WO2019088740A2

WO2019088740A2 - Silicon-based molten composition and method for preparing silicon carbide single crystal using same

Info

Publication number: WO2019088740A2
Application number: PCT/KR2018/013200
Authority: WO
Inventors: 김정환; 이호림; 정찬엽; 고정민; 박만식
Original assignee: 주식회사 엘지화학
Priority date: 2017-11-03
Filing date: 2018-11-01
Publication date: 2019-05-09
Also published as: WO2019088740A3

Abstract

A silicon-based molten composition according to one embodiment of the present invention is used for a solution growth method for forming a silicon carbide single crystal, and is represented by formula 1 below, comprising silicon, chromium (Cr), vanadium (V), and aluminum (Al). SiaCrbVcAld (formula 1) wherein a is 0.4-0.9, b+c is 0.1-0.6, c /(b+c) is 0.05-0.95, and d is 0.01-0.1.

Description

Title of the Invention

Silicon-based molten composition and method for producing silicon carbide single crystal using the same

TECHNICAL FIELD

The present application claims benefit of priority based on Korean Patent Application No. 10-2017-0146280, filed on November 3, 2017, and Korean Patent Application No. 2018-0121270, filed on October 11, 2018 , All of which are incorporated herein by reference in their entirety. The present invention relates to a silicon-based molten composition and a method for producing a silicon carbide single crystal using the same.

TECHNICAL BACKGROUND OF THE INVENTION

Power semiconductor devices are key elements in next-generation systems that use electric energy such as electric vehicles, power systems, and high-frequency mobile communications. For this purpose, it is necessary to select suitable materials for high voltage, high current, and high frequency. Silicon single crystal has been used as a power semiconductor material, but due to its physical limitations, a silicon carbide single crystal which is less in energy loss and can be driven in a more extreme environment is attracting attention.

In order to grow the silicon carbide single crystal, for example, a sublimation method in which silicon carbide is used as a raw material and sublimation is performed at a high temperature of 2000 ^degrees Celsius or more to grow a single crystal, a solution growth method using a crystal pulling method, A chemical vapor deposition method and the like are used.

When the chemical vapor deposition method is used, the film can be grown to a thin film having a limited thickness. When the sublimation method is used, defects such as micropipes and stacking defects are likely to occur, which limits the production cost. Studies on a solution growth method, which is known to have a lower crystal growth temperature than the sublimation method and which are advantageous for large-scale curing and high quality, are underway.

DISCLOSURE OF THE INVENTION

[Problem to be solved] The present invention aims to provide a silicone-based molten composition capable of reducing processing time and cost through providing a rapid crystal growth rate. And a silicon-based molten composition capable of providing a silicon carbide single crystal of excellent quality. And a method for producing a silicon carbide single crystal using the above-described silicon-based molten composition.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

MEANS FOR SOLVING THE PROBLEMS

The silicon-based molten composition for achieving the above-mentioned object is used in a solution growing method for forming a silicon carbide single crystal and is represented by the following formula 1 including silicon, chromium (Cr), vanadium (V) do.

Si _a Cr _b V _c Al _d (Equation 1)

In the formula (1), a is 0.4 or more and 0.9 or less, b + c is 0.1 or more and 0.6 or less, c / (b + c) is 0.05 or more and 0.95 or less, and d is 0.01 or more and 0.1 or less. In the formula (1), a is 0.5 or more and 0.8 or less, b + c is 0.2 or more and 0.5 or less, c / (b + c) is 0.1 or more and 0.9 or less, and d is 0.01 or more and 0.05 or less.

The silicone-based molten composition may have a carbon solubility of 0.04 or more at 1800 ^° C.

The silicone-based molten composition may have a carbon solubility of 0.06 or more at 1900 ^degrees Celsius.

The content ratio of chromium and vanadium may be from 9: 1 to 1: 9.

