JP2013126931A - Apparatus for producing silicon carbide single crystal, and method for producing silicon carbide single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing silicon carbide single crystal that can produce a high-quality silicon carbide single crystal by adjusting a growth condition during growing a crystal, and to provide a method for producing silicon carbide single crystal.SOLUTION: The apparatus for producing silicon carbide single crystal includes: a crucible 3 consisting of a crucible upper part 3a and a crucible lower part 3b; a first support member 7 for supporting at least the crucible lower part 3b selected from the crucible upper part 3a and the crucible lower part 3b; a second support member 8 for supporting a pedestal 4; weight sensors 9 and 10 for detecting weights of the first support member 7 and the second support member 8 respectively independently; and a heating means arranged around the crucible 3. The first support member 7 and the second support member 8 are arranged relatively movably to the vertical direction.

Description

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

Silicon carbide has excellent performance such as excellent heat resistance, large dielectric breakdown voltage, wide energy band gap, high thermal conductivity, etc., so high power power devices, high temperature resistant semiconductor elements, radiation resistant semiconductor elements Application to a high-frequency semiconductor element or the like is possible. Since silicon is approaching the limit of performance improvement from the physical property limit of the material itself, silicon carbide that can take a physical property limit larger than silicon has attracted attention. In recent years, power electronics technology using silicon carbide materials has been expected as an energy-saving technology to reduce energy loss during power conversion and to counter global warming issues.
Research and development of silicon carbide single crystal growth technology has been vigorously advanced as the basic technology.

  As a method for growing a silicon carbide single crystal, a sublimation recrystallization method is widely used. In this method, for example, a seed crystal is attached to a graphite pedestal arranged in a graphite crucible, and a silicon carbide raw material disposed on the bottom of the crucible is heated to 2000 ° C. or more to generate a sublimation gas. A silicon carbide single crystal is grown on the seed crystal by recrystallizing the seed crystal at a temperature lower by several tens to several hundred degrees C (for example, Patent Documents 1 to 3).

  As a silicon carbide single crystal manufacturing apparatus using the sublimation recrystallization method, the crucible is composed of two parts, an upper part of the crucible and a lower part of the crucible. The mechanism adjusts the distance between the surface of the silicon carbide single crystal and the silicon carbide raw material to reduce the change in temperature difference between the surface temperature of the growing silicon carbide single crystal and the temperature of the silicon carbide powder raw material. A device for producing a long and long silicon carbide single crystal is known (for example, Patent Document 3).

FIG. 8 shows a typical silicon carbide single crystal manufacturing apparatus 100.
The single crystal growth apparatus 100 is generally configured by disposing a crucible 103 covered with a heat insulating material 102 inside a vacuum vessel 101 and arranging a heating means 110 outside the vacuum vessel 101.

  Silicon carbide seed crystal 105 is bonded to lower surface 104a of pedestal 104 of lid 103a of crucible 103. Holes 102 a and 102 b are formed in the heat insulating material 102 so that the lower surface and a part of the upper surface of the crucible 103 are exposed.

  The crucible 103 around which the heat insulating material 102 is wound is installed on a support rod 106 at the center inside the vacuum vessel 1. The support bar 106 has a cylindrical shape, and the hole 106 a of the support bar 106 is aligned with the hole 102 a provided in the heat insulating material 102. Thereby, the radiation thermometer 107 arranged under the vacuum vessel 101 can observe the temperature of the lower surface of the crucible 103 through the hole 106a of the support rod 106 and the hole 102a on the lower side of the heat insulating material 102. It is said that. Similarly, the temperature of the upper surface of the crucible 103 can be observed through another hole 102 b on the upper side of the heat insulating material 102 by another radiation thermometer 107 disposed on the vacuum vessel 101.

For the gas exchange inside the vacuum vessel 101, first, the air inside the vacuum vessel 101 is exhausted using a vacuum pump (not shown) connected to the discharge pipe 108, for example, 4 × 10 ⁻³ Pa or less. Reduce pressure. As the vacuum pump, for example, a turbo molecular pump or the like can be used. Thereafter, high-purity Ar gas is introduced into the vacuum vessel 101 from the introduction pipe 109, and the inside of the vacuum vessel 101 (inside the furnace) is set to an environment of 9.3 × 10 ⁴ Pa in an Ar atmosphere, for example.

  The heating means 110 is, for example, a high-frequency heating coil, and can generate a high frequency by passing an electric current to heat the crucible 103 installed in the center of the vacuum vessel 101 to a temperature of 1900 ° C. or higher, for example. Thereby, silicon carbide raw material powder 111 in crucible 103 is heated, and sublimation gas is generated from silicon carbide raw material powder 111.

Next, FIG. 9 shows a conventional silicon carbide single crystal manufacturing apparatus 200 in which the upper part of the crucible can be moved up and down with respect to the lower part of the crucible. In FIG. 9, configurations normally provided such as a vacuum vessel, a heat insulating material, and a heating means are omitted.
Silicon carbide single crystal manufacturing apparatus 200 includes a crucible 230 including a crucible upper portion 230a and a crucible lower portion 230b, and a pedestal 240 attached to the center of the lower surface of the lid portion 230aa of the crucible upper portion 230a. Powdered silicon carbide raw material 260 is accommodated in crucible lower portion 230 b, and silicon carbide seed crystal 250 is attached to the lower surface of pedestal 240 so as to face silicon carbide raw material 260.

  The crucible lower portion 230b is placed on the support surface portion 270a of the first support member 270 and supported thereby to be fixed in place. On the other hand, the crucible upper portion 230 a is supported by the support side portion 280 b of the second support member 280. In addition to the support side portion 280b, the second support member 280 extends in a vertical direction from a support bottom portion 280a located below the support surface portion 270a of the first support member 270, and a lower surface central portion of the support bottom portion 280a. Shaft guide portion 280c. When the shaft portion 270b of the first support member 270 passes through the shaft guide portion 280c, the shaft guide portion 280c can slide using the shaft portion 270b as a guide. By this sliding, the second support member 280 can be moved up and down along the vertical direction with respect to the first support member 270. The raising / lowering of the second support member 280 is performed by forward / reverse driving of the raising / lowering driving device 290 connected to the shaft guide portion 280c.

International Publication No. 2 00/39372 JP 2010-13296 A JP 2009-23880 A JP-A-7-82091

Conventionally, when producing a silicon carbide single crystal by the sublimation recrystallization method, the silicon carbide single crystal has been grown without monitoring the environment inside the crucible. There is a problem that the desired growth cannot be performed due to variations in the raw material of the silicon powder and the yield is low. For example, if the amount of growth is excessive, the number of polycrystals that grow in the vicinity of the silicon carbide single crystal increases, so that the polycrystal is fixed to the silicon carbide single crystal, or the polycrystal is not fixed. Deterioration of the quality of the silicon carbide single crystal is likely to occur due to the occurrence of defects due to the cause, and the problem of single crystal cracking may also occur. Further, when the growth amount is too small, there is a problem that the number of obtainable wafers is reduced.
Although it was possible to observe the inside of the crucible during the growth of the silicon carbide single crystal, a large-scale apparatus such as an X-ray apparatus was required.

  Patent Document 4 discloses a silicon carbide single crystal manufacturing apparatus equipped with a detector capable of measuring the weight of the entire crucible during the growth of a silicon carbide single crystal by a sublimation recrystallization method. There is no description about the structure which measures a raw material sublimation amount independently.

