JP2016088805A - Device and method for producing silicon carbide single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a decrease in growth speed in crystal growth of silicon carbide by a sublimation method.SOLUTION: A silicon carbide single crystal production device 100 includes: a crucible 5 having a top surface 5a, a bottom surface 5b opposite to the top surface 5a, and a cylindrical side surface 5c located between the top surface 5a and the bottom surface 5b; a first resistance heater 2a installed so as to face the top surface 5a; a second resistance heater 2b installed so as to face the bottom surface 5b; a third resistance heater 2c configured to enclose the side surface 5c; and a control part controlling the first resistance heater 2a, the second resistance heater 2b, and the third resistance heater 2c. When temperatures of the top surface 5a, the bottom surface 5b, and the side surface 5c are respectively designated as Ta, Tb, and Tc, the control part controls the first resistance heater 2a, the second resistance heater 2b, and the third resistance heater 2c so as to satisfy 2,100°C≤Tc≤2,400°C and Ta<Tb<Tc.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal manufacturing method.

  In Japanese Translation of PCT International Publication No. 2012-510951 (Patent Document 1), a crucible, a first resistance heater spaced apart above the crucible, and a space below the bottom of the crucible are arranged. An axial gradient growth apparatus comprising a second resistance heater is disclosed.

Special table 2012-510951 gazette

  An object of the present invention is to provide a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal manufacturing method capable of suppressing a decrease in growth rate in crystal growth of silicon carbide by a sublimation method.

  An apparatus for producing a silicon carbide single crystal according to one embodiment of the present invention includes a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface. A first resistance heater provided to face the top surface, a second resistance heater provided to face the bottom surface, a third resistance heater configured to surround the side surface, A control unit that controls the one-resistance heater, the second resistance heater, and the third resistance heater. When the temperature of the top surface is Ta, the temperature of the bottom surface is Tb, and the temperature of the side surface is Tc, the control unit has a first resistance heater such that 2100 ° C. ≦ Tc ≦ 2400 ° C. and Ta <Tb <Tc. The second resistance heater and the third resistance heater are controlled.

  A method for manufacturing a silicon carbide single crystal according to one embodiment of the present invention includes a crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface. A first resistance heater provided to face the top surface, a second resistance heater provided to face the bottom surface, a third resistance heater configured to surround the side surface, and the crucible Preparing a raw material provided in the inside of the crucible and a seed crystal provided facing the raw material in the crucible; and sublimating the raw material to thereby form a silicon carbide single crystal on the seed crystal. And growing the step. In the growth step, the temperature of the side surface is measured between the raw material and the seed crystal in the direction from the top surface to the bottom surface, the temperature of the top surface is Ta, the temperature of the bottom surface is Tb, and the temperature of the side surface is Tc. , The first resistance heater, the second resistance heater, and the third resistance heater are controlled so that Ta <Tb <Tc.

  According to the above, it is possible to suppress a decrease in growth rate in silicon carbide crystal growth by the sublimation method.

It is a conceptual diagram which shows an example of a structure of the manufacturing apparatus of the silicon carbide single crystal which concerns on 1 aspect of this invention. It is typical sectional drawing which shows an example of a structure of the manufacturing apparatus of the silicon carbide single crystal which concerns on 1 aspect of this invention. It is a typical top view which shows an example of a structure of a 1st resistance heater. It is a typical top view showing an example of the composition of the 2nd resistance heater. It is a schematic diagram which shows an example of a structure of a 3rd resistance heater. It is a schematic diagram which shows the positional relationship of a 3rd resistance heater and a crucible. It is a schematic diagram illustrating the measurement position on the side surface of the crucible. It is a flowchart which shows the outline of the manufacturing method of the silicon carbide single crystal which concerns on 1 aspect of this invention. It is a timing chart which shows an example of temperature control and pressure control in a crystal growth process.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

An apparatus for producing a silicon carbide single crystal according to one embodiment of the present invention provides:
[1] A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface, and a crucible provided to face the top surface A first resistance heater, a second resistance heater provided to face the bottom surface, a third resistance heater configured to surround the side surface, the first resistance heater, the second resistance heater, and the third A control unit for controlling the resistance heater. When the top surface temperature is Ta, the bottom surface temperature is Tb, and the side surface temperature is Tc, the control unit sets the first resistance heater, the second resistance heater, the second resistance heater, Control the two-resistance heater and the third resistance heater.

