JP2013220964A - Production apparatus of silicon carbide single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production apparatus of a silicon carbide single crystal capable of suppressing quality deterioration resulting from increase of a carbon ratio, while suppressing cost increase.SOLUTION: A production apparatus 100 includes a crucible 20 having a raw material arrangement surface 21A and a seed crystal arrangement surface 22A. A protrusion 60 projecting from an inner wall 21B of the crucible 20 toward the inside of the crucible 20 is provided between the raw material arrangement surface 21A and the seed crystal arrangement surface 22A.

Description

  The present invention relates to a silicon carbide single crystal manufacturing apparatus including a crucible having a cylindrical shape and a heater for heating the inside of the crucible from the outside of the crucible.

  Conventionally, as a method of manufacturing a silicon carbide single crystal, a method of manufacturing a silicon carbide single crystal using sublimation and recrystallization of a raw material of the silicon carbide single crystal in a crucible is known.

  In such a case, as the raw material is heated, the inner wall of the crucible is carbonized, and carbon powder is scattered from the carbonized portion of the inner wall of the crucible. In other words, the proportion of carbon powder present in the internal space (growth space) of the crucible increases as the heating time of the raw material increases. As a result, the quality of the silicon carbide single crystal deteriorates as the carbon ratio increases.

  In order to suppress such scattering of carbon powder, a technique for covering the entire inner wall of the crucible with tantalum has been proposed (for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-116398

  However, as described above, if the entire inner wall of the crucible is covered with tantalum, the cost of an apparatus for producing a silicon carbide single crystal increases.

  Accordingly, the present invention has been made to solve the above-described problems, and manufacture of a silicon carbide single crystal that can suppress quality deterioration accompanying an increase in the carbon ratio while suppressing an increase in cost. An object is to provide an apparatus.

  A silicon carbide single crystal manufacturing apparatus according to a first feature includes a crucible having a cylindrical shape and a heater for heating the inside of the crucible from the outside of the crucible. The crucible has a raw material arrangement surface on which a raw material of the silicon carbide single crystal is arranged and a seed crystal arrangement surface on which a seed crystal of the silicon carbide single crystal is arranged. The raw material arrangement surface faces the seed crystal arrangement surface. A protruding portion that protrudes from the inner wall of the crucible to the inside of the crucible is provided between the raw material arrangement surface and the seed crystal arrangement surface.

  In the first feature, the surface of the protruding portion is made of tantalum.

  In the first feature, the projecting portion has an annular shape continuous along the inner wall of the crucible.

  In the first feature, the protruding portion is provided separately from the crucible.

  1st characteristic WHEREIN: Seeing from the bottom face or top | upper surface of the said crucible, the said raw material arrangement | positioning surface protrudes on the outer side of the said seed crystal arrangement | positioning surface. When the distance between the outer periphery of the raw material arrangement surface and the outer periphery of the seed crystal arrangement surface is a distance L when viewed from the bottom surface or the top surface of the crucible, the projecting portion from the inner wall of the crucible toward the inside of the crucible The protrusion length of is 1% or more and 100% or less of the interval L.

  In the first feature, a sealing member standing on the raw material arrangement surface side is provided on the outer periphery of the seed crystal arrangement surface. The sealing member is made of graphite.

  In the first feature, a sealing member standing on the raw material arrangement surface side is provided on the outer periphery of the seed crystal arrangement surface. As for the said sealing member, at least one part of the main body comprised with graphite is coat | covered with silicon carbide.

1st characteristic WHEREIN: The bulk density of the graphite which comprises the said sealing member is 1.8 g / cm < ³ > or more.

  In the first feature, the surface polishing finish accuracy of the sealing member is not less than ▽.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing apparatus of the silicon carbide single crystal which makes it possible to suppress the quality degradation accompanying the carbon ratio raise, suppressing the increase in cost can be provided.

FIG. 1 is a diagram illustrating a manufacturing apparatus 100 according to the first embodiment. FIG. 2 is a diagram illustrating the protruding portion 60 according to the first embodiment. FIG. 3 is a flowchart showing the method for manufacturing the silicon carbide single crystal according to the first embodiment.

