JP2011051869A - Method for producing silicon carbide single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a silicon carbide single crystal by which safeness of a production apparatus can be enhanced, elevation of nitrogen concentration during sublimation and single crystal growth can be suppressed, and decrease in the quality of a single crystal can be suppressed while improving the yield. <P>SOLUTION: The method for producing a silicon carbide single crystal includes: a raw material arrangement step S2 of arranging a silicon carbide raw material in a crucible disposed inside the apparatus for producing a silicon carbide single crystal; a seed crystal arrangement step S4 of arranging a seed crystal comprising silicon carbide in the crucible; and a sublimation and growth step S5 of sublimating the silicon carbide raw material and recrystallizing the sublimated silicon carbide raw material on the seed crystal to grow the silicon carbide single crystal. The method includes a heating step S3 of heating the crucible and the silicon carbide raw material at a temperature lower than the sublimation temperature of the silicon carbide raw material while rendering the inside of the crucible into a reducing atmosphere. The heating step S3 is carried out after the raw material arrangement step S2 and prior to the seed crystal arrangement step S4. The sublimation and growth step is carried out while rendering the inside of the crucible into a reduced pressure atmosphere or a rare gas atmosphere. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a silicon carbide single crystal in which a silicon carbide single crystal is produced by a sublimation recrystallization method.

In general, when a silicon carbide single crystal (hereinafter abbreviated as “single crystal”) is used as a substrate for a semiconductor device such as a gallium nitride high-frequency device, a single crystal having a resistivity of 1 × 10 ⁵ [Ω · cm] or more is used. Desired. As a method for producing a single crystal that satisfies this requirement, a method for producing a silicon carbide single crystal by a sublimation recrystallization method has been conventionally known.

When nitrogen is present inside the crucible during the growth process of the single crystal, the single crystal grows containing nitrogen. In particular, in the initial stage of single crystal growth, nitrogen is easily contained in the single crystal. In a silicon carbide single crystal, nitrogen serves as a donor. Therefore, if the single crystal contains nitrogen, the resistivity of the single crystal decreases. For this reason, when the grown single crystal is sliced into a wafer and the resistivity of the wafer is measured, the resistivity of the wafer formed at the initial stage of growth is low. As the growth proceeds and the wafer is formed away from the seed crystal, the resistivity increases, and eventually the resistivity of the wafer shows a value of 1 × 10 ⁵ [Ω · cm] or more. For this reason, the single crystal region formed in the initial stage of growth has a low resistivity and cannot be used as a substrate for a semiconductor device.

  As a method for solving this problem, a method is known in which the inside of a crucible is placed in a hydrogen atmosphere, a silicon carbide raw material is sublimated, and a single crystal is grown (Patent Document 1). By making the inside of the crucible a hydrogen atmosphere and growing the single crystal, the growth surface of the single crystal is prevented from containing nitrogen.

  In addition, a method is known in which a crucible is held for a predetermined time under conditions of a reduced pressure atmosphere and a temperature lower than a sublimation temperature before growing a single crystal (Patent Document 2). Nitrogen is present in the crucible because it is derived from the atmosphere and nitrogen that is chemically bonded to the crucible and the silicon carbide raw material is broken by heating the crucible. In the invention of Patent Document 2, by holding the crucible for a predetermined time under the conditions of a reduced pressure atmosphere and a temperature lower than the sublimation temperature, the chemical bond between nitrogen, the crucible and the silicon carbide raw material is cut, and the nitrogen is removed.

Special table 2007-500667 gazette JP 2008-120616 A

However, in the invention of Patent Document 1, by heating the crucible during sublimation / single crystal growth, the nitrogen chemically bonded to the crucible and the silicon carbide raw material is cut, and the nitrogen concentration inside the crucible increases. Even if sublimation / single crystal growth is performed in a hydrogen atmosphere, nitrogen cannot be completely prevented from being included in the growth surface of the single crystal, and nitrogen was included in the single crystal. Therefore, compared with the conventional case, the single crystal region formed at the initial stage of growth and not having a resistivity of 1 × 10 ⁵ [Ω · cm] or more can be reduced, but further improvement is made to improve the yield. It was sought after.

