KR102318521B1 - Silicon carbide powder - Google Patents

Abstract

The present invention relates to a silicon carbide powder comprising a first silicon carbide powder and a second silicon carbide powder. The silicon carbide powder may include the first silicon carbide powder and the second silicon carbide powder having different particle sizes.

Description

Silicon carbide powder {SILICON CARBIDE POWDER}

The present invention relates to a silicon carbide powder comprising a first silicon carbide powder and a second silicon carbide powder having different particle sizes.

Silicon carbide powder has recently been used as a semiconductor material for various electronic devices and purposes. Silicon carbide powder is particularly useful because of its physical strength and high resistance to chemical attack. Silicon carbide powder also has a radiation hardness, a relatively wide bandgap, a high saturated electron drift velocity, a high operating temperature, and a spectrum of blue, violet, and ultraviolet. ) has excellent electronic properties including absorption and emission of high-energy protons in the region.

There are various methods for the production of silicon carbide powder, and for example, the Acheson method, the carbon thermal reduction method, the liquid phase polymer pyrolysis method, or the CVD method is used. In particular, the high-purity silicon carbide powder synthesis method uses a liquid-phase polymer pyrolysis method or a carbon-thermal reduction method.

That is, the silicon carbide powder can be synthesized by mixing the carbon source and the silicon source material, and performing a carbonization process and a synthesizing process for the mixture.

In order to grow a single crystal from such a silicon carbide powder, a coarse-grained silicon carbide powder may be used. This is because, when a single crystal is grown using fine silicon carbide powder, there is a problem in that the density is lowered. However, when a single crystal is grown using coarse silicon carbide powder, the quality of the single crystal may be deteriorated.

Accordingly, a new silicon carbide powder that can improve the density when a silicon carbide single crystal is grown and has excellent single crystal quality is required.

The embodiment may provide a silicon carbide powder having an excellent density and capable of growing a high-quality silicon carbide single crystal.

The silicon carbide powder according to the embodiment includes a first silicon carbide powder and a second silicon carbide powder, and particle sizes of the first silicon carbide powder and the second silicon carbide powder are different from each other.

The silicon carbide powder according to the embodiment may include silicon carbide powders having different particle sizes. In detail, the silicon carbide powder according to the embodiment may include a first silicon carbide powder having a small particle size and a second silicon carbide powder having a large particle size.

Accordingly, since the silicon carbide powder according to the embodiment includes the second silicon carbide powder having a large particle size, it is possible to improve the density of the silicon carbide powder. Therefore, when the silicon carbide powder is charged into the reaction vessel, it is possible to increase the charging amount.

In addition, it is possible to improve the quality of the single crystal by the first silicon carbide powder having a small particle size during single crystal growth using the silicon carbide powder according to the embodiment.

1 is an SEM photograph of the growth surface of a silicon carbide single crystal prepared according to Example 3 at an initial stage.
FIG. 2 is an SEM photograph taken initially of the growth surface of a silicon carbide single crystal prepared according to Comparative Example 2. FIG.
3 is an SEM photograph of a silicon carbide single crystal prepared according to Example 3.
4 is an SEM photograph of a silicon carbide single crystal prepared according to Comparative Example 2.
5 is a cross-sectional view of a single crystal manufacturing apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The silicon carbide powder according to the embodiment may include silicon carbide powders having different particle sizes. For example, the silicon carbide powder may include a first silicon carbide powder and a second silicon carbide powder. In addition, the first silicon carbide powder and the second silicon carbide powder may have different particle sizes.

In addition, the first silicon carbide powder may be smaller than the second silicon carbide powder. That is, the particle diameter of the second silicon carbide powder may be larger than that of the first silicon carbide powder.

In this case, the particle diameter of the first silicon carbide powder and/or the particle diameter of the second silicon carbide powder may mean an average particle diameter (D50). That is, it may mean a particle diameter corresponding to 50% of the weight percentage in the particle size distribution curve, that is, a particle diameter at which the passing mass percentage is 50%.