  The sublimation method is a crystal growth method in which a raw material placed at the bottom of a crucible is sublimated at a high temperature, and the sublimated raw material (gas) is recrystallized on a seed crystal placed at the top of the crucible. . In the sublimation method, the temperature of the bottom surface of the crucible is controlled to be higher than the temperature of the top surface. However, when the temperature of the side surface of the crucible becomes lower than the temperature of the bottom surface, a part of the sublimated raw material may flow to the low temperature side surface and adhere to the side surface without flowing to the seed crystal. In this case, the amount of raw material supplied to the seed crystal is reduced, and the growth rate of the single crystal is reduced.

  Accordingly, the manufacturing apparatus [1] includes a third resistance heater for heating the side surface of the crucible in addition to the first resistance heater for heating the top surface of the crucible and the second resistance heater for heating the bottom surface of the crucible. Furthermore, the control part of the said manufacturing apparatus controls each resistance heater so that the temperature of a side surface becomes the highest among the top surface, bottom surface, and side surface of a crucible. As a result, the sublimated raw material is supplied to the seed crystal, and a decrease in growth rate due to the flow of the sublimated raw material to the side surface is suppressed.

  [2] The manufacturing apparatus further includes a first measurement unit that measures the temperature of the top surface, a second measurement unit that measures the temperature of the bottom surface, and a third measurement unit that measures the temperature of the side surface. Is preferred. This is to reflect the temperature measurement results of the top surface, the bottom surface, and the side surface in the temperature control.

  [3] The third resistance heater is preferably provided at a position overlapping the measurement position of the side surface measured by the third measurement unit in the direction from the top surface to the bottom surface. This is for accurately controlling the temperature of the side surface.

  [4] The measurement position of the side surface is preferably set to a position where the distance from the top surface is 20 mm or more and 100 mm or less in the direction from the top surface to the bottom surface. This is because the side surface temperature is measured at a position corresponding to the sublimated raw material transfer space, and the side surface temperature is controlled based on the measured side surface temperature.

  [5] It is preferable that the manufacturing apparatus further includes a heat insulating material provided outside the third resistance heater as viewed from the crucible and having a through hole at a position corresponding to the third measurement unit. By arrange | positioning a 3rd measurement part on the outer side of a heat insulating material, a 3rd measurement part can be protected from high temperature with a heat insulating material.

An apparatus for producing a silicon carbide single crystal according to one embodiment of the present invention provides:
[6] A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface, and a crucible provided to face the top surface A first resistance heater, a second resistance heater provided to face the bottom surface, a third resistance heater configured to surround the side surface, the first resistance heater, the second resistance heater, and the third A control unit that controls the resistance heater, a first measurement unit that measures the temperature of the top surface, a second measurement unit that measures the temperature of the bottom surface, a third measurement unit that measures the temperature of the side surface, A heat insulating material provided outside the third resistance heater as viewed from the crucible and having a through hole at a position corresponding to the third measurement unit. The third resistance heater is provided at a position overlapping the measurement position on the side surface measured by the third measurement unit in the direction from the top surface to the bottom surface. The measurement position of the side surface is set to a position where the distance from the top surface is 20 mm or more and 100 mm or less in the direction from the top surface to the bottom surface. When the temperature of the top surface is Ta, the temperature of the bottom surface is Tb, and the temperature of the side surface is Tc, the control unit has a first resistance heater such that 2100 ° C. ≦ Tc ≦ 2400 ° C. and Ta <Tb <Tc. The second resistance heater and the third resistance heater are controlled.

  According to this silicon carbide single crystal manufacturing apparatus, a decrease in growth rate is suppressed.

A method for producing a silicon carbide single crystal according to one embodiment of the present invention includes:
[7] A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface, and a crucible provided to face the top surface 1 resistance heater, 2nd resistance heater provided facing this bottom face, 3rd resistance heater comprised so that this side surface might be surrounded, The raw material provided in the inside of this crucible, The inside of this crucible And a step of preparing a seed crystal facing the raw material and a step of growing a silicon carbide single crystal on the seed crystal by sublimating the raw material. In the growth step, the temperature of the side surface is measured between the raw material and the seed crystal in the direction from the top surface to the bottom surface, the temperature of the top surface is Ta, the temperature of the bottom surface is Tb, and the temperature of the side surface is Tc. , The first resistance heater, the second resistance heater, and the third resistance heater are controlled so that Ta <Tb <Tc.

