SiC SINGLE CRYSTAL MANUFACTURING APPARATUS

Abstract

To provide a SiC single crystal manufacturing apparatus capable of suppressing a temperature fluctuation due to a crucible position even in a case of an enlarged crucible.SOLUTION: A SiC single crystal manufacturing apparatus includes a heat generation source, a soaking plate arranged above the heat generation source, a heating vessel that is positioned inside an outer edge of the soaking plate when seen from a vertical direction and is arranged above the soaking plate, a first cylindrical body arranged so as to cover a side surface positioned at an outer most side of the heating vessel when seen form the vertical direction, and a second cylindrical body arranged so as to cover the first cylindrical body in a state of having a separation part when seen from the vertical direction. A side surface of the first cylindrical body that at least faces the second cylindrical body is composed of a material that partly absorbs infrared and partly reflects infrared. A second surface of the second cylindrical body, which is a side surface facing the first cylindrical body, is composed of a material that at least partly reflects infrared.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for producing single crystal SiC. [Background technology]

[0002] Silicon carbide (SiC) has excellent electrical properties, such as an electric field strength at dielectric breakdown that is about one order of magnitude higher than that of silicon (Si), and a band gap that is about three times larger. In addition, SiC has excellent thermal properties, such as a thermal conductivity that is about three times higher than that of Si. Because of these excellent properties, SiC is expected to be applied to various devices such as power devices, high-frequency devices, and high-temperature operating devices. These devices are fabricated by forming an epitaxial layer that will become the active region of the device on a SiC single crystal substrate obtained by processing a SiC single crystal ingot, using a method such as chemical vapor deposition (CVD).

[0003] Currently, the mainstream method for producing SiC single crystals is the sublimation method, which involves heating the solid raw material SiC powder in a graphite crucible (heating vessel) at a high temperature exceeding 2000°C until it sublimes, and then supplying this sublimation gas to a seed crystal placed at a relatively low temperature to recrystallize it on the seed crystal, producing a single crystal ingot.

[0004] Sublimation method is different from melt growth method using liquid phase, in that it uses growth by gas, and therefore has a fundamental problem that defects are easily generated when grown at high speed. In other words, a certain amount of heating time is required to grow a single single crystal ingot. From this point of view, the applicant has previously proposed a technology for growing multiple single crystal ingots in parallel by arranging multiple crucibles and seed crystals in a single furnace (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-055282 Summary of the Invention [Problem to be solved by the invention]

[0006] SiC devices, which are attracting attention as power semiconductors, are beginning to be required to handle even larger currents. To realize SiC devices that can handle large currents, large SiC wafers are required, and to manufacture large SiC wafers, large single crystal ingots are required. To manufacture large single crystal ingots, the size of the crucible needs to be larger than before.

[0007] However, when multiple large crucibles are arranged and heated in a single furnace, the temperature tends to vary depending on the location of the crucibles. Such temperature variation leads to variation in the crystal growth rate of each single crystal ingot produced in each crucible, which may result in variation in performance.

[0008] In addition, the technology of Patent Document 1 arranges separate heat sources on the bottom and side of the crucible, and adjusts the ratio of the heating energy supplied from each heat source within a predetermined range. However, as the crucible becomes larger, the device itself also becomes larger, so the distance between the heat source arranged on the side and the crucible arranged in the furnace becomes greater, making it difficult for the heat energy from the heat source on the side to reach the crucible. Therefore, a time difference is generated between the timing when the output of the heat source on the side is adjusted and the timing when the heat energy from the heat source on the side after the output is adjusted reaches the crucible. Due to such circumstances, it becomes difficult to control the ratio of the heating energy from the heat source on the bottom and the heating energy from the heat source on the side to be adjusted within a predetermined range.

[0009] In view of the above problems, the present invention has an object to provide a SiC single crystal manufacturing apparatus that can suppress temperature variations depending on the position in the crucible, even when the crucible is large. [Means for solving the problem]

[0010] The SiC single crystal manufacturing apparatus according to the present invention comprises: A heat source; A heat equalizing plate disposed above the heat source so as to cover the heat source when viewed from a vertical direction; a heating vessel including a raw material containing region for containing a solid raw material made of SiC, the raw material containing region being located inside an outer edge of the heat equalizing plate when viewed from the vertical direction and disposed above the heat equalizing plate, and a seed crystal mounting portion for placing a seed crystal of SiC at a position spaced apart from the raw material containing region in the vertical direction; A first cylindrical body arranged to cover the outermost side surface of the heating container when viewed from the vertical direction; A second cylindrical body that covers the first cylindrical body while having a spaced portion when viewed from the vertical direction and is arranged to cover the heat equalizer plate and the heat source; A lid body is arranged to close a part of the upper surface of the second cylindrical body, At least a first surface of the first cylindrical body, which is a side surface facing the second cylindrical body, is made of a material that partially absorbs and partially reflects infrared rays, The second cylindrical body has a second surface, which is a side surface facing the first cylindrical body, made of a material that reflects at least a part of infrared rays, The bottom surface of the lid is made of a material that reflects at least a portion of infrared rays.

[0011] In this specification, "infrared rays" refers to electromagnetic waves that exhibit the ability to propagate heat when emitted.

[0012] According to the above configuration, heat generated from the heat source located below the heat equalizing plate heats the bottom of the heating container through the heat equalizing plate. In addition, infrared rays (radiant heat) emitted from the heat source itself or the heated heat equalizing plate proceed toward the second cylindrical body on the outside. Since the surface (second surface) of the second cylindrical body facing the first cylindrical body located inside is made of a material that reflects at least a part of infrared rays, the infrared rays are reflected by this second surface and proceed toward the first cylindrical body on the inside.

