KR20200053818A - Jig of the reactor for growing silicon carbide single crystal - Google Patents

Abstract

The present invention relates to a jig for fixing a silicon carbide seed for a silicon carbide single crystal growth device, comprising: a reaction chamber in which a uniform pressure atmosphere is created; a crucible provided inside the reaction chamber and including an inner cavity in which molten metal containing silicon or silicon carbide (SiC) is introduced; and a holder which is extended into the crucible from an upper portion of the crucible. In particular, the jig comprises: a jig fixing unit affixed to a lower end of the holder; a blade unit radially extended from an outer surface of the jig fixing unit and inclined with respect to a horizontal direction; at least one jig extension unit extended downwardly from an end portion of the blade unit; a seed fixing unit situated below the jig fixing unit with a predetermined gap therebetween, connected to a lower end of the jig extension unit, and having the seed fixed thereto; and a flow enhancing unit formed in the shape of a protruding blade in a position adjacent to the seed fixing unit, to improve a flow of the molten metal around the seed fixing unit.

Description

Jig of the reactor for growing silicon carbide single crystal

The present invention relates to a jig for a silicon carbide single crystal growth apparatus, and more particularly, to an auxiliary jig fixed to a holder to grow a silicon carbide single crystal.

Compound semiconductor materials such as silicon carbide (SiC), gallium nitride (GaN), and aluminum nitride are widely researched as next-generation semiconductor materials having superior properties to silicon currently used as the most commonly used semiconductor materials. In particular, silicon carbide not only has excellent mechanical strength, has excellent thermal stability and chemical stability, has a very high thermal conductivity of 4 W / cm2 or more, and a very high operating limit of 650 or less compared to 200 or less of silicon. . In addition, when the crystal structure is 3C silicon carbide, 4H silicon carbide, or 6H silicon carbide, the bandgap is 2.5 eV or more, which is very good as a semiconductor material for high-power and low-loss converters, more than twice that of silicon. It is attracting attention as a semiconductor material for optical semiconductors and power conversion.

For the growth of a silicon carbide single crystal, there is an Acheson method of reacting carbon and silica in a high temperature electric furnace of 2000 or more, and a sublimation method of growing a single crystal by subliming at a high temperature of 2000 or more using silicon carbide (SiC) as a raw material. . In addition, chemical vapor deposition using gas sources has been 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 only to a limited thickness as a thin film. Accordingly, research has been focused on a sublimation method in which crystals are grown by subliming silicon carbide at a high temperature. However, the sublimation method is also generally performed at a high temperature of 2200 or more, and has many problems such as micropipes and stacking faults, and thus has limitations in terms of production cost.

In order to solve the problem of the sublimation method, a liquid growth method using a Czochralski method (crystal pulling method) was introduced. The Czochralski method is a method of growing single crystals from a melt. The crystal shape or properties are determined by the pulling rate (growth rate), rotational speed, temperature gradient, or crystal orientation. The liquid phase growth method for a silicon carbide single crystal is generally charged with silicon or silicon carbide powder in a graphite crucible and heated to a high temperature of about 1600 to 1900 to grow crystals from the silicon carbide seed crystal surface located on the top of the crucible. However, with this method, the rate of crystal growth is very low, which is 50 µm / hr or less, and economic efficiency is poor.

In the case of the liquid phase growth method for silicon carbide single crystal growth, the carbon for crystal growth is usually a graphite crucible. That is, as the carbon atoms constituting the graphite crucible are separated into a liquid phase, and then spread into the solution, some of them are moved to the silicon carbide single crystal growth point to grow the single crystal. However, there is a difference between the carbon concentration around the crucible to which the carbon atom is supplied and the carbon concentration around the single crystal growth that disappears as the carbon atom is synthesized with silicon carbide.

Therefore, it is necessary to increase the carbon concentration around the single crystal growth by uniformizing the carbon concentration in the solution in the crucible in a sealed growth furnace operated at a high temperature. To this end, a method of increasing the uniformity of carbon concentration in a solution by rotating a seed crystal fixing rod and / or rotating a crucible, such as a method commonly used in the Czochralski method, is used, but high-speed growth and large capacity More advanced methods are needed for growth.