In silicon carbide single crystal manufacturing equipment using the sublimation recrystallization method, in order to maintain a growth environment of 2000 ° C. or higher, a viewing window for observing the growth environment inside the crucible and the growth conditions (eg, temperature) inside the crucible are measured. It is not desirable to install a window for use in the crucible (for example, a window for measurement with a radiation thermometer) in the crucible. This is because heat escapes from the viewing window.
Also, because of the method of sublimating the powder raw material and supplying the sublimation gas to the silicon carbide seed crystal, if there is a gap in the crucible, the sublimation gas leaks from the gap, and a good growth environment cannot be maintained, In addition, deterioration of members outside the crucible (a heat insulating member and a heater) is caused. Therefore, from this point of view, it is not desirable to install a viewing window or a measurement window in the crucible.

  However, in order to introduce the silicon carbide seed crystal into the crucible, it is necessary to configure the crucible from two parts, and a gap formed in the connecting portion of these parts is necessarily required, and eliminating the gap completely Can not. There is a gap that is formed at the connecting portion between the upper part of the crucible and the lower part of the crucible. Since the temperature in the vicinity of the gap is low, polycrystal silicon carbide is likely to precipitate there, which may hinder relative movement between the crucible upper portion and the crucible lower portion.

  The present invention has been made in view of the above circumstances, and a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal that can manufacture a high-quality silicon carbide single crystal by adjusting the growth conditions during crystal growth. It aims to provide a method.

In order to achieve the above object, the present invention provides the following means.
[1] In a silicon carbide single crystal manufacturing apparatus for supplying a raw material gas onto a silicon carbide seed crystal mounted on a pedestal and growing a silicon carbide single crystal on the silicon carbide seed crystal, the crucible upper portion and the crucible lower portion A crucible, a first support member that supports at least the crucible lower portion of the crucible upper portion and the crucible lower portion, a second support member that supports the pedestal, the first support member, and the second support member. A weight sensor capable of independently detecting weight, and a heating means disposed around the crucible, wherein the first support member and the second support member are movable relative to each other in the vertical direction. A silicon carbide single crystal manufacturing apparatus, which is characterized.
[2] The pedestal is supported on the lower surface of the lid portion of the crucible upper portion, and the first support member supports only the crucible lower portion of the crucible upper portion and the crucible lower portion, and the second support member The apparatus for producing a silicon carbide single crystal according to [1], wherein the crucible upper part is supported and the pedestal is supported via the crucible upper part.
[3] The first support member supports both the crucible upper portion and the crucible lower portion,
The carbonization according to [1], wherein the pedestal protrudes downward from an opening formed in a lid portion on the crucible so that at least a seed crystal mounting surface thereof is located in the crucible. Silicon single crystal manufacturing equipment.
[4] A first protrusion provided on the lower surface of the lid so as to protrude downward along the periphery of the opening so that the inner wall side of the crucible is high and the vertical center side of the crucible is low. The apparatus for producing a silicon carbide single crystal according to [3], further comprising a first protrusion having a downwardly inclined surface inclined to the inner wall of the crucible.
[5] On the side wall of the pedestal, there is provided a second protrusion having an upper inclined surface on the vertical center side of the crucible that is inclined so that the inner wall side of the crucible is high and the vertical center side of the crucible is low. The silicon carbide single crystal manufacturing apparatus according to any one of [3] or [4], wherein
[6] The crucible upper portion includes a crucible upper connecting portion formed at the lower end of the side portion, and the crucible lower portion includes a crucible lower connecting portion formed at the upper end of the side portion, the crucible upper connecting portion, The crucible lower connection part is inclined so that the inner wall side of the crucible is high and the outer wall side is low, and has inclined connection surfaces opposed to each other, according to any one of [1] to [5] Silicon carbide single crystal manufacturing equipment.
[7] The silicon carbide single crystal manufacturing apparatus according to any one of [1] to [6], wherein the second support member is suspended from above.
[8] In a method for producing a silicon carbide single crystal in which a raw material gas is supplied onto a silicon carbide seed crystal attached to a pedestal and a silicon carbide single crystal is grown on the silicon carbide seed crystal, A crucible comprising: a crucible upper portion; and a crucible upper portion and a crucible lower portion, a first support member supporting at least the crucible lower portion, a second support member supporting the pedestal, the first support member, and the second support member. A weight sensor capable of detecting the weight of each of the first and second heating members disposed around the crucible, and the first support member and the second support member are movable relative to each other in the vertical direction. Using a crystal manufacturing apparatus, during the manufacture of the silicon carbide single crystal, the growth amount and / or growth rate of the silicon carbide single crystal is obtained from the weight of the second support member detected using the weight sensor, and the weight sensor The sublimation rate and / or sublimation amount of the silicon carbide powder raw material is determined from the weight of the first support member detected by using the first support member, and the growth rate and / or growth amount and / or the sublimation amount and / or sublimation rate are determined. If it is outside the desired range, at least one of (1) to (4) is performed so as to fall within the range; a method for producing a silicon carbide single crystal;
(1) Adjust the temperature of the crucible upper part or the pedestal and / or the crucible lower part,
(2) The first support member and the second support member are moved relative to each other in the vertical direction, or are raised or lowered at different speeds.
(3) Change the expected growth time of the silicon carbide single crystal.
(4) Adjust the furnace pressure.

  According to the silicon carbide single crystal manufacturing apparatus of the present invention, a crucible composed of a crucible upper portion and a crucible lower portion, a first support member that supports at least the crucible lower portion among the crucible upper portion and the crucible lower portion, and a pedestal supporting first Since the structure including the two support members and the weight sensor capable of independently detecting the weights of the first support member and the second support member is employed, the amount of reduction in the silicon carbide raw material from the detected weight of the first support member The growth amount and growth rate of the silicon carbide single crystal can be determined from (ie, the sublimation amount of the raw material) and the sublimation rate of the raw material, and the detected weight of the second support member. Based on this, when those values deviate from the predetermined range, it is possible to change the growth conditions so that they are within the predetermined range even during the growth of the single crystal. Crystals can be manufactured, yield is improved, and a desired number of wafers that can be acquired can be secured.

  According to the silicon carbide single crystal manufacturing apparatus of the present invention, the crucible upper portion includes a crucible upper connecting portion formed at the lower end of the side portion, and the crucible lower portion includes a crucible lower connecting portion formed at the upper end of the side portion. The crucible upper connecting part and the crucible lower connecting part both have at least a part of the crucible upper part and the crucible by adopting a structure having an inclined connecting surface that is inclined downward as they go from the inside of the crucible to the outside. The amount of polycrystals deposited at the connecting portion with the lower portion can be reduced, and as a result, good relative movement between the crucible upper portion and the crucible lower portion can be ensured.

  According to the method for producing a silicon carbide single crystal of the present invention, the growth amount and / or growth rate of the silicon carbide single crystal is determined from the weight of the second support member detected using the weight sensor during the production of the silicon carbide single crystal. The sublimation rate and / or sublimation amount of the silicon carbide powder raw material is determined from the weight of the first support member detected using the weight sensor, and the growth rate and / or growth amount and / or sublimation amount and / or When the sublimation speed is outside the predetermined range, (1) the temperature of the crucible upper part or pedestal and / or the crucible lower part is adjusted so as to fall within the range, (2) the first support member and the aforementioned Moving the second support members relative to each other in the vertical direction, or raising or lowering them at different speeds, (3) changing the expected growth time of the silicon carbide single crystal, (4) adjusting the pressure in the furnace, Structure to do at least one of Having adopted, the manufacturing of high quality silicon carbide single crystal is made possible, the yield is improved, and it is possible to secure the number expected obtainable wafer.