[0013] The surface (first surface) of the first cylindrical body facing the second cylindrical body located outside is made of a material that partially absorbs and partially reflects infrared rays. Therefore, the first cylindrical body itself is heated by reflecting part of the infrared rays reflected by the second surface back to the second cylindrical body side and absorbing part of the infrared rays. The first cylindrical body is also heated by the heat transmitted from the heated heat equalizing plate. As a result, the heated first cylindrical body functions as a secondary heat source and radiates infrared rays toward the heating container side located inside and the second cylindrical body side located outside. Furthermore, the surface (first surface) of the first cylindrical body facing the second cylindrical body also functions as a reflecting surface, reflecting part of the infrared rays incident from the second cylindrical body side and returning them to the second cylindrical body side.

[0014] The infrared rays emitted from the first surface of the first cylindrical body are reflected again by the second surface of the second cylindrical body and guided to the first cylindrical body. As described above, the infrared rays incident on the first cylindrical body are partially absorbed to heat the first cylindrical body, and partially reflected back to the second cylindrical body. In this way, a portion of the infrared rays is propagated vertically upward while repeatedly reflecting between the first cylindrical body and the second cylindrical body. In other words, the separation portion located between the first cylindrical body and the second cylindrical body forms a propagation path that guides the infrared rays reflected between the first surface of the first cylindrical body and the second surface of the second cylindrical body vertically upward.

[0015] As a result, the first cylindrical body is easily heated even at a position away from the heat equalizer toward the lid body in the vertical direction (a vertically upward position) because infrared rays radiated from the second surface of the second cylindrical body are incident thereon. Therefore, the first cylindrical body functions as a secondary heat source overall in the height direction, and the heating container arranged inside the first cylindrical body can be heated by the infrared rays radiated inward from this first cylindrical body regardless of the height position.

[0016] Furthermore, according to the above configuration, the bottom surface of the lid is also made of a material that reflects infrared rays. Therefore, when infrared rays propagate vertically upward while repeatedly being reflected between the first surface of the first cylindrical body and the second surface of the second cylindrical body, when the infrared rays are incident on the bottom surface of the lid, they are reflected by the bottom surface of the lid and propagate downward. As a result, the heating container can be heated from above.

[0017] According to the SiC single crystal manufacturing apparatus having the above structure, the heat source as the primary heat source is arranged vertically below the heat equalizer plate, but the heating container can be heated not only from the bottom side but also from the side and top side. The thermal energy from the side and top is not supplied directly from the primary heat source, but from infrared rays from the first cylindrical body that functions as a secondary heat source heated by heat transfer or radiation, and infrared rays reflected from the reflecting surface. Therefore, the ratio of the thermal energy supplied to the heating container from the side and top to the thermal energy supplied to the heating container from the bottom is uniquely determined by the material, shape, size, etc. of the first cylindrical body, the second cylindrical body, and the lid.

[0018] In other words, if the materials, shapes, dimensions, etc. of the first cylindrical body, the second cylindrical body, and the lid are adjusted in advance to achieve the desired heat balance, even if the output of the heat source as the primary heat source arranged below the heat equalizer plate is adjusted for temperature control, the heat balance according to the heating direction is unlikely to be significantly disrupted due to this output control. Therefore, even when a large heating container is used, the occurrence of temperature variation according to the position of the heating container is suppressed.

[0019] The second surface of the second cylindrical body may have a higher infrared reflectance than the first surface of the first cylindrical body. More specifically, the second cylindrical body may be made of a main material having thermal insulation properties, and a coating material or sheet material having a higher infrared reflectance than the main material may be formed on the second surface.

[0020] In this specification, "having thermal insulation properties" refers to a thermal conductivity of 10 [W / (m·K)] or less.

[0021] As described above, the first cylindrical body has a function of reflecting a part of infrared rays toward the second cylindrical body, and also has a function of radiating infrared rays inward as a secondary heat source to heat the heating container arranged inside the first cylindrical body from the side. In contrast, the second cylindrical body only needs to have a function of reflecting infrared rays toward the first cylindrical body, and does not necessarily need to function as a secondary heat source. In other words, it is more preferable that the second cylindrical body has a higher reflectivity to infrared rays than the first cylindrical body.

[0022] In particular, by constructing the second cylindrical body from a main material having thermal insulation properties, the amount of heat discharged to the outside through the second cylindrical body can be reduced, and the thermal energy generated from the heat source can be efficiently supplied to the heating container. In this specification, the "main material" refers to a material that accounts for 50% or more by mass of the constituent materials.

[0023] The second cylindrical body and the cover may be configured from the same member. Furthermore, the second cylindrical body and the cover may be an integral member.

[0024] The lid may have an opening for releasing heat in at least a part of a region facing the top of the heating container when viewed in the vertical direction.

[0025] The SiC single crystal manufacturing apparatus includes a plurality of the heating containers, All of the plurality of heating containers are arranged so as to be located inside an outer edge of the heat equalizing plate when viewed in the vertical direction, The first cylindrical body may be arranged so as to cover the outermost heating containers when viewed from the vertical direction.

[0026] According to the above configuration, the outermost heating container is heated from the side by infrared rays radiated from the first cylindrical body, and the heating containers located inside are heated from the side by infrared rays radiated from the adjacent heating containers. As described above, the heat source as the primary heat source is present below the heat equalizer plate, and there is no need to provide separate heat sources on the sides and above.

[0027] Therefore, even if the output of the heat source as the primary heat source arranged below the heat equalizer plate is adjusted for temperature control, the heat balance according to the heating direction is unlikely to be significantly disrupted by this output control. Therefore, even if multiple heating containers are used, the occurrence of temperature variation according to the position of the heating container is suppressed. As a result, it is possible to manufacture multiple large SiC ingots in parallel while suppressing the variation in performance.

