KR20190070404A - Reactor for growing silicon carbide single crystal - Google Patents

Abstract

Disclosed by the present invention is a silicon carbide single crystal growth device. The present invention enables high speed growth and high capacity growth by melting graphite partially at a high temperature and forming a high density carbon area at the growth position of silicon carbide single crystal as a mobile unit is made of the graphite while evenly maintaining the density of carbon in a crucible by increasing the movement of fluid in the crucible by the mobile unit. According to the present invention, the silicon carbide single crystal growth device includes: a reaction chamber which is created to have a predetermined pressure; a crucible included in the reaction chamber and formed with a graphite material to have an inner space unit into which molten metal including silicon or silicon carbide (SiC) is charged; a holder extended from the upper part of the crucible to the inside of the crucible; a jig fixating a silicon carbide seed in a state of being separated at a predetermined interval from the lower end of the holder by being extended to the lower side of the holder; a mobile unit installed in the lower end side of the silicon carbide holder and making the molten metal flow in a predetermined direction by rotating as the holder rotates; and an induction coil heating the crucible.

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.

The present invention also provides a silicon carbide single crystal growing apparatus capable of suppressing trapping of a bubble having a size of several micrometers to several tens of micrometers in a grown layer.

The present invention also provides a silicon carbide single crystal growth apparatus capable of inducing a strong flow of a fluid in a crucible, separating bubbles trapped in the upper portion of the seed from the seed, and being discharged to the outside.

The present invention also provides a silicon carbide single crystal growth apparatus capable of increasing the supply rate of carbon to increase the carbon density around the seed.

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 the top of the crucible to the inside of the crucible; A jig extending downward from the holder and having a silicon carbide seed fixed at a predetermined distance from a lower end of the holder; A moving part provided at a lower end side of the silicon carbide holder and rotated together with the rotation of the holder to convect the molten metal in a predetermined direction; And an induction coil for heating the crucible.

The jig may further include: a jig fixing unit fixed to a lower end of the holder; At least one jig extension portion extending downward from the jig fixing portion; And a seed fixing part extending from the lower end of the jig extension part toward the center to fix the seed.

The jig may be formed of at least one of carbon and ceramic materials.

The jig extension part may be formed in a plurality of bars extending downward at a predetermined angle around the jig fixing part.

The jig extension part may be formed in a cylindrical shape extending downward from the periphery of the jig fixing part.

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

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 peripheral surface of the moving portion 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.

In addition, according to the present invention, the growth direction of the seed is located at an upper position, and bubbles having a size of several micrometers to several tens of micrometers are prevented from being trapped in a grown layer.

Further, according to the present invention, bubbles trapped in the upper portion of the seed can be separated from the seed through a strong flow of the fluid in the crucible to be discharged to the outside.

According to the present invention, the parts accommodated in the crucible such as the moving part and the jig are made of carbon material, so that the supply rate of carbon can be increased and the carbon density around the seed can be increased.

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 perspective view showing a state of a jig according to an embodiment.
FIG. 6 is a perspective view showing a state where a jig and an upper rod are combined according to an embodiment.
7 is a perspective view showing a state of a jig according to another embodiment.
FIG. 8 is a perspective view showing a state where a jig and an upper rod according to the embodiment of FIG. 7 are combined. FIG.
9 is a perspective view showing a state in which a moving unit and a jig are combined according to another embodiment.
10 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 floating portion fixing portion (13). The upper rod 11 is formed in a tubular shape having a certain length from the top. The floating portion 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.

The holder 10 forms a support structure that supports the growth of silicon carbide crystals. However, in the embodiments according to the present invention, a structure for indirectly supporting the silicon carbide seed directly under the holder 10, rather than directly supporting the silicon carbide seed, is introduced.

Referring to FIG. 2, the moving unit 20 is provided to be positioned above 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 extrapolated to the upper rod 10 and fixed to the upper end of the flow portion fixing portion 13 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 moving portion fixing portion 13 and inclined with respect to the horizontal direction.

A jig according to an embodiment will be described with reference to Figs. 5 to 8. Fig. FIG. 5 is a perspective view showing a state of a jig according to an embodiment, and FIG. 6 is a perspective view showing a state where a jig and an upper rod according to an embodiment are combined. 7 is a perspective view showing a jig according to another embodiment, and FIG. 8 is a perspective view showing a state where a jig and an upper rod according to the embodiment of FIG. 7 are combined.