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

In addition, the present invention is a jig and crucible for a silicon carbide single crystal growth apparatus capable of suppressing traps of bubbles having a size of several µm to several tens of µm in a growth layer and controlling micro-flow of molten metal. Provides

In addition, the present invention is a jig capable of inducing a strong flow of fluid in the crucible, controlling the fine flow around the seed to separate bubbles from the seed, discharging it to the outside, and increasing the supply rate of carbon to increase the carbon density around the seed. , A crucible and a silicon carbide single crystal growth apparatus including them.

A reaction chamber formed in a constant pressure atmosphere, a crucible provided in the reaction chamber and formed with an inner space portion into which molten metal containing silicon or silicon carbide (SiC) is charged, and extending from the top of the crucible to the inside of the crucible A jig for fixing a silicon carbide seed provided in a silicon carbide single crystal growth apparatus including a holder,

The jig according to the present invention includes a jig fixing part fixed to the lower side of the holder; A wing portion extending radially from an outer circumferential surface of the jig fixing portion and being inclined with respect to a horizontal direction; At least one or more jig extensions extending downward from an end side of the wing portion; A seed fixing part which is positioned at a predetermined interval under the jig fixing part, is connected to the lower ends of the jig extending part, and the seed is fixed; And a flow improving unit formed in a blade shape protruding at a position adjacent to the seed fixing unit to improve the flow of molten metal around the seed fixing unit.

In addition, the jig extension may be formed in a plurality of bar shapes extending downward at a predetermined angle around the jig fixing portion.

In addition, the flow improving unit may include a side flow improving unit extending from the jig extension to form a constant angle with respect to the central axis direction of the holder.

In addition, a base ring member formed in a ring shape to connect the lower ends of the jig extension; And a connecting arm extending from the base ring member toward the center and connected to the seed fixing part.

In addition, the flow improving portion may include a bottom flow improving portion extending to form a constant angle with respect to the horizontal direction from the connecting arm.

In addition, the bottom flow improving unit may extend at an angle upward with respect to the horizontal direction.

In addition, the seed fixing portion may be formed in a circular plate shape.

In addition, the jig may be formed of at least one of carbon and ceramic materials.

According to the present invention, by increasing the flow of the fluid in the crucible, while uniformly maintaining the density of the carbon in the crucible and simultaneously forming the flow portion with graphite, it is partially melted at high temperature to form a high-density carbon region at the growth position of the silicon carbide single crystal, thereby increasing It has the effect of enabling growth and large-capacity growth.

In addition, according to the present invention, by placing the seed growth direction upward, there is an effect that can suppress the bubble (bubble) of the size of several ㎛ ~ several dozen㎛ trap (trap) to the growth layer (grown layer).

In addition, according to the present invention, a strong flow of fluid in the crucible is formed, and bubbles captured on the top of the seed are separated from the seed through fine flow control around the seed so that it can be discharged to the outside, and the carbon density is formed high around the seed. By doing so, it is possible to create an environment favorable for seed growth.

1 is a schematic view showing a state of a silicon carbide single crystal growth apparatus according to this embodiment.
2 is a schematic perspective view showing a state of an upper rod according to an embodiment of the present invention.
3 is a perspective view showing the appearance of a jig according to an embodiment.
4 is a perspective view showing a jig and a holder in accordance with an embodiment.
5 and 6 are each a perspective view and a cross-sectional view showing a state of a crucible according to an embodiment.
7 and 8 are a perspective view and a cross-sectional view showing a state of a crucible according to another embodiment.
9 and 10 are each a perspective view and a cross-sectional view showing a state of a crucible according to another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the absence of specific definitions or references, terms indicating directions used in this description are based on conditions indicated in the drawings. In addition, the same reference numerals refer to the same members throughout each embodiment. On the other hand, each configuration displayed on the drawing may exaggerate its thickness or dimensions for convenience of description, and does not mean that it should actually be configured at a ratio between the corresponding dimensions or configurations.