[0028] From the above viewpoint, it is preferable that each of the heating containers is not covered with a member having thermal insulation properties and is configured to allow heat propagation by radiation between adjacent heating containers. Effect of the Invention

[0029] According to the SiC single crystal manufacturing apparatus of the present invention, even if the heating container is enlarged, it is possible to suppress temperature variations depending on the position of the heating container. [Brief description of the drawings]

[0030] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of one embodiment of a SiC single crystal manufacturing apparatus of the present invention. [Diagram 2] 2 is a schematic plan view of the SiC single crystal manufacturing apparatus shown in FIG. 1 with a lid removed. FIG. [Diagram 3] FIG. 2 is a cross-sectional view showing a schematic structure of a heating container. [Figure 4] FIG. 2 is a schematic plan view of the lid. [Diagram 5]This is an enlarged view of a portion of Figure 1, with a schematic diagram of infrared propagation. [Figure 6] FIG. 3 is a plan view showing a model of a SiC single crystal manufacturing apparatus prepared as Example 1, following FIG. 2. [Figure 7A] FIG. 3 is a plan view showing a model of a SiC single crystal manufacturing apparatus prepared as Comparative Example 1, following the example of FIG. 2. [Figure 7B] FIG. 2 is a cross-sectional view of a model of a SiC single crystal manufacturing apparatus prepared as Comparative Example 1, shown following FIG. [Figure 8A] FIG. 3 is a plan view showing a model of a SiC single crystal manufacturing apparatus prepared as Comparative Example 2, following FIG. 2. [Figure 8B] FIG. 2 is a cross-sectional view showing a model of a SiC single crystal manufacturing apparatus prepared as Comparative Example 2, following the example of FIG. [Figure 9A] FIG. 3 is a plan view showing a model of a SiC single crystal manufacturing apparatus prepared as Reference Example 1, following FIG. 2. [Figure 9B] FIG. 2 is a cross-sectional view showing a model of a SiC single crystal manufacturing apparatus prepared as Reference Example 1, following the example of FIG. [Figure 10A] This is a cross-sectional view of 3D measurements when a 6-inch single crystal ingot is grown with uniform temperature distribution. [Figure 10B] This is a cross-sectional view of 3D measurements when a 6-inch single crystal ingot is grown with non-uniform temperature distribution. [Figure 11] 1. FIG. 3 is a cross-sectional view showing the configuration of another embodiment of the SiC single crystal manufacturing apparatus of the present invention, following the example of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] An embodiment of a SiC single crystal manufacturing apparatus according to the present invention will be described below with reference to the drawings as appropriate. Note that the drawings are all schematic illustrations, and the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

[0032] FIG. 1 is a cross-sectional view showing a schematic configuration of one embodiment of a SiC single crystal manufacturing apparatus. In the following description, the XYZ coordinate system shown in FIG. 1 will be referred to as appropriate. Here, when a positive or negative direction is to be distinguished when expressing a direction, it is described with a positive or negative sign, such as "+Z direction" and "-Z direction". When a direction is to be expressed without distinguishing between positive and negative directions, it is simply described as "Z direction". That is, in this specification, when it is simply described as "Z direction", both "+Z direction" and "-Z direction" are included. In FIG. 1, the Z direction corresponds to the vertical direction.

[0033] FIG. 2 is a schematic plan view of SiC single crystal manufacturing apparatus 1 shown in FIG. 1 with lid 50 removed, and corresponds to a plan view seen from the +Z side in the -Z direction.

[0034] Fig. 3 is a cross-sectional view showing a schematic structure of heating vessel 10 included in SiC single crystal manufacturing apparatus 1 shown in Fig. 1. Fig. 4 is a schematic plan view of lid body 50, which corresponds to a plan view seen from the +Z side in the -Z direction, similar to Fig. 2. Fig. 5 is a partially enlarged view of Fig. 1, and the state of infrared propagation is also shown.

[0035] The structure of the SiC single crystal manufacturing apparatus 1 will be described in detail below with reference to FIGS.

[0036] (Heat source 3) As shown in Fig. 1, the SiC single crystal manufacturing apparatus 1 includes a heat source 3. This heat source 3 functions as a primary heat source.

[0037] In the SiC single crystal manufacturing apparatus 1 of this embodiment, the type of heat source 3 is not particularly limited, and any known heating method such as resistance heating or induction heating can be used. In view of the controllability of the amount of heat generated from the heat source 3, it is preferable to use resistance heating, and it is more preferable to have a structure equipped with a three-phase AC power supply mechanism.

[0038] (Soaking plate 5) As shown in FIG. 1, the SiC single crystal manufacturing apparatus 1 includes a heat equalizer plate 5 located on the +Z side of a heat source 3.

[0039] The heat spreader plate 5 is provided for the purpose of spreading the heat radiated from the heat source 3 in the XY plane direction. In view of this, it is preferable that the heat spreader plate 5 exhibits anisotropic thermal conduction properties, in which the thermal conductivity in the XY plane direction is higher than the thermal conductivity in the Z direction. As an example, the heat spreader plate 5 is made of a C / C composite material or a laminate of multiple carbon members. In FIG. 5, the state in which the heat Ea is propagated in the XY plane direction by the heat spreader plate 5 is shown by a two-dot chain line.

[0040] The heat is radiated from the heat source 3, and the heat is equal to or higher than 2000°C. For this reason, the heat is equal to or higher than 2000°C is made of a material that ensures strength even in a temperature environment of 2000°C or higher. The above-mentioned material examples can be used in such a temperature environment. It is preferable that not only the heat is equal to 5, but also each of the elements of the SiC single crystal manufacturing apparatus 1, which will be described later, be made of a material that ensures strength even in a temperature environment of 2000°C or higher.

[0041] 1, the heat equalizing plate 5 has a larger area in the XY plane than the heat source 3, so when viewed from the +Z side, the heat source 3 is hidden below the heat equalizing plate 5. In this case, the heat equalizing plate 5 is disposed so as to cover the heat source 3 when viewed from the +Z side, so the heat source 3 is not shown in FIG.

[0042] However, this does not exclude the case where the area of ​​the heat equalizer plate 5 in the XY plane direction is smaller than that of the heat source 3 in the SiC single crystal manufacturing apparatus 1. For example, when the heat source 3 is configured to have resistance heating means arranged in a ring shape on a plate-shaped member, or when the heat source 3 is configured by arranging individual resistance heating means in a ring shape, the heat generated from the heat source 3 tends to concentrate at the arrangement points of the resistance heating means. For this reason, the heat equalizer plate 5 is provided from the viewpoint of spreading the heat in the XY plane direction. In other words, the relative size relationship between the heat equalizer plate 5 and the heat source 3 when viewed from the Z direction is arbitrary.