  Hereinafter, a manufacturing apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Outline of Embodiment]
An apparatus for manufacturing a silicon carbide single crystal according to an embodiment includes a crucible having a cylindrical shape and a heater for heating the inside of the crucible from the outside of the crucible. The crucible has a raw material arrangement surface on which a raw material of the silicon carbide single crystal is arranged and a seed crystal arrangement surface on which a seed crystal of the silicon carbide single crystal is arranged. The raw material arrangement surface faces the seed crystal arrangement surface. A protruding portion that protrudes from the inner wall of the crucible to the inside of the crucible is provided between the raw material arrangement surface and the seed crystal arrangement surface.

  In the embodiment, a protruding portion that protrudes from the inner wall of the crucible to the inside of the crucible is provided between the raw material arrangement surface and the seed crystal arrangement surface. Therefore, the carbon powder scattered from the carbonized portion of the inner wall of the crucible is blocked by the protruding portion and hardly reaches the seed crystal arrangement surface. Even if the entire inner wall of the crucible is not covered with tantalum, quality deterioration accompanying an increase in the carbon ratio can be suppressed.

[First Embodiment]
(Configuration of manufacturing equipment)
Hereinafter, the manufacturing apparatus according to the first embodiment will be described. FIG. 1 is a diagram illustrating a manufacturing apparatus 100 according to the first embodiment.

  As shown in FIG. 1, the manufacturing apparatus 100 includes a quartz tube 10, a crucible 20, a support rod 30, and a heating unit 40.

  The quartz tube 10 is made of quartz and forms the outer shape of the manufacturing apparatus 100. For example, the quartz tube 10 has a cylindrical shape and accommodates the crucible 20 in a state where the airtightness in the quartz tube 10 is high.

  The crucible 20 has a crucible body 21 and a crucible lid 22.

  The crucible main body 21 has a bottom part and a side wall, and the bottom part and the side wall are integrally formed. The bottom of the crucible body 21 has a raw material arrangement surface 21A, and a raw material 210 of silicon carbide single crystal is arranged on the raw material arrangement surface 21A. For example, the side wall of the crucible body 21 has a cylindrical shape. When viewed from the bottom surface of the crucible 20 or the top surface of the crucible 20, the raw material arrangement surface 21A has a circular shape.

Here, the crucible body 21 is made of, for example, graphite. The bulk density of the graphite constituting the crucible body 21 is 1.8 g / cm ³ or more. Moreover, it is preferable that the surface polishing finishing accuracy of the crucible main body 21 is not less than ▽▽ of JIS standard (JIS standard B0601-2001).

  That is, the surface of the crucible body 21 preferably has an average arithmetic roughness Ra ≦ 6.3a and a maximum height Rz ≦ 25S. The reference length of the average arithmetic roughness Ra is 2.5 mm, and the reference length of the maximum height Rz is 2.5 mm. The evaluation length of the average arithmetic roughness Ra is 12.5 mm, and the evaluation length of the maximum height Rz is 12.5 mm.

  The crucible lid 22 is configured to close the opening of the crucible body 21. The crucible lid 22 has a seed crystal arrangement surface 22A, and a seed crystal 220 of a silicon carbide single crystal is arranged on the seed crystal arrangement surface 22A. The seed crystal arrangement surface 22A is a surface facing the raw material arrangement surface 21A in the crucible 20. Seen from the bottom surface of the crucible 20 or the top surface of the crucible 20, the seed crystal arrangement surface 22A has, for example, a circular shape.

  The support rod 30 is a rod-shaped member that supports the crucible 20 in the quartz tube 10. Specifically, the support rod 30 supports the crucible body 21 and is configured to be movable along the A direction.

  The heating unit 40 is provided on the outer periphery of the quartz tube 10 and heats the raw material 210 and the seed crystal 220 disposed in the crucible 20. That is, the heating unit 40 heats the inside of the crucible 20 from the outside of the crucible 20. Specifically, the heating unit 40 is configured by a plurality of coils, and the plurality of coils are arranged along the outer periphery of the quartz tube 10.

  In the first embodiment, the crucible lid body 22 is provided on the outer periphery of the seed crystal arrangement surface 22A, and has a sealing member 50 erected from the seed crystal arrangement surface 22A. Specifically, the sealing member 50 includes a wall body 50A and a flange body 50B. The wall body 50A is erected in the A direction from the seed crystal arrangement surface 22A, and the flange body 50B projects from the tip of the wall body 50A to the outside of the crucible lid body 22.

