JP2016135720A - Production method of silicon carbide single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a silicon carbide single crystal, which improves use efficiency of a raw material.SOLUTION: The production method of the silicon carbide single crystal 20 includes the following process. A crucible 5 having an inner side face 10a and a bottom face 10b is provided. The raw material 12 which contacts the inner face 10a and the bottom face 10b, and a seed crystal 11 facing the raw material 12 are arranged inside the crucible 5. The silicon carbide single crystal 20 is grown on the seed crystal 11 by sublimation of the raw material 12. After the process for growing the silicon carbide single crystal 20, Raman spectrum intensity at a Raman shift of 1590 cmis larger than that in the Raman shift derived from silicon carbide, in at least a part of the raw material 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a silicon carbide single crystal.

  In recent years, in order to enable a semiconductor device to have a high breakdown voltage and a low loss, silicon carbide is being adopted as a material constituting the semiconductor device.

  Japanese Patent Laying-Open No. 2010-275190 (Patent Document 1) discloses a method for producing a silicon carbide single crystal by sublimating a silicon carbide raw material and recrystallizing the sublimated source gas on a seed crystal. . According to the method for producing a silicon carbide single crystal, in the step of sublimating the silicon carbide single crystal, by changing the distance between the high-frequency induction heating coil and the graphite crucible, the region having the highest temperature in the raw material is temporally changed. It is changing.

JP 2010-275190 A

  An object of one embodiment of the present invention is to provide a method for producing a silicon carbide crystal in which the use efficiency of raw materials is improved.

A method for manufacturing a silicon carbide single crystal according to one embodiment of the present invention includes the following steps. A crucible having an inner surface and a bottom surface is prepared. A raw material in contact with the inner side surface and the bottom surface and a seed crystal facing the raw material are arranged inside the crucible. A silicon carbide single crystal is grown on the seed crystal by sublimating the raw material. After the step of growing the silicon carbide single crystal, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum at the Raman shift derived from silicon carbide in at least a part of the raw material.

  According to the above, it is possible to provide a method for producing a silicon carbide single crystal in which the use efficiency of raw materials is improved.

It is a flowchart which shows schematically the manufacturing method of the silicon carbide single crystal which concerns on one embodiment of this invention. It is a cross-sectional schematic diagram which shows the process of preparing the crucible in the manufacturing method of the silicon carbide single crystal which concerns on one embodiment of this invention, and the process of arrange | positioning a raw material and a seed crystal. It is a cross-sectional schematic diagram which shows the process of sublimating the silicon carbide single crystal in the manufacturing method of the silicon carbide single crystal which concerns on one embodiment of this invention. It is a cross-sectional schematic diagram which shows the 1st modification of the process of sublimating the silicon carbide single crystal in the manufacturing method of the silicon carbide single crystal which concerns on one embodiment of this invention. It is a cross-sectional schematic diagram which shows the 2nd modification of the process of sublimating the silicon carbide single crystal in the manufacturing method of the silicon carbide single crystal which concerns on one embodiment of this invention. It is a cross-sectional schematic diagram which shows the 3rd modification of the process of sublimating the silicon carbide single crystal in the manufacturing method of the silicon carbide single crystal which concerns on one embodiment of this invention. It is a figure which shows the relationship between the temperature of a crucible, and time. It is a figure which shows the relationship between the pressure in a chamber, and time. It is a figure which shows the relationship between the Raman shift and the Raman spectrum intensity in the raw material before sublimation. It is a figure which shows the relationship between the Raman shift and the Raman spectrum intensity in the raw material after sublimation.

At a certain point in the step of growing the silicon carbide single crystal, if the temperature difference in the raw material is large, the sublimated raw material gas is cooled to the portion of the raw material having a low temperature and recrystallized. Therefore, the use efficiency of the raw material is lowered. In particular, when the sublimed source gas is cooled and recrystallized on the inner side surface of the crucible, the recrystallized silicon carbide adheres firmly to the inner side surface. Once the recrystallized silicon carbide adheres to the inner surface, it is very difficult to remove the silicon carbide from the inner surface. For this reason, it is difficult to grow a silicon carbide single crystal using the crucible again after the raw material is sublimated using the crucible to grow the silicon carbide single crystal.
[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

(1) The manufacturing method of the silicon carbide single crystal 20 which concerns on 1 aspect of this invention is equipped with the following processes. A crucible 5 having an inner side surface 10a and a bottom surface 10b is prepared. A raw material 12 in contact with the inner side surface 10 a and the bottom surface 10 b and a seed crystal 11 facing the raw material 12 are disposed inside the crucible 5. Silicon carbide single crystal 20 is grown on seed crystal 11 by sublimating raw material 12. After the step of growing silicon carbide single crystal 20, in at least a part of raw material 12, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Thereby, the use efficiency of the raw material 12 improves.

