WO2012015261A2

WO2012015261A2 - Silicon carbide and method for manufacturing the same

Info

Publication number: WO2012015261A2
Application number: PCT/KR2011/005579
Authority: WO
Inventors: Jung Eun Han; Sang Myung Kim; Byung Sook Kim
Original assignee: Lg Innotek Co., Ltd.
Priority date: 2010-07-30
Filing date: 2011-07-28
Publication date: 2012-02-02
Also published as: KR20120012345A; WO2012015261A3

Abstract

Provided is a method for manufacturing silicon carbide. In the method, silicon source and carbon source are mixed, and the mixed sources are heated to form silicon carbide. Herein, in the mixing of the sources, a molar ratio of carbon contained in the carbon source to silicon contained in the silicon source is in a range of 1.5 to 3.

Description

SILICON CARBIDE AND METHOD FOR MANUFACTURING THE SAME

The present disclosure relates to a silicon carbide and a method for manufacturing the same.

Silicon carbide (SiC) has physical and chemical stability and superior heat resistance and thermal conductivity. Thus, the silicon carbide has good thermal stability and strength at high temperature and superior abrasion resistance. Accordingly, the silicon carbide is being widely used in manufacturing fields of high-temperature materials, high-temperature semiconductors, abrasion-resistant materials, automotive components, etc.

The silicon carbide may be manufactured by mixing sources such as a silicon source and a carbide source and then heating the mixed sources. In a manufacturing method of silicon carbide, it is very important to increase a recovery rate of high purity silicon carbide through a simple process.

Embodiments provide a method for manufacturing silicon carbide which is capable of increasing recovery rate of high purity silicon carbide through a simple process, and silicon carbide manufactured using this method.

In one embodiment, a method for manufacturing silicon carbide includes: mixing sources of silicon source and carbon source; and heating the mixed sources to form silicon carbide, wherein, in the mixing of the sources, a molar ratio of carbon contained in the carbon source to silicon contained in the silicon source is in a range of 1.5 to 3.

In the mixing of the sources, a molar ratio of carbon contained in the carbon source to silicon contained in the silicon source may be in a range of 2 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 selected from the group consisting of graphite, carbon black, carbon nanotube (CNT), and fullerene (C₆₀).

The organic carbon compound may include at least one selected from the group consisting of penol, franc, xylene, polyimide, polyunrethane, polyvinyl alcohol, polyacrylonitrile, and 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.

A recovery rate of the silicon carbide may be 12.8% or more, e.g., 23.8% or more.

The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

A method for manufacturing silicon carbide according to the embodiments can improve productivity and purity by specifying a molar ratio of carbon to silicon. Resultantly, the manufactured silicon carbide can have low residual carbon and oxygen contents to thereby exhibit high purity.

Fig. 1 is a flowchart illustrating a method for manufacturing silicon carbide according to an embodiment.

Fig. 2 is a graph showing diffraction peaks of silicon carbides prepared according to Manufacturing Examples 1 to 5, which are analyzed by X-ray diffraction (XRD) spectroscopy.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Referring to Fig. 1, a method for manufacturing silicon carbide will now be described according an embodiment. Fig. 1 is a flowchart illustrating a method for manufacturing silicon carbide according to an embodiment.

Referring to Fig. 1, the method for manufacturing silicon carbide according to the current embodiment includes a source mixing process ST10 and a heating process ST20. Each process will be described in more detail below.

In the source mixing process ST10, a silicon (Si) source and a carbon (C) source are prepared and then mixed with each other.

The silicon source may include various materials providing Si. For example, the silicon source may include silica. Silica powder, silica sol, silica gel, quartz powder may be used as the silicon source. However, the embodiment is not limited to these silicon source, and an organic silicon compound containing Si may also be used as the silicon source.

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

Examples of the solid carbon source may include graphite, carbon black, carbon nanotube (CNT), and fullerene (C₆₀).

Examples of the organic carbon compound may include penol, franc, xylene, polyimide, polyunrethane, polyvinyl alcohol, polyacrylonitrile, and poly (vinyl acetate). In addition, cellulose, sugar, pitch, tar, or the like may be used.

These carbon source and silicon source may be mixed by a wet mixing process using a solvent, or a dry mixing process without using a solvent.

The silicon source and carbon source are mixed by a ball mill and attrition mill, and then a powder mixture is recovered. The powder mixture may be recovered after sifted through a sieve.

In the source mixing process ST10, a molar ratio of carbon contained in the solid carbon source to silicon contained in the silicon source (hereinafter, referred to as "a molar ratio of carbon to silicon") is in the range of about 1.5 to about 3. When a molar ratio of carbon to silicon exceeds 3, carbon is abundant and thus residual carbon, which does not participate in reaction but remains, is increased. This may lead to a decrease in recovery rate. In contrast, when a molar ratio of carbon to silicon is less than about 1.5, silicon is abundant and thus residual silicon, which does not participate in reaction but remains, is increased. This may cause a recovery rate to be decreased. That is, a molar ratio of carbon to silicon is determined in consideration of a recovery rate.