  Furthermore, in the invention of Patent Document 1, the crucible is heated in a hydrogen atmosphere. It is necessary to hold the silicon carbide raw material at a temperature higher than 2000 ° C. for a long time in order to sublimate and grow single crystals. The crucible is exposed to high-temperature hydrogen for a long time, and the crucible may be corroded. Furthermore, since hydrogen is a flammable gas, there is a concern about the danger of holding it at a high temperature for a long time. Thus, the invention of Patent Document 1 has a problem with the safety of the apparatus.

  In the invention of Patent Document 2, after attaching the seed crystal to the crucible, the crucible is held for a predetermined time under the conditions of a reduced pressure atmosphere and a temperature lower than the sublimation temperature. Even at a temperature lower than the sublimation temperature, the silicon carbide raw material may sublimate in a small amount. The sublimated silicon carbide raw material may be precipitated as 3C-SiC on the surface of the seed crystal. Thereby, the quality of the single crystal was lowered.

  The present invention has been made in view of such circumstances, and provides a method for producing a silicon carbide single crystal that increases the safety of the apparatus and improves the yield while suppressing the deterioration of the quality of the single crystal. The purpose is to do.

  In order to solve the above-described problems, the present invention has the following features. A first feature of the present invention is that a silicon carbide raw material (silicon carbide raw material) is placed in a crucible (crucible 10) installed in an apparatus (single crystal manufacturing apparatus 1) for manufacturing a silicon carbide single crystal (silicon carbide single crystal 70). 20), a seed crystal placement step (seed crystal placement step S4) in which a seed crystal made of silicon carbide (seed crystal 30) is placed in a crucible, and a silicon carbide raw material is sublimated. And a sublimation / growth step (sublimation / growth step S5) for growing the silicon carbide single crystal by recrystallizing the sublimated silicon carbide raw material into a seed crystal, And a heating step (heating step S3) for heating the crucible and the silicon carbide raw material at a temperature lower than the sublimation temperature of the silicon carbide raw material, and after the raw material arranging step and before the seed crystal arranging step The heating process is performed on the inside of the crucible. The in the reduced pressure atmosphere or a rare gas atmosphere, and the gist to carry out sublimation-growth process.

  Making the inside of the crucible a reducing atmosphere means filling the inside of the crucible with a reducing gas. Making the inside of the crucible into a reduced-pressure atmosphere means reducing the inside of the crucible by removing the gas inside the crucible. Making the inside of the crucible a rare gas atmosphere means filling the inside of the crucible with a rare gas.

  The gist of the second feature of the present invention is that, in the heating step, the gas for reducing atmosphere is introduced into the crucible and the gas inside the crucible is led out to the outside of the crucible.

  The gist of the third feature of the present invention is that the gas to be reduced is a gas containing hydrogen.

  The gist of the fourth feature of the present invention is that the temperature below the sublimation temperature is 500 ° C. or more and 2000 ° C. or less.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the safety | security of an apparatus and improving a yield, the manufacturing method of the silicon carbide single crystal which suppresses the fall of the quality of a single crystal can be provided.

It is a figure explaining the manufacturing method of the silicon carbide single crystal 70 which concerns on this embodiment. It is a schematic sectional drawing of the single crystal manufacturing apparatus 1 which concerns on this embodiment. It is a schematic sectional drawing of the single crystal manufacturing apparatus 1 which concerns on this embodiment. It is a schematic sectional drawing of the single crystal manufacturing apparatus 1 which concerns on this embodiment. It is a figure which shows the relationship between the resistivity of a wafer, and the growth distance of the single crystal 70. FIG.

  An example of a method for manufacturing silicon carbide single crystal 70 according to the present embodiment 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 are different from actual ones. Accordingly, 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.

  A method for manufacturing silicon carbide single crystal 70 according to the present embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a diagram illustrating a method for manufacturing a silicon carbide single crystal 70 according to the present embodiment. 2 to 4 are schematic cross-sectional views of the single crystal manufacturing apparatus 1 according to this embodiment.

(1) Schematic Configuration of Manufacturing Apparatus First, the configuration of the single crystal manufacturing apparatus 1 according to the present invention will be described with reference to FIG.