It is a cross-sectional schematic diagram which shows the silicon carbide single crystal manufacturing apparatus of 1st Embodiment which concerns on this invention. It is the cross-sectional schematic diagram which expanded the vicinity of the crucible upper connection part and crucible lower connection part of the silicon carbide single crystal manufacturing apparatus of 2nd Embodiment which concerns on this invention. It is a cross-sectional schematic diagram which shows the silicon carbide single crystal manufacturing apparatus of 3rd Embodiment which concerns on this invention. It is a cross-sectional schematic diagram which shows the state after a silicon carbide single crystal grew in the silicon carbide single crystal manufacturing apparatus of 3rd Embodiment which concerns on this invention. (A) It is a cross-sectional schematic diagram which shows partially the silicon carbide single crystal manufacturing apparatus of 4th Embodiment which concerns on this invention. (B) It is a cross-sectional schematic diagram which shows the state after a silicon carbide single crystal grew. It is a cross-sectional schematic diagram which shows precipitation of the silicon carbide polycrystal in the silicon carbide single crystal manufacturing apparatus of the 4th Embodiment concerning this invention. It is a cross-sectional schematic diagram which shows the silicon carbide single crystal manufacturing apparatus of 5th Embodiment concerning this invention. It is a cross-sectional schematic diagram which shows the conventional silicon carbide single crystal manufacturing apparatus. It is a cross-sectional schematic diagram which shows the conventional silicon carbide single crystal manufacturing apparatus.

Hereinafter, a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal manufacturing method according to an embodiment to which the present invention is applied will be described in detail with reference to the drawings. The present invention can be applied to a vapor phase growth method such as a sublimation recrystallization method and a CVD method. As an example, a case where a sublimation recrystallization method is used will be described.
The drawings referred to in the following description are drawings for explaining the silicon carbide single crystal manufacturing apparatus and the silicon carbide single crystal manufacturing method of the present embodiment, and the size, thickness, dimensions, etc. of each part shown in the drawings are as follows: It may be different from the dimensional relationship of an actual silicon carbide single crystal manufacturing apparatus or the like. In addition, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not necessarily limited to these, and can be appropriately changed and implemented without changing the gist thereof. Also, illustrations and explanations of normally used components such as a vacuum vessel and heating means may be omitted.

[Silicon carbide single crystal manufacturing apparatus (first embodiment)]
First, FIG. 1 shows a silicon carbide single crystal manufacturing apparatus to which the first embodiment of the present invention is applied. In addition, the structure with which the normal silicon carbide single crystal manufacturing apparatuses, such as a vacuum vessel and a heat insulating material, were not shown in figure.

  In the silicon carbide single crystal manufacturing apparatus, the crucible 3 covered with a heat insulating material, the first support member 7, the second support member 8, and the weights of these support members 7 and 8 are independently provided in a vacuum vessel. The first weight sensor 9 and the second weight sensor 10 to be detected are roughly configured.

  The crucible 3 includes a cavity 11 inside, and a sufficient amount of silicon carbide raw material 6 is accommodated in the lower part of the cavity of the crucible 3 to grow a silicon carbide single crystal on the silicon carbide seed crystal 5. Has been. Silicon carbide raw material 6 is accommodated in the form of powder. A space necessary for crystal growth of the silicon carbide single crystal is secured above the cavity portion 11. With this configuration, a silicon carbide single crystal can be grown on the growth surface 5a of the silicon carbide seed crystal 5 by a sublimation recrystallization method.

  The crucible 3 is constituted by a crucible upper portion 3a and a crucible lower portion 3b that can move relative to each other in the vertical direction. Silicon carbide raw material 6 is accommodated in crucible lower part 3b. Even if only one of the crucible upper part 3a and the crucible lower part 3b is movable or both are movable, the effects of the present invention can be obtained. However, in the first embodiment, the crucible lower part 3b is fixed, and only the crucible upper part 3a is provided. The case where is movable will be described. Since silicon carbide raw material 6 is housed in crucible lower portion 3b, when the crucible lower portion 3b is fixed and the crucible upper portion 3a is movable, the change in the heating environment of silicon carbide raw material 6 is small. There is an advantage that more stable growth can be made possible.

  The material of the crucible 3 is preferably a material that is stable at high temperatures and generates little impure gas, and graphite (graphite), graphite coated with silicon carbide, silicon carbide or tantalum carbide (TaC), or the like is used. Is preferred.

  The crucible upper portion 3a is formed by a lid portion 3aa and a side portion 3ab that is formed in a cylindrical shape from the outer periphery of the lid portion 3aa and extends toward the crucible lower portion 3b. The crucible upper part 3a may be supported by the crucible lower part 3b and the second support member 8, but at least when the weight of the crucible upper part 3a is detected by the first weight sensor 9, it is supported by the crucible lower part 3b. Instead, it is configured to be supported only by the second support member 8.

  A columnar pedestal 4 protruding downward is provided at the center of the lower surface of the lid 3aa of the crucible upper part 3a. The pedestal 4 may be a member integrated with the crucible upper part 3a or may be configured to be coupled to the crucible upper part 3a by a member independent of the crucible upper part 3a. For this bonding, mechanical bonding, bonding with an adhesive, or the like can be used. When the crucible upper part 3a is assembled to the crucible lower part 3b, the pedestal 4 protrudes toward the crucible lower part 3b. The lower surface of this pedestal 4 is a seed crystal mounting surface 4a to which silicon carbide seed crystal 5 is joined. The side 3ab of the crucible upper part 3a extends downward from the pedestal 4, and therefore the seed crystal mounting surface 4a of the pedestal 4 is located in the crucible 3 (cavity 11).

  The crucible lower part 3b is formed by a bottom part 3ba and a side part 3bb which is formed in a cylindrical shape from the outer peripheral part of the bottom part 3ba and extends toward the crucible upper part 3a. The crucible lower part 3 b is supported by the first support member 7.

  The lower part of the side part 3ab of the crucible upper part 3a is provided with a connecting part (crucible upper part connecting part) 3aba, and the upper part of the side part 3bb of the crucible lower part 3b is provided with a connecting part (crucible lower part connecting part) 3bba. The crucible 3 is configured by connecting the crucible upper part 3a and the crucible lower part 3b by joining the part 3aba and the connecting part 3bba.

Each of the connecting portion 3aba and the connecting portion 3bba has sliding surfaces 3A and 3B which are slidably contacted with each other so as to be relatively movable, and are arranged so as to match the sliding surfaces 3A and 3B.
When the sliding surfaces 3A and 3B are combined, the bottom portion 3ba faces the lid portion 3aa of the crucible upper portion 3a.
In the present embodiment, the sliding surfaces 3A and 3B are in slidable contact, but the surface corresponding to the sliding surfaces 3A and 3B may not be in direct contact with each other and may be configured to move relative to each other.

The connecting portion 3aba is in contact with the connecting surface 3bbaa of the connecting portion 3bba or closest to the connecting surface 3bbaa when the relative position of the sliding surface 3A and the crucible upper portion 3a relative to the crucible lower portion 3b is the lowest. 3 aba and a support receiving surface 3 abab supported in contact with the upper end surface 8 </ b> A of the second support member 8.
The connecting portion 3bba is in contact with the connecting surface 3abaa of the connecting portion 3aba or closest to the connecting surface 3abaa when the relative position of the sliding surface 3B and the crucible upper portion 3a relative to the crucible lower portion 3b is the lowest. 3 bbaa.
When the connecting surface 3abaa and the connecting surface 3bbaa are not in contact with each other (closest to each other), it is desirable that the gap formed between them be as small as possible so that the leakage of sublimation gas inside the crucible is minimized.

  The first support member 7 includes a support surface portion 7a and a shaft portion 7b extending in the vertical direction from the center of the lower surface of the support surface portion 7a. A crucible lower part 3 b is disposed on the support surface part 7 a of the first support member 7, whereby the first support member 7 supports the crucible lower part 3 b in which the silicon carbide raw material 6 is accommodated. The shaft portion 7b extends in the vertical direction from the support surface portion 7a with the central axis direction of the crucible 3 as the axial direction.