A method of manufacturing a silicon carbide single crystal according to an embodiment includes the steps of preparing a silicon carbide seed crystal, a step of preparing a silicon based molten composition containing silicon, Cr, vanadium (V) and aluminum (A1) Forming a melt by adding carbon (C) to the silicon-based molten composition; and growing the silicon carbide single crystal on the seed crystal by over-etching the melt. Si _a Cr _b V _c Al _d (Equation 1)

In the formula (1), _a is 0.4 or more and 0.9 or less, b + c is 0.1 or more and 0.6 or less, c / (b + c) is 0.05 or more and 0.95 or less, and d is 0.01 or more and 0.1 or less. 【Effects of the Invention]

The silicon-based molten composition according to one embodiment can reduce process time and cost by providing a rapid crystal growth rate. In addition, a silicon carbide single crystal of excellent quality can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic cross-sectional view of an apparatus for producing a silicon carbide single crystal according to an embodiment.

FIG. 2 is a graph showing the solubility and solubility of solutes according to Examples and Comparative Examples. FIG. Fig. 3 is a cross-sectional image of the precipitated solid according to Examples and Comparative Examples. Fig. 4 is an AIMD simulation image for examining carbon solubility in Examples and Comparative Examples.

5 is a graph showing the mean square displacement (MSD) of carbon atoms for the examples and the comparative examples.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing the present invention, the structure of the well-known functional black is omitted for clarity of the description of the present invention.

In order to clearly illustrate the present disclosure, portions that are not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification. In addition, since the sizes and thicknesses of the individual components shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited thereto.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. And some layers and regions and thicknesses are exaggerated for convenience of explanation in the drawings. It will be understood that when a layer, film, region, plate, or the like is referred to as being "on" or "on" another portion, But also the case where there is another part in the middle. Hereinafter, the silicone-based molten composition according to one embodiment will be described. The silicon-based molten composition according to one embodiment may include silicon (Si), chromium (Cr), vanadium (V), and aluminum (Al). The silicone-based molten composition can be expressed by the following formula (1).

Si _a Cr _b V _c Al _d (Equation 1)

In the formula 1 _a is 0.4 or more 0.9 or less, and b + c is 0.1 or more and 0.6 or less, and c / (b + c) is 0.05 or more and 0.95, d may be equal to or less than 0.01 or more 0.1. a + b + c + d = 1.

More preferably, a may be 0.5 or more and 0.8 or less, b + c may be 0.2 or more and 0.5 or less, c / (b + c) may be 0.1 or more and 0.9 or less, &Lt; / RTI >

In other words, the content of silicon in the silicon-based molten composition may be 50 at% or more and 80 at% or less. The sum of the contents of chromium and vanadium can be 20 at% or more and 50 at or less. The content of aluminum is 1 at% or more

It can be less than 5 at.

When the content of chromium and vanadium is included in a content lower than the above-mentioned conditions, the solubility of carbon in the silicon-based molten composition is lowered, and the growth rate of the silicon carbide single crystal can be remarkably reduced. The effect of improving the carbon solubility in the silicone-based molten composition may be insignificant.

Or in the case where chromium and vanadium are contained in a larger amount than the above-mentioned conditions, a compound of metal and silicon may be produced, or carbon in the silicon melt may be precipitated in the form of graphite or metal carbide rather than silicon carbide. In addition, the difference in carbon solubility due to the difference in carbon solubility and temperature at the corresponding temperature increases, and the driving force for generating silicon carbide may become excessively large. In this case, polycrystallization of silicon carbide occurs and the quality of the silicon carbide crystal may be deteriorated.

The aluminum (A1) may be contained in the silicon-based molten composition represented by the formula (1) in an amount of 1 at¾ or more and 10 at% or less, preferably 1 at% or more and 5 at% or less. Aluminum (Al) can suppress the generation of polycrystals in the growth process of the silicon carbide single crystal and improve the crystallinity of the obtained silicon carbide single crystal. Aluminum (A1) provides uniform crystal nuclei throughout the growth surface of the silicon carbide single crystal. As a result, a silicon carbide single crystal having a flat shape can be obtained. Silicon carbide polycrystals grow when the growth surface contains non-uniform crystal nuclei.