  In this manufacturing method, the temperature of the side surface of the crucible is measured between the raw material and the seed crystal. This measurement position is a position corresponding to the transport space of the sublimated raw material. In this manufacturing method, the temperature of the side surface is controlled to be the highest among the top surface, the bottom surface, and the side surface of the crucible. Thereby, it can suppress that the sublimated raw material flows into the side surface side. Therefore, it is possible to suppress a decrease in growth rate due to the sublimated raw material flowing to the side surface side.

  [8] In the growing step, the temperature of the side surface is preferably 2100 ° C. or higher and 2400 ° C. or lower.

  [9] In the growing step, the temperature difference between the side surface temperature and the bottom surface temperature may be less than 100 ° C.

  [10] In the growing step, the pressure inside the crucible may be 0.5 kPa or more and 5 kPa or less.

  [11] In the manufacturing method described above, after the growing step, the step of adjusting so that Tc = Tb = Ta, and the temperature of the top surface, the bottom surface, and the side surface are lowered after the adjusting step. It is preferable to further include a process. This is for suppressing the occurrence of thermal strain in the grown silicon carbide single crystal.

A method for producing a silicon carbide single crystal according to one embodiment of the present invention includes:
[12] A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface, and a crucible provided to face the top surface 1 resistance heater, 2nd resistance heater provided facing this bottom face, 3rd resistance heater comprised so that this side surface might be surrounded, The raw material provided in the inside of this crucible, The inside of this crucible And a step of preparing a seed crystal facing the raw material and a step of growing a silicon carbide single crystal on the seed crystal by sublimating the raw material. In the growing step, the pressure inside the crucible is controlled to 0.5 kPa or more and 5 kPa or less, and the temperature of the side surface is measured between the raw material and the seed crystal in the direction from the top surface to the bottom surface. Further, in the growth step, when the top surface temperature is Ta, the bottom surface temperature is Tb, and the side surface temperature is Tc, 2100 ° C. ≦ Tc ≦ 2400 ° C., Ta <Tb <Tc and Tc−Tb <100 ° C. Thus, the first resistance heater, the second resistance heater, and the third resistance heater are controlled.

  According to this manufacturing method, a decrease in growth rate can be suppressed.

[Details of the embodiment of the present invention]
Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present embodiment is not limited thereto. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated. In the crystallographic description of the present 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 {}. Here, a negative crystallographic index is usually expressed by adding a “−” (bar) above a number, but in this specification, by attaching a negative sign before the number. It represents a negative index in crystallography.

[Silicon carbide single crystal manufacturing equipment]
First, an outline of a silicon carbide single crystal manufacturing apparatus according to the present embodiment will be described. FIG. 1 is a conceptual diagram illustrating an example of the configuration of the manufacturing apparatus 100. A manufacturing apparatus 100 shown in FIG. 1 is an apparatus for manufacturing a silicon carbide single crystal by a sublimation method. The manufacturing apparatus 100 includes a crucible 5, a resistance heater 2, a measuring unit 9, a power supply 8, and a control unit 20. The control unit 20 determines the amount of power to be supplied to the resistance heater 2 and issues a command to the power supply 8. The power supply 8 supplies power to the resistance heater 2 based on a command from the control unit 20. The resistance heater 2 receives resistance and is heated by resistance, and radiates heat to heat the crucible 5. As described later, in this embodiment, when the temperature of the top surface 5a of the crucible 5 shown in FIG. 2 is Ta, the temperature of the bottom surface 5b of the crucible 5 is Tb, and the temperature of the side surface 5c of the crucible 5 is Tc, 2100 ° C. ≦ The control unit 20 shown in FIG. 1 controls the resistance heater 2 so that Tc ≦ 2400 ° C. and Ta <Tb <Tc, thereby suppressing a decrease in growth rate.

  As shown in FIG. 1, the manufacturing apparatus 100 may include a measurement unit 9. This is for accurately controlling the temperature of the crucible 5. In this case, the measurement unit 9 measures the temperature of the crucible 5 at a predetermined measurement position and transmits the measurement result to the control unit 20. The control unit 20 adjusts the amount of power to be supplied to the resistance heater 2 based on the measurement result of the measurement unit 9. That is, the control unit 20 performs feedback control. However, in the present embodiment, it is only necessary to control the temperatures Ta, Tb, and Tc so as to satisfy the above relationship, and the measuring unit 9 is not essential. Hereinafter, the configuration of the manufacturing apparatus 100 will be described in more detail.

