC (s) + 2CO (g)

In one example, the Acheson method is a representative synthesis method for synthesizing silicon carbide, by using a large Acheson melting furnace to mix a silicon source and a carbon source flowing a current to react at a high temperature of about 2200 ℃ to 2400 ℃ to produce silicon carbide It is a way.

In addition, the CVD synthesis method is a method of synthesizing silicon carbide by reacting a gas containing silicon and carbon at a high temperature, there is a thermal decomposition CVD method and a plasma CVD method. At this time, SiCl ₂ , SiH ₂ gas may be used as the silicon source, and CH ₄ , C ₃ H ₄ , CCl ₄ gas, or the like may be used as the carbon source.

In addition, the liquid phase pyrolysis method and the carbon thermal reduction method are methods for synthesizing high-purity fine silicon carbide powder at low temperature, and are a method for producing ethyl silicate and phenol resins as carbon sources and silicon sources.

At this time, the mixing ratio of each raw material in the mixing step of the carbon source and the silicon source is related to the recovery rate of silicon carbide. That is, when too much carbon is added, the amount of carbon is high, so that the amount of carbon remaining does not participate in the reaction, and thus the amount of carbon remaining is high, thereby reducing the recovery rate. In addition, when too little carbon is added, the amount of silicon is high so that the amount of residual silicon remaining without participating in the reaction is high, which may lower the recovery rate.

Accordingly, the molar ratio of carbon source to silicon source may be an important factor in determining the recovery rate of silicon carbide.

Therefore, it is required to determine the molar ratio of the silicon source and the carbon source that can minimize the residual carbon source while obtaining the optimum silicon carbide recovery rate.

The embodiment is to provide a method for producing silicon carbide and the silicon carbide produced thereby to increase the recovery rate of high purity silicon carbide in a simple process.

Silicon production method according to the embodiment, the raw material mixing step of mixing a silicon source and a carbon source; And a heating step of heating the mixed raw material to form silicon carbide. In the raw material mixing step, the mole ratio of carbon included in the carbon source to silicon included in the silicon source is 2.5 to 2.8.

The carbon source may include a solid carbon source or an organic carbon compound.

The solid carbon source may include at least one material selected from the group consisting of graphite, carbon black, carbon nanotubes (CNT), and fullerenes (C ₆₀ ).

The organic carbon compound may include phenol, franc, xylene, polyimide, polyurethane, polyvinyl alcohol, polyacrylonitrile and polyacrylonitrile. At least one material selected from the group consisting of vinyl acetate (poly (vinyl acetate)).

The silicon source may include a dry silicon source. The silicon source may include at least one selected from the group consisting of silica powder, silica sol, silica gel, and quartz powder.

The recovery rate of the silicon carbide may be 33.3% or more.

Silicon carbide according to the embodiment is produced by the above-described method for producing silicon carbide.

The method for producing silicon carbide according to the embodiment can improve the productivity and purity by limiting the molar ratio of carbon to silicon. The silicon carbide produced thereby may have high purity due to low residual carbon and oxygen content.

1 is a process flowchart of a method of manufacturing silicon carbide according to an embodiment.
FIG. 2 is a diagram showing peaks of silicon carbide prepared by Preparation Examples 1 to 5 by X-ray diffraction (XRD) spectroscopy.
3 is a scanning electron micrograph of silicon carbide prepared according to Preparation Example 1. FIG.
4 is a scanning electron micrograph of silicon carbide prepared according to Preparation Example 2. FIG.
5 is a scanning electron micrograph of silicon carbide prepared according to Preparation Example 3. FIG.
6 is a scanning electron micrograph of silicon carbide prepared according to Preparation Example 4. FIG.
7 is a scanning electron micrograph of silicon carbide prepared according to Preparation Example 5. FIG.
8 is a scanning electron micrograph of silicon carbide prepared according to Comparative Example 1. FIG.
9 is a scanning electron micrograph of silicon carbide prepared according to Comparative Example 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 will be described with reference to FIG. 1. 1 is a process flowchart of a silicon carbide and a method of manufacturing the same according to the embodiment.

Referring to FIG. 1, the method of manufacturing silicon carbide according to the present embodiment includes a raw material mixing step ST10 and a heating step ST20. Each step is described in more detail as follows.

In the raw material mixing step (ST10), a silicon source (Si source) and a carbon source (C source) are prepared and mixed.

The silicon source can include various materials that can provide silicon. In one example, the silicon source may comprise silica. Examples of such silicon sources include silica powder, silica sol, silica gel, and quartz powder. However, the embodiment is not limited thereto, and an organosilicon compound including silicon may be used as the silicon source.