Note that the intensity of the Raman spectrum in Raman shift from silicon carbide herein, Raman shift ^{796cm -1, 774cm -1, 768cm -1} , 789cm -1, the Raman spectrum at least one of 798 cm ^-1 Means strength. Polytype 3C silicon carbide has a Raman spectrum peak at a Raman shift of 796 cm ⁻¹ . Silicon carbide of polytype 4H has a Raman spectrum peak at a Raman shift of 774 cm ⁻¹ . Silicon carbide polytypes 6H, the Raman shift has a peak of the Raman spectrum at least one of ^{768cm -1, 789cm -1, 798cm -1} .

(2) In the method for manufacturing silicon carbide single crystal 20 according to (1) above, after the step of growing silicon carbide single crystal 20, a surface passing through gravity center G of raw material 12 and parallel to bottom surface 10b, inner surface 10a, In the portion of the raw material 12 in contact with the tangent line S, the intensity of the Raman spectrum when the Raman shift is 1590 cm ⁻¹ may be larger than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Thereby, since the part of the raw material 12 which contact | connects the inner surface 10a sublimes without recrystallization, it can suppress that the raw material 12 adheres firmly to the inner surface 10a. Therefore, since the raw material 12 after sublimation can be easily removed from the crucible 5, the crucible 5 can be reused.

(3) In the method for manufacturing silicon carbide single crystal 20 according to (1) or (2) above, after the step of growing silicon carbide single crystal 20, the Raman shift is 1590 cm ^{− at the} portion located at the center of gravity G of raw material 12. The intensity of the Raman spectrum in ¹ may be larger than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Thereby, the use efficiency of the part of the raw material 12 in the part located in the gravity center G of the raw material 12 improves.

(4) In the method for manufacturing silicon carbide single crystal 20 according to any one of (1) to (3) above, after the step of growing silicon carbide single crystal 20, Raman shift is 1590 cm ⁻¹ in the entire raw material 12. The intensity of the Raman spectrum may be larger than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Thereby, the use efficiency of the raw material 12 improves as a whole.
[Details of the embodiment of the present invention]
The details of the embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated. In the crystallographic description in this specification, the individual orientation is indicated by [], the collective orientation is indicated by <>, the individual plane is indicated by (), and the collective plane is indicated by {}. As for the negative index, “−” (bar) is attached on the number in crystallography, but in this specification, a negative sign is attached before the number.

A method for manufacturing a silicon carbide single crystal according to an embodiment of the present invention will be described.
First, a step of preparing a crucible (S10: FIG. 1) is performed. Specifically, for example, silicon carbide single crystal manufacturing apparatus 100 shown in FIG. 2 is prepared. The manufacturing apparatus 100 includes a crucible 5, a first resistance heater 1, a second resistance heater 2, a third resistance heater 3, a chamber 6, a lower radiation thermometer 9a, a side radiation thermometer 9b, It mainly has a radiation thermometer 9c. The crucible 5 includes a pedestal 5 a configured to hold the seed crystal 11 and a storage portion 5 b configured to store the raw material 12. The pedestal 5a has a seed crystal holding surface 5a2 in contact with the back surface 11a of the seed crystal 11, and a top surface 5a1 opposite to the seed crystal holding surface 5a2. The accommodating portion 5b has an outer side surface 5b1, an outer bottom surface 5b2, an inner side surface 10a, and a bottom surface 10b. Each of the outer side surface 5b1 and the inner side surface 10a is cylindrical, and preferably cylindrical. The internal space of the crucible 5 is defined by the inner side surface 10a, the bottom surface 10b, and the seed crystal holding surface 5a2. Thus, the crucible 5 having the outer surface 5b1, the outer bottom surface 5b2, the inner surface 10a, the bottom surface 10b, and the top surface 5a1 is prepared.

  The first resistance heater 1, the second resistance heater 2, and the third resistance heater 3 are provided outside the crucible 5 and inside the chamber 6. A heat insulating material (not shown) may be provided between each of the first resistance heater 1, the second resistance heater 2, and the third resistance heater 3 and the chamber 6. The first resistance heater 1 is provided to face the outer bottom surface 5b2. The first resistance heater 1 is separated from the outer bottom surface 5b2. The first resistance heater 1 has a first portion 1a and a second portion 1b in contact with the first portion 1a. The second part 1b is located outside the first part 1a. In the direction perpendicular to the outer bottom surface 5b2, the thickness tb of the second portion 1b is smaller than the thickness ta of the first portion 1a. Thereby, the amount of heat supplied to the outer peripheral portion can be made larger than the amount of heat supplied to the central portion of the raw material 12. The thickness ta is, for example, 1.2 times or more of the thickness tb, preferably 1.5 times or more, and more preferably 3 times or more.