The silicon-based molten composition according to an embodiment includes silicon (Si), a difference in carbon solubility according to the melt temperature, a degree of carbon (Cr) and vanadium (V) that increases the carbon solubility value at that temperature and stabilizes carbon in the melt, By containing aluminum (A1) which improves the crystallinity of the carbide single crystal in a predetermined content, a silicon carbide single crystal of higher quality can be obtained. Also, the silicon-based molten composition according to one embodiment can provide a fast single crystal growth rate, so that the time and cost for obtaining can be reduced. Hereinafter, a method of obtaining a silicon carbide single crystal using the above-described silicon-based molten composition will be described with reference to the production apparatus of FIG. 1 is a schematic cross-sectional view of a manufacturing apparatus used for growing a silicon carbide single crystal.

Referring to FIG. 1, an apparatus for manufacturing a silicon carbide single crystal according to an embodiment of the present invention includes a honeycomb chamber 100, a crucible 300 located inside the honeycomb chamber 100, a seed crystal 210 extending into the crucible 300, And a heating member 400 for heating the crucible 300 and the seed crystal supporting unit 230 connected to the seed crystal 210. [

The reaction chamber 100 is in a closed form including an empty interior space and the interior thereof can be maintained in an atmosphere such as a constant pressure. Although not shown, a vacuum pump and a gas tank for atmosphere control may be connected to the chamber 100. A vacuum pump and an atmosphere control gas tank may be used to make the inside of the chamber 100 vacuum, and then an inert gas such as argon gas may be charged.

The silicon carbide seed crystal 210 may be connected to the seed crystal support 230 and the moving member 250 to be located inside the crucible 300, And may be arranged to be in contact with the melt provided inside the crucible 300. Such a melt may comprise the silicone-based molten composition described above.

According to one embodiment, a meniscus may be formed between the surface of the silicon carbide seed crystal 210 and the melt. The meniscus refers to a curved surface formed on the melt by the surface tension generated when the lower surface of the silicon carbide seed crystal 210 is slightly lifted after contact with the melt. When a meniscus is formed to grow a silicon carbide single crystal, generation of polycrystals can be suppressed and a single crystal of higher quality can be obtained.

The silicon carbide seed crystal 210 is made of a silicon carbide single crystal. The crystal structure of the silicon carbide seed crystal 210 is the same as the crystal structure of the silicon carbide single crystal to be produced. For example, when a 4H polymorphic silicon carbide single crystal is produced, a 4H polymorphic silicon carbide seed crystal 210 can be used. 4H polymorphic silicon carbide seed crystal 210 is used, the crystal growth plane may be a (0001) plane or a (000-1) plane or a plane at an angle of 8 degrees or less from a (0001) plane or a It can be a picture plane.

The seed crystal supporting portion 230 connects the silicon carbide seed crystal 210 and the moving member 250. One end of the seed crystal supporting part 230 may be connected to the moving member 250 and the other end may be connected to the seed crystal 210.

The seed crystal supporting portion 230 is connected to the moving member 250 and can move up and down along the height direction of the crucible 300. Specifically, the seed crystal supporting portion 230 may be moved to the inside of the crucible 300 for the growth process of the silicon carbide single crystal or may be moved to the outside of the crucible 300 after the growth process of the silicon carbide single crystal is completed. In addition, although the present invention has been described with respect to the embodiment in which the seed crystal supporting portion 230 moves in the up and down direction, it is not limited thereto and may be moved or rotated in any direction, and may include known means for this.

The seed crystal supporting portion 230 can be detached from the moving member 250. In order to obtain a silicon carbide single crystal is coupled to the movable member 250 may be provided inside the crucible <300), since the growth process of the single crystal is completed, it can be separated from the ^mobile, element 250. The movable member 250 is connected to a driving unit (not shown) Can be moved or rotated. The moving member 250 may include known means for moving up or down or rotating.

The crucible 300 may be in the form of a container having an open upper side and may include an outer circumferential surface 300a and a lower surface 300b except for the upper surface. It goes without saying that the crucible 300 may have any form for forming the silicon carbide single crystal without limitation to the above-described form. The crucible 300 may be charged with a molten raw material such as silicon or silicon carbide powder.

The crucible 300 may be a material containing carbon such as graphite or silicon carbide, and the crucible 300 itself may be used as a source of the carbon raw material. Alternatively, a crucible made of a ceramic material can be used, and the material or the source for supplying carbon can be provided separately.