  FIG. 2 is a schematic cross-sectional view showing an example of the configuration of the manufacturing apparatus 100. As shown in FIG. 2, the manufacturing apparatus 100 includes a chamber 6, and the chamber 6 includes a crucible 5, a first resistance heater 2 a, a second resistance heater 2 b, a third resistance heater 2 c, and a heat insulating material 15. Yes. The heat insulating material 15, the crucible 5, and each resistance heater are comprised, for example from graphite. The heat insulating material 15, the crucible 5 and each resistance heater may contain impurities inevitably mixed in the manufacturing process. The impurity here is, for example, a metal derived from a cutting tool or the like used for manufacturing.

  In addition, the manufacturing apparatus 100 includes a first measurement unit 9a, a second measurement unit 9b, and a third measurement unit 9c outside the chamber 6.

〔crucible〕
The crucible 5 includes a pedestal 3 configured to hold the seed crystal 11 and a bottomed cylindrical storage portion 4 that can store the raw material 12. The pedestal 3 has a seed crystal holding surface 3 a in contact with the back surface 11 b of the seed crystal 11. In the pedestal 3, the opposite side of the seed crystal holding surface 3 a constitutes the top surface 5 a of the crucible 5. The accommodating part 4 has a cylindrical shape, for example, and constitutes a bottom surface 5 b and a side surface 5 c of the crucible 5. That is, the crucible 5 has a top surface 5a, a bottom surface 5b opposite to the top surface 5a, and a cylindrical side surface 5c located between the top surface 5a and the bottom surface 5b.

[Resistance heater]
Each resistance heater receives heat from the power source to generate heat and radiates heat to heat the crucible 5.

  The first resistance heater 2a is provided away from the top surface 5a and facing the top surface 5a. The second resistance heater 2b is provided apart from the bottom surface 5b and facing the bottom surface 5b. 3 and 4 are schematic views showing an example of a planar shape when the first resistance heater 2a and the second resistance heater 2b are viewed from the normal direction of the top surface 5a or the bottom surface 5b. As shown in FIGS. 3 and 4, the first resistance heater 2a and the second resistance heater 2b preferably have a shape in which two curves that move away from the center as they turn meet at the center. For example, the first resistance heater 2a and the second resistance heater 2b may be Fermat's spiral shape.

  As shown in FIG. 3, the first resistance heater 2a is connected to the first power source 8a, and receives power from the first power source 8a. The width W1 of the first resistance heater 2a in FIG. 3 is smaller than the outer diameter of the housing portion 4 (width W3 in FIG. 2) and larger than the inner diameter of the opening of the housing portion 4 (width W4 in FIG. 2). It is preferable.

  As shown in FIG. 4, the second resistance heater 2b is connected to the second power source 8b, and receives power from the second power source 8b. The width W2 of the second resistance heater 2b in FIG. 4 is preferably larger than the diameter of the inner bottom surface of the accommodating portion 4 (width W5 in FIG. 2).

  The third resistance heater 2c is configured to be separated from the side surface 5c and surround the side surface 5c. FIG. 5 is a schematic diagram showing an example of the configuration of the third resistance heater 2c. As shown in FIG. 5, the third resistance heater 2c includes a first portion 1x extending along a direction D (see FIG. 2) from the top surface 5a toward the bottom surface 5b, and a first portion on the bottom surface 5b side. A second portion 2x provided continuously with 1x and extending along the circumferential direction of the side surface 5c; and a third portion 3x provided continuously with the second portion 2x and extending along the direction D. And a fourth portion 4x provided continuously with the third portion 3x on the top surface 5a side and extending along the circumferential direction of the side surface 5c. The first part 1x, the second part 2x, the third part 3x, and the fourth part 4x constitute a heater unit 10x. The third resistance heater 2c is formed in an annular shape by continuously providing a plurality of heater units 10x.

  FIG. 6 is a schematic diagram showing a positional relationship between the third resistance heater 2c and the crucible 5 when viewed along the direction D from the top surface 5a toward the bottom surface 5b. In FIG. 6, the normal direction of the paper surface corresponds to the direction D in FIG. As shown in FIG. 6, when viewed in the direction D, the third resistance heater 2c is provided so as to surround the side surface 5c and has a ring shape. The third resistance heater 2c is connected to the third power source 8c and receives power from the third power source 8c.