  When the thickness ta of the first portion 1a is the same as the thickness tb of the second portion 1b, the temperature of the central portion of the raw material 12 tends to be higher than the temperature of the outer peripheral portion. By making the thickness tb smaller than the thickness ta, the temperature distribution in the raw material 12 can be reduced in the direction parallel to the surface 12a of the raw material 12. The first portion 1 a is disposed at a position facing the center of gravity G of the raw material 12. Preferably, in the direction parallel to the outer bottom surface 5b2, the width W3 of the first portion 1a is smaller than the width W2 of the internal space of the accommodating portion 5b (that is, the width W2 of the raw material 12). Preferably, when viewed along a direction perpendicular to the outer bottom surface 5b2 (in plan view), the first portion 1a is surrounded by the inner side surface 10a. The first portion 1a and the second portion 1b face the outer bottom surface 5b2. In plan view, the outer edge of the second portion 1 b may surround the outer surface 5 b 1 of the crucible 5. The width W1 of the upper surface of the first resistance heater 1 may be larger than the width of the outer bottom surface 5b2. Thereby, the uniformity of the temperature of the raw material 12 in the direction parallel to the outer bottom surface 5b2 can be improved.

  The second resistance heater 2 is configured to surround the outer side surface 5b1. The second resistance heater 2 is annular. The second resistance heater 2 is separated from the outer surface 5b1. The third resistance heater 3 is provided to face the top surface 5a1. The third resistance heater 3 is separated from the top surface 5a1. The crucible 5, the heat insulating material, the first resistance heater 1, the second resistance heater 2 and the third resistance heater 3 are made of, for example, carbon, and preferably made of graphite. Carbon (graphite) may contain impurities mixed in during production.

  The lower radiation thermometer 9a is provided at a position facing the outer bottom surface 5b2 outside the chamber 6, and is configured to be able to measure the temperature of the outer bottom surface 5b2 through the window 6a. The lower radiation thermometer 9a may be provided at a position facing the first resistance heater 1, and may be configured to be able to measure the temperature of the first resistance heater 1. The side radiation thermometer 9b is provided at a position facing the outer side surface 5b1 outside the chamber 6, and is configured to be able to measure the temperature of the outer side surface 5b1 through the window 6b. The side radiation thermometer 9b may be provided at a position facing the second resistance heater 2, and may be configured to measure the temperature of the second resistance heater 2. The upper radiation thermometer 9c is provided at a position facing the top surface 5a1 outside the chamber 6, and is configured to be able to measure the temperature of the top surface 5a1 through the window 6c. The upper radiation thermometer 9c may be provided at a position facing the third resistance heater 3, and may be configured to be able to measure the temperature of the third resistance heater 3.

  As the radiation thermometers 9a, 9b, 9c, for example, a pyrometer (model number: IR-CAH8TN6) manufactured by Chino Co., Ltd. can be used. The measurement wavelength of the pyrometer is, for example, 1.55 μm and 0.9 μm. The emissivity setting value of the pyrometer is, for example, 0.9. The distance coefficient of the pyrometer is 300, for example. The measurement diameter of the pyrometer is obtained by dividing the measurement distance by the distance coefficient. For example, when the measurement distance is 900 mm, the measurement diameter is 3 mm.

  Next, the step of arranging the raw material and the seed crystal (S20: FIG. 1) is performed. Specifically, as shown in FIG. 2, seed crystal 11 and raw material 12 are arranged inside crucible 5. Specifically, the raw material 12 is arrange | positioned in the accommodating part 5b so that the inner surface 10a and the bottom face 10b of the accommodating part 5b may be contact | connected. Raw material 12 is, for example, a silicon carbide raw material, and is preferably polycrystalline silicon carbide powder. A seed crystal 11 is arranged in the crucible 5 so as to face the surface 12 a of the raw material 12. The seed crystal 11 is fixed to the seed crystal holding surface 5a2 using, for example, an adhesive. The seed crystal 11 is, for example, a polytype 4H hexagonal silicon carbide substrate. The seed crystal 11 has a surface 11b facing the surface 12a and a back surface 11a fixed to the seed crystal holding surface 5a2. The diameter of the surface 11b is, for example, 100 mm or more, and preferably 150 mm or more. For example, the surface 11b may be a surface off by about 8 ° or less from the {0001} plane, or a surface off by about 8 ° or less from the (0001) plane. As described above, the raw material 12 in contact with the inner side surface 10 a and the bottom surface 10 b and the seed crystal 11 facing the raw material 12 are arranged inside the crucible 5.

  Next, a step of growing a silicon carbide single crystal (S30: FIG. 1) is performed. As shown in FIG. 3, silicon carbide single crystal 20 is grown on surface 11 b of seed crystal 11 by sublimating raw material 12. Specifically, the crucible 5 is heated by the first resistance heater 1, the second resistance heater 2, and the third resistance heater 3. As shown in FIG. 7, the crucible 5 that was at the temperature A2 at the time T0 is heated to the temperature A1 at the time T1. The temperature A2 is, for example, room temperature. The temperature A1 is, for example, a temperature of 2000 ° C. or higher and 2400 ° C. or lower. Both the raw material 12 and the seed crystal 11 are heated so that the temperature decreases from the outer bottom surface 5b2 toward the top surface 5a1. From time T1 to time T6, the crucible 5 is maintained at the temperature A1. As shown in FIG. 8, the inside of the chamber 6 is maintained at the pressure P1 from the time T0 to the time T2. The pressure P1 is, for example, atmospheric pressure. The atmospheric gas in the chamber 6 is an inert gas such as argon gas, helium gas, or nitrogen gas.