  For example, the sealing member 50 is made of graphite. Or the sealing member 50 has the structure by which at least one part of the main body comprised with graphite is coat | covered with silicon carbide.

Here, the bulk density of the graphite constituting the sealing member 50 is preferably 1.8 g / cm ³ or more, like the crucible body 21. Further, like the crucible body 21, the surface polishing finishing accuracy of the sealing member 50 is preferably not less than ▽.

  In the first embodiment, a protruding portion 60 that protrudes from the inner wall 21B of the crucible 20 to the inside of the crucible 20 is provided between the raw material arrangement surface 21A and the seed crystal arrangement surface 22A. When viewed from the bottom surface of the crucible 20 or the top surface of the crucible 20, the protruding portion 60 has an annular shape that continues along the inner wall 21 </ b> B of the crucible 20. The protruding portion 60 has a function of blocking carbon powder scattered from the carbonized portion of the inner wall 21 </ b> B of the crucible 20.

  Here, the protruding portion 60 is preferably made of tantalum. Thereby, tantalum carbide is generated on the surface of the protruding portion 60 by the reaction between the carbon powder scattered from the carbonized portion of the inner wall 21 </ b> B of the crucible 20 and tantalum. As a result, the amount of carbon powder scattered from the carbonized portion of the inner wall 21 </ b> B of the crucible 20 reaching the seed crystal 220 is further reduced.

  The protruding portion 60 may be provided integrally with the crucible 20 (here, the crucible body 21), or may be provided separately from the crucible 20 (here, the crucible body 21). When the protruding portion 60 is provided separately from the crucible 20, the protruding portion 60 is placed on the raw material 210.

  For example, when the protruding portion 60 is made of tantalum, the protruding portion 60 is preferably provided as a separate body from the crucible 20 so that the protruding portion 60 can be replaced.

(Protruding part)
Below, the protrusion part which concerns on 1st Embodiment is demonstrated. FIG. 2 is a diagram illustrating the protruding portion 60 according to the first embodiment. FIG. 2 is a view of the crucible 20 viewed from the bottom surface of the crucible 20 or the top surface of the crucible 20.

Here, the length L ₁ is the distance from the inner wall 21B of the crucible 20 to the center O of the crucible 20 (the diameter of the crucible 20). The length L ₂ is the distance from the outer periphery of the seed crystal disposed surface 22A to the center O of the crucible 20 (the diameter of the seed crystal placing surface 22A). Spacing L ₃ is a distance between the outer periphery of the outer periphery and the seed crystal placement surface 22A of the material placement surface 21A. That is, the interval _{L 3} is a value obtained by subtracting the length _{L 2} from the length _{L 1.} The protruding length L ₄ is the protruding length of the protruding portion 60 that extends from the inner wall 21 </ b> B of the crucible 20 toward the inside of the crucible 20.

Here, the protrusion length L ₄ is preferably 1% or more and 100% or less of the length L ₁ . Preferably, the protrusion length L ₄ is 20% or more and 100% or less of the length L ₁ . Since the protrusion length L ₄ is 20% or more of the length L _1, the carbon powder scattered from carbonized portion of the inner wall 21B of the crucible 20 is blocked more effectively by the projecting portion 60. On the other hand, since the projecting length L ₄ is 100% or less of the length L ₁ , carbon powder and silicon powder scattered from the raw material arranging surface 21A due to heating of the raw material arranging surface 21A are not obstructed by the projecting portion 60 and seed crystals 220 is reached.

(Method for producing silicon carbide single crystal)
Below, the manufacturing method of the silicon carbide single crystal which concerns on 1st Embodiment is demonstrated. FIG. 3 is a flowchart showing the method for manufacturing the silicon carbide single crystal according to the first embodiment. In the following, a case where a silicon carbide single crystal is manufactured using manufacturing apparatus 100 described above will be described.

  As shown in FIG. 3, in step 10, seed crystal 220 composed of a silicon carbide single crystal is prepared.

  In step 20, seed crystal 220 composed of silicon carbide single crystal and raw material 210 of silicon carbide single crystal are placed in crucible 20. Specifically, the seed crystal 220 is arranged on the seed crystal arrangement surface 22 </ b> A of the crucible lid body 22, and the raw material 210 is arranged on the raw material arrangement surface 21 </ b> A of the crucible body 21.