The second support member 8 includes a support bottom portion 8a positioned below the support surface portion 7a of the first support member 7, and a cylindrical support side portion extending from the outer periphery of the support bottom portion 8a toward the crucible upper portion 3a. 8b, and a shaft guide portion 8c extending in the vertical direction from the center of the lower surface of the support bottom portion 8a.
The upper end surface 8A of the second support side portion 8b is in contact with the lower end surface 3abab of the side portion 3ab of the crucible upper portion 3a, and the second support member 8 is configured to support the crucible upper portion 3a by this contact. . The pedestal 4 provided on the lid 3aa of the crucible upper part 3a is supported by the second support member 8 through the crucible upper part 3a.

  The support side portion 8b of the second support member 8 has a larger diameter than the crucible lower portion 3b supported by the first support member 7, and is constant between the inner surface of the support side portion 8b and the outer surface of the crucible lower portion 3b. The support side portion 8b is provided outside the crucible lower portion 3b in a state where the gap is formed. The shaft portion 7b of the first support member 7 passes through the shaft guide portion 8c of the second support member 8 so as to be relatively movable. The shaft guide portion 8c is provided such that its central axis coincides with the central axis of the crucible upper portion 3a. The second support member 8 is connected to the elevating drive device 15 and moves up and down by forward and reverse driving of the elevating drive device 15. In this configuration, the second support member 8 can be moved relative to the first support member 7 in the vertical direction by forward / reverse driving of the lift drive device 15.

  As the second support member 8 moves up and down, the crucible upper portion 3a is moved in the vertical direction with respect to the crucible lower portion 3b, and the distance between the growth surface of the silicon carbide single crystal and the surface (raw material surface) of the silicon carbide raw material 6 is increased. In other words, the growth rate and growth surface shape of the silicon carbide single crystal can be changed. Further, although the distance between the growth surface and the raw material surface gradually changes as the silicon carbide single crystal grows, the distance can also be maintained by moving the second support member 8 up and down. The upward movement of the crucible upper portion 3a is performed within a range in which the sliding surfaces 3A and 3B are kept facing each other. Therefore, the crucible upper portion 3a moves upward, and the connection surface of the connecting portion 3aba can also continue the growth of the silicon carbide single crystal without opening the inside of the crucible 3.

  As a material of the first support member 7 and the second support member 8, graphite is preferable.

The first weight sensor 9 is provided on the first support member 7, and the second weight sensor 10 is provided on the second support member 8.
The first weight sensor 9 is disposed on, for example, the shaft portion 7b of the first support member 7, and detects the weight (including the weight of the silicon carbide raw material 6) of the first support member 7 and the crucible lower portion 3b supported by the first support member 7. . During the growth of the silicon carbide single crystal, the weight of the first support member and the crucible lower part 3b does not change, but the weight of the silicon carbide raw material 6 is reduced by sublimation of the raw material gas, so the weight detected by the first weight sensor 9 is reduced. To do. The first weight sensor 9 detects a decrease in the total weight, that is, a decrease in the weight of the first support member 7 and the crucible lower portion 3b (including the silicon carbide raw material 6) supported by the first support member 7, thereby detecting a decrease in the silicon carbide raw material 6. .

  The second weight sensor 10 is disposed, for example, at the center portion of the support bottom 8a of the second support member 8, and the weight of the second support member 8 and the crucible upper portion 3a supported by the second support member 8 (base 4, silicon carbide seed crystal). 5 and the weight of the silicon carbide single crystal grown thereon). In the growth of the silicon carbide single crystal, the weights of the second support member 8, the crucible upper portion 3 a, the pedestal 4, and the silicon carbide seed crystal 5 do not change, but the silicon carbide single crystal grows on the silicon carbide seed crystal 5. Since the weight of the silicon carbide single crystal increases, the weight detected by the second weight sensor 10 increases. The second weight sensor 10 has the total weight, that is, the weight of the second support member 8 and the crucible upper portion 3a supported by the second support member 8 (including the weight of the pedestal 4, the silicon carbide seed crystal 5 and the silicon carbide single crystal grown thereon). The weight increase of the silicon carbide single crystal grown on the silicon carbide seed crystal 5 is detected.

As described above, the first weight sensor 9 detects the weight reduction of the silicon carbide raw material 6 through the configuration supported by the first support member 7, and the second weight sensor 10 has the configuration supported by the second support member 8. And detecting the weight of the silicon carbide single crystal grown.
In the present embodiment, since the first weight sensor 9 is provided on the first support member 7 and the second weight sensor 10 is provided on the second support member 8, the weight change of the silicon carbide raw material 6 and the grown silicon carbide. The weight of the single crystal can be obtained independently. A load cell can be used as such weight sensors 9 and 10, and even a slight change in weight can be reliably detected by using a semiconductor piezoresistive pressure sensor system, a spring type pressure sensor system, or the like. Can do.

  A control circuit 16 is connected to the first weight sensor 9 and the second weight sensor 10, and the detected weight is output to the control circuit 16. The control circuit 16 has a calculation unit, calculates one or both of the growth amount and the growth rate of the silicon carbide single crystal from the input weight change of the second support member 8 and the configuration supported by the second support member 8, and inputs One or both of the sublimation amount and the sublimation speed of the silicon carbide raw material 6 can be calculated from the weight change of the first support member 7 and the structure supported by the first support member 7.

Based on the calculation result of the control circuit 16, the drive of the raising / lowering drive apparatus 15 can be controlled, and the up-down moving amount and moving speed of the 2nd support member 8 can be adjusted. By this adjustment, the growth rate and growth amount of the silicon carbide single crystal can be adjusted.
Further, heating means such as a high-frequency heating coil as shown in FIG. 8 is disposed outside the crucible 3 through the vacuum container, and current supply to the heating means is performed based on the calculation result of the control circuit 16. By adjusting, the heating temperature of the crucible 3 can be adjusted. Thereby, the temperature of the crucible upper part 3a or the base 4 or the crucible lower part 3b can be adjusted. By this temperature adjustment, the growth rate and growth amount of the silicon carbide single crystal can be adjusted.
Further, the expected growth time of the silicon carbide single crystal can be changed based on the calculation result of the control circuit 16.
Furthermore, the pressure in the vacuum vessel can be adjusted based on the calculation result of the control circuit 16. Also by this pressure adjustment, the growth rate and growth amount of the silicon carbide single crystal can be adjusted.
In addition, although the structure which adjusts growth conditions automatically using a control circuit was demonstrated, based on the weight obtained from the 1st weight sensor 9 and the 2nd weight sensor 10, you may adjust growth conditions manually. .

  Next, a method for manufacturing a silicon carbide single crystal using the silicon carbide single crystal manufacturing apparatus of FIG. 1 will be described.