  At time T2, the pressure in the chamber 6 is reduced from the pressure P1 to the pressure P2. The pressure P2 is, for example, not less than 0.5 kPa and not more than 2 kPa. From time T3 to time T4, the pressure in the chamber 6 is maintained at the pressure P2. At a certain time between time T2 and time T3, sublimation of the raw material 12 starts. The sublimated silicon carbide is recrystallized on the surface 11 b of the seed crystal 11. From time T3 to time T4, the inside of the chamber 6 is maintained at the pressure P2. From time T3 to time T4, raw material 12 continues to sublime, and silicon carbide single crystal 20 (see FIG. 3) grows on surface 11b. That is, the raw material 12 is heated by the first resistance heater 1, the second resistance heater 2, and the third resistance heater 3 to sublimate the raw material 12, thereby growing the silicon carbide single crystal 20 on the surface 11 b. In the step of growing the silicon carbide single crystal, the raw material 12 is maintained at a temperature at which silicon carbide is sublimated, and the seed crystal 11 is maintained at a temperature at which silicon carbide is recrystallized.

  Specifically, during the step of growing the silicon carbide single crystal (that is, from the time when the sublimation of the raw material silicon carbide starts to the time when the sublimation ends), the raw material 12 in the direction along the surface 12 a of the raw material 12. The raw material 12 is sublimated while maintaining the difference between the maximum temperature and the minimum temperature at 10 ° C. or less. The time when the sublimation of the raw material 12 starts is substantially the same as the time when the growth of the silicon carbide single crystal 20 starts. The time when the sublimation of the raw material 12 is completed is almost the same as the time when the growth of the silicon carbide single crystal 20 is completed. During the process of growing the silicon carbide single crystal, the raw material 12 may be sublimated while maintaining the difference between the maximum temperature and the minimum temperature in the radial direction of the bottom surface of the raw material 12 at 10 ° C. or less.

  During the step of growing the silicon carbide single crystal, the temperature near the outer periphery of the raw material 12 may be higher than the temperature near the center of the raw material 12. Preferably, a difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction along the surface 12a of the raw material 12 is maintained at 10 ° C. or less, a surface passing through the center of gravity G of the raw material 12 and parallel to the bottom surface 10b, The raw material 12 is sublimated while maintaining the temperature of the portion of the raw material 12 in contact with the tangent S with the side surface 10 a higher than the temperature of the portion of the raw material 12 positioned at the center of gravity G of the raw material 12.

  During the step of growing the silicon carbide single crystal, the temperature near the center of the raw material 12 may be higher than the temperature near the outer periphery of the raw material 12. Preferably, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction along the surface 12a of the raw material 12 is maintained at 10 ° C. or less, and the temperature of the portion of the raw material 12 located at the center of gravity G of the raw material 12 is The raw material 12 is sublimated while maintaining a temperature higher than the temperature of the portion of the raw material 12 that is in contact with the tangent S between the inner surface 10a and a surface passing through the center of gravity G of 12 and parallel to the bottom surface 10b.

  Preferably, during the step of growing the silicon carbide single crystal, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction along the surface 12a of the raw material 12 is 5 ° C. or less (more preferably 4 ° C. or less, more preferably The raw material 12 is sublimated while being maintained at 3 ° C. or lower. Preferably, during the step of growing the silicon carbide single crystal, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the plane perpendicular to the surface 12a is 5 ° C. or less (more preferably 4 ° C. or less, more preferably 3 ° C. The raw material 12 is sublimated while maintaining the following.

  Preferably, during the step of growing the silicon carbide single crystal, the difference between the maximum temperature and the minimum temperature of the raw material 12 in a plane parallel to the surface 12a is 10 ° C. or less (more preferably 5 ° C.) in all regions of the raw material 12. The raw material 12 is sublimated while being maintained at a temperature of not higher than ° C., more preferably not higher than 4 ° C., more preferably not higher than 3 ° C. Preferably, during the step of growing the silicon carbide single crystal, the difference between the maximum temperature and the minimum temperature of the raw material 12 in a plane perpendicular to the surface 12a is 5 ° C. or less (more preferably 4 ° C.) in all regions of the raw material 12. The raw material 12 is sublimated while being maintained at or below 3 ° C., more preferably 3 ° C. or below.