[0043] In FIG. 1, the heat source 3 and the heat equalizing plate 5 are spaced apart in the Z direction, but the present invention does not exclude the case where the heat source 3 and the heat equalizing plate 5 are in contact with each other.

[0044] (Heating container 10) 1, the SiC single crystal manufacturing apparatus 1 includes a heating container 10 disposed at a position on the +Z side of a heat equalizing plate 5. The SiC single crystal manufacturing apparatus 1 of the present embodiment includes a plurality of heating containers 10, 10, . . .

[0045] As shown in FIG. 2, all of the multiple heating containers 10, 10, . . . are located inside the outer edge 5a of the heat equalizing plate 5 when viewed in the Z direction.

[0046] 3, the heating vessel 10 has a source material containing region 13 for containing a solid source material 11S made of SiC, and a seed crystal mounting portion 16 for disposing a seed crystal 12 of SiC at a position spaced apart from the solid source material 11S in the Z direction. The heating vessel 10 is also called a crucible.

[0047] The raw material containing region 13 is a bottomed cylindrical body having a cylindrical side portion 14 and a bottom portion 15, and contains the solid raw material 11S in a portion of the internal space. In the example of Fig. 3, an annular seed crystal mounting portion 16 is arranged connected to the +Z side of the side portion 14, and a SiC seed crystal 12 is stably held on the upper surface of the seed crystal mounting portion 16. The -Z side surface of the arranged seed crystal 12 is exposed to the internal space of the raw material containing region 13.

[0048] When the heating vessel 10 is heated, the solid source material 11S contained in the source material containing region 13 is heated and sublimated, and is transformed into the gas source material 11G. When this gas source material 11G reaches the -Z side surface of the seed crystal 12, a SiC single crystal grows.

[0049] In the SiC single crystal manufacturing apparatus 1 of this embodiment, the size of the SiC seed crystal 12 attached by the seed crystal attachment portion 16 is not particularly limited. However, the SiC single crystal manufacturing apparatus 1 of this embodiment has the effect of suppressing temperature variations according to the position of the heating vessel 10, even when a large SiC single crystal is grown using a large crystal having a diameter of 6 inches (152.4 mm) or more or 8 inches (203.2 mm) or more. This point will be described later.

[0050] In the present invention, the detailed structure of seed crystal attachment portion 16 is not particularly limited, but for example, a method of providing a seat protruding from the inner wall of side portion 14 to hold the outer periphery of seed crystal 12 can be used.

[0051] From the viewpoint of increasing the vapor pressure of the gaseous source material 11G generated by sublimation of the solid source material 11S, it is preferable that the heating vessel 10 is provided with a lid portion 19 as shown in FIG.

[0052] Since the heating vessel 10 becomes hot when the solid raw material 11S is sublimated to grow the SiC single crystal, it is preferable that the heating vessel 10 is made of a material that can withstand high temperatures. Examples of materials that can withstand such high temperatures include one or more materials belonging to the group consisting of graphite, graphite coated with tantalum, and tantalum carbide.

[0053] (First cylindrical body 30) As shown in FIGS. 1 and 2, the SiC single crystal manufacturing apparatus 1 includes a first cylindrical body 30 disposed so as to cover the multiple heating vessels 10, 10, . . . when viewed from the Z direction.

[0054] In this embodiment, as shown in Fig. 1, the first cylindrical body 30 is held on the upper surface of the heat equalizing plate 5, and the upper surface of the heat equalizing plate 5 functions as the bottom surface, thereby forming a cylindrical space that is open at the top. However, the first cylindrical body 30 itself may have a bottom. In addition, the present invention does not exclude the case where the first cylindrical body 30 and the heat equalizing plate 5 are separated from each other in the Z direction.

[0055] When the first cylindrical body 30 receives infrared rays radiated from a heater, it absorbs some of the infrared rays and is heated, while reflecting some of the infrared rays. More specifically, the first surface 31 located on the outside of the surfaces of the first cylindrical body 30 realizes the function of absorbing some of the infrared rays while reflecting some of the infrared rays. The inner surface of the first cylindrical body 30 may also realize the same function.

[0056] An example of the first cylindrical body 30 that realizes such a function is a structure made of carbon fiber felt or a plurality of carbon plate-like members arranged with gaps between them.

[0057] The outer surface (first surface 31) of the first cylindrical body 30 may have a lower reflectance than absorptance when receiving infrared rays. On the other hand, the inner surface of the first cylindrical body 30 may function solely as a surface that radiates infrared rays from the first cylindrical body 30 after heating. However, the inner surface of the first cylindrical body 30 may also have a function of reflecting part of the infrared rays, similar to the first surface 31.

[0058] (Second cylindrical body 40) As shown in FIGS. 1 and 2, the SiC single crystal manufacturing apparatus 1 includes a second cylindrical body 40 disposed so as to cover the first cylindrical body 30 with a separating portion 60 formed therebetween.

[0059] More specifically, the second cylindrical body 40 is disposed so as to cover not only the first cylindrical body 30 but also the heat equalizing plate 5 and the heat source 3 from the sides.

[0060] The second cylindrical body 40 has a function of reflecting at least a part of the infrared rays emitted from the heating body, particularly on the inner surface (second surface 41). The second surface 41 of the second cylindrical body 40 may have a higher reflectance of infrared rays than the first surface 31 of the first cylindrical body 30.

[0061] Preferably, the second cylindrical body 40 is made of a main material exhibiting thermal insulation properties, and a coating material or sheet material having a higher infrared reflectance than the main material is formed on the second surface 41. An example of such a material is a molded thermal insulation material mainly composed of carbon, with a graphite sheet mainly composed of carbon and exhibiting metallic luster formed on the surface. Other examples of coating materials include carbides of high-melting point metals such as tantalum carbide and niobium carbide.