When the silicon source and the carbon source are mixed in such a way to satisfy the condition that the molar ratio of carbon to silicon is in the range of about 1.5 to about 3, it is possible to increase the recovery rate of silicon carbide to about 13% or higher, for example, 12.8% or higher.

Here, to reduce residual oxygen content and residual carbon content while further increasing a recovery rate, the molar ratio of carbon to silicon may be set to about 2 to about 2.8. This makes it possible to increase the recovery rate of silicon carbide to about 24% or higher, for example, 23.8%. Further, the residual oxygen content may be decreased to 1% or lower, and the residual carbon content may be decreased to 1% or lower. Specifically, the residual oxygen content may be decreased to about 0.1% or lower, and the residual carbon content may be decreased to almost 0.

Thereafter, in the heating process ST20, the powder mixture (i.e., the mixed sources) is heated to form silicon carbide. In more detail, the powder mixture is weighted in a graphite crucible, then put into a high-temperature reaction furnace such as a graphite furnace, and then heated. Here, the powder mixture may be heated at about 1,300 C or higher for about 30 minutes or longer, e.g., for about 1 hour to about 7 hours. The inside of the high temperature furnace may be vacuum or inert gas (e.g., argon or hydrogen) atmosphere.

In the heating process ST20, silicon carbide is formed according to following

Reaction Formulae

1 and 2, and a total Reaction formula 3.

[Reaction Formula 1]

SiO₂(s) + C(s) -> SiO(g) + CO(g)

[Reaction Formula 2]

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

[Reaction Formula 3]

SiO₂(s) + 3C(s) -> SiC(s) + 2CO(g)

In the method for manufacturing silicon carbide using the dry silicon source and the solid carbon source, SiO gas is formed and volatilized, as shown in Reaction Formula 1. Considering this fact, the molar ratio of carbon to silicon is set to include a range less than 3 in the current embodiment. In particular, in the case where the molar ratio of carbon to silicon is set to about 2 to about 2.8, residual carbon and oxygen contents can be reduced while increasing a recovery rate. Accordingly, it is possible to improve productivity and characteristics of silicon carbide.

The silicon carbide, which is manufactured according to the above-described method, can have low residual carbon and oxygen contents to thereby exhibit high purity. The silicon carbide manufactured through the above-described method may be processed into a predetermined shape through press sintering. As a result, the processed silicon carbide may be used as a susceptor in a deposition apparatus or a wafer carrier apparatus.

Hereinafter, a method for manufacturing silicon carbide according to Manufacturing Examples 1 to 5 and Comparative Examples 1 and 2 will be described in more detail. The manufacturing examples are merely exemplarily provided to explain the present disclosure in more detail, and thus the present disclosure is not limited to the manufacturing examples below.

Manufacturing Example 1

Silica power and carbon black were mixed with each other through ball mill. Here, a molar ratio of carbon contained in the carbon block to silicon contained in the silica powder was 3. A powder mixture was recovered using a sieve, and then dried in a spray dryer. Afterwards, the dried powder mixture was put into a graphite furnace in an argon atmosphere and heated at 1,800 C for 3 hours to manufacture silicon carbide.

Manufacturing Example 2

Silicon carbide was manufactured according to the same method as Manufacturing Example 1 except that the molar ratio of carbon contained in the carbon block to silicon contained in the silica powder is 2.8.

Manufacturing Example 3

Silicon carbide was manufactured according to the same method as Manufacturing Example 1 except that the molar ratio of carbon contained in the carbon block to silicon contained in the silica powder is 2.5.

Manufacturing Example 4

Silicon carbide was manufactured according to the same method as Manufacturing Example 1 except that the molar ratio of carbon contained in the carbon block to silicon contained in the silica powder is 2.

Manufacturing Example 5

Silicon carbide was manufactured according to the same method as Manufacturing Example 1 except that the molar ratio of carbon contained in the carbon block to silicon contained in the silica powder is 1.5.

Comparative Example 1

Silicon carbide was manufactured according to the same method as Manufacturing Example 1 except that the molar ratio of carbon contained in the carbon block to silicon contained in the silica powder is 3.2.

Comparative Example 2

Silicon carbide was manufactured according to the same method as Manufacturing Example 1 except that the molar ratio of carbon contained in the carbon block to silicon contained in the silica powder is 1.3.

Fig. 2 is a graph showing diffraction peaks of silicon carbides according to Manufacturing Examples 1 to 5, which are analyzed by X-ray diffraction (XRD) spectroscopy.