The heating member 400 can heat or melt the material contained in the crucible 300 by heating the crucible 300. The heating member 400 may use a resistance heating means or an induction heating type heating means. Specifically, the heating member 400 may be formed by a resistance type in which the heating member 400 generates heat, or may be formed by an induction heating method in which the heating member 400 is formed of an induction coil and a crucible 300 is heated by flowing a high frequency current through the induction coil . However, it goes without saying that any heating member can be used without being limited to the above-described method.

The apparatus for manufacturing silicon carbide according to one embodiment may further include a rotating member 500. The rotary member 500 is coupled to the lower surface of the crucible 300 to rotate the crucible 300. A high quality silicon carbide single crystal can be grown in the silicon carbide seed crystal 210 which can provide a melt of uniform composition through the rotation of the crucible 300. [ Hereinafter, a method for manufacturing a silicon carbide single crystal using the aforementioned silicon-based molten composition and an apparatus for producing a silicon carbide single crystal will be described. First, an initial molten raw material containing the above-described silicon-based molten composition is charged into the crucible 300. The initial molten feed may be in powder form, but is not limited thereto. If the crucible 300 comprises a carbon material, then the initial molten material is But may include carbon, but not limited thereto, the initial molten raw material may include carbon.

The crucible 300 on which the initial melting material is mounted is heated using the heating member 400 in an inert atmosphere such as argon gas. The initial molten material in the crucible 300 changes to a melt containing carbon (C), silicon (Si), and metals (chromium, vanadium, aluminum). .

After the crucible 300 reaches a predetermined temperature, the silicon carbide supersaturated state is induced by the temperature difference between the melt in the crucible 300 and the seed crystal 210. A silicon carbide single crystal grows on the seed crystal 210 with this supersaturation as a driving force.

As the silicon carbide single crystal grows, the conditions for depositing silicon carbide from the melt may vary. At this time, silicon and carbon are added to meet the composition of the melt over time, so that the melt can be maintained within a certain range of composition. The added silicon and carbon may be introduced continuously or discontinuously.

When the silicon-based molten composition according to an embodiment of the present invention is used, since the growth rate of the obtained single crystal can be fast, the time and cost required for the process can be reduced. Hereinafter, embodiments and comparative examples of the present invention will be described with reference to FIGS. 2 to 5. FIG. FIG. 2 is a graph showing carbon solubility according to Examples and Comparative Examples, FIG. 3 is an image of the precipitate deposited according to Examples and Comparative Examples, and FIG. 4 is a graph showing the carbon solubility of AIMD FIG. 5 is a graph showing an analysis of an average remotely controlled displacement (MSD) value of carbon atoms for the Examples and Comparative Examples. FIG.

Example 1 is Si ₀ . ₆ (Cr-V) ₀ . ₃₇ Al ₀ . ₀₃ (Cr: V = 9: 1), and Example 2 is Si ₀ . ₆ (Cr-V) o. _{37 Alo.o3 (Cr: V = 3} : l) , and Example 3 was Si _0. ₆ (Cr-V) ₀ . ₃₇ A1 (). ₀₃ (Cr: V = 1: 1), and Example 4 is Si ₀ . ₆ (Cr-V) ₀ . ₃₇ Al ₀ . ₀₃ (Cr: V = 1: 3), and Example 5 is Si ₀ . ₆ (Cr-V) o. ₃₇ Alo.o3 (Cr: V = 1: 9).

In Comparative Example 1, Si ₀ . ₆ Cr ₀ . ₃₇ Al ₀ . ₀₃ , and Comparative Example 2 is Si ₀ . ₆ V ₀ . ₃₇ Al ₀ . ₀₃ , Comparative Example 3 _{_{Si 0.6 (Cr-Fe) 0.37}} Al 0.03 (Cr: Fe = 3: l) , and Comparative Example 4 _{_{Si 0.6 (Cr- Fe) o .37}} Alo.o3 (Cr: Fe = l: l ), And Comparative Example 5 is Si ₀ . ₆ (Cr-Fe) ₀ . ₃₇ Al ₀ . ₀₃ (Cr: Fe = 1: 3), and Comparative Example 6 is Si ₀ . _{6 (Cr-V-Fe)} 0.37 Al 0.03 (Cr: V: Fe = l: 1: 1) , and Comparative Example 7 _{Si 0 .88 (Cr-V)} o.o8Alo.04 (Cr: V = l : l), and Comparative Example 8 is Si ₀ . ₃₂ (Cr-V) ₀ . ₆₄ Al ₀ . ₀₄ (Cr: V = 1: 1).