[0062] (Cover 50) 1 and 2, the SiC single crystal manufacturing apparatus 1 includes a lid 50 disposed so as to close a portion of the upper surface of the second cylindrical body 40. More specifically, as shown in FIGS. 1 and 4, the lid 50 has a heat extraction opening 53 in at least a portion of the region facing the top of the heating vessel 10 in the Z direction.

[0063] The lid body 50, like the second surface 41 of the second cylindrical body 40, has the function of reflecting at least a portion of the infrared rays when it receives the infrared rays radiated from the heating body, on at least the -Z side surface (bottom surface 51).

[0064] The lid body 50 may be made of the same material as the second cylindrical body 40. Furthermore, the lid body 50 may be made of an integral member with the second cylindrical body 40.

[0065] (Heat flow) Next, the flow of heat in the SiC single crystal manufacturing apparatus 1 will be described with reference to FIG.

[0066] Heat generated from the heat source 3 as a primary heat source is received by the heat equalizing plate 5 as infrared rays E0, and heats the heat equalizing plate 5. When the heat source 3 is in contact with the heat equalizing plate 5, the heat from the heat source 3 is directly transferred to the heat equalizing plate 5, thereby heating it. The heated heat equalizing plate 5 propagates heat in the XY plane direction (heat Ea).

[0067] The heated heat equalizing plate 5 functions as a secondary heat source, radiating infrared rays E1 to the +Z side to heat the heating container 10 from the -Z side. In addition, the first cylindrical body 30 is heated by infrared rays from the heat equalizing plate 5 or by thermal conduction.

[0068] When the -Z side region of the first cylindrical body 30 is heated, it functions as a secondary heat source and emits infrared rays E2. The heating container 10 is heated from the side by the infrared rays E2 emitted inward from the first cylindrical body 30. In addition, the infrared rays E3 emitted outward from the first cylindrical body 30 are incident on the second surface 41 of the second cylindrical body 40. Note that there may be cases where a part of the infrared rays E1 from the heat equalizing plate 5 or a part of the infrared rays E0 from the heat source 3 are incident on the second cylindrical body 40.

[0069] As described above, the second surface 41 of the second cylindrical body 40 is made of a material that is reflective to infrared rays. Therefore, the infrared rays E3 that travel toward the outside and are incident on the second surface 41 of the second cylindrical body 40 are reflected by the second surface 41 of the second cylindrical body 40 and returned to the first cylindrical body 30 located inside. In addition, the second cylindrical body 40 may be partially heated so that the second cylindrical body 40 emits infrared rays as a secondary heat source.

[0070] When the infrared rays E3 emitted from the second cylindrical body 40 are received by the first surface 31 of the first cylindrical body 30, a portion of the infrared rays E3 is absorbed, thereby heating the first cylindrical body 30. As a result, the first cylindrical body 30 functions as a secondary heat source, and emits infrared rays E2 inward in the same manner as described above, thereby heating the heating container 10 from the side. Also, a portion of the infrared rays E3 is reflected again by the first surface 31 of the first cylindrical body 30 and returned to the second cylindrical body 40 side.

[0071] That is, the infrared rays E3 are propagated in the +Z direction while being repeatedly reflected within the spaced apart portion 60. As a result, the infrared rays E3 are incident on the first cylindrical body 30 at different positions in the Z direction, and the first cylindrical body 30 is heated by the infrared rays E3 even at positions away from the heat equalizer plate 5 in the Z direction.

[0072] Furthermore, when a portion of the infrared rays E3 is incident on the bottom surface 51 of the lid body 50, it is reflected by the bottom surface 51 of the lid body 50 and propagates downward, heating the heating container 10 from above.

[0073] As described above, according to the SiC single crystal manufacturing apparatus 1 of this embodiment, the heat source 3 as the primary heat source is arranged on the -Z side of the heat equalizer plate 5, but it is possible to heat the heating container 10 not only from the bottom side, but also from the side and top sides.

[0074] As described above, the heating of the heating container 10 from above is caused by infrared rays E3 reflected from the reflecting surface. The heating of the outermost heating container 10 from the side is caused by infrared rays E2 from the first cylindrical body 30 which functions solely as a secondary heat source. The heating of the inner heating container 10 from the side is caused by infrared rays E2 from a heated heating container 10 arranged adjacent to the outer side. At this time, the heating container 10 itself functions as a secondary heat source.

[0075] Therefore, according to the above configuration, the heating vessel 10 can be heated from the side and from above without arranging a primary heat source on the side or top surface. As a result, even if the output of the heat source 3 as the primary heat source is adjusted for temperature control, it is possible to substantially maintain the ratio of thermal energy in each heating direction for the heating vessel 10. Therefore, in the SiC single crystal manufacturing apparatus 1, by appropriately adjusting the materials, shapes, dimensions, etc. of the first cylindrical body 30, the second cylindrical body 40, and the lid body 50 in advance, it is possible to adjust the temperature of the heating vessel 10 while maintaining a preferable heat balance.

[0076] In other words, according to the SiC single crystal manufacturing apparatus 1, the material, shape, dimensions, etc. of the first cylindrical body 30, the second cylindrical body 40, and the lid body 50 are appropriately adjusted in advance so that the heating state can be made substantially uniform regardless of the position of each heating vessel 10, 10, ..., thereby suppressing the occurrence of temperature variation according to the position of the heating vessels 10, 10, .... This makes it possible to manufacture multiple SiC ingots in parallel while suppressing the variation in performance.

[0077] [verification] The fact that temperature variations are suppressed by the above-mentioned SiC single crystal manufacturing apparatus 1 will be described in detail with reference to examples.

[0078] Example 1 Fig. 6 is a plan view showing a model of the SiC single crystal production apparatus 1 prepared as Example 1, following Fig. 2. As the model of Example 1, one equipped with 19 heating containers 10, 10, ... was used.

[0079] A cylindrical second cylinder 40 was prepared, and a heat source 3 consisting of a resistance heating means having a three-phase AC power supply mechanism was placed at the bottom of the second cylinder 40. A molded heat insulating material mainly composed of carbon and having a graphite sheet material applied to the surface was used as the second cylinder 40.