  Next, from time T4 to time T5, the pressure in the chamber 6 increases from the pressure P2 to the pressure P1 (see FIG. 8). As the pressure in the chamber 6 increases, sublimation of the raw material 12 is suppressed. Thereby, the process of growing a silicon carbide single crystal is substantially completed. In other words, the sublimation of the raw material 12 ends at a certain point in time T4 and time T5. At time T6, the heating of the crucible 5 is stopped and the crucible 5 is cooled. After the temperature of crucible 5 reaches around room temperature, silicon carbide single crystal 20 is taken out from crucible 5.

FIG. 9 is a Raman spectrum of the raw material 12 before sublimation. The Raman spectrum of the raw material 12 can be measured in a backscattering configuration using, for example, 532 nm incident light. When the material 12 is irradiated with light, light having a frequency different from the frequency of the incident light is scattered. The difference in frequency between incident light and scattered light is the Raman shift. The peak (maximum value) of the Raman spectrum when the Raman shift is 1590 cm ⁻¹ is the peak of the Raman spectrum derived from graphite.

As shown in FIG. 9, in the raw material 12 before sublimation, for example, peaks are observed at the positions of Raman shifts a, b, c and d. That is, the peak of the Raman spectrum intensity is observed in the Raman shift derived from silicon carbide. The Raman shifts a and b are Raman shifts derived from polytype 6H silicon carbide. The Raman shift c is a Raman shift derived from polytype 3C silicon carbide. The Raman shift d is a Raman shift derived from polytype 6H and 3C silicon carbide. In the Raman spectrum shown in FIG. 9, the peak of the Raman spectrum is not observed in the Raman shift derived from polytype 4H silicon carbide. Therefore, it is estimated that the portion of the raw material 12 includes polytype 6H silicon carbide and polytype 3C silicon carbide, but does not include polytype 4H. As shown in FIG. 9, the peak of the Raman spectrum is hardly observed at the position of the Raman shift derived from graphite. That is, in the raw material 12 before sublimation, the intensity of the Raman spectrum in the Raman shift derived from graphite is smaller than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Specifically, the Raman spectrum intensity when the Raman shift is 1590 cm ⁻¹ is the Raman spectrum intensity when the Raman shift is 796 cm ^−1, the Raman spectrum intensity when the Raman shift is 774 cm ^{−1, and} the Raman spectrum when the Raman shift is 768 cm ⁻¹ . The intensity of the spectrum, the Raman shift having a Raman shift of 789 cm ^−1, and the Raman shift having a Raman shift of 798 cm ⁻¹ are at least smaller than the intensity of the Raman spectrum.

FIG. 10 is a Raman spectrum of the raw material 12 after sublimation. When the raw material 12 is sublimated using the method described in the above embodiment, the peak intensity of the Raman spectrum derived from silicon carbide decreases and the peak intensity of the Raman spectrum derived from graphite increases. That is, after the step of growing the silicon carbide single crystal, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum at the Raman shift derived from silicon carbide in at least a part of the raw material 12. Specifically, the Raman spectrum intensity when the Raman shift is 1590 cm ⁻¹ is the Raman spectrum intensity when the Raman shift is 796 cm ^−1, the Raman spectrum intensity when the Raman shift is 774 cm ^{−1, and} the Raman spectrum when the Raman shift is 768 cm ⁻¹ . The intensity of the spectrum, the Raman shift at 789 cm ^−1, and the Raman shift at 798 cm ⁻¹ are greater than the intensity of the Raman spectrum at 798 cm ⁻¹ . Preferably, the intensity of the Raman spectra Raman shift at 1590 cm ^-1, greater than the intensity of the Raman spectrum in Raman shift 796cm ^-1, the Raman shift is greater than the intensity of the Raman spectrum at 774cm ^-1, the Raman shift 768cm greater than the intensity of the Raman spectrum at ^-1, greater than the intensity of the Raman spectrum in Raman shift 789Cm ^-1, and a Raman shift is greater than the intensity of the Raman spectrum at 798 cm ^-1. As shown in FIG. 10, in the Raman spectrum of the raw material 12 after sublimating the raw material 12 using the method described in the above embodiment, a peak is observed at the position of the Raman shift derived from graphite. The peak is hardly observed at the position of the Raman shift derived from.

After the step of growing the silicon carbide single crystal, a Raman spectrum at a Raman shift of 1590 cm ⁻¹ in the portion of the raw material 12 passing through the center of gravity G of the raw material 12 and parallel to the bottom surface 10b and the tangent S to the inner side surface 10a. The intensity of may be greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. The volume or mass of the raw material 12 may be any volume or mass that can ensure a significant signal-to-noise ratio in Raman scattering measurement. For example, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction along the surface 12a of the raw material 12 is maintained at 10 ° C. or less, the surface passing through the center of gravity G of the raw material 12 and parallel to the bottom surface 10b; By sublimating the raw material 12 while maintaining the temperature of the part of the raw material 12 in contact with the tangent S to 10a higher than the temperature of the part of the raw material 12 located at the center of gravity G of the raw material 12, as shown in FIG. The raw material 12 which shows such a Raman spectrum is obtained.