[Measurement section]
As shown in FIG. 2, a heat insulating material 15 is provided outside each resistance heater when viewed from the crucible 5. Further, a chamber 6 is provided outside the heat insulating material 15. The first measurement unit 9a, the second measurement unit 9b, and the third measurement unit 9c are provided outside the chamber 6 and are protected from high temperatures by the heat insulating material 15.

  For each measurement unit, for example, a radiation thermometer is used. For example, a pyrometer manufactured by Chino Co., Ltd. (model number “IR-CAH8TN6”) is suitable. For example, the measurement wavelength of the pyrometer may be 1.55 μm and 0.9 μm. The emissivity setting value of the pyrometer is 0.9, for example, and the distance coefficient is 300, for example. At this time, 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.

  As shown in FIG. 2, the first measuring unit 9a is provided to face the top surface 5a and measures the temperature Ta of the top surface 5a. On the straight line connecting the measurement position 5a1 on the top surface 5a and the first measurement unit 9a, the chamber 6 is provided with a view port 6a, and the heat insulating material 15 is provided with a through hole 15a. The viewport 6a is, for example, a quartz window. As shown in FIG. 3, the first resistance heater 2a has a gap 2a1. The first measurement unit 9a captures the radiated light from the measurement position 5a1 through the viewport 6a, the through hole 15a, and the gap 2a1, and measures the temperature Ta at the measurement position 5a1. In the present embodiment, the distance between the measurement position 5a1 and the first measurement unit 9a is preferably 300 mm or more and 1000 mm or less, and more preferably 500 mm or more and 800 mm or less.

  The 2nd measurement part 9b is provided facing the bottom face 5b, and measures the temperature Tb of the bottom face 5b. Similar to the first measurement unit 9a, the second measurement unit 9b captures the radiated light from the measurement position 5b1 through the view port 6b, the through hole 15b, and the gap 2b1 (see FIG. 4), and the temperature at the measurement position 5b1. Tb is measured. In the present embodiment, the distance between the measurement position 5b1 and the second measurement unit 9b is preferably 300 mm or greater and 1000 mm or less, and more preferably 500 mm or greater and 800 mm or less.

  The 3rd measurement part 9c is provided facing the side surface 5c, and measures the temperature Tc of the side surface 5c. A view port 6c and a through hole 15c are provided on a straight line connecting the measurement position 5c1 on the side surface 5c and the third measurement unit 9c. As shown in FIG. 5, the third resistance heater 2c has a gap 2c1. As shown in FIG. 7, the third measurement unit 9c captures the radiated light from the measurement position 5c1 through the viewport 6c (see FIG. 2), the through hole 15c and the gap 2c1, and calculates the temperature Tc at the measurement position 5c1. measure. In the present embodiment, the distance between the measurement position 5c1 and the third measurement unit 9c is preferably 300 mm or greater and 1000 mm or less, and more preferably 500 mm or greater and 800 mm or less.

  As shown in FIG. 2, the measurement position 5c1 is preferably set to a position where the distance L from the top surface 5a is 20 mm or more and 100 mm or less in the direction D from the top surface 5a to the bottom surface 5b. Since this position is a position substantially corresponding to the transfer space of the sublimated raw material 12, the growth rate can be prevented from decreasing by controlling the temperature at this position. The distance L is more preferably 30 mm or more and 90 mm or less, particularly preferably 40 mm or more and 80 mm or less, and most preferably 50 mm or more and 70 mm or less.

  At this time, it is preferable that the third resistance heater 2c is provided so as to heat a position corresponding to the measurement position 5c1. That is, the third resistance heater 2c is preferably provided at a position overlapping the measurement position 5c1 measured by the third measurement unit 9c in the direction D from the top surface 5a to the bottom surface 5b. This is for accurately controlling the temperature of the side surface 5c.

(Control part)
The temperature Ta of the top surface 5a measured by the first measuring unit 9a, the temperature Tb of the bottom surface 5b measured by the second measuring unit 9b, and the temperature Tc of the side surface 5c measured by the third measuring unit 9c are sent to the control unit 20. Sent.

  Based on the measurement results of the first measurement unit 9a, the second measurement unit 9b, and the third measurement unit 9c, the controller 20 determines that the measured temperatures are 2100 ° C. ≦ Tc ≦ 2400 ° C. and Ta <Tb <Tc. The amount of power to be supplied to the first resistance heater 2a, the second resistance heater 2b, and the third resistance heater 2c is determined so as to be the target temperature of each temperature determined to satisfy the condition, and the first power supply 8a, Commands are issued to the second power source 8b and the third power source 8c, respectively. Thereby, a silicon carbide single crystal can be grown while suppressing a decrease in growth rate.

