KR20190058963A - Reactor for growing silicon carbide single crystal - Google Patents

Abstract

The present invention relates to an apparatus for growing a silicon carbide single crystal by a liquid growth method. According to the present invention, the apparatus comprises: a reaction chamber formed under a constant pressure atmosphere; a crucible made of a graphite material, provided in the reaction chamber, and formed with an inner space part in which a molten metal containing silicon or silicon carbide (SiC) is charged; a holder extending from an upper portion of the crucible to the inside of the crucible, and fixed with a silicon carbide seed which is a time point of growing silicon carbide from the molten metal at a lower end thereof; a flow part provided to be adjacent to an upper portion of the silicon carbide seed, and rotated in accordance with the rotation of the holder to convect the molten metal in a predetermined direction; and an induction coil for heating the crucible. According to the present invention, the density of carbon in the crucible is uniformly maintained by increasing the flow of the fluid in the crucible by the flow part, and the flow part is formed of the graphite at the same time, such that a high-density carbon region is formed at a growth position of a silicon carbide single crystal by being partially melted at high temperature, thereby allowing high-speed growth and mass-growth.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a silicon carbide single crystal growing apparatus,

The present invention relates to an apparatus for growing a silicon carbide single crystal by a liquid phase growth method.

BACKGROUND ART Compound semiconductor materials such as silicon carbide (SiC), gallium nitride (GaN), and aluminum nitride have been extensively studied as next-generation semiconductor materials having excellent characteristics compared to silicon currently used as a semiconductor material. In particular, silicon carbide is excellent not only in mechanical strength but also in thermal stability and chemical stability, and has a very high thermal conductivity of not less than 4 W / cm ² , and its operating temperature limit is as low as 650 high. In the case where the crystal structure is 3C silicon carbide, 4H silicon carbide, and 6H silicon carbide, the band gap is 2.5 eV or more, which is twice as high as that of silicon. Therefore, it is excellent as a semiconductor material for high power and low- And a semiconductor material for power conversion.

Generally, for the growth of silicon carbide single crystal, there is a sublimation method in which a single crystal is grown by sublimation at a high temperature of 2,000 or more using silicon carbide (SiC) as a raw material, Acheson method in which carbon and silica are reacted in a high- . In addition, a method of chemical vapor deposition using a gas source is being used.

However, the Acheson method is very difficult to obtain a high purity silicon carbide single crystal, and the chemical vapor deposition method can grow to a thickness limited level only as a thin film. Therefore, it has been focused on a sublimation method for growing crystals by sublimation of silicon carbide at a high temperature. However, the sublimation method is also generally performed at a high temperature of 2200 or more, and there is a possibility that various defects such as micropipes and stacking faults are generated, resulting in a limitation in production unit cost.

In order to solve the problem of the sublimation method, a liquid phase growth method employing a Czochralski (crystal pulling method) was introduced. The Czochralski method is a method of growing a single crystal from a melt. The crystal shape and properties are determined by the pulling rate (growth rate), the rotation speed, the temperature gradient, or the crystal orientation. In the liquid phase growth method for silicon carbide single crystal, generally, silicon or silicon carbide powder is charged into a graphite crucible and then heated to a high temperature of about 1600 to 1900 to grow crystals from the silicon carbide seed crystal surface located in the upper part of the crucible. However, in this method, the rate of crystal growth is as low as 50 탆 / hr or less, resulting in poor economical efficiency.

In the case of the liquid phase growth method for growing silicon carbide single crystal, carbon for crystal growth usually uses a graphite crucible. That is, as the carbon atoms constituting the graphite crucible are separated into liquid phases, they are then spread into the solution, and a part of the carbon atoms move to the silicon carbide single crystal growth point to grow single crystals. However, there is a difference between the carbon concentration around the crucible in which the carbon atoms are supplied and the carbon concentration around the single crystal growth that disappears when the carbon atoms are synthesized with silicon carbide.

Therefore, it is necessary to increase the carbon concentration around the single crystal growth by making the carbon concentration in the solution in the crucible uniform in the closed growth line operated at a high temperature. In order to accomplish this, a method is employed in which a seed fixing bar fixed with seed crystals is rotated and / or a crucible is rotated to increase the uniformity of carbon concentration in the solution, as in the method used in the Czochralski method. However, More advanced methods are required for growth.

The present invention provides a growth apparatus suitable for high-speed growth and large-capacity growth of a silicon carbide single crystal.