  As shown in FIG. 3, the single crystal manufacturing apparatus 1 includes a crucible 10 and a quartz tube 60 that covers at least a side surface of the crucible 10. The quartz tube 60 is provided with an introduction path 80 and a lead-out path 90. The introduction path 80 introduces gas from the outside of the single crystal manufacturing apparatus 1 to the inside of the single crystal manufacturing apparatus 1. The lead-out path 90 leads the gas from the inside of the single crystal manufacturing apparatus 1 to the outside of the single crystal manufacturing apparatus 1. The atmosphere inside the single crystal manufacturing apparatus 1 is adjusted by deriving and introducing gas from the introduction path 80 and the lead-out path 90. A heating coil (not shown) for heating the crucible 10 is provided on the outer periphery of the quartz tube 60. The crucible 10 is covered with a heat insulating material (not shown). The crucible 10 is installed inside the single crystal manufacturing apparatus 1. Specifically, the crucible 10 is fixed to the inside of the quartz tube 60 via the support rod 50.

  The crucible 10 includes a crucible body 10a and a crucible lid (seed crystal base) 10b. The crucible body 10a contains a silicon carbide raw material 20 which is a sublimation raw material. A seed crystal 30 made of silicon carbide is fixed to the crucible lid (seed crystal base) 10b. Seed crystal 30 is fixed at a position substantially opposite silicon carbide raw material 20. The surface of seed crystal 30 that is substantially opposite to silicon carbide raw material 20 is growth surface 35. The surface opposite to the growth surface 35 of the seed crystal 30 is fixed to the crucible lid (seed crystal pedestal) 10 b by the adhesive layer 40.

(2) Manufacturing method of silicon carbide single crystal Next, the manufacturing method of the silicon carbide single crystal 70 which concerns on this embodiment is demonstrated, referring FIGS. 1-4. As shown in FIG. 1, the method for manufacturing the silicon carbide single crystal 70 according to the present embodiment includes steps S1 to S5.

(2-1) Raw material preparatory process Process S1 is raw material preparatory process S1 which is the process by which the silicon carbide raw material 20 is prepared. The silicon carbide raw material 20 may be prepared by any manufacturing method. For example, silicon carbide produced by a chemical vapor deposition method (CVD method) may be used as the silicon carbide raw material 20, or a silicon carbide precursor is produced from a silicon-containing raw material and a carbon-containing raw material, and the produced silicon carbide precursor is produced. Silicon carbide obtained by firing the body may be used as the silicon carbide raw material 20.

(2-2) Raw material arrangement | positioning process Process S2 is raw material arrangement | positioning process S2 which arrange | positions the silicon carbide raw material 20 in the crucible 10 installed in the inside of the single crystal manufacturing apparatus 1. FIG. As shown in FIG. 2, silicon carbide raw material 20 prepared in raw material preparation step S1 is placed in crucible body 10a. After the silicon carbide raw material 20 is disposed, the crucible lid body 10b is attached to the crucible body 10a.

(2-3) Heating Step Step S3 is a heating step S3 in which the inside of the crucible 10 is placed in a reducing atmosphere and the crucible 10 and the silicon carbide raw material 20 are heated at a temperature lower than the sublimation temperature of the silicon carbide raw material 20.

  As shown in FIG. 2, a reducing gas is introduced from the introduction path 80 into the single crystal manufacturing apparatus 1 in order to make the inside of the crucible 10 a reducing atmosphere. By deriving a reducing gas from the inside of the single crystal manufacturing apparatus 1 to the outside of the single crystal manufacturing apparatus 1 from the lead-out path 90, the inside of the single crystal manufacturing apparatus 1 is filled with the reducing gas. Although the crucible lid 10b is attached to the crucible body 10a, the crucible is not sealed, and thus has a certain air permeability. Therefore, when the inside of the single crystal manufacturing apparatus 1 is filled with the reducing gas, the inside of the crucible 10 is also filled with the reducing gas. The inside of the crucible 10 becomes a reducing atmosphere.

Examples of the reducing gas include silane (SiH ₄ ), hydrocarbon-based gas, and the like in addition to hydrogen. If a gas that is not a combustible gas is used, the risk of the crucible 10 being corroded is reduced. Considering the manufacturing cost, the influence on the human body, etc., it is preferable to use a reducing atmosphere with hydrogen.

