Sic single crystal manufacturing apparatus

Abstract

To provide an apparatus for producing an SiC single crystal capable of suppressing the variation of the temperature of a crucible.SOLUTION: The SiC single crystal manufacturing apparatus includes a chamber, a heating chamber, and a growth chamber. The heating compartment is disposed in the chamber and includes a heat source. The growth chamber is disposed in the chamber and located above the heating chamber. The growth chamber includes a plurality of crucibles, a heat insulation part, and an outer peripheral heat conduction part. The plurality of crucibles are provided side by side in a horizontal direction, into which a SiC raw material can be charged and to which a SiC seed crystal can be attached. The heat insulating unit has a plurality of through holes corresponding to the plurality of crucibles. Each of the through-holes forms a heat channel for flowing heat supplied from a heat source upward through the corresponding crucible. The peripheral heat conduction portion is disposed on a periphery of the plurality of crucibles, and conducts heat supplied from the heat source to the crucibles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a SiC single crystal manufacturing apparatus, and more specifically to a SiC single crystal manufacturing apparatus for manufacturing SiC (Silicon Carbide) single crystals. [Background technology]

[0002] SiC single crystals, which have a wide band gap and high thermal conductivity, are attracting a great deal of attention in the fields of electronic circuits that require high voltage resistance and electronic materials used at high temperatures.

[0003] The main method for producing SiC single crystals is the sublimation recrystallization method, in which raw SiC powder is sublimated at temperatures exceeding 2000°C in a cylindrical graphite crucible, and then recrystallized on a seed crystal at a relatively low temperature to obtain a single crystal ingot.

[0004] To create such a high-temperature environment exceeding 2000°C, a high-frequency induction heating furnace is used, which directly heats the crucible itself by utilizing the induced current generated in the graphite crucible by applying high-frequency waves. By controlling the heating area using the induced current, a temperature gradient is established in which the temperature decreases from the SiC raw material placed at the bottom of the crucible to the seed crystal placed at the top, and this temperature gradient promotes the sublimation and recrystallization reactions.

[0005] In this method, since the sidewall of the cylindrical crucible is primarily heated, the temperature tends to decrease toward the center of the cylindrical diameter, making it particularly difficult for the SiC raw material powder located near the center of the cylindrical axis of the crucible to sublimate, resulting in a problem of reduced raw material utilization. For this reason, various efforts have been made to effectively transfer heat to the vicinity of the axial center (see, for example, Japanese Patent No. 5892209 (Patent Document 1)).

[0006] On the other hand, in conventional SiC single crystal manufacturing, it is common to grow one ingot per furnace, as mentioned above, and for mass production, it is necessary to increase the number of furnaces, which makes it difficult to achieve economies of scale when increasing mass production volumes.

[0007] One solution to this problem is to install multiple crucibles in a single furnace, allowing multiple ingots to be grown in parallel simultaneously. However, with the high-frequency induction heating method described above, the heating area depends on the distance from the coil. Therefore, when multiple crucibles are installed in a furnace, only the crucible sidewalls near the coil are heated. Therefore, Japanese Patent Publication No. 6872346 (Patent Document 2) proposes to overcome this problem by installing three sets of compartments in a high-frequency furnace and rotating them on two axes for parallel processing. However, maintaining rotational motion in an ultra-high-temperature environment exceeding 2000°C for a long period of time poses significant challenges.

[0008] On the other hand, in Japanese Patent Laid-Open No. 2022-55282 (Patent Document 3), multiple crucibles are installed horizontally, and heat sources are placed below and to the sides to achieve uniform heating of the multiple crucibles (group of crucibles). When the horizontal cross-sectional area of ​​each crucible is A and the cross-sectional area of ​​the heat source placed below is B, the crucible cross-section is heated from a wider surface so that B / A ≥ 2. Furthermore, to prevent the temperature drop at the periphery due to heat loss toward the periphery of the cylindrical furnace, heat sources are also installed on the sides, and the heating energy C from the bottom and the heating energy D from the side are controlled so that C / D ≥ 1.2. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5892209 [Patent Document 2] Patent No. 6872346 [Patent Document 3] Japanese Patent Publication No. 2022-55282 [Patent Document 4] Patent No. 3762559 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present disclosure is to provide a SiC single crystal manufacturing apparatus capable of suppressing temperature variations among a plurality of crucibles. [Means for solving the problem]