[Method for producing silicon carbide single crystal]
If another situation of this embodiment is followed, the manufacturing method of a silicon carbide single crystal will be provided. FIG. 8 is a flowchart showing an outline of the manufacturing method. As shown in FIG. 8, the manufacturing method includes a preparation step (S10), a crystal growth step (S20), a temperature adjustment step (S30), and a temperature lowering step (S40). Hereinafter, each step will be described.

[Preparation process (S10)]
In the preparation step (S10), for example, the manufacturing apparatus 100 described above is prepared. That is, as shown in FIG. 2, a crucible 5 having a top surface 5a, a bottom surface 5b opposite to the top surface 5a, and a cylindrical side surface 5c located between the top surface 5a and the bottom surface 5b, A first resistance heater 2a provided facing the surface 5a, a second resistance heater 2b provided facing the bottom surface 5b, and a third resistance heater 2c configured to surround the side surface 5c are prepared. Is done.

  Next, the raw material 12 and the seed crystal 11 are placed in the crucible 5. Raw material 12 is, for example, silicon carbide polycrystalline powder. The raw material 12 is disposed in the accommodating portion 4 of the crucible 5. Seed crystal 11 is, for example, a polytype 4H silicon carbide single crystal substrate. The back surface 11b of the seed crystal 11 is fixed to the seed crystal holding surface 3a of the pedestal 3 with an adhesive, for example. The diameter of the seed crystal 11 is, for example, 100 mm or more, preferably 150 mm or more. The growth surface 11a of the seed crystal 11 is preferably a surface that is inclined by 1 ° or more and 8 ° or less from the (0001) plane or the (000-1) plane. As shown in FIG. 2, the growth surface 11 a of the seed crystal 11 is disposed in the crucible 5 so as to face the raw material 12.

[Crystal growth step (S20)]
In the crystal growth step (S20), the silicon carbide single crystal is grown on the growth surface 11a by sublimating the raw material 12 in the crucible 5.

  FIG. 9 is a timing chart showing an example of temperature control and pressure control in the crystal growth step (S20). The temperature control here is executed by, for example, the control unit 20 described above.

  As shown in FIG. 9, at time t0, the temperature Ta of the top surface 5a, the temperature Tb of the bottom surface 5b, and the temperature Tc of the side surface 5c are all the temperature A2. From time t0 to time t1, the temperatures Ta, Tb, and Tc are raised to the target temperature (temperature A1a, temperature A1b, temperature A1c in FIG. 9), and held at the target temperature after time t1 until time t5. . At this time, as shown in FIG. 2, in the manufacturing apparatus 100, the temperature Tc of the side surface 5c is measured at a portion corresponding to the space between the raw material 12 and the seed crystal 11 in the direction D from the top surface 5a to the bottom surface 5b. The In FIG. 9, the temperatures Ta, Tb, and Tc have reached the target temperature at the time t1, but the target temperature may not be reached at the same time.

  As shown in FIG. 9, in the present embodiment, each resistance heater is controlled from the temperature rising stage so that Ta <Tb <Tc. In this way, by controlling the temperature Tc to be the highest among the temperatures Ta, Tb, and Tc, the sublimated raw material 12 is suppressed from flowing toward the side surface 5c, and the accompanying decrease in the growth rate is suppressed. Is done.

  The target value of temperature Tc (temperature A1c in FIG. 9) is 2100 ° C. or higher and 2400 ° C. or lower. This is because a practical growth rate can be realized within this range, and a decrease in the growth rate during growth can be suppressed. The temperature A1c may be 2150 ° C. or higher and 2350 ° C. or lower, and may be 2200 ° C. or higher and 2300 ° C. or lower.

  From the time point t0 to the time point t2 past the time point t1 when the temperatures Ta, Tb and Tc reach the target temperature, the pressure inside the chamber 6 is maintained at the pressure P1. That is, the pressure inside the crucible 5 is maintained at the pressure P1. The pressure P1 is, for example, atmospheric pressure. At this time, the atmosphere inside the chamber 6 is preferably an inert gas atmosphere such as argon gas, helium gas, nitrogen gas or the like.