[0080] The heat source 3 is a heater used as a resistance heating means, and is arranged in a circular ring shape with its center aligned with the center of the bottom of the second cylindrical body 40 and its diameter smaller than the inner diameter of the bottom of the second cylindrical body 40.

[0081] A heat equalizing plate 5 made of anisotropic C / C composite material was placed on the top surface of the heat source 3. The position of the heat equalizing plate 5 was adjusted so that its center coincided with the center of the annular shape formed by the heat source 3. The material used for the heat equalizing plate 5 had a thermal conductivity of 4 W / (m K) in the Z direction and 30 W / (m K) in the XY plane directions at room temperature.

[0082] On the upper surface of the heat equalizing plate 5, 19 heating containers 10, 10, ... were installed at equal intervals in an arrangement manner as shown in Fig. 6. More specifically, one heating container 10c was installed at the center position, six heating containers 10, 10, ... were installed concentrically around the heating container 10c (heating container group 10b), and 12 heating containers 10, 10, ... were installed concentrically around the heating container 10c (heating container group 10a). The heating container 10 has a raw material storage area 13 made of a bottomed cylinder (see Fig. 3), and contains SiC powder (manufactured by Pacific Random Co., Ltd., model number: GMF-H) as solid raw material 11S from the bottom 15 to a predetermined height. Furthermore, a seed crystal 12 having a diameter of 6 inches (about 150 mm) was placed by a seed crystal mounting part 16 at a position spaced a predetermined distance from the upper surface of the solid raw material 11S in the Z direction.

[0083] A cylindrical first cylindrical body 30 was placed on the upper surface of the heat equalizing plate 5. The position of the first cylindrical body 30 was adjusted so that the center position of the first cylindrical body 30 coincided with the center position of the heat equalizing plate 5. A member made of carbon fiber felt was used for the first cylindrical body 30. As shown in FIG. 6, the first cylindrical body 30 was placed so that the inner surface of the first cylindrical body 30 surrounded 19 heating containers 10. The distance between the outer surface (first surface 31) of the first cylindrical body 30 and the inner surface (second surface 41) of the second cylindrical body 40 was set to 50 mm.

[0084] A lid body 50 was placed so as to cover the upper surface of the second cylindrical body 40. However, the lid body 50 used had openings 53 for heat removal formed at locations corresponding to above the tops of the 19 heating containers 10, 10, ...

[0085] The lid body 50 was a disk-shaped member made of the same material as the second cylindrical body 40. In addition, the 19 openings 53 provided in the lid body 50 had a size smaller than the diameter of the heating container 10.

[0086] Using the model of Example 1, a heating operation was carried out for 120 hours while controlling the output of heat source 3 so that the temperature of the upper surface of heat equalizing plate 5 was kept constant at 2350°C.

[0087] As a result of the above verification, the output of the heat source 3 was controlled within a range of 91kW±2kW, and the temperature of the upper surface of the heat equalizing plate 5 was maintained at 2350°C. At this time, the upper temperature of the innermost heating container 10c was 2113°C, the average value of the upper temperature of the six heating container groups 10b located on the outer side adjacent to the heating container 10c was 2110°C, and the average value of the upper temperature of the twelve heating container groups 10a located on the outer side was 2119°C. As a result, the difference between the maximum temperature and the minimum temperature of each group was 9°C, which was kept to 0.5% or less of the overall average (the overall average was 2116°C). The temperature values ​​were rounded off to the nearest tenth place. The ratio of the temperature difference to the overall average temperature was rounded off to the nearest tenth place. The same applies to the following examples and the like.

[0088] In other words, it was confirmed that the model of Example 1 allows heating of the 19 heating containers 10, 10, . . . under uniform temperature conditions.

[0089] Example 2 The heating operation was performed under the same conditions as in Example 1, except that the distance between the outer surface (first surface 31) of the first cylindrical body 30 and the inner surface (second surface 41) of the second cylindrical body 40 was set to 25 mm.

[0090] As a result of the verification using the model of Example 2, similarly to Example 1, the output of the heat source 3 was controlled within the range of 91 kW±2 kW, and the temperature of the upper surface of the heat equalizing plate 5 was maintained at 2350°C.

[0091] At this time, the temperature at the top of the innermost heating container 10c was 2121° C., the average temperature at the top of the group of six heating containers 10b located on the outside adjacent to the heating container 10c was 2122° C., and the average temperature at the top of the group of 12 heating containers 10a located on the outermost side was 2133° C. As a result, the difference between the maximum and minimum temperatures of each group was 12° C., which was kept below 0.57% of the overall average.

[0092] In other words, it was confirmed that in the model of Example 2 as well, the 19 heating containers 10, 10, . . . could be heated under uniform temperature conditions.

[0093] Example 3 The heating operation was performed under the same conditions as in Example 1, except that the distance between the outer surface (first surface 31) of the first cylindrical body 30 and the inner surface (second surface 41) of the second cylindrical body 40 was set to 15 mm.

[0094] As a result of the verification using the model of Example 3, similarly to Example 1, the output of the heat source 3 was controlled within the range of 91 kW±2 kW, and the temperature of the upper surface of the heat equalizing plate 5 was maintained at 2350° C.

[0095] At this time, the temperature at the top of the innermost heating container 10c was 2115° C., the average temperature at the top of the group of six heating containers 10b located on the outside adjacent to the heating container 10c was 2115° C., and the average temperature at the top of the group of 12 heating containers 10a located on the outermost side was 2122° C. As a result, the difference between the maximum and minimum temperatures of each group was 7° C., which was kept within 0.5% of the overall average.

[0096] In other words, it was confirmed that in the model of Example 3 as well, the 19 heating containers 10, 10, . . . could be heated under uniform temperature conditions.

[0097] Comparative Example 1 7A and 7B are diagrams illustrating a model of SiC single crystal production apparatus 1 prepared as Comparative Example 1, following the example of FIGS. 2 and 1, respectively.

[0098] The model of Comparative Example 1 is different from the model of Example 1 in that it does not include a first cylindrical body 30. On the other hand, an annular second heat generating source 61 is mounted inside the second cylindrical body 40. The surface of the second heat generating source 61 is disposed so as to be exposed to the heating containers 10, 10, ... side. The other points are common to the model of Example 1.