The first weight sensor 9 detects a change in the weight of the first support member 7 and the configuration supported by the first support member 7 (the crucible lower portion 3b containing the silicon carbide raw material 6). Control circuit 16 calculates one or both of the sublimation amount and sublimation speed of silicon carbide raw material 6 based on this detected value. The second weight sensor 10 detects a change in weight of the second support member 8 and the structure supported by the second support member 8 (including the crucible upper portion 3a and the pedestal 4 (including the silicon carbide seed crystal and the silicon carbide single crystal grown thereon). The control circuit 16 calculates one or both of the growth amount and growth rate of the silicon carbide single crystal based on the detected value.
After that, the control circuit 16 compares the calculated growth rate and / or growth amount and / or sublimation amount and / or sublimation rate with a preset reference value, and if the result of comparison is outside the predetermined range. First, the growth conditions of the silicon carbide single crystal are adjusted so as to fall within the range.
Specifically, the temperature of the crucible upper part 3a or the pedestal 4 and / or the crucible lower part 3b is adjusted by adjusting the heating means. That is, by increasing the temperature of the crucible upper part 3a or the pedestal 4, it is suppressed that the source gas is deposited on the growth surface and the growth rate is lowered, while by reducing the temperature of the crucible upper part 3a or the pedestal 4, The deposition of the source gas on the growth surface is promoted to increase the growth rate. Further, by increasing the temperature of the crucible lower part 3b, the sublimation rate of the silicon carbide raw material 6 is increased, the amount of the raw material gas reaching the growth surface is increased and the growth rate of the single crystal is increased. By lowering the temperature, the sublimation rate of the silicon carbide raw material 6 is lowered, the amount of the raw material gas reaching the growth surface is reduced, and the growth rate of the single crystal is lowered. Thus, the growth rate and / or growth amount of the single crystal and / or the sublimation amount and / or sublimation rate of the silicon carbide raw material can be set within a predetermined range.
Alternatively, in order to adjust the growth conditions of the silicon carbide single crystal, the first support member 7 and the second support member 8 are moved relative to each other in the vertical direction, or are raised or lowered at different speeds. Thereby, by changing the distance between the pedestal and the silicon carbide raw material, the distance between the growth surface of the single crystal and the raw material surface can be changed, and the growth rate and / or growth amount can be kept within a predetermined range.
Alternatively, the expected growth time of the silicon carbide single crystal is changed in order to adjust the growth conditions of the silicon carbide single crystal. This makes it possible to keep the growth amount of the single crystal within a predetermined range.
Alternatively, the pressure in the vacuum vessel is adjusted in order to adjust the growth conditions of the silicon carbide single crystal. Thereby, the growth rate and / or growth amount of the single crystal and / or the sublimation amount and / or sublimation rate of the silicon carbide raw material can be set within a predetermined range.
By performing one or more of the above adjustments, the growth conditions can be adjusted even during the growth of the single crystal. As a result, a high-quality silicon carbide single crystal can be manufactured, the yield can be improved, and the desired number of wafers that can be acquired can be secured.

[Silicon carbide single crystal production apparatus (second embodiment)]
FIG. 2 is an enlarged schematic cross-sectional view of the vicinity of the crucible upper connecting portion and the crucible lower connecting portion of the silicon carbide single crystal manufacturing apparatus of the second embodiment.

  The structure different from the first embodiment is that the crucible upper connecting portion 21 has an inclined connecting surface 21a inclined below the side portion 3ab so that the inner wall side of the crucible is higher and the outer wall side is lower. 22 is the point which has the inclination connection surface 22a provided in the upper end of the side part 3bb so that it may incline so that the inner wall side of a crucible may be high and an outer wall side may become low, and it may oppose the inclination connection surface 21a. The opposing inclined connecting surfaces 21a and 22a are inclined in the same direction.

In the second embodiment shown in FIG. 2, the crucible upper connecting portion 21 is provided integrally with an inclined portion 21 </ b> A having an inclined connecting surface 21 a on the inner side of the crucible 3, and is provided outside the crucible lower connecting portion 22. And a vertical wall portion 21 </ b> B extending vertically downward so as to cover in a non-contact manner. In addition, the structure which does not have the vertical wall part 21B may be sufficient.
On the other hand, the crucible lower connecting part 22 differs from the crucible lower connecting part 3bba of the first embodiment in that it has an inclined connecting surface 22a, but by extending the side part 3bb of the crucible lower part 3b as it is. It is formed and is common to the crucible lower connection part 3bba of the first embodiment in that it is provided on an extension line of the side part 3ab of the crucible upper part 3a.

The effects of the silicon carbide single crystal manufacturing apparatus according to this embodiment will be described.
In FIG. 2, a solid line arrow indicates the direction of gas flow in the crucible 3 during crystal growth, and a broken line indicates an isotherm during crystal growth. These are the outlines or trends of gas flow and isotherms for the purpose of clearly explaining the effects of the present invention.
In the sublimation recrystallization method, the silicon carbide raw material 6 accommodated in the crucible lower part 3b is sublimated at a high temperature, and the sublimation gas is deposited on the silicon carbide seed crystal attached to the base on the lid 3aa of the crucible upper part 3a lower than that temperature. Is recrystallized, so that isotherms with lower temperatures line up from the bottom to the top.
Since the sublimation gas as a whole flows in a direction substantially orthogonal to the isotherm, it is considered that the sublimation gas flows as indicated by G1 as a whole in the vicinity of the connecting portion between the crucible upper portion 3a and the crucible lower portion 3b. The crucible upper connecting portion 21 and the crucible lower connecting portion 22 of the present embodiment each have an inclined connecting surface 21a and an inclined connecting surface 22a that are inclined so that the inner wall side of the crucible is high and the outer wall side is low. And the crucible lower connecting portion 22 are inclined downwardly from the inner wall side to the outer wall side of the crucible, so that the sublimation gas (gas flow G2) entering the gap 23 is inside the crucible. Since this is opposite to the gas flow, entry into the gap 23 is suppressed. As a result, the amount of polycrystalline silicon carbide formed in the gap 23 is reduced, so that the relative movement between the crucible upper portion and the crucible lower portion can be smoothly performed even during the growth of the silicon carbide single crystal.

[Silicon Carbide Single Crystal Manufacturing Apparatus (Third Embodiment)]
In FIG. 3, the silicon carbide single crystal manufacturing apparatus of 3rd Embodiment is shown.

  The main structure different from the first embodiment is that the pedestal is not the crucible upper part but is attached to the second support member, and the crucible upper part and the crucible lower part where the crucible does not move relative to each other. Note that the first weight sensor is provided on the first support member, the second weight sensor is provided on the second support member, and the second support member is connected to the lifting / lowering drive device as shown in FIG. This is the same as the embodiment.

As in the first embodiment, the second support member 18 in the present embodiment includes a support bottom 18a, a cylindrical support side 18b extending upward from the support bottom 18a, and a lower surface central portion of the support bottom 18a. And a shaft guide portion 18c extending in the vertical direction. In addition to this, the second support member 18 includes a support lid portion 18e and a support side wall portion 18d. The support side wall portion 18d is provided so as to continue upward from the support side portion 18b in a cylindrical shape, and the support lid portion 18e is connected to the upper end of the support side wall portion 18d. It is connected to. Similarly to the first embodiment, the second support member 18 can be moved in the vertical direction by the elevating drive device 15.
The 1st support member 17 has the support surface part 17a and the shaft part 7b similarly to 1st Embodiment.

The crucible upper portion 13a has a lower end portion connected to the crucible lower portion 13b and a side portion (side wall) 13ab extending vertically in the crucible 3, and a lid portion 13aa provided at the upper end of the side portion 3ab in a direction orthogonal to the vertical direction. It has. An opening 13ac through which the pedestal 4 passes is formed in the central portion of the lid portion 13aa.
The crucible upper portion 13a is supported on the upper portion of the crucible lower portion 13b and does not move relative to the crucible lower portion 13b. The crucible upper portion 13a is supported on the support surface portion 17a of the first support member 17 via the crucible lower portion 13b, and both the crucible upper portion 13a and the crucible lower portion 13b are supported by the first support member 17. It is in a state.

  The pedestal 14 is fixed to the center portion of the lower surface of the support lid portion 18 e of the second support member 18. On the other hand, an opening 13ac is formed in the central portion of the lid 13aa of the crucible upper portion 13a, and the base 14 fixed to the second support member 18 is inserted into the crucible 13 through the opening 13ac. ing. Thereby, seed crystal attachment surface 14a of pedestal 14 is located in crucible 13, and silicon carbide seed crystal 5 is attached to the lower surface of seed crystal attachment surface 14a. In the third embodiment, the pedestal 14 moves in the vertical direction in the crucible 13 by the vertical movement of the second support member 18 by the lifting drive device 15.