The first silicon carbide powder may have a particle diameter of about 0.5 μm to about 10 μm. When the particle diameter of the first silicon carbide powder is less than 0.5 μm, the density of the silicon carbide powder may be reduced. When the particle diameter of the first silicon carbide powder exceeds 10 μm, the quality of a single crystal made of the silicon carbide powder may be deteriorated.

In addition, the second silicon carbide powder may have a particle diameter of about 120㎛ to about 400㎛. When the particle diameter of the second silicon carbide powder is less than 120㎛, the density of the silicon carbide powder may be reduced. When the particle diameter of the second silicon carbide powder exceeds 400 μm, the quality of a single crystal made of the silicon carbide powder may be deteriorated.

That is, the silicon carbide powder according to the embodiment may be a mixed powder comprising a first silicon carbide powder having a particle diameter of about 0.5 μm to about 10 μm and a second silicon carbide powder having a particle diameter of about 120 μm to about 400 μm. have.

When the silicon carbide powder according to the embodiment is charged into the reaction vessel by the second silicon carbide powder having a large particle size, the charging amount may be increased, and thus process efficiency may be improved. In addition, when manufacturing a silicon carbide single crystal using the silicon carbide powder. Single crystal quality can be improved by the first silicon carbide powder having a small particle size.

That is, when a single crystal is grown with the silicon carbide powder according to the embodiment, the amount of charge in the reaction vessel can be improved, and the quality of the single crystal can be improved.

In addition, the weight ratio of the first silicon carbide powder and the second silicon carbide powder may be different from each other. For example, the first silicon carbide powder and the second silicon carbide powder may be included in different weight ratios with respect to the entire silicon carbide powder.

In detail, the weight ratio of the second silicon carbide powder may be greater than the weight ratio of the first silicon carbide powder.

For example, the weight ratio of the first silicon carbide powder to the second silicon carbide powder may be 20:80 to 5:95. That is, the first silicon carbide powder is included in an amount of about 5 wt% to about 20 wt% with respect to the total silicon carbide powder, and the second silicon carbide powder is about 80 wt% to about 95 wt% with respect to the total silicon carbide powder. % by weight.

When the first silicon carbide powder is included in less than about 5% by weight or more than about 20% by weight with respect to the entire silicon carbide powder, when preparing a silicon carbide single crystal using the silicon carbide powder, the particle size is large. Single crystal quality may be deteriorated by the second silicon carbide powder.

When the second silicon carbide powder is included in an amount of less than about 80% by weight, or more than about 95% by weight based on the total silicon carbide powder, the density of the silicon carbide powder is lowered and the silicon carbide powder is charged into the reaction vessel. When doing so, the charging amount may be lowered.

The silicon carbide powder according to the embodiment may include the first silicon carbide powder and the second silicon carbide powder having different particle sizes in a weight ratio of 20:80 to 5:95. Accordingly, by improving the density of the silicon carbide powder by the silicon carbide powder having a large particle size, the loading amount can be improved, and the single crystal quality can be improved when the single crystal is grown by the silicon carbide powder having a small particle size.

That is, the density of the silicon carbide powder according to the embodiment may be the same as or similar to the density of the second silicon carbide powder having a large particle size. For example, the density of the silicon carbide powder according to the embodiment may be 1.8 g/cm 3 to 2.1 g/cm 3 .

In addition, the silicon carbide powder according to the embodiment may include silicon carbide powders having different particle shapes. That is, the first silicon carbide powder and the second silicon carbide powder may have different particle shapes.

The particles of the first silicon carbide powder may have a beta phase. That is, the first silicon carbide powder may have a beta phase that is a low-temperature stable phase. However, the embodiment is not limited thereto, and it goes without saying that the particles of the first silicon carbide powder may have an alpha phase.