The jig 90 according to the present embodiment has a configuration in which the silicon carbide seed is indirectly fixed in a state in which the jig 90 according to the present embodiment extends downward of the holder 10a and is spaced apart from the lower end of the holder by a predetermined distance as shown in Figs. .

More specifically, the jig 90 includes a jig fixing portion 91, a jig extending portion 94, and a seed fixing portion 92.

The jig fixing section 91 is extrapolated to the lower end side of the holder so that the jig can be fixed to the holder 10a and the jig extending section 94 extends downward from the jig fixing section, And separates the lower end of the holder 10a. The jig extension 94 according to the present embodiment is formed in a cylindrical shape as a whole. At this time, if necessary, the through-holes passing through the inside and outside of the jig extension portion 94 can be cut into various numbers and shapes.

The seed fixing portion 92 is provided at the lower end of the jig extension portion 94 to fix the seed 94. [ A seed 15 is fixed or attached to the upper surface of the seed fixing portion 92, in which case the growth direction of the seed is directed upward. The jig 90 may be formed of at least one of carbon and ceramic materials.

The jig fixing unit 91 and the seed fixing unit 92 may be connected to the jig extension 94 through connection arms 93a and 93b, respectively. The connecting arms 93a and 93b are formed in a thin bar shape and may be provided at a predetermined angle in a radial direction with respect to the center axis of the jig 90. [

7 and 8, the jig according to another embodiment differs from the jig described above in the construction of the jig extension portion 94a. The jig extension portion 94a according to the present embodiment can be formed in a plurality of bar shapes extending downward at regular angles around the jig fixing portion 91. [ At this time, the shape of the jig extended portion 94a can be implemented in various forms and there is no particular limitation.

A jig according to another embodiment will be described with reference to Fig. 9 is a perspective view showing a state in which a moving unit and a jig are combined according to another embodiment.

The jig 90b according to the present embodiment shows a case in which the above-described moving portion of Fig. 2 and the jig of Fig. 7 are integrally formed. That is, the connection arm 93 at the upper part constituting the jig of Fig. 7 is replaced with the wing 23. That is, the wing portion 23 forms the upper support structure of the jig 90b, so that the structure is simple and efficient convection can be formed.

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. 10 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 moving part 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 are provided with a jig 90 for fixing the silicon carbide seed 15 at the lower end. At the lower end of the jig 90, the seed 15 is fixed from the molten metal at the time of silicon carbide growth.

The silicon carbide seed 15 rotates together with the rotations of the holders 11 and 13 and the jig 90 of the crucible 30. [ Further, the silicon carbide seeds 34 can move upward and downward together as the single crystals grow as the holders 11 and 13 move up and down as needed. In this case, the growth direction of the silicon carbide seed 34 is formed upward.

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.

The wing portion 23 or the jig 90 is formed of graphite material so that the crucible 30 is partially melted in the molten metal such that the crucible 30 is supplied with a carbon component to form an environment in which the silicon carbide seed 15 can grow Carbon. At this time, the wing portion 23 is positioned above the silicon carbide seed 15 to induce the convection of the molten metal 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
90: Jig

Claims (11)

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 the top of the crucible to the inside of the crucible;
A jig extending downward from the holder and having a silicon carbide seed fixed at a predetermined distance from a lower end of the holder;
A moving part provided at a lower end side of the silicon carbide holder and rotated together with the rotation of the holder to convect the molten metal in a predetermined direction; And
And an induction coil for heating the crucible. The method according to claim 1,
The jig,
A jig fixing unit fixed to a lower end side of the holder;
At least one jig extension portion extending downward from the jig fixing portion; And
And a seed fixing part extending from the lower end of the jig extension part toward the center to fix the seed. 3. The method of claim 2,
Wherein the jig is made of at least one of carbon and a ceramic material. 3. The method of claim 2,
Wherein the jig extension portion is formed in a plurality of bar shapes extending downward at a predetermined angle around the jig fixing portion. 3. The method of claim 2,
Wherein the jig extension part is formed in a cylindrical shape extending downward from the periphery of the jig fixing part. The method according to claim 1,
Wherein the flow portion is formed of a graphite material. The method according to claim 6,
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 according to claim 6,
Wherein the flow portion includes a wing portion extending radially from an outer circumferential surface of the moving portion 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. 10. The method of claim 9,
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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