  The first weight sensor 19 detects the weights of the first support member 17 and the components supported by the first support member 17 (the crucible upper portion 13a and the crucible lower portion 13b containing the silicon carbide raw material 6). Thus, first weight sensor 19 can detect a change in weight of silicon carbide raw material 6 accommodated in crucible lower portion 13b. The second weight sensor 20 detects the weight of the second support member 18 including the base 14. Thereby, the second weight sensor 20 can detect a change in weight of the silicon carbide single crystal grown on the pedestal 14.

  Next, a method for manufacturing a silicon carbide single crystal using the silicon carbide single crystal manufacturing apparatus shown in FIG. 3 will be described.

The first weight sensor 19 detects a change in the weight of the first support member 17 and the configuration supported by the first support member 17 (the crucible upper portion 13a and the crucible lower portion 13b containing the silicon carbide raw material 6). Control circuit 16 calculates one or both of the sublimation amount and sublimation speed of silicon carbide raw material 6 based on this detected value. The second weight sensor 20 detects a change in the weight of the second support member 18 and the structure supported by the second support member 18 (including the pedestal 14 (including the silicon carbide seed crystal and the silicon carbide single crystal grown thereon). Calculates one or both of the growth amount and growth rate of the silicon carbide single crystal based on the detected value.
After that, the control circuit 16 compares the calculated growth rate and / or growth amount and / or sublimation amount and / or sublimation rate with a preset reference value, and if the result of comparison is outside the predetermined range. First, the growth conditions of the silicon carbide single crystal are adjusted so as to fall within the range.
Specifically, the temperature of the crucible upper part 13a or the pedestal 14 and / or the crucible lower part 13b is adjusted by adjusting the heating means. That is, by increasing the temperature of the crucible upper portion 13a or the pedestal 14, the deposition rate of the sublimation gas is suppressed and the growth rate is reduced, while the temperature of the crucible upper portion 13a or the pedestal 14 is decreased. The deposition rate of the sublimation gas is promoted to increase the growth rate. Further, by raising the temperature of the crucible lower portion 13b, the sublimation speed of the silicon carbide raw material 6 is increased, the amount of sublimation gas reaching the growth surface is increased, and the growth rate of the single crystal is increased. By lowering the temperature, the sublimation rate of the silicon carbide raw material 6 is decreased, the amount of sublimation gas reaching the growth surface is decreased, and the growth rate of the single crystal is decreased. Thus, the growth rate and / or growth amount of the single crystal and / or the sublimation amount and / or sublimation rate of the silicon carbide raw material can be set within a predetermined range.
Alternatively, in order to adjust the growth conditions of the silicon carbide single crystal, the first support member 17 and the second support member 18 are moved relative to each other in the vertical direction, or are raised or lowered at different speeds. Thereby, by changing the distance between the pedestal and the silicon carbide raw material, the distance between the growth surface of the single crystal and the raw material surface can be changed, and the growth rate and / or growth amount can be kept within a predetermined range.
Alternatively, the expected growth time of the silicon carbide single crystal is changed in order to adjust the growth conditions of the silicon carbide single crystal. This makes it possible to keep the growth amount of the single crystal within a predetermined range.
Alternatively, the pressure in the vacuum vessel is adjusted in order to adjust the growth conditions of the silicon carbide single crystal. Thereby, the growth rate and / or growth amount of the single crystal and / or the sublimation amount and / or sublimation rate of the silicon carbide raw material can be set within a predetermined range.
By performing one or more of the above adjustments, it is possible to produce a high-quality silicon carbide single crystal by adjusting the growth conditions even during the growth of the single crystal, and to improve the yield, It is possible to secure the desired number of wafers that can be acquired.

FIG. 4 is a schematic diagram showing a state in which silicon carbide single crystal 26 is grown on silicon carbide seed crystal 5 using the silicon carbide single crystal manufacturing apparatus shown in FIG.
As the silicon carbide single crystal 26 grows on the silicon carbide seed crystal 5, the distance between the growth surface of the silicon carbide single crystal 26 and the surface of the silicon carbide raw material (raw material surface) changes.
Along with the growth of silicon carbide single crystal 26 on silicon carbide seed crystal 5, polycrystalline silicon carbide 27 is grown on the lower surface of lid portion 13aa of crucible upper portion 13a.

[Silicon carbide single crystal manufacturing apparatus (fourth embodiment)]
FIG. 5 is a schematic cross-sectional view enlarging the vicinity of the pedestal of the silicon carbide single crystal manufacturing apparatus of the fourth embodiment.

Also in this embodiment, the pedestal is not fixed to the upper part of the crucible, but is fixed to the second support member, as in the third embodiment. The main difference from the third embodiment is that a first protrusion 35 having a downward inclined surface 35a is formed on the lid 33aa of the crucible upper portion 33a, and a second protrusion 37 having an upward inclined surface 37a. Is formed on the side wall 24 b of the base 24.
In the present embodiment, the lid 33aa of the crucible upper portion 33a is provided with the first protrusion 35, and the side wall 24b of the base 24 is provided with the second protrusion 37. However, the second protrusion 37 is provided on the side wall 24b of the base 24. A configuration in which the first protrusion 35 is simply provided on the lid 33aa of the crucible upper portion 3a may be employed.
The first weight sensor is provided on the first support member, the second weight sensor is provided on the second support member, and the second support member is connected to the lifting / lowering drive device as in the first embodiment. It is.

  In this embodiment, the crucible upper part 33a is supported by the upper part of the crucible lower part similarly to 3rd Embodiment. The crucible upper portion 33a has a lower end connected to the lower portion of the crucible, and a side portion (side wall) 33ab extending vertically in the crucible 33, and a lid portion 33aa provided at the upper end of the side portion 33ab in a direction perpendicular to the vertical direction. And. An opening 33ac through which the pedestal 24 passes is formed in the center portion of the lid portion 33aa.

  The second support member 18 is provided so as to connect the cylindrical support side wall portion 18d provided so as to continue upward from the cylindrical support side portion 18b (see FIG. 3) and the upper end of the support side wall portion 18d. And a supporting lid portion 18e. The pedestal 24 is fixed to the lower center portion of the support lid portion 18 e of the second support member 18. Similarly to the third embodiment, the pedestal 24 protrudes downward from an opening 33ac formed in the lid portion 33aa of the crucible upper portion 33a, so that the seed crystal mounting surface 24a is located in the crucible. Silicon carbide seed crystal 5 is attached to the lower surface of seed crystal attachment surface 24a. Also in the present embodiment, the crucible upper portion 33a and the crucible lower portion 33b are in a fixed state as in the third embodiment, whereas the second support member 18 can move in the vertical direction, and this movement allows the pedestal 24 to move. Moves up and down in the crucible.

  The first projecting portion 35 is provided on the lower surface of the lid portion 33aa of the crucible upper portion 33a so as to protrude downward along the periphery of the opening 33ac of the lid portion 33aa. The first protrusion 35 has a lower inclined surface 35a that is inclined so that the inner wall 33abA side of the crucible is higher and the vertical center side of the crucible is lower, on the side facing the inner wall 33abA of the crucible. By having the vertical surface 35b on the vertical center side, the vertical section tapering downward is formed in a triangular tube shape. The downward inclined surface 35a is located on the side facing the side portion (side wall) 33ab of the crucible upper portion 33a. The vertical surface 35 b is located on the side facing the side wall 24 b of the pedestal 24, and linearly extends in the vertical direction with a gap 42 between the vertical surface 35 b and the side wall 24 b of the pedestal 4.