[0099] Using the model of Comparative Example 1, control of the output of the heat source 3 and the second heat source 61 was started so that the temperature of the upper surface of the heat equalizing plate 5 was constant at 2350°C, and the temperature of the inner surface (side surface temperature) of the second cylindrical body 40 was constant at 2320°C. At the initial point in time, the output of the heat source 3 was set to 87 kW, and the output of the second heat source 61 was set to 25 kW. However, after 70 hours or more had passed, the output of the heat source 3 was reduced to 80 kW while the temperature was maintained, while the output of the second heat source 61 was increased to 32 kW. Thereafter, the heating operation was performed for a total of 120 hours while maintaining the target temperatures.

[0100] As a result, it was confirmed that the temperature at the top of the heating vessels 10, 10, ... rose by about 20°C on average compared to Example 1. From this result, it is presumed that even if the set temperature conditions were the same, the temperature distribution changed due to mutual interference between the heat sources (heat source 3 and second heat source 61) during the long operation period of 120 hours.

[0101] Comparative Example 2 8A and 8B are diagrams illustrating a model of SiC single crystal production apparatus 1 prepared as Comparative Example 2, following the example of FIGS. 2 and 1, respectively.

[0102] The model of Comparative Example 2 corresponds to the model of Example 1 from which the first cylindrical body 30 has been removed, and the rest of the model was the same as that of Example 1.

[0103] Using the model of Comparative Example 2, a heating operation was performed for 120 hours while controlling the output of heat source 3 so that the temperature of the upper surface of heat equalizing plate 5 was kept constant at 2350°C.

[0104] As a result of verification using the model of Comparative Example 2, the temperature of the upper surface of the heat equalizing plate 5 was maintained at 2350° C. under control of the output of the heat source 3 within the range of 98 kW±2 kW.

[0105] At this time, the upper temperature of the innermost heating container 10c was 2159°C, the average upper temperature of the six heating container groups 10b located on the outer side adjacent to the heating container 10c was 2164°C, and the average upper temperature of the twelve heating container groups 10a located on the outer side was 2192°C. As a result, the difference between the maximum and minimum temperatures of each group was 33°C, which was more than 1.5% of the overall average. This value of 33°C is more than twice as high as that of each of Examples 1 to 3.

[0106] That is, it was confirmed that, according to the model of Comparative Example 2, there was variation in the temperature conditions for the 19 heating containers 10, 10, . . . compared with each of Examples 1 to 3.

[0107] (Reference example 1) 9A and 9B are diagrams illustrating a model of SiC single crystal manufacturing apparatus 1 prepared as Reference Example 1, following the example of FIGS. 2 and 1, respectively.

[0108] The model of Reference Example 1 corresponds to the model of Example 1 in which the first cylindrical body 30 is removed and the outer surface of each of the heating containers 10, 10, ... is covered with a third cylindrical body 63 made of the same material as the first cylindrical body 30. The rest is common to the model of Example 1.

[0109] Using the model of Reference Example 1, a heating operation was carried out for 120 hours while controlling the output of heat source 3 so that the temperature of the upper surface of heat equalizing plate 5 was kept constant at 2350°C.

[0110] As a result of verification using the model of Reference Example 1, the temperature of the upper surface of the heat equalizing plate 5 was maintained at 2350° C. while the output of the heat source 3 was controlled within the range of 95 kW±2 kW.

[0111] At this time, the upper temperature of the innermost heating container 10c was 2107°C, the average upper temperature of the six heating container groups 10b located on the outer side adjacent to the heating container 10c was 2112°C, and the average upper temperature of the twelve heating container groups 10a located on the outer side was 2152°C. As a result, the difference between the maximum and minimum temperatures of each group was 45°C, which was about 2.1% of the overall average. This value of 45°C is more than four times that of each of Examples 1 to 3.

[0112] That is, it was confirmed that, also in the model of Reference Example 1, there was variation in the temperature conditions for the 19 heating containers 10, 10, ... compared with each of Examples 1 to 3. Table 1 summarizes the results of the above-mentioned verification.

[0113] [Table 1]

[0114] In comparison between Reference Example 1 and Examples 1 to 3, in the model of Reference Example 1, each of the heating containers 10, 10, ... is covered with a third cylindrical body 63 made of a member made of carbon fiber felt, so it is assumed that the propagation of radiant heat between adjacent heating containers 10, 10, ... is suppressed. On the other hand, in Examples 1 to 3, it is assumed that infrared rays E2 (see FIG. 5) derived from radiant heat from the first cylindrical body 30 functioning as a secondary heat source are irradiated to the outermost heating container group 10a to heat the outermost heating container group 10a from the side, while the heated heating container group 10a itself functions as a secondary heat source and irradiates infrared rays derived from radiant heat to the heating container group 10b arranged inside, thereby heating the heating container group 10b from the side as well. Similarly, it is assumed that the heating container 10c located at the very center is heated from the side by the heated heating container group 10b itself functioning as a secondary heat source, irradiating the heating container 10c located inside with infrared rays derived from radiant heat.

[0115] FIG. 10A is a trace drawing of a cross section of a 3D measurement when a 6-inch single crystal ingot is grown with a uniform temperature distribution. FIG. 10B is a trace drawing of a cross section of a 3D measurement when a 6-inch single crystal ingot is grown with a purposely non-uniform temperature distribution in the XY plane direction. In detail, in the case of FIG. 10A, the degree of temperature variation according to position is suppressed to 1% or less of the average temperature, and in the case of FIG. 10B, the degree of temperature variation is 5% of the average temperature. It is confirmed that the shape of the single crystal ingot in FIG. 10B is distorted (asymmetrical from left to right in the drawing) compared to FIG. 10A. This suggests that the temperature conditions of the heating vessel 10 during growth differ depending on the location, which affects the shape of the single crystal ingot and also affects the performance obtained.