A silicon carbide single crystal growth apparatus according to the present invention includes: a reaction chamber formed in a constant pressure atmosphere; A crucible made of graphite material provided in the reaction chamber and having an inner space portion filled with a silicon or a molten metal containing silicon carbide (SiC); A holder extending from an upper portion of the crucible to an inner side of the crucible and fixing a silicon carbide seed at a lower end of the furnace at the time of silicon carbide growth; A moving unit provided adjacent to an upper portion of the silicon carbide seed and rotated together with the holder to rotate the molten metal in a predetermined direction; And an induction coil for heating the crucible.

Further, the flow portion may be formed of a graphite material.

The holder may further include: an upper rod formed in a tubular shape having a predetermined length from an upper portion; And a seed fixing part integrally formed at a lower portion of the upper rod and having a diameter corresponding to the diameter of the silicon carbide seed and fixing the silicon carbide seed.

The flow unit may further include: a coupling unit extruded into the upper rod; And a wing portion extending radially from the outer circumferential surface of the engaging portion and inclined with respect to the horizontal direction.

The flow portion may include a wing portion extending radially from the outer circumferential surface of the seed fixing portion and inclined with respect to the horizontal direction.

And a driving unit disposed under the crucible for rotating the crucible.

The driving unit may include a driving rod that is a center of rotation.

The induction coil may be provided on the outer peripheral surface side of the crucible.

According to the present invention, the flow of the fluid in the crucible is increased by the flow portion to uniformly maintain the density of the carbon in the crucible, and at the same time, the flow portion is formed into graphite to partially melt at a high temperature, So that high-speed growth and large-capacity growth are enabled.

1 is a schematic perspective view showing an upper rod according to an embodiment of the present invention.
2 is a schematic perspective view illustrating a view of a flow portion according to one embodiment.
3 is a perspective view showing a state where the upper rod of FIG. 1 and the flow portion of FIG. 2 are combined.
4 is a schematic perspective view showing an upper rod according to another embodiment.
5 is a schematic view showing a state of a silicon carbide single crystal growing apparatus according to this embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the absence of special definitions or references, the terms used in this description are based on the conditions indicated in the drawings. The same reference numerals denote the same members throughout the embodiments. For the sake of convenience, the thicknesses and dimensions of the structures shown in the drawings may be exaggerated, and they do not mean that the dimensions and the proportions of the structures should be actually set.

1 to 3, a holder including an upper rod according to an embodiment will be described. FIG. 1 is a schematic perspective view showing an upper rod according to an embodiment of the present invention, FIG. 2 is a schematic perspective view showing a state of a flow portion according to an embodiment, FIG. 3 is a cross- In which the flow portion of the gasket is joined.

Referring to FIG. 1, the holder 10 according to the present embodiment is formed to have a predetermined length extending from the top of the crucible to the inside of the crucible. The silicon carbide seed, which is the starting point of silicon carbide growth, is fixed to the lower end of the holder 10 from the molten metal.

The holder (10) includes an upper rod (11) and a seed fixing portion (13). The upper rod 11 is formed in a tubular shape having a certain length from the top. The seed fixing portion 13 is integrally provided at the lower portion of the upper rod 11 and is formed to have a diameter corresponding to the diameter of the silicon carbide seed. A silicon carbide seed 15 is fixed to the lower end of the seed fixing portion 13.

Thus, the holder 10 forms a supporting structure for supporting the growth of silicon carbide crystals.

Referring to FIG. 2, the moving unit 20 is provided adjacent to the upper portion of the silicon carbide seed, and functions to convect the molten metal in a predetermined direction by rotating together with the rotation of the holder. The moving part 20 has a coupling part 21 and a wing part 23.

The engaging portion 21 is formed in the shape of a hollow circular plate so as to be extrapolated to the upper rod 11. The wing portion 23 extends radially from the outer peripheral surface of the engaging portion 21 and is formed into a plate shape inclined with respect to the horizontal direction.

At this time, the flow portion 20 may be formed of a graphite material. The flow portion 20 is formed of a graphite material to partially melt in the molten metal to increase the density of carbon in the molten metal.

The flow portion 20 is fixed to the upper end of the seed fixing portion 13 by being extrapolated to the upper rod 10 as shown in Fig. As the moving part 20 rotates, the molten metal immersed in the moving part 20 flows in a certain direction.

A holder including an upper rod according to another embodiment will be described with reference to FIG. 4 is a schematic perspective view showing an upper rod according to another embodiment.

The flow portion according to the present embodiment does not have a separate engaging portion but includes only the wing portion 23 only. In this case, the wing portion 23 may be formed in a plate shape extending radially from the outer peripheral surface of the seed fixing portion 13 and inclined with respect to the horizontal direction.