  Next, crucible 10 and silicon carbide source material 20 are heated at a temperature lower than the sublimation temperature of silicon carbide source material 20. By this heating, the chemical bond between the crucible 10 or the silicon carbide raw material 20 and nitrogen is broken. Furthermore, since the inside of the crucible 10 is a reducing atmosphere, the surfaces of the crucible 10 and the silicon carbide raw material 20 are reduced and subjected to hydrogen termination treatment. Specifically, the surfaces of the crucible 10 and the silicon carbide raw material 20 have stable carbon-hydrogen bonds (C—H bonds) or silicon-hydrogen bonds (Si—H bonds). Thereby, even if the crucible 10 and the silicon carbide raw material 20 are exposed to air, nitrogen does not recombine. Since the raw material arranging step S2 is performed before the heating step S3, nitrogen bonded to the surface of the silicon carbide raw material 20 can be removed. Further, the surface of the silicon carbide raw material 20 can be subjected to hydrogen termination.

  The heating temperature is a temperature lower than the sublimation temperature of silicon carbide raw material 20. Thereby, the silicon carbide raw material 20 of the surface which has a stable coupling | bonding does not sublime. Therefore, nitrogen removal and hydrogen termination treatment can be sufficiently performed on the surface of the silicon carbide raw material 20. The heating temperature is preferably 500 ° C. or higher and 2000 ° C. or lower. Since the treatment is performed at a temperature of 2000 ° C. or less, the safety of the single crystal manufacturing apparatus 1 is high as compared with the case where it is held at a temperature higher than 2000 ° C. in a hydrogen atmosphere. When the temperature is less than 500 ° C., nitrogen removal and hydrogen termination are difficult to occur. When the temperature is higher than 2000 ° C., silicon carbide raw material 20 is sublimated. When silicon carbide raw material 20 sublimates, it adheres to the inside of crucible 10. For this reason, the silicon carbide raw material 20 used for the growth of the single crystal 70 decreases. Further, the crucible lid 10b cannot be easily removed from the crucible body 10a. Further, the sublimated silicon carbide raw material 20 adheres also to the crucible lid (seed crystal pedestal) 10b for fixing the seed crystal 30, so that the seed crystal 30 cannot be firmly fixed to the seed crystal pedestal 10b. Moreover, since it is under a high temperature hydrogen atmosphere, the crucible 10 may be corroded.

  You may perform simultaneously the process which makes the inside of the crucible 10 a reducing atmosphere, and the process which heats the crucible 10 and the silicon carbide raw material 20. FIG. In addition, it is preferable to introduce a gas to be a reducing atmosphere from the introduction path 80 and lead the gas inside the apparatus to the outside of the apparatus from the outlet path 90 even after the inside of the crucible 10 is made a reducing atmosphere. That is, it is preferable to introduce a gas for reducing atmosphere into the crucible 10 and to lead the gas inside the crucible 10 to the outside of the crucible 10. Thereby, the nitrogen whose bond has been cut is excluded to the outside of crucible 10, and therefore, the nitrogen whose bond has been cut does not bond again to crucible 10 and silicon carbide raw material 20. Furthermore, since the gas used for the reducing atmosphere consumed by the hydrogen termination treatment is introduced from the introduction path 80, the crucible 10 and the silicon carbide raw material 20 can be sufficiently subjected to the hydrogen termination treatment.

(2-4) Seed Crystal Placement Step Step S4 is a seed crystal placement step S4 in which the seed crystal 30 made of silicon carbide is placed in the crucible 10. The crucible lid (seed crystal base) 10b is removed from the crucible body 10a. The seed crystal 30 made of silicon carbide is placed on the removed crucible lid (seed crystal base) 10b. Specifically, the seed crystal 30 is fixed to the seed crystal pedestal 10 b when the adhesive constitutes the adhesive layer 40. Examples of the adhesive include a phenol resin.