  In step 30, the seed crystal 220 and the raw material 210 are heated to sublimate the raw material 210, and the sublimated raw material 210 is recrystallized in the seed crystal 220. Specifically, the seed crystal 220 and the raw material 210 disposed in the crucible 20 are heated by the heating unit 40 provided on the outer periphery of the quartz tube 10.

(Function and effect)
In the first embodiment, a protruding portion 60 that protrudes from the inner wall 21B of the crucible 20 to the inside of the crucible 20 is provided between the raw material arrangement surface 21A and the seed crystal arrangement surface 22A. Therefore, the carbon powder scattered from the carbonized portion of the inner wall 21B of the crucible 20 is blocked by the projecting portion 60 and hardly reaches the seed crystal arrangement surface 22A. Even if the entire inner wall of the crucible 20 is not covered with tantalum, quality deterioration accompanying an increase in the carbon ratio can be suppressed.

[Evaluation results]
Evaluation result 1: Number of occurrences of carbon inclusion Evaluation result 2: Support for the fact that the protrusion length L ₄ is 20% or more and 100% or less of the length L ₁ Evaluation result 3: The bulk density of graphite constituting the sealing member is 1 .Backing up to a point of 8 g / cm ³ or more Evaluation result 4: Backing up to a point where the surface polishing finish accuracy of the sealing member is more than ▽▽

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment, when viewed from the bottom surface of the crucible 20 or the top surface of the crucible 20, the protruding portion 60 has an annular shape that continues along the inner wall 21 </ b> B of the crucible 20. However, the embodiment is not limited to this. The protruding portion 60 may have a discontinuous annular shape along the inner wall 21 </ b> B of the crucible 20. In such a case, it is preferable that the projecting portion 60 is provided at 99% or more of the entire circumference of the inner wall 21B of the crucible 20.

  DESCRIPTION OF SYMBOLS 10 ... Quartz tube, 20 ... Crucible, 21 ... Crucible body, 21A ... Raw material arrangement surface, 21B ... Inner wall, 22 ... Crucible lid body, 22A ... Seed crystal arrangement surface, 30 ... Support rod, 40 ... Heating part, 50 ... Sealing Stop member, 60 ... projecting portion, 100 ... manufacturing apparatus, 210 ... raw material, 220 ... seed crystal

Claims (9)

A silicon carbide single crystal manufacturing apparatus comprising a crucible having a cylindrical shape and a heater for heating the inside of the crucible from the outside of the crucible,
The crucible has a raw material arrangement surface on which a raw material of the silicon carbide single crystal is arranged, and a seed crystal arrangement surface on which a seed crystal of the silicon carbide single crystal is arranged,
The raw material arrangement surface is opposed to the seed crystal arrangement surface,
A manufacturing apparatus, characterized in that a protruding portion that protrudes from the inner wall of the crucible to the inside of the crucible is provided between the raw material arrangement surface and the seed crystal arrangement surface.   The manufacturing apparatus according to claim 1, wherein a surface of the protruding portion is made of tantalum.   The manufacturing apparatus according to claim 1, wherein the protruding portion has an annular shape continuous along the inner wall of the crucible.   The manufacturing apparatus according to claim 1, wherein the protruding portion is provided separately from the crucible. When viewed from the bottom or top surface of the crucible, the raw material arrangement surface projects outside the seed crystal arrangement surface,
When the distance between the outer periphery of the raw material arrangement surface and the outer periphery of the seed crystal arrangement surface is a distance L when viewed from the bottom surface or the top surface of the crucible, the projecting portion from the inner wall of the crucible toward the inside of the crucible 2. The manufacturing apparatus according to claim 1, wherein a protruding length of is 1% to 100% of the interval L. 3. The outer periphery of the seed crystal arrangement surface is provided with a sealing member standing on the raw material arrangement surface side,
The manufacturing apparatus according to claim 1, wherein the sealing member is made of graphite. The outer periphery of the seed crystal arrangement surface is provided with a sealing member standing on the raw material arrangement surface side,
The manufacturing apparatus according to claim 1, wherein the sealing member has at least a part of a main body made of graphite covered with silicon carbide. The manufacturing apparatus according to claim 6, wherein a bulk density of graphite constituting the sealing member is 1.8 g / cm ³ or more.   The manufacturing apparatus according to claim 6, wherein the surface polishing finish accuracy of the sealing member is ▽▽ or more.

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