The particles of the second silicon carbide powder may have an alpha phase. That is, the particles of the second silicon carbide powder may have an alpha phase, which is a high-temperature stable phase. However, the embodiment is not limited thereto, and it goes without saying that the particles of the second silicon carbide powder may have a beta phase.

The method for producing a silicon carbide powder according to an embodiment includes the steps of preparing a first silicon carbide powder, preparing a second silicon carbide powder, and mixing the first silicon carbide powder and the second silicon carbide powder can do.

The step of preparing the first silicon carbide powder may be a step of preparing a fine silicon carbide powder.

Preparing the first silicon carbide powder may include mixing a silicon source (Si source) and a carbon source (C source), and heat-treating the mixed silicon source and carbon source.

The silicon source may include various materials capable of providing silicon. For example, the silicon source may include silica. In addition to silica, silica powder, silica sol, silica gel, quartz powder, etc. may be used as the silicon source. However, the embodiment is not limited thereto, and an organosilicon compound including silicon may be used as the silicon source.

In addition, the carbon source may include a solid carbon source or an organic carbon compound. The solid carbon source may include at least one of graphite, carbon black, carbon nanotube (CNT), and fullerene (C _{60 ).}

Examples of the organic carbon compound include phenol, franc, xylene, polyimide, polyurethane, polyvinyl alcohol, polyacrylonitrile, And it may include at least one of polyvinyl acetate (poly (vinyl acetate)). In addition, it may include cellulose, sugar, pitch or tar.

The carbon source and the silicon source may be mixed with the carbon source and the silicon source by a wet mixing process using a solvent or a dry mixing process without using a solvent.

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

The silicon source and the carbon source may be mixed in a predetermined ratio. For example, a mole ratio of carbon contained in the carbon source to silicon contained in the silicon source (hereinafter, “the molar ratio of carbon to silicon”) may be about 1:1.5 to about 1:3. When the molar ratio of carbon to silicon exceeds about 3, the amount of carbon remaining increases without participating in the reaction due to a large amount of carbon, thereby reducing the recovery rate. In addition, when the molar ratio of carbon to silicon is less than about 1.5, the amount of silicon remaining increases without participating in the reaction because the amount of silicon is large, thereby reducing the recovery rate. That is, the molar ratio of carbon to silicon is determined in consideration of the recovery rate.

In this case, considering that the silicon source is volatilized in a gaseous state at a high temperature in the reaction step, the molar ratio of carbon to silicon may be about 1.8 to about 2.7.

Then, it goes through a synthesis step. That is, the silicon carbide powder may be formed by heat-treating the mixed powder in which the silicon source and the carbon source are mixed. The synthesis step may be divided into a carbonization process and a synthesis process.

In the carbonization process, the organic carbon compound may be carbonized to generate carbon. The carbonization process may be performed at a temperature of about 600 °C to about 1200 °C. In more detail, the carbonization process may be performed at a temperature of about 800 °C to about 1100 °C. When the solid carbon source is used as a carbon source, the carbonization process may not proceed.

Thereafter, the synthesis process proceeds. In the synthesis process, the silicon source and the solid carbon source react or the silicon source and the organic carbon compound react to form a silicon carbide powder by the entire reaction formula of Reaction Scheme 3 according to the steps of Reaction Schemes 1 and 2 below. have.

[Scheme 1]

SiO2(s) + C(s) -> SiO(g) + CO(g)

[Scheme 2]

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

[Scheme 3]

SiO2(s) + 3C(s) -> SiC(s) + 2CO(g)

The heating temperature may be about 1300° C. or higher so that the above-described reaction can occur smoothly. At this time, by setting the heating temperature to about 1300° C. to about 1900° C., the first silicon carbide powder produced may have a beta phase, which is a low-temperature stable phase. The beta phase may be formed of fine particles to improve the strength of the silicon carbide powder. However, the embodiment is not limited thereto, and the silicon carbide powder may have an alpha phase, which is a high-temperature stable phase, by setting the heating temperature to exceed about 1900°C. The synthesis process may be performed for about 2 to 4 hours.