  As shown in FIG. 3, the crucible lid 10b to which the seed crystal 30 is fixed is attached to the crucible body 10a. At this time, even if the inside of the crucible 10 is exposed to the atmosphere, since the surfaces of the crucible 10 and the silicon carbide raw material 20 have C—H bonds or Si—H bonds, nitrogen contained in the atmosphere and the crucible 10 Alternatively, the silicon carbide raw material 20 is not chemically bonded again. Therefore, in the sublimation / growth step S5, nitrogen derived from the crucible 10 and the silicon carbide raw material 20 is not generated, and an increase in the nitrogen concentration inside the crucible 10 can be suppressed. The seed crystal 30 is extremely small compared to the crucible 10 and the silicon carbide raw material 20. Therefore, nitrogen is not generated from the seed crystal 30 so as to affect the nitrogen concentration inside the crucible 10.

(2-5) Sublimation / Growth Step Step S5 is a sublimation / growth step of growing silicon carbide single crystal 70 by sublimating silicon carbide source material 20 and recrystallizing sublimated silicon carbide source material 20 into seed crystal 30. S5. A current is passed through the heating coil to heat silicon carbide raw material 20. Generally, the heating temperature is 2000 ° C to 2500 ° C. It is preferable to heat the seed crystal 30 so that the temperature of the seed crystal 30 is slightly lower than that of the silicon carbide raw material 20. The silicon carbide raw material 20 thus heated sublimates. Sublimated silicon carbide raw material 20 is recrystallized on seed crystal 30 arranged on seed crystal pedestal 10b.

  When the sublimation / growth step S5 is performed, since the inside of the crucible 10 is set to a reduced pressure atmosphere or a rare gas atmosphere, an increase in the nitrogen concentration inside the crucible 10 derived from the atmosphere can be suppressed. Furthermore, as described above, the heating step S4 can suppress an increase in the nitrogen concentration inside the crucible 10 derived from the crucible 10 and the silicon carbide raw material 20 in the sublimation / growth step S5.

  As shown in FIG. 4, when a growth direction is a direction from the growth surface 35 to the silicon carbide raw material 20 with reference to the growth surface 35 where the seed crystal 30 and the single crystal 70 are in contact, the silicon carbide single crystal 70 (single Crystal Ingot) grows along the growth direction over time.

Assuming that the position of the single crystal 70 where the resistivity of the wafer is 1 × 10 ⁵ [Ω · cm] when the slicing is performed is the resistance boundary h, the growth terminal H of the single crystal 70 is as shown in FIG. Only a single crystal 70 exceeding the resistance boundary h can be used as a semiconductor device. That is, if the single crystal 70 is not grown larger than the low resistance region R in which the resistivity from the growth surface 35 of the seed crystal 30 to the resistance boundary h is less than 1 × 10 ⁵ [Ω · cm], it is used for a semiconductor device. I wo n’t. In the method for manufacturing the silicon carbide single crystal 70 according to this embodiment, the yield of the single crystal 70 that can be used as a substrate for a semiconductor device is improved by reducing the low resistance region R.

(3) Example In the heating process in which the crucible 10 and the silicon carbide raw material 20 are heated at a temperature lower than the sublimation temperature of the silicon carbide raw material 20, the inside of the crucible 10 may or may not be in a reducing atmosphere. The effect on the rate was compared.

In the example, the silicon carbide raw material 20 was placed in the graphite crucible 10. After attaching the crucible lid 10b to the crucible body 10a, the inside of the single crystal production apparatus 1 was set to a pressure of 5 × 10 ⁻³ Pa or less and a temperature of 1500 ° C. was maintained for 30 hours. Next, while maintaining the temperature at 1500 ° C., argon gas containing 10% hydrogen was introduced as a reducing atmosphere. After the internal pressure of the single crystal manufacturing apparatus 1 was set to 90 kPa, an argon gas containing 10% hydrogen was introduced at a constant flow rate, and the flow rate of the derived gas was adjusted so as to maintain the pressure at 90 kPa. The conditions of reducing atmosphere and 1500 ° C. were maintained for 10 hours. Thereafter, argon gas was introduced, and the crucible 10 was naturally cooled.

In the comparative example, the silicon carbide raw material 20 was placed in the graphite crucible 10 as in the example. After attaching the crucible lid 10b to the crucible body 10a, the inside of the single crystal production apparatus 1 was set to a pressure of 5 × 10 ⁻³ Pa or less and a temperature of 1500 ° C. was maintained for 30 hours. Then, argon gas was introduced and the crucible 10 was naturally cooled. The process which hold | maintains the conditions of reducing atmosphere and 1500 degreeC for 10 hours was not performed.