A silicon carbide single crystal growth apparatus according to an embodiment of the present invention will be described with reference to FIG. 1. 1 is a schematic view showing a state of a silicon carbide single crystal growth apparatus according to this embodiment.

The silicon carbide single crystal growth apparatus according to the present embodiment includes a reaction chamber 41, a crucible 30, holders 11, 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. Meanwhile, a vacuum pump and a gas cylinder for controlling the atmosphere 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 in which molten metal containing silicon or silicon carbide (SiC) is charged is formed. The crucible 30 is made of graphite, and the crucible 30 itself can be used as a source of carbon.

The holders 11 and 13 include an upper rod 11 and a fixing portion 13 and may include a moving portion 23. The holders 11 and 13 extend from the top of the crucible 30 to the inside of the crucible 30, and a jig 90 for fixing the silicon carbide seed 15 is provided at the bottom. At the lower end of the jig 90, a seed 15 that is a starting point of silicon carbide growth from the molten metal is fixed.

The silicon carbide seed 15 rotates with the rotation of the holders 11, 13 and the jig 90 of the crucible 30. In addition, as the single crystal grows, the silicon carbide seeds 34 can move up and down together as the holders 11 and 13 move up and down as necessary. In this case, the growth direction of the silicon carbide seed 34 is formed upward.

The jig 90 is a configuration for fixing the silicon carbide seed 15, while allowing the molten metal 60 to flow in a constant direction through the wing portion 95 and the flow improving portion, which will be described below, and at the same time, the flow of the molten metal. By improving the supply of carbon components around the silicon carbide seed 15, it is possible to form a silicon carbide region with a high carbon density on and around the silicon carbide seed 15.

Meanwhile, an induction coil 43 for heating the crucible 30 is included. An induction coil 43 is provided on the outer circumferential surface side of the crucible 30 as shown. In addition to the induction coil 43, a resistive heating element or the like may be used. The induction coil 43 may be provided on the outer peripheral surface side of the crucible 30.

In addition, a driving unit 50 disposed under the crucible 30 to rotate 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 supporting the driving rod 51 to be rotatable.

The holder 10 according to an embodiment will be described with reference to FIG. 2. 2 is a schematic perspective view showing a state of a holder according to an embodiment of the present invention.

The holder 10 according to the present embodiment is formed to have a constant length so as to extend from the top of the crucible to the inside of the crucible. The holder 10 includes an upper rod 11 and a fixing portion 13. The upper rod 11 is formed in a tubular shape having a constant length from the top. The fixing part 13 is provided integrally with the lower part of the upper rod 11.

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

A jig according to an embodiment will be described with reference to FIGS. 3 and 4. 3 is a perspective view showing the shape of a jig according to an embodiment, and FIG. 4 is a perspective view showing the shape of a jig and an upper rod according to an embodiment.

The jig 90 according to this embodiment is configured to extend in the downward direction of the holder 10 and indirectly fix the silicon carbide seed in a state spaced apart from the lower end of the holder.

Specifically, the jig 90 includes a jig fixing portion 91, a wing portion 95, a jig extension portion 94, a base ring member 99, a connecting arm 93, a seed fixing portion 92 and a flow improving portion (96, 97).

The jig fixing part 91 is extrapolated to the lower side of the holder so that the jig can be fixed to the holder 10, and the wing part 95 extends radially from the jig fixing part 91. The wing portion 95 is provided to be inclined at a certain angle with respect to the horizontal direction to induce the flow of molten metal in the vertical direction around the jig. The wing portion 95 according to the present embodiment is formed integrally with the jig, thereby simplifying the manufacture of the holder.

The jig extension 94 extends downward from the end side of the wing 95, and is a component that separates the seed fixing part 92 and the lower end of the holder 10. The jig extension 94 according to this embodiment is preferably formed in a cylindrical shape as a whole, but there is no particular limitation. At this time, it is also possible to cut the through-hole through the jig extension 94 into various numbers and shapes as necessary.