The process of preparing the first silicon carbide powder described above is only an example, and the first silicon carbide powder may be manufactured according to various methods.

The preparing of the second silicon carbide powder may include grain growth of the first silicon carbide powder. In detail, the first silicon carbide powder may be heat-treated at a high temperature to grow a particle size. For example, the first silicon carbide powder may be heat-treated at a temperature of about 1900° C. to about 2200° C. to increase the particle size. Due to the grain growth of the first silicon carbide powder, a second silicon carbide powder may be formed. The second silicon carbide powder may have an alpha phase, which is a high-temperature stable phase. The step of grain growth may be in a vacuum or an inert atmosphere. For example, it may be an argon atmosphere.

Subsequently, the step of mixing the first silicon carbide powder and the second silicon carbide powder may be mixed by a ball mill, an attrition mill, or the like.

Hereinafter, the present invention will be described in more detail through silicon carbide powder according to Examples and Comparative Examples. These embodiments are merely presented as examples in order to explain the present invention in more detail. Therefore, the present invention is not limited to these examples.

Example 1

A first silicon carbide powder was prepared by mixing fumed silica and a phenol resin. At this time, the average particle diameter (D ₅₀ ) of the first silicon carbide powder was about 1.03㎛.

The first silicon carbide powder was grain-grown at a high temperature to prepare a second silicon carbide powder. At this time, the average particle diameter (D ₅₀ ) of the second silicon carbide powder was about 230㎛.

The first silicon carbide powder and the second silicon carbide powder were mixed in a weight ratio of 20:80. At this time, the first silicon carbide powder and the second silicon carbide powder were uniformly mixed using a Teflon ball. Thus, a silicon carbide powder according to Example 1 was prepared.

The silicon carbide powder according to Example 1 was added to the reaction vessel.

Then, the single crystal manufacturing apparatus was heated to a temperature of about 2100° C. at a pressure of about 25 mbar to prepare a silicon carbide single crystal.

Example 2

A silicon carbide powder and a silicon carbide single crystal were prepared under the same particle size and reaction conditions as in Example 1, except that the first silicon carbide powder and the second silicon carbide powder were mixed in a weight ratio of 10:90.

Example 3

A silicon carbide powder and a silicon carbide single crystal were prepared under the same particle size and reaction conditions as in Example 1, except that the first silicon carbide powder and the second silicon carbide powder were mixed in a weight ratio of 5:95.

An SEM picture of the initially grown surface of the prepared silicon carbide single crystal is shown in FIG. 1 , and an SEM picture of the prepared silicon carbide single crystal is shown in FIG. 3 .

Comparative Example 1

A silicon carbide powder and a silicon carbide single crystal were prepared under the same particle size and reaction conditions as in Example 1, except that only the first silicon carbide powder was used.

Comparative Example 2

A silicon carbide powder and a silicon carbide single crystal were prepared under the same particle size and reaction conditions as in Example 1, except that only the second silicon carbide powder was used.

An SEM photograph of the initially grown surface of the prepared silicon carbide single crystal is shown in FIG. 2 , and an SEM photograph of the prepared silicon carbide single crystal is shown in FIG. 4 .

Comparative Example 3

A silicon carbide powder and a silicon carbide single crystal were prepared under the same particle size and reaction conditions as in Example 1, except that the first silicon carbide powder and the second silicon carbide powder were mixed in a weight ratio of 50:50.