  In both the example and the comparative example, after the above treatment, the seed crystal 30 made of silicon carbide was fixed to the crucible lid 10b removed from the crucible body 10a. The crucible lid 10b on which the seed crystal 30 was fixed was attached to the crucible body 10a. In the argon atmosphere, the crucible 10 was heated to grow the single crystal 70.

  The grown single crystal 70 was sliced into wafers, and the resistivity of each wafer was measured at room temperature. The relationship between the resistivity of the wafer and the growth distance of the single crystal 70 is shown in FIG.

  FIG. 5 shows that the resistivity of the single crystal 70 of the example has increased from the initial stage of growth. When the low resistance region R1 of the example and the low resistance region R2 of the comparative example in the growth direction were compared, the result was that the low resistance region R1 of the example was about 30% smaller.

  From the above, it was confirmed that the resistivity of the single crystal 70 increased from the initial stage of growth and the low resistance region R was reduced by the method for manufacturing the single crystal 70 according to the present embodiment.

(4) Action / Effect According to the method for manufacturing silicon carbide single crystal 70 according to the present embodiment described above, the inside of crucible 10 is placed in a reducing atmosphere, and crucible 10 and silicon carbide source material 20 are made of silicon carbide source material 20. It has heating process S3 heated at the temperature below sublimation temperature. Thus, nitrogen chemically bonded to the surface of crucible 10 or silicon carbide source material 20 is cut, and the surfaces of crucible 10 and silicon carbide source material 20 are subjected to hydrogen termination. Due to the hydrogen termination treatment, the surfaces of the crucible 10 and the silicon carbide raw material 20 have stable carbon-hydrogen bonds (C—H bonds) or silicon-hydrogen bonds (Si—H bonds). Since the silicon carbide raw material 20 is heated at a temperature lower than the sublimation temperature, the surface silicon carbide raw material 20 having a stable bond does not sublime. Therefore, nitrogen removal and hydrogen termination treatment can be sufficiently performed on the surface of the silicon carbide raw material 20.

  In order to perform heating process S3 after raw material arrangement | positioning process S2, the nitrogen couple | bonded with the surface of the silicon carbide raw material 20 can be removed by heating process S3. Further, the surface of the silicon carbide raw material 20 can be subjected to hydrogen termination.

  Since the heating step S3 is performed before the seed crystal arrangement step S4, the seed crystal 30 is not fixed to the seed crystal base 10b when the heating step S3 is performed. Therefore, even if silicon carbide raw material 20 is sublimated in a minute amount during heating step S <b> 3, it does not precipitate as 3C—SiC on the surface of seed crystal 30. Therefore, it can suppress that the quality of the single crystal 70 falls.

  Even if the inside of the crucible 10 is exposed to the atmosphere in the seed crystal arranging step S4, the surfaces of the crucible 10 and the silicon carbide raw material 20 have a C—H bond or a Si—H bond, so nitrogen contained in the atmosphere. The crucible 10 or the silicon carbide raw material 20 is not chemically bonded again. Accordingly, in the sublimation / growth step S <b> 5, it is possible to suppress an increase in the nitrogen concentration inside the crucible 10 derived from the crucible 10 and the silicon carbide raw material 20.

  Since the sublimation / growth step S5 is performed by setting the inside of the crucible 10 to a reduced pressure atmosphere or a rare gas atmosphere, it is possible to suppress an increase in the nitrogen concentration inside the crucible 10 derived from the atmosphere.

  The inside of single crystal manufacturing apparatus 1 is set in a reducing atmosphere, and crucible 10 and silicon carbide raw material 20 are heated at a temperature lower than the sublimation temperature of silicon carbide raw material 20. Since the reducing atmosphere is not necessarily limited to hydrogen, the risk of the crucible 10 being corroded is reduced.

  Even in a reducing atmosphere with hydrogen, the crucible 10 is heated at a temperature lower than the sublimation temperature, so that the risk of the crucible 10 being corroded and the risk of flammable gas are reduced. For this reason, compared with the case where sublimation / growth process S5 is performed in hydrogen atmosphere, the safety | security of the single crystal manufacturing apparatus 1 is high.