The operation of the silicon carbide single crystal growing apparatus including the silicon carbide single crystal growing apparatus according to one embodiment will be described with reference to FIG. 5 is a schematic view showing a state of a silicon carbide single crystal growing apparatus according to this embodiment.

The silicon carbide single crystal growing apparatus according to the present embodiment includes a reaction chamber 41, a crucible 30, holders 11 and 13, a flow portion 23 and an induction coil 43.

The reaction chamber 41 is formed in a constant pressure atmosphere. The reaction chamber 41 is filled with an inert gas such as argon or helium. Under this atmosphere, a constant pressure atmosphere is formed. On the other hand, a vacuum pump and a gas cylinder for atmosphere control are connected to the reaction chamber 41 through a valve to maintain a constant pressure.

The crucible 30 is provided in the reaction chamber 41, and an inner space portion into which silicon or silicon containing silicon carbide (SiC) is charged is formed. The crucible 30 is made of a graphite material, and the crucible 30 itself can be used as a carbon source.

The holders 11 and 13 include the upper rod 11 and the seed fixing part 13 as described above and may include the moving part 23. [ The holders 11 and 13 extend from the upper part of the crucible 30 to the inside of the crucible 30 and the silicon carbide seed 15 which is the starting point of the silicon carbide growth from the molten metal is fixed at the lower end.

The silicon carbide seed 15 rotates together with the rotations of the holders 11 and 13 of the crucible 30. The silicon carbide seed 34 is held by the holders 11 and 13 when the single crystal grows, You can move up and down together by moving. When the downward single crystal grows from the silicon carbide seed 34, the height can be adjusted so as to secure such a growth space.

As described above, the moving part or the wing part 23 rotates together with the holders 11 and 13 as they rotate, so that the molten metal 60 flows in one direction in one direction. At this time, the molten metal is mixed so that the carbon density is uniformly formed.

In addition, since the wing portion 23 is formed of graphite material, the crucible 30 is partially melted in the molten metal to supply carbon, such as to create an environment in which the silicon carbide seed 15 can grow by supplying the carbon component . At this time, the wing portion 23 is positioned adjacent to the upper portion of the silicon carbide seed 15, so that a region having a high carbon density can be formed around the silicon carbide seed 15.

On the other hand, an induction coil 43 for heating the crucible 30 is included. An induction coil 43 is provided on the outer circumferential surface of the crucible 30 as shown in the figure. In addition to the induction coil 43, a resistance heating element or the like can be used. The induction coil 43 may be provided on the outer peripheral surface side of the crucible 30.

And a driving unit 50 disposed at a lower portion of the crucible 30 and rotating the crucible 30 may be provided. The driving unit 50 may include a driving rod 51 serving as a center of rotation and a driving base 53 for supporting the driving rod 51 so as to be rotatable.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. have.

10: Holder
11: Upper rod
13:
15: Silicon carbide seed
20:
21:
23: wing portion
30: Crucible
41: reaction chamber
43: induction coil
50:
51: driving rod
53:
60: melt

Claims (8)

A reaction chamber formed in a constant pressure atmosphere;
A crucible made of graphite material provided in the reaction chamber and having an inner space portion filled with a silicon or a molten metal containing silicon carbide (SiC);
A holder extending from an upper portion of the crucible to an inner side of the crucible and fixing a silicon carbide seed at a lower end of the furnace at the time of silicon carbide growth;
A moving unit provided adjacent to an upper portion of the silicon carbide seed and rotated together with the holder to rotate the molten metal in a predetermined direction; And
And an induction coil for heating the crucible. The method according to claim 1,
Wherein the flow portion is formed of a graphite material. The method according to claim 1,
Wherein the holder comprises:
An upper rod formed in a tubular shape having a predetermined length from the upper portion; And
And a seed fixing portion integrally formed at a lower portion of the upper rod and having a diameter corresponding to a diameter of the silicon carbide seed and having the silicon carbide seed fixed thereto. The method of claim 3,
Wherein the flow-
A coupling portion extrapolating to the upper rod; And
And a blade portion extending radially from an outer circumferential surface of the coupling portion and being inclined with respect to a horizontal direction. The method of claim 3,
Wherein the flow portion includes a wing portion extending radially from an outer circumferential surface of the seed fixing portion and inclined with respect to a horizontal direction. The method according to claim 1,
And a driving unit disposed below the crucible for rotating the crucible. The method according to claim 1,
Wherein the driving unit includes a driving rod which is a center of rotation. The method according to claim 1,
And the induction coil is provided on an outer peripheral surface side of the crucible.

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