Comparative Example 4

A silicon carbide powder and a silicon carbide single crystal were prepared under the same particle size and reaction conditions as in Example 1, except that the first silicon carbide powder and the second silicon carbide powder were mixed in a weight ratio of 30:70.

water
(ppm) density
(g/㎤) single crystal quality
(MPD/cm2) Crystal length (mm) after 80 hours of growth Example 1 0.72 1.828 1.6 24.6 Example 2 0.58 1.955 1.4 26.9 Example 3 0.43 2.017 1.1 27.7 Comparative Example 1 0.94 0.490 1.3 15.2 Comparative Example 2 0.43 1.954 20.4 26.7 Comparative Example 3 0.88 0.782 1.7 17.9 Comparative Example 4 0.70 1.548 1.3 20.3

Referring to Table 1, it can be seen that the density of the silicon carbide powder according to Examples 1 to 3 is large. On the other hand, it can be seen that the density of the silicon carbide powder according to Comparative Example 1, Comparative Example 3, and Comparative Example 4 was small.

That is, in the silicon carbide powder according to Examples 1 to 3, the density is improved by controlling the weight ratio of the first silicon carbide powder and the second silicon carbide powder having different particle sizes to 20:80 to 5:95. can Specifically, the density of the silicon carbide powder according to Examples 1 to 3 may be the same as or similar to the density of the second silicon carbide powder according to Comparative Example 2. For example, the density of the silicon carbide powder according to the embodiment may be 1.8 g/cm 3 to 2.1 g/cm 3 .

In detail, when a silicon carbide single crystal is grown using the silicon carbide powder according to the embodiment, as the density of the silicon carbide powder is improved, the loading amount can be improved when the silicon carbide powder is charged into the reaction vessel. Accordingly, process efficiency may be improved when a silicon carbide single crystal is grown using the silicon carbide powder according to the embodiment.

In addition, when the silicon carbide single crystal is grown using the silicon carbide powder according to the embodiment, it can be seen that the crystal length of the silicon carbide single crystal is long. That is, as the density of the silicon carbide powder increases, the size of the silicon carbide single crystal may increase.

For example, as the density of the silicon carbide powder according to the embodiment is improved, the crystal length of the silicon carbide single crystal may be increased. Accordingly, process efficiency may be improved when a silicon carbide single crystal is grown using the silicon carbide powder according to the embodiment.

In addition, since the silicon carbide powder according to Examples 1 to 3 includes the first silicon carbide powder having a small particle size, it was found that the single crystal quality of the silicon carbide single crystal prepared from the silicon carbide powder according to Examples 1 to 3 was excellent. can

That is, since the first silicon carbide powder can make the growth surface at the initial stage of silicon carbide single crystal growth uniform, the silicon carbide single crystal prepared from the silicon carbide powder according to Examples 1 to 3 has excellent quality.

Referring to FIG. 1 , it can be seen that the grain size of the growth surface photographed at the initial stage of growth of the silicon carbide single crystal prepared according to Example 3 is uniform.

In addition, referring to FIG. 3 , it can be seen that the quality of the silicon carbide single crystal prepared from the silicon carbide powder according to Example 3 is excellent. That is, it can be seen that the silicon carbide single crystal prepared from the silicon carbide powder according to Example 3 has no defects. In addition, the silicon carbide single crystal may have a low concentration of impurities.

On the other hand, it can be seen that in the silicon carbide single crystal prepared from the second silicon carbide powder according to Comparative Example 2, the quality of the single crystal is deteriorated.

Referring to FIG. 2 , it can be seen that the grain size of the growth surface photographed at the initial stage of growth of the silicon carbide single crystal prepared according to Comparative Example 2 is not uniform. Accordingly, it can be seen that the quality of the silicon carbide single crystal prepared from the silicon carbide powder according to Comparative Example 2 is deteriorated.

In addition, referring to FIG. 4 , it can be seen that the quality of the silicon carbide single crystal prepared from the silicon carbide powder according to Comparative Example 2 is poor. That is, it can be seen that the silicon carbide single crystal prepared from the silicon carbide powder according to Comparative Example 2 has defects. The defect may include a crystal defect.

5 is a cross-sectional view of a single crystal manufacturing apparatus.