  According to the method for manufacturing silicon carbide single crystal 70 according to the present embodiment, in the heating process, the gas for reducing atmosphere is introduced into crucible 10 and the gas inside crucible 10 is led out of crucible 10. . Thereby, nitrogen whose bond with crucible 10 or silicon carbide source material 20 is cut is excluded to the outside of crucible 10, so that the nitrogen whose bond is cut does not bond again with crucible 10 and silicon carbide source material 20. Therefore, it is possible to sufficiently remove nitrogen from the crucible 10 and the silicon carbide raw material 20. In addition, hydrogen termination treatment is sufficiently performed by introducing a gas for reducing atmosphere.

  According to the method for manufacturing silicon carbide single crystal 70 according to the present embodiment, the gas used in the reducing atmosphere is a gas containing hydrogen. Considering the production cost and the influence on the human body, it is preferable to use a reducing atmosphere with hydrogen.

According to the method for manufacturing silicon carbide single crystal 70 according to the present embodiment, the temperature below the sublimation temperature is 500 ° C. or more and 2000 ° C. or less. Since the treatment is performed at a temperature of 2000 ° C. or less, the safety of the single crystal manufacturing apparatus 1 is high as compared with the case where it is held at a temperature higher than 2000 ° C. in a hydrogen atmosphere. When the temperature is less than 500 ° C., nitrogen removal and hydrogen termination are difficult to occur. When the temperature is higher than 2000 ° C., silicon carbide raw material 20 is sublimated. When silicon carbide raw material 20 sublimates, it adheres to the inside of crucible 10. For this reason, the silicon carbide raw material 20 used for the growth of the single crystal 70 decreases. Further, the crucible lid 10b cannot be easily removed from the crucible body 10a. Further, the sublimated silicon carbide raw material 20 adheres also to the crucible lid (seed crystal pedestal) 10b for fixing the seed crystal 30, so that the seed crystal 30 cannot be firmly fixed to the seed crystal pedestal 10b. Moreover, since it is under a high temperature hydrogen atmosphere, the crucible 10 may be corroded.

DESCRIPTION OF SYMBOLS 1 ... Single crystal manufacturing apparatus, 10 ... Crucible, 10a ... Crucible body, 10b ... Crucible lid (seed crystal base), 20 ... Silicon carbide raw material, 30 ... Seed crystal, 40 ... Adhesive layer, 50 ... Supporting rod, 60 ... Quartz tube, 70 ... silicon carbide single crystal (single crystal), 80 ... introduction path, 90 ... lead-out path, H ... growth terminal, h ... resistance boundary value, R ... low resistance area, R1 ... low resistance area of the embodiment, R2 ... Low resistance region of comparative example, S1 ... Raw material preparation step, S2 ... Raw material placement step, S3 ... Heating step, S4 ... Seed crystal placement step, S5 ... Sublimation / growth step

Claims (4)

A raw material arranging step of arranging a silicon carbide raw material in a crucible installed inside an apparatus for producing a silicon carbide single crystal;
A seed crystal placement step of placing a seed crystal made of silicon carbide in the crucible;
Sublimation of the silicon carbide raw material, and recrystallization of the sublimated silicon carbide raw material into the seed crystal, thereby producing a silicon carbide single crystal comprising a sublimation / growth step of growing a silicon carbide single crystal,
A heating step of heating the crucible and the silicon carbide raw material at a temperature lower than the sublimation temperature of the silicon carbide raw material with the inside of the crucible in a reducing atmosphere;
After the raw material placement step, before the seed crystal placement step, perform the heating step,
A method for producing a silicon carbide single crystal, wherein the sublimation / growth step is carried out under a reduced pressure atmosphere or a rare gas atmosphere inside the crucible.   2. The method for producing a silicon carbide single crystal according to claim 1, wherein in the heating step, a gas for forming the reducing atmosphere is introduced into the crucible, and the gas inside the crucible is led out of the crucible.   The method for producing a silicon carbide single crystal according to claim 1 or 2, wherein the gas to be reduced is a gas containing hydrogen. 4. The method for producing a silicon carbide single crystal according to claim 1, wherein the temperature lower than the sublimation temperature is 500 ° C. or more and 2000 ° C. or less. 5.

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