[0011] The SiC single crystal manufacturing apparatus according to the present disclosure includes a chamber, a heating chamber, and a growth chamber. The heating chamber is provided within the chamber and includes a heat source. The growth chamber is provided within the chamber and is disposed above the heating chamber. The growth chamber includes multiple crucibles, a heat insulating section, and a peripheral heat conducting section. The multiple crucibles are arranged horizontally side by side, and can be charged with SiC raw material and can have a SiC seed crystal attached thereto. The heat insulating section is disposed above the multiple crucibles and has multiple through holes corresponding to the multiple crucibles. Each of the through holes forms a heat channel for flowing heat upward from the corresponding crucible. The peripheral heat conducting section is disposed on the periphery of the multiple crucibles and conducts heat supplied from the heat source to the crucibles. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a vertical cross-sectional view showing the structure of an SiC single crystal manufacturing apparatus according to the first embodiment. [Figure 2] FIG. 2 is a plan view showing the arrangement of crucibles in the SiC single crystal manufacturing apparatus shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing an example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 5] FIG. 5 is a vertical cross-sectional view showing the structure of an SiC single crystal manufacturing apparatus according to the second embodiment. [Figure 6]FIG. 6 is a cross-sectional view showing an example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view showing another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view showing yet another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 9] FIG. 9 is a cross-sectional view showing yet another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 10] FIG. 10 is a vertical cross-sectional view showing the structure of an SiC single crystal manufacturing apparatus according to the third embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing an example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 12] FIG. 12 is a cross-sectional view showing another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 13] FIG. 13 is a cross-sectional view showing yet another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 14] FIG. 14 is a cross-sectional view showing yet another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 15] FIG. 15 is a vertical cross-sectional view showing the structure of an SiC single crystal manufacturing apparatus according to the fourth embodiment. [Figure 16] FIG. 16 is a cross-sectional view showing an example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 17] FIG. 17 is a cross-sectional view showing another example of the SiC single crystal manufacturing apparatus shown in FIG. [Figure 18] FIG. 18 is a graph showing growth indexes of Example 1 according to Embodiment 1 shown in FIG. 1 and Comparative Example. [Figure 19] FIG. 19 is a graph showing the crucible temperature variation index for Example 1 according to Embodiment 1 shown in FIG. 1 and the comparative example. [Figure 20] FIG. 20 is a graph showing growth indexes of Example 2 according to Embodiment 2 shown in FIG. 5 and Comparative Example. [Figure 21]FIG. 21 is a graph showing the crucible temperature variation index for Example 2 according to Embodiment 2 shown in FIG. 5 and the comparative example. [Figure 22] FIG. 22 is a plan view showing Example 3 (t2=5 mm) according to Embodiment 3 shown in FIG. [Figure 23] FIG. 23 is a plan view showing Example 3 (t2=10 mm) according to Embodiment 3 shown in FIG. [Figure 24] FIG. 24 is a plan view showing Example 3 (t2=15 mm) according to Embodiment 3 shown in FIG. [Figure 25] FIG. 25 is a graph showing growth indexes of Example 3 according to the third embodiment shown in FIG. 10 and a comparative example. [Figure 26] FIG. 26 is a graph showing the crucible temperature variation index of Example 3 according to the third embodiment shown in FIG. 10 and the comparative example. [Figure 27] FIG. 27 is a graph showing growth indexes of Example 4 according to Embodiment 4 shown in FIG. 15 and Comparative Example. [Figure 28] FIG. 28 is a graph showing the crucible temperature variation index for Example 4 according to Embodiment 4 shown in FIG. 15 and the comparative example. [Figure 29] FIG. 29 is a graph showing all of the growth indices shown in FIGS. [Figure 30] FIG. 30 is a graph showing all the crucible temperature variation indices shown in FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Outline of the embodiment> The SiC single crystal manufacturing apparatus according to this embodiment includes a chamber, a heating chamber, and a growth chamber. The heating chamber is provided within the chamber and includes a heat source. The growth chamber is provided within the chamber and is disposed above the heating chamber. The growth chamber includes multiple crucibles, a heat insulating section, and a peripheral heat conducting section. The multiple crucibles are arranged horizontally side by side, and can be charged with SiC raw material and can have SiC seed crystals attached thereto. The heat insulating section has multiple through holes corresponding to the multiple crucibles. Each of the through holes forms a heat channel for flowing heat supplied from the heat source upward through the corresponding crucible. The peripheral heat conducting section is disposed on the periphery of the multiple crucibles and conducts heat supplied from the heat source to the crucibles.