Referring to Fig. 2, it can be observed that peaks appear between about 35 and 36 degrees, around 60 degrees, and between 72 and 73 degrees. From this result, it can be understood that silicon carbides according to Manufacturing Examples 1 to 5 are synthesized.

Also, recovery rates of silicon carbides, which were manufactured according to Manufacturing Examples 1 to 5 and Comparative Examples 1 and 2, range in silicon carbides were measured. These results are shown in Table 1 below.

Table 1

	Recovery Rate [%]	Residual oxygen cotent [%]	Residual carbon cotent [%]	Particle sizerange [D10(um)-D90(um)]
Manufacturing Example 1	41.6	0.1	8	0.27-2.44
Manufacturing Example 2	38	0.131	-	0.36-3.3
Manufacturing Example 3	33.3	0.27	-	0.49-3.15
Manufacturing Example 4	23.8	0.927	-	0.49-3.8
Manufacturing Example 5	12.8	3.075	-	0.53-4.2
Comparative Example 1	40.0	1.13	10	0.12-9.2
Comparative Example 2	15.0	11	-	0.10-6.11

Referring to Table 1, according to Manufacturing Examples 1 to 5, it can be understood that the silicon carbides have excellent recovery rate of 12.8% or more, and also the residual oxygen and carbon contents can be kept to a predetermined level or less. In particular, according to Manufacturing Examples 1 to 4, it can be understood that the recovery rate is increased to 23.8% or ore, and thus high-quality silicon carbides can be manufactured with high productivity. Also, according to Manufacturing Examples 2 to 4, the residual oxygen content can be decreased to about 0.1% or lower, and the residual carbon content can be decreased to almost 0 while the recovery rate is maintained to 23.8% or more.

On the contrary, in Comparative Examples 1 and 2, it can be observed that the residual oxygen content and/or residual carbon content are too high to cause characteristics of silicon carbide to be deteriorated.

Referring to Table 1, it can be observed that silicon carbides manufactured according to Manufacturing Examples 1 to 5 are formed with uniform particle diameter. Specifically, silicon carbides manufactured according to Manufacturing Examples 1 to 5 were measured to have a particle size in the range of 0.27 um to 4.2 um. On the contrary, in Comparative Examples 1 and 2, it can be observed that particle diameters are not uniform due to non-synthesized sources. In specific, silicon carbides according to Comparative Examples 1 and 2 were measured to have a particle size in the range of 0.10 um to 9.2 um.

Features, structures, and effects described in the above embodiments are incorporated into at least one embodiment of the present disclosure, but are not limited to only one embodiment. Moreover, features, structures, and effects exemplified in one embodiment can easily be combined and modified for another embodiment by those skilled in the art. Therefore, these combinations and modifications should be construed as falling within the scope of the present disclosure.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. For example, each element specifically described in the embodiments may be modified. Therefore, these combinations and modifications should be construed as falling within the scope of the present disclosure.

Claims

A method for manufacturing silicon carbide, the method comprising:

mixing a silicon source and carbon source; and

heating a mixture of the silicon and carbon sources to form silicon carbide,

wherein, in the mixing of the sources, a molar ratio of carbon contained in the carbon source to silicon contained in the silicon source is in a range of 1.5 to 3.
The method according to claim 1, wherein, in the mixing a silicon source and carbon source, a molar ratio of carbon contained in the carbon source to silicon contained in the silicon source is in a range of 2 to 2.8.
The method according to claim 1, wherein the carbon source comprises a solid carbon source or an organic carbon compound.
The method according to claim 3, wherein the solid carbon source comprises at least one selected from the group consisting of graphite, carbon black, carbon nanotube (CNT), and fullerene (C60).
The method according to claim 3, wherein the organic carbon compound comprises at least one selected from the group consisting of penol, franc, xylene, polyimide, polyunrethane, polyvinyl alcohol, polyacrylonitrile, and poly (vinyl acetate).
The method according to claim 1, wherein the silicon source comprises a dry silicon source.
The method according to claim 5, wherein the silicon source comprises at least one selected from the group consisting of silica powder, silica sol, silica gel, and quartz powder.
The method according to claim 1, wherein a recovery rate of the silicon carbide is 12.8% or more.
The method according to claim 8, wherein a recovery rate of the silicon carbide is 23.8% or more.
The method according to claim 2, wherein, after the heating the mixture of the silicon and carbon sources, residual oxygen content in the silicon carbide is less than 1%.
The method according to claim 10, wherein, after the heating the mixture of the silicon and carbon sources, residual oxygen content in the silicon carbide is less than 0.1%.
The method according to claim 10, wherein, after the heating the mixture of the silicon and carbon sources, residual carbon content in the silicon carbide is less than 1%.
The method according to claim 12, wherein, after the heating the mixture of the silicon and carbon sources, residual carbon content in the silicon carbide is less than 0.1%.
A silicon carbide manufactured by the method of any one of claims 1 to 9.