The lower end of the jig extension 94 is connected to the base ring member 99. The base ring member 99 is formed in a ring shape so that the lower ends of the jig extensions 94 are connected. In this case, even if the jig rotates, the flow of molten metal by the base ring member 99 hardly occurs.

The seed fixing part 92 is provided at the lower end of the jig extension 94 and is a component for fixing the silicon carbide seed. The seed is fixed or attached to the upper surface of the seed fixing part 92, and in this case, the growth direction of the seed is formed upward. The jig 90 may be formed of at least one of carbon and ceramic materials. The seed fixing portion 92 is preferably formed in a circular plate shape.

The base ring member 99 and the seed fixing part 92 may be connected through a connecting arm 93. The connecting arm 93 is formed in a thin bar shape, and may be provided at a predetermined angle radially based on the central axis of the jig 90.

The flow improving section includes a side flow improving section 96 and a bottom flow improving section 97.

The side flow improvement unit 96 extends from the jig extension 94 to form a constant angle with respect to the central axis direction of the holder, and extends from the jig extension 94 in the opposite direction to the rotational direction of the jig. desirable. The side flow improvement unit 96 formed as described above includes carbon and intermittently lowers the flow of the molten metal, so that a constant vortex is formed at the end of the side flow improvement unit 96 so that the carbon component is temporarily removed from the seed fixing unit 92. It functions to allow you to stay around.

The bottom flow improving section 97 extends from the connecting arm 93 to form a constant angle with respect to the horizontal direction. At this time, it is preferable that the bottom flow improving unit 97 extends to the opposite side of the rotation direction of the jig 90. The bottom flow improving unit 97 may be formed to be inclined in either the upward or downward direction. In this case, the flow of molten metal is improved so that it can be utilized again by supporting the stagnated carbon component at the bottom of the crucible. On the other hand, the bottom flow improving unit 97 may be formed to be inclined upward. In this case, similarly, by forming a constant vortex around the seed fixing portion 92, the residence time of the carbon can be increased.

The jig 90 rotates together in combination with the holder 10 described above, and has an effect of controlling the strong flow of the molten metal as described above and controlling the fine flow around the seed.

A crucible according to an embodiment of the present invention will be described with reference to FIGS. 5 to 10. 5 and 6 are each a perspective view and a cross-sectional view showing the shape of a crucible according to an embodiment, FIGS. 7 and 8 are a perspective view and a cross-sectional view showing the shape of a crucible according to another embodiment, respectively, FIGS. 9 and 10 Each is a perspective view and a cross-sectional view showing the shape of a crucible according to another embodiment.

5 and 6, the crucible according to the present embodiment is provided in a reaction chamber formed of a constant pressure atmosphere to form an inner space portion in which molten metal containing silicon or silicon carbide (SiC) is charged.

In particular, the crucible 30 is formed in a concave-convex shape in which the inner circumferential surfaces of the concave portion 32 and the protruding portion 31 are repeated on the basis of the cross-section, wherein the concave portion and the protruding portion have a constant length in the vertical direction. At this time, the recess 32 and the protrusion 31 may be formed in an arc shape based on the cross section. Also, referring to FIG. 6, in the case of the crucible 30 according to the present embodiment, the concave portion 32 and the protruding portion 31 are formed to have a predetermined length in the vertical direction.

That is, in the vertical direction, the concave portion 32 may be considered to form a constant flow path, and in the horizontal direction, the crucible 30 and the molten metal are relatively rotated due to the repetitive structure of the concave portion 32 and the protruding portion 31. The molten metal is affected by the structure of the crucible 30.

At this time, it is preferable that the pair of concave portions 32 and the protrusions 31 are formed in 6 to 24 pairs on the inner circumferential surface of the crucible 30 based on the cross section. It is possible to be formed with a number other than this, but if too small, it becomes a shape close to the plane, so that the action according to the uneven shape is insufficient, and in too many cases, the action according to the uneven shape is insufficient due to the formation of the concave / convex pair too small.