The carbon source may comprise a solid carbon source or an organic carbon compound.

Examples of the solid carbon source include graphite, carbon black, carbon nano tube (CNT), and fullerene (C ₆₀ ).

The organic carbon compound may be phenol, franc, xylene, polyimide, polyurethane, polyvinyl alcohol, polyacrylonitrile, or Polyvinyl acetate (poly (vinyl acetate)) and the like. In addition, cellulose, sugar, pitch, tar and the like can be used.

Such a carbon source and a silicon source can be mixed by a wet mixing process using a solvent or a dry mixing process using no solvent.

The silicon source and the carbon source are mixed by a method such as a ball mill or attrition bill to recover the mixed powder. The mixed powder can be caught and recovered by a sieve.

In this raw material mixing step (ST10), the mole ratio of carbon contained in the carbon source to silicon contained in the silicon source (hereinafter, referred to as molar ratio of carbon to silicon) is 1.5 to 3. When the molar ratio of carbon to silicon is more than 3, the amount of carbon is high so that the amount of carbon remaining does not participate in the reaction, and thus the recovery rate may be reduced. In addition, when the molar ratio of carbon to silicon is less than 1.5, the amount of silicon is large and the amount of residual silicon remaining without participating in the reaction may be high, thereby reducing the recovery rate. That is, the molar ratio of carbon to silicon is determined in consideration of the recovery rate.

In this way, when the silicon source and the carbon source are mixed to satisfy the molar ratio of carbon to silicon of 1.5 to 3, the recovery rate of silicon carbide can be made about 13% or more, for example, 12.8% or more.

At this time, in order to reduce the residual oxygen content and the residual carbon content while further improving the recovery rate, the molar ratio of carbon to silicon may be 2 to 2.8. Then, the recovery rate of silicon carbide can be made into about 24% or more, for example, 23.8% or more. And residual oxygen content can be made into about 0.1% or less, and residual carbon content can be obtained to the level close to about zero.

In addition, in order to further improve the recovery rate, the molar ratio of carbon to silicon can be 2.5 to 2.8. Then, the recovery rate of silicon carbide can be about 33% or more, for example, 33.3% or more. And residual oxygen content can be made into about 0.1% or less, and residual carbon content can be obtained to the level close to about zero.

Subsequently, in the heating step ST20, the mixed powder (that is, the mixed raw materials) is heated to form silicon carbide. More specifically, the mixed powder is weighed in a graphite crucible and then heated in a high temperature reactor, for example, a graphite furnace and heated. In this case, the heating temperature may be 1300 or more, and the heating time may be 30 minutes or more, for example, 1 hour to 7 hours. The inside of the high temperature reactor may be a vacuum or an inert gas (eg, argon or hydrogen) atmosphere.

In the heating step ST20, silicon carbide is formed according to the overall scheme of Scheme 3 by the steps of Schemes 1 and 2 below.

[Reaction Scheme 1]

SiO ₂ (s) + C (s)-> SiO (g) + CO (g)

[Reaction Scheme 2]

SiO (g) + 2C (s)-> SiC (s) + CO (g)

Scheme 3

SiO ₂ (s) + 3C (s)-> SiC (s) + 2CO (g)

As described above, in the method of manufacturing silicon carbide using a dry silicon source and a solid carbon source, SiO gas may be formed and volatilized as in Scheme 1. In consideration of this, in the present embodiment, the molar ratio of carbon to silicon is included to be less than 3. In particular, when the molar ratio of carbon to silicon is 2 to 2.8, and preferably, the molar ratio of carbon to silicon is 2.5 to 2.8, the residual carbon and oxygen content can be reduced while increasing the recovery rate of silicon carbide. As a result, the productivity and characteristics of silicon carbide can be improved.

The silicon carbide thus prepared may have high purity due to low residual carbon content and residual oxygen content. Such silicon carbide may be processed into a predetermined shape through press sintering or the like, and may be used as a susceptor or the like for deposition equipment or wafer carrier equipment.

Hereinafter, the present invention will be described in more detail through the production methods of silicon carbide according to Preparation Examples 1 to 5 and Comparative Examples 1 and 2. These preparations are only presented by way of example in order to explain the present invention in more detail, the present invention is not limited to these preparations.

Manufacturing example  One

The silica powder and carbon black were mixed by ball mill. At this time, the molar ratio of carbon contained in carbon black to silicon contained in silica powder was 3.0. The powder was collected using a sieve, dried in a spray dryer, and then placed in an argon atmosphere graphite furnace, and heated at 1800 for 3 hours to prepare silicon carbide.