After the step of growing the silicon carbide single crystal, in the portion located at the center of gravity G of the raw material 12, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Also good. For example, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction along the surface 12 a of the raw material 12 is maintained at 10 ° C. or less, and the temperature of the portion of the raw material 12 located at the center of gravity G of the raw material 12 is 10 by sublimating the raw material 12 while maintaining a temperature higher than the temperature of the portion of the raw material 12 that is in contact with the tangent S of the inner surface 10a and the surface parallel to the bottom surface 10b through the center of gravity G of FIG. The raw material 12 which shows such a Raman spectrum is obtained.

After the step of growing the silicon carbide single crystal, in the entire raw material 12, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ may be larger than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. For example, during the process of growing a silicon carbide single crystal, in all regions of the raw material 12, the difference between the maximum temperature and the minimum temperature of the raw material 12 in a plane perpendicular to the surface 12a is maintained at 5 ° C. or less. By sublimating 12, a raw material 12 having a Raman spectrum as shown in FIG. 10 is obtained. It should be noted that arbitrary ten portions of the raw material 12 were measured, and in all of the ten portions, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ was greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Is larger, the intensity of the Raman spectrum at the Raman shift of 1590 cm ⁻¹ is estimated to be larger than the intensity of the Raman spectrum at the Raman shift derived from silicon carbide in the entire raw material 12.

  Next, the same crucible 5 may be reused to grow the silicon carbide single crystal 20 again. Specifically, silicon carbide single crystal 20 grown on raw material 12 and seed crystal 11 after sublimation is taken out from crucible 5 together with seed crystal 11. Next, a new raw material 12 and a new seed crystal 11 are placed in the same crucible 5. The arrangement method of the raw material 12 and the seed crystal 11 is the same as the above-described step of arranging the raw material and the seed crystal (S20: FIG. 1). Next, silicon carbide single crystal 20 is manufactured again by performing the above-described step of growing silicon carbide single crystal (S30: FIG. 1). Preferably, using the same crucible 5, the step of arranging the raw material and the seed crystal (S20: FIG. 1) and the step of growing the silicon carbide single crystal (S30: FIG. 1) are repeatedly performed. In addition, only the accommodating part 5b may be reused and a new base 5a may be used.

  Next, the 1st modification of the manufacturing apparatus 100 of a silicon carbide single crystal is demonstrated. The manufacturing apparatus 100 according to the first modification differs from the manufacturing apparatus 100 shown in FIG. 3 in that the thickness of the second portion 1b of the first resistance heater 1 decreases from the center side toward the outer peripheral side. Other configurations are almost the same as those of the manufacturing apparatus 100 shown in FIG. Hereinafter, a description will be given focusing on the configuration different from the manufacturing apparatus 100 shown in FIG.

  As shown in FIG. 4, the thickness of the second portion 1 b of the first resistance heater 1 decreases from the center side toward the outer periphery side. The thickness of the second portion 1b may be monotonously decreased or gradually decreased in the direction from the center side toward the outer peripheral side. The thickness of the second portion 1b is maximum at the boundary with the first portion 1a, and the thickness of the second portion 1b is minimum at the outermost peripheral portion. By configuring the first resistance heater 1 as described above, the amount of heat supplied to the portion of the raw material 12 in contact with the tangent line S can be made larger than the amount of heat supplied to the portion of the raw material 12 positioned at the center of gravity G. . As a result, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction parallel to the surface 12a of the raw material 12 can be reduced.

  Next, the 2nd modification of the manufacturing apparatus 100 of a silicon carbide single crystal is demonstrated. The manufacturing apparatus 100 according to the second modification is different from the manufacturing apparatus 100 shown in FIG. 3 in that the thickness of the first resistance heater 1 is constant, but the thickness of the second resistance heater 2 is different. About a structure, it is substantially the same as the manufacturing apparatus 100 shown in FIG. Hereinafter, a description will be given focusing on the configuration different from the manufacturing apparatus 100 shown in FIG.

  As shown in FIG. 5, the thickness of the first resistance heater 1 is constant in a direction parallel to the outer bottom surface 5b2. The second resistance heater 2 has a third portion 2a and a fourth portion 2b in contact with the third portion 2a. The fourth portion 2 b is located on the raw material 12 side in the direction from the seed crystal 11 toward the raw material 12. In the direction perpendicular to the outer surface 5b1, the thickness of the fourth portion 2b is smaller than the thickness of the third portion 2a. Preferably, the thickness of the fourth portion 2b in the direction perpendicular to the outer side surface 5b1 is smaller than the thickness of the first resistance heater 1 in the direction perpendicular to the outer bottom surface 5b2. By configuring the first resistance heater 1 and the second resistance heater 2 as described above, the amount of heat supplied to the portion of the raw material 12 in contact with the tangent line S is greater than the amount of heat supplied to the portion of the raw material 12 positioned at the center of gravity G. Can also be increased. As a result, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction parallel to the surface 12a of the raw material 12 can be reduced.