  From time t2 to time t3, the pressure inside the chamber 6 is reduced from the pressure P1 to the pressure P2. The pressure P2 may be not less than 0.5 kPa and not more than 5 kPa. In this range, it is possible to suppress the occurrence of discharge in the chamber 6 while suppressing a decrease in the growth rate. The pressure P2 is more preferably 0.5 kPa to 3 kPa, and particularly preferably 0.5 kPa to 2 kPa. Thereafter, the pressure inside the chamber 6 is maintained at the pressure P2 until the time point t4.

  Sublimation of the raw material 12 and recrystallization on the seed crystal 11 are started between time t2 and time t3. During crystal growth, the temperature difference (Tb−Ta) between the temperature Tb of the bottom surface 5b and the temperature Ta of the top surface 5a is, for example, 10 ° C. or more and 200 ° C. or less, and may be 10 ° C. or more and 150 ° C. or less. 10 degreeC or more and 100 degrees C or less may be sufficient.

  At this time, the temperature difference (Tc−Tb) between the temperature Tc of the side surface 5c and the temperature Tb of the bottom surface 5b may be less than 100 ° C. Thereby, it can suppress that the surface temperature of a raw material rises from the internal temperature of a raw material, suppressing the fall of a growth rate.

  The temperature difference (Tc−Tb) may be 80 ° C. or less. The lower limit of the temperature difference (Tc−Tb) may be 5 ° C.

  After growing the silicon carbide single crystal having a desired height, the pressure inside the chamber 6 is returned from the pressure P2 to the pressure P1 from the time point t4 to the time point t5. Thereby, the pressure inside the crucible 5 rises, sublimation of the raw material 12 is suppressed, and the raw material 12 does not sublime eventually. Thereby, the crystal growth step (S20) is substantially completed.

[Temperature adjustment step (S30)]
After the crystal growth step (S20), the temperature Ta of the top surface 5a, the temperature Tb of the bottom surface 5b, and the temperature Tc of the side surface 5c may be adjusted to be substantially the same temperature. That is, each resistance heater may be controlled so that Ta = Tb = Tc from time t5 to time t6. This is because if the temperature difference among the temperatures Ta, Tb, and Tc is large when the temperature is lowered, thermal strain may be applied to the grown silicon carbide single crystal.

[Cooling step (S40)]
From time t6 when Ta = Tb = Tc, the supply of electric power to each resistance heater is stopped, and the crucible 5 is cooled. After the temperature of the crucible 5 reaches around room temperature, the silicon carbide single crystal is taken out from the crucible 5. As described above, a silicon carbide single crystal can be produced while suppressing a decrease in growth rate.

  As mentioned above, although one embodiment of the present invention was described, it should be thought that the embodiment indicated this time is illustration and restrictive at no points. The scope of the present invention is shown not by the embodiments described above but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

2 resistance heater 2a first resistance heater 2b second resistance heater 2c third resistance heater 2a1, 2b1, 2c1 gap 1x first portion 2x second portion 3x third portion 4x fourth portion 10x heater unit 3 pedestal 3a seed crystal holding surface 4 Container 5 Crucible 5a Top 5b Bottom 5c Sides 5a1, 5b1, 5c1 Measurement position 6 Chambers 6a, 6b, 6c Viewport 8 Power supply 8a First power supply 8b Second power supply 8c Third power supply 9 Measurement part 9a First measurement part 9b 2nd measurement part 9c 3rd measurement part 11 Seed crystal 11a Growth surface 11b Back surface 12 Raw material 15 Heat insulating material 15a, 15b, 15c Through-hole 20 Control part 100 Manufacturing apparatus A1a, A1b, A1c, A2, Ta, Tb, Tc Temperature D direction L Distance P1, P2 Pressure W1, W2, W3, W4, W5 Width t0, t1, t2, t3, t4, t5, t6

Claims (12)