Manufacturing example  2

Silicon carbide was prepared in the same manner as in Preparation Example 1, except that the molar ratio of carbon included in carbon black to silicon included in silica powder was 2.8.

Manufacturing example  3

Silicon carbide was prepared in the same manner as in Preparation Example 1, except that the molar ratio of carbon included in carbon black to silicon included in silica powder was 2.5.

Manufacturing example  4

Silicon carbide was prepared in the same manner as in Preparation Example 1, except that the molar ratio of carbon included in carbon black to silicon included in silica powder was 2.0.

Manufacturing example  5

Silicon carbide was manufactured in the same manner as in Preparation Example 1, except that the molar ratio of carbon included in carbon black to silicon included in silica powder was 1.5.

Comparative example  One

Silicon carbide was prepared in the same manner as in Preparation Example 1, except that the molar ratio of carbon included in carbon black to silicon included in silica powder was 3.2.

Comparative example  2

Silicon carbide was prepared in the same manner as in Preparation Example 1, except that the molar ratio of carbon included in carbon black to silicon included in silica powder was 1.3.

2 shows a peak of silicon carbide prepared by Preparation Examples 1 to 5 by X-ray diffraction (XRD) spectroscopy.

Referring to FIG. 2, it can be seen that in Preparation Examples 1 to 5, peaks were formed between approximately 35 degrees and 36 degrees, between 60 degrees, and between 72 degrees and 73 degrees. It can be seen from this that silicon carbide was synthesized according to Production Examples 1 to 5.

Scanning electron microscope (SEM) photographs of silicon carbides prepared according to Preparation Examples 1 to 5 and Comparative Examples 1 and 2 are shown in FIGS. 3 to 9, respectively.

3 to 7, it can be seen that the silicon carbide prepared according to Preparation Examples 1 to 5 was formed to have a uniform particle diameter. On the other hand, in Comparative Examples 1 and 2 it can be seen that the particle size is non-uniform due to the raw material not synthesized.

In addition, the recovery rate, residual oxygen and carbon content in silicon carbide prepared in Preparation Examples 1 to 5 and Comparative Examples 1 and 2 were measured. The results are shown in Table 1 below.

Recovery rate [%] Residual Oxygen Content [%] Residual Carbon Content [%] Production Example 1 41.6 0.1 8 Production Example 2 38.0 0.131 - Production Example 3 33.3 0.27 - Production Example 4 23.8 0.927 - Production Example 5 12.8 3.075 - Comparative Example 1 40.0 1.13 - Comparative Example 2 15.0 11 10

Referring to Table 1, it can be seen that according to Preparation Examples 1 to 5, the recovery rate is excellent at 12.8% or more, but the residual oxygen content and the residual carbon content can be maintained within a predetermined level. According to Production Examples 1 to 4, the recovery rate can be 23.8% or more, and in particular, Production Examples 2 to 3 can be made the recovery rate to 33.3% or more, indicating that high quality silicon carbide can be produced with high productivity. On the other hand, in Comparative Examples 1 and 2 it can be seen that the residual oxygen content and / or residual carbon content is very high that the silicon carbide properties can be reduced.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. In addition, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

In addition, the above description has been made with reference to the embodiments, which are merely examples and are not intended to limit the invention. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (8)

A raw material mixing step of mixing the silicon source and the carbon source; And
A heating step of forming silicon carbide for heating the mixed raw materials
Including,
In the raw material mixing step, the molar ratio of carbon contained in the carbon source to silicon contained in the silicon source is 2.5 to 2.8 method for producing silicon carbide. The method of claim 1,
A method for producing silicon carbide, wherein the carbon source comprises a solid carbon source or an organic carbon compound. The method of claim 2,
Method for producing silicon carbide wherein the solid carbon source comprises at least one material selected from the group consisting of graphite, carbon black, carbon nano tube (CNT) and fullerene (C ₆₀ ) . The method of claim 2,
The organic carbon compounds include phenol, franc, xylene, polyimide, polyurethane, polyvinyl alcohol, polyacrylonitrile and polyacrylonitrile. Method for producing silicon carbide comprising at least one material selected from the group consisting of vinyl (poly (vinyl acetate)). The method of claim 1,
A method for producing silicon carbide, wherein the silicon source comprises a dry silicon source. The method of claim 5,
And the silicon source comprises at least one selected from the group consisting of silica powder, silica sol, silica gel, and quartz powder. The method of claim 1,
The manufacturing method of the silicon carbide whose recovery rate of the said silicon carbide is 33.3% or more. Silicon carbide produced by the method for producing silicon carbide according to any one of claims 1 to 7.

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