  Next, the 3rd modification of the manufacturing apparatus 100 of a silicon carbide single crystal is demonstrated. The manufacturing apparatus 100 according to the third modification is different from the manufacturing apparatus 100 shown in FIG. 3 in that the thickness of the second resistance heater 2 is different, and the other configurations are substantially the same as those of the manufacturing apparatus 100 shown in FIG. The same. Hereinafter, a description will be given focusing on the configuration different from the manufacturing apparatus 100 shown in FIG.

  As shown in FIG. 6, the second resistance heater 2 has a third portion 2a and a fourth portion 2b in contact with the third portion 2a. The fourth portion 2 b is located on the raw material 12 side in the direction from the seed crystal 11 toward the raw material 12. In the direction perpendicular to the outer surface 5b1, the thickness of the fourth portion 2b is smaller than the thickness of the third portion 2a. The thickness of the fourth portion 2b in the direction perpendicular to the outer side surface 5b1 may be the same as or smaller than the thickness of the second portion 1b of the first resistance heater 1 in the direction perpendicular to the outer bottom surface 5b2. It may be large. By configuring the first resistance heater 1 and the second resistance heater 2 as described above, the amount of heat supplied to the portion of the raw material 12 in contact with the tangent line S is greater than the amount of heat supplied to the portion of the raw material 12 positioned at the center of gravity G. Can also be increased. As a result, the difference between the maximum temperature and the minimum temperature of the raw material 12 in the direction parallel to the surface 12a of the raw material 12 can be reduced.

Next, the effect of the method for manufacturing a silicon carbide single crystal according to the present embodiment will be described.
According to the method for manufacturing silicon carbide single crystal 20 according to the present embodiment, crucible 5 having inner side surface 10a and bottom surface 10b is prepared. A raw material 12 in contact with the inner side surface 10 a and the bottom surface 10 b and a seed crystal 11 facing the raw material 12 are disposed inside the crucible 5. Silicon carbide single crystal 20 is grown on seed crystal 11 by sublimating raw material 12. After the step of growing silicon carbide single crystal 20, in at least a part of raw material 12, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Thereby, the use efficiency of the raw material 12 improves.

In addition, according to the method for manufacturing silicon carbide single crystal 20 according to the present embodiment, after the step of growing silicon carbide single crystal 20, a surface that passes through center of gravity G of raw material 12 and is parallel to bottom surface 10b, inner surface 10a, In the portion of the raw material 12 in contact with the tangent line S, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum at the Raman shift derived from silicon carbide. Thereby, the portion of the raw material 12 in contact with the inner side surface 10a is sublimated without being recrystallized, so that the raw material 12 can be prevented from sticking to the inner side surface 10a. Therefore, since the raw material 12 after sublimation can be easily removed from the crucible 5, the crucible 5 can be reused.

Furthermore, according to the method for manufacturing silicon carbide single crystal 20 according to the present embodiment, after the step of growing silicon carbide single crystal 20, the Raman spectrum with a Raman shift of 1590 cm ⁻¹ in the portion located at the center of gravity G of raw material 12. The intensity of is greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. Thereby, the use efficiency of the part of the raw material 12 in the part located in the gravity center G of the raw material 12 improves.

Furthermore, according to the method for manufacturing silicon carbide single crystal 20 according to the present embodiment, after the step of growing silicon carbide single crystal 20, the intensity of the Raman spectrum at the Raman shift of 1590 cm ⁻¹ is It is larger than the intensity of the Raman spectrum in the Raman shift derived from silicon. Thereby, the use efficiency of the raw material 12 improves as a whole.

  Next, the relationship between the temperature difference in the raw material 12 in the process of growing the silicon carbide single crystal 20 and whether or not the crucible 5 can be reused will be described.

  First, silicon carbide single crystal 20 was manufactured using eight types of manufacturing conditions shown in Table 1. Conditions 1 to 4 are manufacturing conditions according to the comparative example, and conditions 5 to 8 are manufacturing conditions according to the example. In conditions 1 to 4, the temperature distribution in the raw material 12 is controlled so that the temperature difference of the raw material 12 in the radial direction is larger than 10 ° C., and the raw material 12 is sublimated to form a silicon carbide single crystal on the seed crystal 11. 20 grown. Under conditions 5 to 8, the temperature distribution in the raw material 12 is controlled so that the temperature difference between the radial raw materials is 10 ° C. or less, and the raw material 12 is sublimated to form the silicon carbide single crystal 20 on the seed crystal 11. Grown up. In Table 1, the radial temperature difference is the difference between the highest temperature and the lowest temperature of the raw material 12 in the direction parallel to the surface 12a of the raw material 12. The vertical temperature difference is a difference between the highest temperature and the lowest temperature of the raw material 12 in a direction perpendicular to the surface 12 a of the raw material 12. The plus sign indicates that the temperature of the surface 12a of the raw material 12 is lower than the temperature of the bottom of the raw material 12, and the minus sign indicates that the temperature of the surface 12a of the raw material 12 is higher than the temperature of the bottom of the raw material 12. Show.