[0116] [Another embodiment] Another embodiment of the SiC single crystal manufacturing apparatus according to the present invention will be described below.

[0117] <1> Fig. 11 is a cross-sectional view showing the configuration of another embodiment of the SiC single crystal manufacturing apparatus 1 following Fig. 1. Unlike the above-mentioned embodiment, the SiC single crystal manufacturing apparatus 1 shown in Fig. 11 includes a single heating vessel 10.

[0118] Even with a SiC single crystal manufacturing apparatus 1 equipped with a single heating vessel 10 as shown in FIG. 11, the same effects as those of the above embodiment can be obtained.

[0119] That is, even with the SiC single crystal manufacturing apparatus 1 shown in FIG. 11, the heat source 3 as the primary heat source is arranged on the -Z side of the heat equalizer plate 5, and yet it is possible to heat the heating container 10 not only from the bottom side, but also from the side and top sides.

[0120] 5, heating of the heating container 10 from above is caused by infrared rays E3 reflected from the reflecting surface, and heating from the side is caused by infrared rays E2 from the first cylindrical body 30 which functions exclusively as a secondary heat source. Therefore, even if the size of the heating container 10 is increased, heating of the heating container 10 from the side and above is possible without arranging a primary heat source on the side or top surface.

[0121] As a result, even if the output of the heat source 3 as the primary heat source is adjusted for temperature control, it is possible to substantially maintain the ratio of thermal energy in each heating direction for the heating vessel 10. Therefore, in the SiC single crystal manufacturing apparatus 1, by appropriately adjusting the materials, shapes, dimensions, etc. of the first cylindrical body 30, the second cylindrical body 40, and the lid body 50 in advance, it is possible to adjust the temperature of the heating vessel 10 while maintaining a preferable heat balance. This makes it possible to manufacture a relatively large SiC ingot while suppressing the variation in performance.

[0122] <2> In the present invention, the heat source 3 as the primary heat source may be disposed on the -Z side of the heat equalizing plate 5, and the number of heat sources is not limited. However, since the presence of multiple heat sources 3, 3, ... may cause thermal crosstalk between the heat sources 3, 3, ... even on the bottom side of the heating container 10, it is more preferable that the heat source 3 is a single body.

[0123] In addition, compared to the case where a separate heat source is arranged on the side or top surface, the effect of thermal crosstalk that occurs when multiple heat sources 3, 3, ... are arranged on the -Z side of the heat equalizing plate 5 is significantly smaller. More specifically, even if multiple heat sources 3, 3, ... are arranged on the -Z side of the heat equalizing plate 5, the effect on the ratio of thermal energy in each heating direction for the heating container 10 is small. [Explanation of symbols]

[0124] 1: SiC single crystal manufacturing equipment 3: Heat source 5: Soaking plate 5a: Outer edge of heat plate 10: Heating container 10a: Heating container group 10b: Heating container group 10c: Heating container 11G: Gas source 11S: Solid raw material 12: Seed crystal 13: Raw material storage area 14: Side of raw material storage area 15: Bottom of raw material storage area 16: Seed crystal attachment part 19: Lid of heating container 30: First cylindrical body 31: First surface (of the first cylindrical body) 40:Second cylindrical body 41: Second surface (of the second cylindrical body) 50: Lid 51: Bottom of the lid 53: Opening 60: Separation part 61: Second heat source 63:Third cylindrical body E0,E1,E2,E3: Infrared Ea: Heat

Claims

1. A heat source; A heat equalizing plate disposed above the heat source so as to cover the heat source when viewed from a vertical direction; a heating vessel including a raw material containing region for containing a solid raw material made of SiC, the raw material containing region being located inside an outer edge of the heat equalizing plate when viewed from the vertical direction and disposed above the heat equalizing plate, and a seed crystal mounting portion for placing a seed crystal of SiC at a position spaced apart from the raw material containing region in the vertical direction; A first cylindrical body arranged to cover the outermost side surface of the heating container when viewed from the vertical direction; A second cylindrical body that covers the first cylindrical body while having a spaced portion when viewed from the vertical direction and is arranged to cover the heat equalizer plate and the heat source; A lid body is arranged to close a part of the upper surface of the second cylindrical body, At least a first surface of the first cylindrical body, which is a side surface facing the second cylindrical body, is made of a material that partially absorbs and partially reflects infrared rays, The second cylindrical body has a second surface, which is a side surface facing the first cylindrical body, made of a material that reflects at least a part of infrared rays, A SiC single crystal manufacturing apparatus, characterized in that a bottom surface of the lid body is made of a material that reflects at least a portion of infrared rays.

2. 2. The SiC single crystal manufacturing apparatus of claim 1, wherein the separation portion located between the first cylindrical body and the second cylindrical body forms a propagation path for guiding infrared light reflected between the first surface and the second surface vertically upward.

3. 2. The SiC single crystal manufacturing apparatus according to claim 1, wherein the second surface of the second cylindrical body has a higher reflectivity to infrared rays than the first surface of the first cylindrical body.

4. The SiC single crystal manufacturing apparatus of claim 3, characterized in that the second cylindrical body is made of a main material having thermal insulation properties, and a coating material or sheet material having a higher reflectivity to infrared rays than the main material is formed on the second surface.

5. 2. The SiC single crystal manufacturing apparatus according to claim 1, wherein the second cylindrical body and the lid body are made of the same material.

6. 2. The SiC single crystal manufacturing apparatus according to claim 1, wherein the lid has an opening for releasing heat in at least a part of an area facing a top of the heating vessel when viewed from the vertical direction.

7. A plurality of the heating containers are provided, All of the plurality of heating containers are arranged so as to be located inside an outer edge of the heat equalizing plate when viewed in the vertical direction, The SiC single crystal manufacturing apparatus according to any one of claims 1 to 6, characterized in that the first cylindrical body is arranged to cover the outermost heating containers when viewed from the vertical direction.

8. The SiC single crystal manufacturing apparatus according to claim 7, characterized in that each of the heating containers is not covered with a material having thermal insulation properties and is configured to enable heat transmission by radiation between adjacent heating containers.

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