2 is a thermodynamic calculation program Fact Sage (SGTE database), in Examples 1 to 5 and Comparative Examples 1 to 6. FIG 1900 for silicon-based melt (° C) and 1800 ^(° C) in accordance with the using ( ^° C) and 1800 ^° C ( ^° C), respectively. The carbon solubility is a ratio of the number of moles of dissolved carbon to the total number of moles of the silicon melt containing dissolved carbon.

FIG Comparative Example 2 to Comparative Example 6 prepared in Examples 1 to 5 in the case of a silicon-based molten composition 1900 in accordance ^(° C) and Fig. ^(° carbon solubility and 1900 at 1800 ^(° C) As shown in the 2 C) and the carbon solubility difference of 1800 ^degrees Celsius ( ^° C).

It was confirmed that the silicone-based molten composition according to the embodiment including both chromium and vanadium exhibited a high carbon solubility compared with the comparative example using vanadium solely or the comparative example including chromium and iron or the comparative example including chromium, vanadium and iron Respectively.

Specifically, in the case of a silicone-based molten composition containing a crown, the difference in carbon solubility depending on the temperature difference may be large. On the other hand, the silicon-based molten composition containing vanadium may have a large carbon solubility value at the temperature. The carbon contained in the silicon-based molten composition containing vanadium may have stable energy, so that the amount of carbon contained in the crucible may be eluted into the silicon-based molten composition. Therefore, it can be seen that, in the case of the silicone-based molten composition including both of chromium and vanadium, the carbon solubility value at the corresponding temperature as well as the carbon solubility difference due to the difference in silver content is large as in the present embodiment example. Next, Fig. 3 is an image of a sample deposited by the sequential method according to Examples 2 to 4 and Comparative Examples 1 to 8.

In order to obtain these properties, firstly, The initial raw material corresponding to the chemical composition is charged into the graphite crucible. And after placing the SiC seed crystal (Φ 10隱) to the crucible top and geupnyaeng was nyaenggak to 1900. Fig. ^(° C) was 2 hours melt at a rate in the following per minute Fig. ^(° C) 1600 Fig. ^(° C) Ung (SiC single crystal) was obtained.

In Comparative Examples 1 and 2, a small amount of hexagonal silicon carbide single crystal was precipitated in the seed crystal, and in Comparative Examples 3 to 6, the silicon carbide precipitate having hexagonal shape in the seed crystal was scarcely found or very small.

Comparative Example 7 is a case where the content (b + c) of chromium and vanadium is less than 0.1. In the case of Comparative Example 7, since the content of silicon is larger than those of Examples, the silicon has a characteristic of expanding its volume during solidification. As shown in FIG. 3, a convex spherical protrusion upward from the center of the crucible at the time of melting of the melt can be generated. These protrusions cover most of the silicon carbide termination crystals, but some of the exposed silicon carbide seed crystals do not show growth of the silicon carbide single crystals. In other words, it was confirmed that the content of chromium and vanadium contained in the melt was remarkably small, so that silicon carbide was not grown to grow.

And Comparative Example 8 is a case where the content (b + c) of chromium and vanadium exceeds 0.6. At this time, it can be confirmed that the silicon carbide seed crystals disappeared after the process was terminated. This is because the chemical activity of SiC contained in the silicon carbide seed crystal is smaller than that of the crucible, so that the metal contained in the melt dissolves the silicon carbide seed crystal rather than dissolving the carbon in the crucible.

On the other hand, in Examples 1 to 5, it was visually observed that a large hexagonal silicon carbide crystal precipitated in the vicinity of seed crystal. The results of FIG. 3 confirm that the degree of precipitation of the silicon carbide single crystal is superior to that of the comparative example.