  In condition 1, the temperature difference in the vertical direction was maintained at −1 ° C. and the temperature difference in the radial direction was maintained at 11 ° C. during the process of growing the silicon carbide single crystal 20. Under condition 2, the temperature difference in the vertical direction was maintained at 13 ° C. and the temperature difference in the radial direction was maintained at 18 ° C. during the process of growing the silicon carbide single crystal 20. Under condition 3, the temperature difference in the vertical direction was maintained at 7 ° C. and the temperature difference in the radial direction was maintained at 15 ° C. during the step of growing the silicon carbide single crystal 20. In condition 4, the vertical temperature difference was maintained at 4 ° C. and the radial temperature difference was maintained at 15 ° C. during the process of growing silicon carbide single crystal 20. Under condition 5, the temperature difference in the vertical direction was maintained at 3 ° C. and the temperature difference in the radial direction was maintained at 4 ° C. during the process of growing the silicon carbide single crystal 20. Under condition 6, the temperature difference in the vertical direction was maintained at 3 ° C. and the temperature difference in the radial direction was maintained at 3 ° C. during the process of growing the silicon carbide single crystal 20. Under condition 7, the temperature difference in the vertical direction was maintained at 4 ° C. and the temperature difference in the radial direction was maintained at 4 ° C. during the process of growing the silicon carbide single crystal 20. In condition 8, the vertical temperature difference was maintained at 3 ° C. and the radial temperature difference was maintained at 5 ° C. during the step of growing the silicon carbide single crystal 20.

  Next, Table 1 shows the result of whether or not the crucible can be reused. When silicon carbide single crystal 20 was grown under the conditions according to conditions 1 to 4, recrystallized silicon carbide adhered to inner side surface 10a of crucible 5. For this reason, the crucible 5 could not be reused. When silicon carbide single crystal 20 was grown under conditions according to conditions 5 to 8, silicon carbide hardly adhered to inner side surface 10a of crucible 5. Therefore, the crucible 5 could be reused. From the above results, while controlling the temperature distribution in the raw material 12 so that the temperature difference of the raw material 12 in the radial direction is 10 ° C. or less, the raw material 12 is sublimated to grow the silicon carbide single crystal 20 on the seed crystal 11. By doing so, it was confirmed that the crucible 5 can be reused.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 1st resistance heater 1a 1st part 1b 2nd part 2 2nd resistance heater 2a 3rd part 2b 4th part 3 3rd resistance heater 5 Crucible 5a2 Seed crystal holding surface 5a Base 5a1 Top surface 5b1 Outer side surface 5b2 Outer bottom surface 5b Housing 6 Chamber 6a, 6b, 6c Window 9a Lower radiation thermometer (radiation thermometer)
9b Side radiation thermometer 9c Upper radiation thermometer 10a Inner side surface 10b Bottom surface 11 Seed crystal 11a Back surface 11b, 12a Surface 12 Raw material 20 Silicon carbide single crystal 100 Manufacturing apparatus A1, A2 Temperature G Center of gravity P1, P2 Pressure S Tangential T0, T1 , T2, T3, T4, T5, T6 Time points W1, W2, W3 width ta, tb thickness

Claims (4)

Preparing a crucible having an inner surface and a bottom surface;
Placing the raw material in contact with the inner side surface and the bottom surface, and a seed crystal facing the raw material inside the crucible;
A step of growing a silicon carbide single crystal on the seed crystal by sublimating the raw material,
After the step of growing the silicon carbide single crystal, in at least a part of the raw material, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. A method for producing a single crystal. After the step of growing the silicon carbide single crystal, in the portion of the raw material that passes through the center of gravity of the raw material and is in contact with the tangent line to the inner surface, the Raman shift is 1590 cm ⁻¹ . 2. The method for producing a silicon carbide single crystal according to claim 1, wherein the intensity is larger than an intensity of a Raman spectrum in a Raman shift derived from silicon carbide. After the step of growing the silicon carbide single crystal, in the portion located at the center of gravity of the raw material, the intensity of the Raman spectrum at a Raman shift of 1590 cm ⁻¹ is greater than the intensity of the Raman spectrum in the Raman shift derived from silicon carbide. The manufacturing method of the silicon carbide single crystal of Claim 1 or Claim 2. After the step of growing the silicon carbide single crystal, in the entire raw material, the intensity of the Raman spectrum at a Raman shift of 1590 cm ^-1 is greater than the intensity of the Raman spectrum in a Raman shift derived from silicon carbide. The method for producing a silicon carbide single crystal according to claim 3.

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