A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface;
A first resistance heater provided facing the top surface;
A second resistance heater provided facing the bottom surface;
A third resistance heater configured to surround the side surface;
A control unit that controls the first resistance heater, the second resistance heater, and the third resistance heater;
When the top surface temperature is Ta, the bottom surface temperature is Tb, and the side surface temperature is Tc,
The control unit controls the first resistance heater, the second resistance heater, and the third resistance heater so that 2100 ° C. ≦ Tc ≦ 2400 ° C. and Ta <Tb <Tc. manufacturing device. A first measuring unit for measuring the temperature of the top surface;
A second measuring unit for measuring the temperature of the bottom surface;
The apparatus for manufacturing a silicon carbide single crystal according to claim 1, further comprising: a third measurement unit that measures the temperature of the side surface.   3. The silicon carbide according to claim 2, wherein the third resistance heater is provided at a position overlapping a measurement position of the side surface measured by the third measurement unit in a direction from the top surface toward the bottom surface. Single crystal manufacturing equipment.   4. The silicon carbide single crystal according to claim 3, wherein the measurement position of the side surface is set to a position where a distance from the top surface is 20 mm or more and 100 mm or less in a direction from the top surface to the bottom surface. manufacturing device.   The heat-insulating material which is provided in the outer side of the said 3rd resistance heater seeing from the said crucible, and has a through-hole in the position corresponding to a said 3rd measurement part is further provided in any one of Claims 2-4. An apparatus for producing a silicon carbide single crystal. A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface;
A first resistance heater provided facing the top surface;
A second resistance heater provided facing the bottom surface;
A third resistance heater configured to surround the side surface;
A control unit for controlling the first resistance heater, the second resistance heater, and the third resistance heater;
A first measuring unit for measuring the temperature of the top surface;
A second measuring unit for measuring the temperature of the bottom surface;
A third measuring unit for measuring the temperature of the side surface;
A heat insulating material provided outside the third resistance heater as viewed from the crucible and having a through hole at a position corresponding to the third measurement unit;
The third resistance heater is provided at a position overlapping the measurement position of the side surface measured by the third measurement unit in the direction from the top surface toward the bottom surface.
The measurement position of the side surface is set at a position where the distance from the top surface is 20 mm or more and 100 mm or less in the direction from the top surface to the bottom surface,
When the top surface temperature is Ta, the bottom surface temperature is Tb, and the side surface temperature is Tc,
The control unit controls the first resistance heater, the second resistance heater, and the third resistance heater so that 2100 ° C. ≦ Tc ≦ 2400 ° C. and Ta <Tb <Tc. manufacturing device. A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface;
A first resistance heater provided facing the top surface;
A second resistance heater provided facing the bottom surface;
A third resistance heater configured to surround the side surface;
Raw materials provided inside the crucible;
Preparing a seed crystal provided facing the raw material inside the crucible;
Growing a silicon carbide single crystal on the seed crystal by sublimating the raw material, and
In the growing step,
In the direction from the top surface to the bottom surface, the temperature of the side surface is measured between the raw material and the seed crystal,
When the top surface temperature is Ta, the bottom surface temperature is Tb, and the side surface temperature is Tc,
A method for producing a silicon carbide single crystal, wherein the first resistance heater, the second resistance heater, and the third resistance heater are controlled so that Ta <Tb <Tc.   The method for producing a silicon carbide single crystal according to claim 7, wherein, in the growing step, the temperature of the side surface is 2100 ° C. or higher and 2400 ° C. or lower.   The method for producing a silicon carbide single crystal according to claim 7 or 8, wherein, in the growing step, a temperature difference between the temperature of the side surface and the temperature of the bottom surface is less than 100 ° C.   The method for producing a silicon carbide single crystal according to any one of claims 7 to 9, wherein, in the growing step, a pressure inside the crucible is controlled to 0.5 kPa or more and 5 kPa or less. After the growing step, adjusting so that Tc = Tb = Ta,
The silicon carbide single unit according to any one of claims 7 to 10, further comprising a step of lowering a temperature of the top surface, a temperature of the bottom surface, and a temperature of the side surface after the adjusting step. Crystal production method. A crucible having a top surface, a bottom surface opposite to the top surface, and a cylindrical side surface located between the top surface and the bottom surface;
A first resistance heater provided facing the top surface;
A second resistance heater provided facing the bottom surface;
A third resistance heater configured to surround the side surface;
Raw materials provided inside the crucible;
Preparing a seed crystal provided facing the raw material inside the crucible;
Growing a silicon carbide single crystal on the seed crystal by sublimating the raw material, and
In the growing step,
Controlling the pressure inside the crucible to 0.5 kPa or more and 5 kPa or less,
In the direction from the top surface to the bottom surface, the temperature of the side surface is measured between the raw material and the seed crystal,
When the top surface temperature is Ta, the bottom surface temperature is Tb, and the side surface temperature is Tc,
A silicon carbide single crystal that controls the first resistance heater, the second resistance heater, and the third resistance heater so that 2100 ° C. ≦ Tc ≦ 2400 ° C., Ta <Tb <Tc and Tc−Tb <100 ° C. Manufacturing method.