Next, FIG. 4 and FIG. 5 will be described. 4 is an AIMD simulation image for examining the carbon solubility of Comparative Examples 1, 2, and 1, and FIG. 5 is a graph showing the AIMD simulation results for Comparative Example 1, Comparative Example 2 and Example 1, And the displacement value (MSD).

Figs. 4 and 5 show the DFK density function function theory for carbon solubility characteristics analysis) (MSD) simulation of carbon using AIMD (first principles molecular dynamics) after optimizing the interface models of Comparative Example 1, Comparative Example 2 and Example 1, respectively. AIMD calculations were performed for 5 ps at 4000 K to observe the movement and change of carbon atoms in a short time.

Comparative Example 1, Comparative Example 2 and Example 1, simulation results for the composition of both the lower circle bump Yan carbon after the lapse of 5 _ps> woman was confirmed that the diffusion into the silicon-based melt. Particularly, the degree of diffusion of carbon atoms was most prominent in Example 1, and it was confirmed that Comparative Example 2 and Comparative Example 1 were spread to a similar low level.

Also, as shown in FIG. 5, it was confirmed that the mean square displacement value (MSD) of carbon atoms was high in Comparative Example 1 and Comparative Example 2 versus Example 1. The molten silicon composition containing both of chromium and vanadium can have a high carbon solubility and a higher crystal growth rate than the comparative example using only chromium or vanadium alone.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is obvious to those who have. Accordingly, it should be understood that such modifications or alterations should not be understood individually from the technical spirit and viewpoint of the present invention, and that modified embodiments fall within the scope of the claims of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

100: chamber

210: seed crystal

300: Crucible

400: heating member

500: rotating member

Claims

[Claims]

[Claim 1]

1. A silicon-based molten composition for use in a solution growth method for forming a silicon carbide single crystal, the silicon-based molten composition being represented by the following formula (1) including silicon, chrome (Cr), vanadium (V)

Si _a Cr _b V _c Al _d (Equation 1)

In the above formula (1), a is 0.4 or more and 0.9 or less, b + c is 0.1 or more and 0.6 or less, c / (b + c) is 0.05 or more and 0.95 or less, and d is 0.01 or more and 0.1 or less. [Claim 2]

The method of claim 1,

In the above formula (1), _a is 0.5 or more and 0.8 or less, and b + c is 0 or less.

2 or more and 0.5 or less, c / (b + c) is 0.1 or more and 0.9 or less, and d is 0.01 or more and 0.05 or less.

[Claim 3]

In paragraph 1,

Wherein the silicone-based molten composition has a carbon solubility of 0.04 or more at 1800 ^degrees Celsius.

[4]

The method of claim 1,

^Wherein: the silicon-based molten composition is a silicon-based melt compositions have more than one carbon solubility 0.06 eseo 1900 also ^(° C).

[Claim 5]

The method of claim 1,

Wherein the content ratio of chromium and vanadium is from 9: 1 to 1: 9.

[Claim 6]

Preparing a silicon carbide seed crystal,

- preparing a silicone-based molten composition comprising silicon, chromium (Cr), vanadium (V) and aluminum (A1)

(C) is added to the silicone-based molten composition to form a melt Step, and

And a step of subcooling the melt to grow a silicon carbide single crystal on the seed crystal.

Si _a Cr _b V _c Al _d (Equation 1)

In the above formula (1), a is 0.4 or more and 0.9 or less, b + c is 0.1 or more and 0.6 or less, c / (b + c) is 0.05 or more and 0.95 or less, and d is 0.01 or more and 0.1 or less.

7.

The method of claim 6,

Wherein _a is 0.5 or more and 0.8 or less, b + c is 0.2 or more and 0.5 or less, c / (b + c) is 0.1 or more and 0.9 or less, and d is 0.01 or more and 0.05 or less.

8.

The method of claim 6,

[Claim 9]

The method of claim 6,

Wherein the silicon-based molten composition has a carbon solubility of 0.06 or more at 1900 ^degrees Celsius.

Claim 10

The method of claim 6,

Wherein the content ratio of chromium and vanadium is from 9: 1 to 1: 9.