Meanwhile, as illustrated in FIGS. 7 and 8, the longitudinal direction of the recess 32 and the protrusion 31 may be formed at a constant angle A1 with respect to the vertical direction. When the crucible 30 is rotated when the longitudinal direction of the concave portion 32 and the protruding portion 31 is vertical, it simply affects the rotational force of the molten metal in the horizontal direction, but in this way, the concave portion 32 and the protruding portion 31 When is formed to have a length in a diagonal line, there is an effect that can further exert the influence of the up and down direction in the outer convection of the molten metal.

9 and 10, the protrusion 33 may be a boundary line between adjacent recesses in the repeating structure of the recess 32. Specifically, the crucible 30b according to the present embodiment can form a relatively uneven structure by repeatedly forming only the concave portion 32. That is, instead of processing to form a separate protrusion 33, the protrusion 33 that protrudes relatively linearly to the boundary between the protrusions 32 having arc-shaped cross-section edges by repeatedly forming the protrusion 32 is formed. To form.

In the case of the concavo-convex structure described above, the concave portion 32 and the protruding portion 31 must be processed respectively to form a shape, but the crucible 30b according to the present embodiment is formed by a method such as simply etching repeatedly only the concave portion 32 By doing so, the uneven structure can be completed. That is, considering the crucible formed of carbon material, it has advantageous characteristics in terms of the manufacturing process.

The preferred embodiments of the present invention have been described above, but the technical spirit of the present invention is not limited to the above-described preferred embodiments, and may be variously implemented within a range not departing from the technical spirit of the present invention as specified in the claims. have.

10: holder
11: upper rod
13: jig fixing part
15: silicon carbide seed
30: crucible
41: reaction chamber
43: induction coil
50: driving unit
51: driving rod
53: Drive base
60: molten metal
90: jig
95: wing
96: side flow improvement
97: bottom flow improving part

Claims (8)

A reaction chamber that is formed in a constant pressure atmosphere, a crucible provided in the reaction chamber and into which a molten metal containing silicon or silicon carbide (SiC) is charged is formed, and a crucible extending from the top of the crucible to the inside of the crucible A jig for fixing a silicon carbide seed provided in a silicon carbide single crystal growth apparatus including a holder,
A jig fixing part fixed to the lower side of the holder;
A wing portion extending radially from an outer circumferential surface of the jig fixing portion and being provided to be inclined with respect to a horizontal direction;
At least one or more jig extensions extending downward from an end side of the wing portion;
A seed fixing part which is positioned at a predetermined interval under the jig fixing part, is connected to the lower ends of the jig extending part, and the seed is fixed; And
It is formed in a blade shape protruding at a position adjacent to the seed fixing portion, a flow improving portion for improving the flow of molten metal around the seed fixing portion; Single crystal growth jig comprising a. According to claim 1,
The jig extension is a silicon carbide single crystal growth apparatus formed in a plurality of bar shapes extending downward at a constant angle around the jig fixing portion. According to claim 2,
The flow improving portion is a single crystal growth jig including a side flow improving portion extending to form a constant angle with respect to the central axis direction of the holder from the jig extension. According to claim 2,
A base ring member formed in a ring shape to connect the lower ends of the jig extensions; And
A jig for single crystal growth, including; a connecting arm extending from the base ring member toward the center and connected to the seed fixing part. The method of claim 4,
The flow improving portion is a jig for single crystal growth including a bottom flow improving portion extending to form a constant angle with respect to the horizontal direction from the connecting arm. The method of claim 4,
The bottom flow improving part is a jig for single crystal growth extending at a predetermined angle upward with respect to the horizontal direction. According to claim 1,
The seed fixing portion is a jig for single crystal growth formed in a circular plate shape. According to claim 1,
The jig is a silicon carbide single crystal growth apparatus formed of at least one of carbon and ceramic materials.

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