  The second projecting portion 37 is provided on the side wall 24b of the base 24 so as to stand in an oblique state so as to be positioned below the first projecting portion 35. Moreover, the 2nd protrusion part 37 equips the crucible's vertical center side with the upper inclined surface 37a which inclines so that the inner wall 33abA side of a crucible may be high and the vertical center side of a crucible may become low. It is preferable to face each other in parallel so as to form a predetermined gap 43 between the upper inclined surface 37a and the lower inclined surface 35a of the first protrusion 35.

  Next, the effect of the silicon carbide single crystal manufacturing apparatus shown in FIG. 5 will be described.

  The source gas sublimated from the silicon carbide source flows upward in the crucible and precipitates and grows as a single crystal on the silicon carbide seed crystal 5 attached to the pedestal 24. A solid line arrow G <b> 3 in FIG. 5A indicates the flow of the source gas that has passed through the pedestal 24 without being deposited on the pedestal 24. The temperature distribution around the pedestal 24 is high on the silicon carbide raw material side as shown by the dashed isotherm in FIG. 5A, and the temperature decreases toward the upper side (the lid portion 33aa of the crucible upper portion 33a). The source gas around the pedestal 24 as a whole moves along the direction perpendicular to the isotherm. The temperature of the source gas G3 decreases as it flows upward, and when it becomes supersaturated, it deposits as silicon carbide polycrystal 27 on the lid portion 3aa of the crucible upper portion 33a (see FIG. 5B).

In the present embodiment, a lower inclined surface 35a is formed on the first protrusion 35 formed on the lid portion 33aa of the crucible upper portion 33a, and the lower inclined surface 35a is inclined in the direction opposite to the flow of the source gas G3. Yes. With this configuration, a flow (arrow G4) opposite to this flow can be formed in the source gas G3 flowing upward. Thereby, it can suppress that source gas enters into the clearance 42 (opening 33ac) between the vertical surface 35b of the 1st projection part 35, and the side wall 24b of the base 24. FIG. In addition, the second protrusion 37 provided on the side wall 24b of the pedestal 24 is such that the source gas G3 that has flowed upward is directly between the vertical surface 35b of the first protrusion 35 and the side wall 24b of the pedestal 24. The entry into the opening 33ac) can be prevented. Further, the raw material gas is prevented from entering the gap 43 formed between the lower inclined surface 35a of the first protruding portion 35 and the upper inclined surface 37a of the second protruding portion 37. By forming the first protrusion 35 and the second protrusion 37, it is possible to further suppress the source gas from entering the gap 43 (opening 33ac).
With these configurations and operations, it is possible to suppress the precipitation of silicon carbide polycrystals on the vertical surface 35b and the side wall 24b, and the relative movement between the pedestal and the upper portion of the crucible becomes possible even during the growth of the silicon carbide single crystal.

[Silicon carbide single crystal manufacturing apparatus (fifth embodiment)]
As a fifth embodiment, a structure of a silicon carbide single crystal manufacturing apparatus to which the present invention shown in FIG. 6 is applied will be described.

The main configuration different from the first embodiment is that a second support member 48 that supports the base 4 and the crucible upper portion 3a is suspended from above by a suspension member (not shown). .
The first weight sensor 9 is provided on the first support member 7 and the second weight sensor 40 is provided on the second support member 48 in the same manner as in the first embodiment.

  Next, a method for manufacturing a silicon carbide single crystal using the silicon carbide single crystal manufacturing apparatus of FIG. 6 will be described.

The first weight sensor 9 detects a change in the weight of the first support member 7 and the configuration supported by the first support member 7 (the crucible lower portion 3b containing the silicon carbide raw material 6). A control circuit (not shown) calculates one or both of the sublimation amount and the sublimation speed of the silicon carbide raw material 6 based on the detected value. The second weight sensor 40 detects a change in the weight of the second support member 48 and the components supported by the second support member 48 (including the crucible upper portion 3a and the pedestal 4 (including the silicon carbide seed crystal and the silicon carbide single crystal grown thereon). The control circuit calculates one or both of the growth amount and growth rate of the silicon carbide single crystal based on the detected value.
Thereafter, the control circuit compares the calculated growth rate and / or growth amount and / or sublimation amount and / or sublimation rate with a preset reference value, and if the result of comparison is outside the predetermined range. Adjust the heating means so as to fall within the range, move the first support member 7 and the second support member 48 relative to each other in the vertical direction, or raise or lower at different speeds. Change the expected growth time of the single crystal or adjust the pressure in the vacuum vessel (furnace).
By performing one or more of the above adjustments, it is possible to produce a high-quality silicon carbide single crystal by adjusting the growth conditions even during the growth of the single crystal, and to improve the yield, It is possible to secure the desired number of wafers that can be acquired.

[Silicon carbide single crystal manufacturing apparatus (sixth embodiment)]
As a sixth embodiment, a structure of a silicon carbide single crystal manufacturing apparatus to which the present invention shown in FIG. 7 is applied will be described.

The difference from the third embodiment is that the second support member 58 that supports the base 14 and the crucible upper portion 13a is suspended from above by a suspension member (not shown).
The first weight sensor 19 is provided on the first support member 17 and the second weight sensor 50 is provided on the second support member 58, which is the same as in the third embodiment.

  Next, a method for manufacturing a silicon carbide single crystal using the silicon carbide single crystal manufacturing apparatus of FIG. 7 will be described.

The first weight sensor 19 detects a change in the weight of the first support member 17 and the configuration supported by the first support member 17 (the crucible lower portion 13b containing the silicon carbide raw material 6). A control circuit (not shown) calculates one or both of the sublimation amount and the sublimation speed of the silicon carbide raw material 6 based on the detected value. The second weight sensor 50 detects a change in weight of the second support member 58 and the structure (including the silicon carbide seed crystal and the silicon carbide single crystal grown thereon) supported by the second support member 58. The control circuit One or both of the growth amount and growth rate of the silicon carbide single crystal are calculated based on the detected value.
Thereafter, the control circuit compares the calculated growth rate and / or growth amount and / or sublimation amount and / or sublimation rate with a preset reference value, and if the result of comparison is outside the predetermined range. Adjust the heating means so as to fall within the range, move the first support member 17 and the second support member 48 relative to each other in the vertical direction, raise or lower at different speeds, silicon carbide Change the expected growth time of the single crystal or adjust the pressure in the vacuum vessel (furnace).
By performing one or more of the above adjustments, it is possible to produce a high-quality silicon carbide single crystal by adjusting the growth conditions even during the growth of the single crystal, and to improve the yield, It is possible to secure the desired number of wafers that can be acquired.

  In the following examples, a silicon carbide single crystal was manufactured using the silicon carbide single crystal manufacturing apparatus shown in FIG.

Example 1
A silicon carbide seed crystal having a diameter of 75 mm was used and adhered to the pedestal using an adhesive.
When the temperature in the crucible was 2400 ° C. and a silicon carbide single crystal was grown for 100 hours, a silicon carbide single crystal having a length of 30 mm grew. At this time, the weight of the second support member and the component supported by the second support member increased by 700 g, and the weight of the first support member and the component supported by the second support member decreased by 800 g. The difference of 100 g in weight is considered to be mainly caused by the escape of the raw material gas outside the crucible. The ingot obtained in this example was a high-quality single crystal with no mixing or cracking of different polymorphs.

(Example 2)
As in Example 1, a silicon carbide seed crystal having a diameter of 75 mm was used, and when a silicon carbide single crystal was grown at a temperature in the crucible of 2400 ° C., the second support member and the support member were supported by this after 80 hours had passed. The weight of the constructed component was increased by 490 g, and the weight of the first support member and the component supported thereon was decreased by 560 g. If the growth for 100 hours is continued as it is, the length of the grown silicon carbide single crystal was expected to be shorter than a predetermined length (30 mm). Therefore, when the growth time was extended to 115 hours, a silicon carbide single crystal having a length of 30 mm could be grown. The obtained ingot was a high-quality single crystal without mixing and cracking of different polymorphs.