Referring to Figure 5, the method for producing a silicon carbide single crystal growth using the silicon carbide powder according to the embodiment, preparing the silicon carbide powder according to the embodiment, filling the silicon carbide powder in a reaction vessel, Putting the reaction vessel into a single crystal growth apparatus and heating the single crystal growth apparatus may include.

Since the step of preparing the silicon carbide powder according to the embodiment is the same as the method for producing the silicon carbide powder described above, the following description will be omitted.

Subsequently, the silicon carbide powder 200 may be filled in the reaction vessel 100 , and the reaction vessel accommodating the silicon carbide powder may be introduced into the single crystal growth apparatus 1000 .

Subsequently, in the step of heating the single crystal growth apparatus, heat may be applied to the reaction vessel 100 . Although not shown in the drawings, an exothermic induction part may be located outside the reaction vessel 100 to apply heat to the reaction vessel 100 . The reaction vessel 100 may generate heat by itself by the exothermic induction unit.

The heating induction unit may be, for example, a high-frequency induction coil. The reaction vessel 100 can be heated by allowing a high-frequency current to flow through the high-frequency induction coil. That is, the raw material accommodated in the reaction vessel 100 may be heated to a desired temperature.

For example, the raw material accommodated in the reaction vessel 100 may be heated to a temperature of about 2000 °C to about 2200 °C. In addition, the pressure of the reaction vessel 100 may be about 5 mbar to about 50 mbar. That is, when the silicon carbide single crystal is grown, the temperature and pressure of the reaction vessel 100 may be constant. In detail, the reaction vessel 100 may have a temperature of about 2000° C. to about 2200° C. and a pressure of about 5 mbar to about 50 mbar.

Accordingly, the silicon carbide powder accommodated in the reaction vessel 100 is sublimed, may move to the seed crystal 400 in the reaction vessel 100 , and a single crystal 410 may grow from the seed crystal 400 .

Specifically, a temperature gradient having different heating temperature regions is formed in the upper and lower portions of the reaction vessel 100 by the exothermic induction unit. Sublimation of the silicon carbide powder occurs due to this temperature gradient, and the sublimated silicon carbide gas moves to the surface of the seed crystal 400 having a relatively low temperature. Accordingly, the silicon carbide gas may be recrystallized to grow a single crystal 410 .

The silicon carbide powder according to the embodiment may be used when a silicon carbide single crystal is grown. That is, the silicon carbide powder having a small particle size reduces defects or defects of the single crystal during single crystal growth, thereby improving the surface quality of the single crystal.

In addition, the density of the silicon carbide powder can be improved by the silicon carbide powder having a large particle size, and thus, when the silicon carbide powder is charged in the reaction vessel during single crystal growth, the loading amount can be increased, so that the process efficiency can be improved have.

Features, structures, effects, etc. described in the above-described embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

In addition, although the embodiments have been mainly described above, these are merely examples and do not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are exemplified above in the range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiments may be implemented by modification. And the differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (8)

Comprising a first silicon carbide powder and a second silicon carbide powder,
The first silicon carbide powder has a beta phase and a particle diameter of 0.5 μm to 10 μm,
The second silicon carbide powder has an alpha phase and a particle diameter of 120 μm to 400 μm,
The density of the first and second silicon carbide powder is 1.8 g/cm 3 to 2.1 g/cm 3 of silicon carbide powder. delete delete The method of claim 1,
The weight ratio of the first silicon carbide powder and the second silicon carbide powder is 20:80 to 5:95 silicon carbide powder. The method of claim 1,
The first silicon carbide powder contains 5 wt% to 20 wt% with respect to the entire silicon carbide powder,
The second silicon carbide powder is a silicon carbide powder containing 80% by weight to 95% by weight based on the entire silicon carbide powder. delete delete A silicon carbide single crystal comprising the silicon carbide powder according to any one of claims 1, 4, and 5.

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