(Example 3)
As in Example 1, a silicon carbide seed crystal having a diameter of 75 mm was used, and when a silicon carbide single crystal was grown at a temperature in the crucible of 2400 ° C., the second support member and the support member were supported by this after 80 hours had passed. The weight of the constructed component was increased by 620 g, and the weight of the first support member and the component supported thereon was reduced by 700 g. If the growth for 100 hours is continued as it is, the length of the grown silicon carbide single crystal is expected to be longer than a predetermined length (30 mm). Therefore, when the growth time was shortened to 90 hours, a silicon carbide single crystal having a length of 30 mm could be grown. The obtained ingot was a high-quality single crystal without mixing and cracking of different polymorphs.

Example 4
A silicon carbide seed crystal having a diameter of 75 mm was used in the same manner as in Example 1 and a silicon carbide single crystal was grown at a temperature in the crucible of 2400 ° C. When 50 hours had passed, the second support member and the support were supported by this. The weight of the constructed component was increased by 280 g, and the weight of the first support member and the component supported by the first supporting member was reduced by 320 g. In this example, comparison was made with reference growth conditions based on a conventionally obtained crystal growth database. As a result, it was found that the sublimation rate of the silicon carbide raw material and the growth rate of the silicon carbide single crystal were slower than the reference growth conditions. Based on this, the temperature at the top of the crucible was lowered by 10 ° C., and the temperature at the bottom of the crucible was raised by 10 ° C. to grow crystals. After 100 hours, the weight of the second support member and the component supported by the second support member increased by 700 g, and the weight of the first support member and the component supported by the second support member decreased by 800 g. The obtained ingot had a length of 30 mm and was a high-quality single crystal without mixing and cracking of different polymorphs.

(Example 5)
As in Example 1, a silicon carbide seed crystal having a diameter of 75 mm was used, and when a silicon carbide single crystal was grown at a temperature of 2300 ° C. in the crucible, the second support member and the support member were supported by this when 50 hours had passed. The weight of the constructed component was increased by 280 g, and the weight of the first support member and the component supported by the first supporting member was reduced by 320 g. In this example, comparison was made with reference growth conditions based on a conventionally obtained crystal growth database. As a result, it was found that the sublimation rate of the silicon carbide raw material and the growth rate of the silicon carbide single crystal were slower than the reference growth conditions. Based on this, the position of the crucible was raised by 5 mm, and the crystal was grown by increasing the temperature difference between the crucible upper part and the crucible lower part. After 100 hours, the weight of the second support member and the component supported by the second support member increased by 700 g, and the weight of the first support member and the component supported by the second support member decreased by 800 g. The obtained ingot had a length of 30 mm and was a high-quality single crystal without mixing and cracking of different polymorphs.

  The silicon carbide single crystal manufacturing apparatus and the silicon carbide single crystal manufacturing method of the present invention can be used for manufacturing a silicon carbide single crystal having a high quality growth amount.

3, 13, 33 Crucible 3a, 13a, 33a Crucible upper part 3aa, 13aa, 33aa Lid part 3ab, 13ab, 33ab Side part 3b, 13b, 33b Crucible lower part 4, 14, 24 Base 4a, 14a, 24a Seed crystal mounting surface 5 Silicon carbide seed crystal 6 Silicon carbide raw material 7, 17 First support members 8, 18, 48, 58 Second support members 9, 19 First weight sensors 10, 20, 40, 50 Second weight sensors 13ac, 33ac Opening 15 Driving device 21 Crucible upper connecting portion 21a Inclined connecting surface 22 Crucible lower connecting portion 22a Inclined connecting surface 24b Side wall 26 Silicon carbide single crystal 33abA Inner side wall 35 First protrusion 35a Lower inclined surface 37 Second protruding portion 37a Upper inclined surface 110 Heating Means G1, G2, G3, G4 Gas flow

Claims (8)

In a silicon carbide single crystal manufacturing apparatus for supplying a source gas on a silicon carbide seed crystal attached to a pedestal and growing a silicon carbide single crystal on the silicon carbide seed crystal,
A crucible composed of a crucible upper part and a crucible lower part,
Of the crucible upper part and the crucible lower part, a first support member that supports at least the crucible lower part,
A second support member for supporting the pedestal;
A weight sensor capable of independently detecting the weights of the first support member and the second support member;
An apparatus for producing a silicon carbide single crystal comprising heating means disposed around the crucible, wherein the first support member and the second support member are movable relative to each other in the vertical direction. The pedestal is supported on the lower surface of the lid at the top of the crucible,
The first support member supports only the crucible lower part among the crucible upper part and the crucible lower part,
2. The silicon carbide single crystal manufacturing apparatus according to claim 1, wherein the second support member supports the crucible upper portion and supports the pedestal via the crucible upper portion. The first support member supports both the crucible upper part and the crucible lower part,
2. The carbonization according to claim 1, wherein the pedestal protrudes downward from an opening formed in a lid portion of the crucible upper portion so that at least a seed crystal mounting surface thereof is located in the crucible. Silicon single crystal manufacturing equipment.   A first projection provided on the lower surface of the lid so as to protrude downward along the periphery of the opening, and is inclined so that the inner wall side of the crucible is high and the vertical center side of the crucible is low The silicon carbide single crystal manufacturing apparatus according to claim 3, further comprising a first protrusion having a downward inclined surface on a side facing the inner wall of the crucible.   The side wall of the pedestal is provided with a second protrusion having an upward inclined surface on the vertical center side of the crucible that is inclined so that the inner wall side of the crucible is high and the vertical center side of the crucible is low. The silicon carbide single crystal manufacturing apparatus according to any one of claims 3 and 4. The crucible upper part comprises a crucible upper connection part formed at the lower end of the side part,
The crucible lower part comprises a crucible lower connection part formed at the upper end of the side part,
The crucible upper connecting part and the crucible lower connecting part are inclined so that the inner wall side of the crucible is high and the outer wall side is low, and have inclined connection surfaces facing each other. The silicon carbide single crystal manufacturing apparatus according to one item.   The silicon carbide single crystal manufacturing apparatus according to any one of claims 1 to 6, wherein the second support member is suspended from above. In a method for producing a silicon carbide single crystal, a raw material gas is supplied onto a silicon carbide seed crystal attached to a pedestal, and a silicon carbide single crystal is grown on the silicon carbide seed crystal.
A crucible composed of a crucible upper portion and a crucible lower portion; a first support member that supports at least the crucible lower portion of the crucible upper portion and the crucible lower portion; a second support member that supports the pedestal; and the first support member And a weight sensor capable of independently detecting the weight of the second support member, and a heating means disposed around the crucible, wherein the first support member and the second support member move relative to each other in the vertical direction. Using a silicon carbide single crystal manufacturing device that is possible,
During the production of the silicon carbide single crystal, the growth amount and / or growth rate of the silicon carbide single crystal is obtained from the weight of the second support member detected using the weight sensor, and the weight sensor is used to detect the growth rate. The sublimation rate and / or sublimation amount of the silicon carbide powder raw material is determined from the weight of the first support member, and the growth rate and / or growth amount and / or the sublimation amount and / or sublimation rate are outside the desired range. In the case, at least one of (1) to (4) is performed so as to fall within the range; a method for producing a silicon carbide single crystal,
(1) Adjust the temperature of the crucible upper part or the pedestal and / or the crucible lower part,
(2) The first support member and the second support member are moved relative to each other in the vertical direction, or are raised or lowered at different speeds.
(3) Change the expected growth time of the silicon carbide single crystal.
(4) Adjust the furnace pressure.

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