[0014] According to the above configuration, although there is no heat source on the periphery of the multiple crucibles, the peripheral heat conduction parts are arranged on the periphery of the multiple crucibles, so that the heat supplied from the heat source is transferred from the periphery to the multiple crucibles via the peripheral heat conduction parts, thereby suppressing a temperature drop inside the crucibles near the periphery.

[0015] The outer peripheral heat conduction portion may include an outer peripheral space that communicates with the heating chamber.

[0016] The growth chamber may further include individual heat conducting portions disposed around each of the crucibles to conduct heat supplied from the heat source to the crucibles.

[0017] In this case, since the individual heat conduction parts are arranged on the outer periphery of each crucible, the heat supplied from the heat source is transferred to each crucible via the individual heat conduction parts, and as a result, the temperature inside all the crucibles can be made roughly uniform.

[0018] The individual heat conducting portions may include individual spaces that communicate with the heating chamber.

[0019] The heat insulating portion may extend from above the plurality of crucibles to between the plurality of crucibles.

[0020] In this case, the presence of insulating material between the multiple crucibles prevents heat transfer between the multiple crucibles, so that the temperatures in the multiple crucibles can be controlled independently of each other.

[0021] The heat insulating portion may include a plurality of cylindrical portions corresponding to a plurality of crucibles.

[0022] The heat insulating section may include gaps between three adjacent cylindrical sections among the plurality of cylindrical sections.

[0023] In this case, the heat supplied from the heat source is transferred to each crucible through the gap.

[0024] The heat insulating portion may include a core material that fills the voids.

[0025] In this case, heat supplied from the heat source is transmitted to each crucible via the core material.

[0026] <Details of the embodiment> The present embodiment will be described in detail below with reference to the drawings.

[0027] <Embodiment 1> Referring to FIG. 1 , a SiC single crystal manufacturing apparatus 10 according to the first embodiment includes a chamber 12, a heating chamber 14, and a growth chamber 16. The heating chamber 14 is provided within the chamber 12 and includes a heat source 140. The growth chamber 16 is provided within the chamber 12 and is disposed above the heating chamber 14. The growth chamber 16 includes a plurality of crucibles 160, a heat insulating section 161, and an outer peripheral space 169. The crucibles 160 are arranged horizontally side by side, and can be charged with SiC raw materials 162 and can accommodate SiC seed crystals 163. The heat insulating section 161 has a plurality of through-holes 164 corresponding to the plurality of crucibles 160. The heat insulating section 161 is made of a heat insulating material. Each of the through-holes 164 forms a heat channel for flowing heat supplied from the heat source 140 upward through the corresponding crucible 160, as indicated by the arrows in FIG. 1 . The outer space 169 is disposed around the outer periphery of the plurality of crucibles 160 and conducts heat supplied from the heat source 140 to the crucibles 160 .

[0028] Hereinafter, the plurality of crucibles 160 may be collectively referred to as a crucible group 160. Furthermore, the through-holes 164 may be referred to as heat channels 164.

[0029] Each crucible 160 includes a container having a cylindrical sidewall and a bottom, and a container lid. The crucible 160 is made of graphite. A SiC seed crystal 163 is fixed to the back surface of the lid of the crucible 160. The heat insulating portion 161 extends between the multiple crucibles 160. That is, the heat insulating portion 161 also exists between the multiple crucibles 160.

[0030] The heat insulating section 161 includes a lid 165 that covers the through-hole (heat channel) 164. The lid 165 adjusts the temperature region within the heat channel 164. Specifically, the thicker the lid 165, the less heat flows, resulting in a higher temperature region. On the other hand, the thinner the lid 165, the more heat flows, resulting in a lower temperature region. The lid 165 also prevents radiant light emitted from the high-temperature upper surface of the crucible 160 from directly reaching the chamber 12. Since the chamber 12 is made of stainless steel, it is necessary to avoid direct exposure to radiant light from the crucible 160, which is a heat source exceeding 2000°C. It is desirable to keep the temperature of the upper surface of the lid 165, which is made of a heat insulating material, and the surface facing the chamber 12 at 1000°C or less.

[0031] The heat insulating section 161 has an outer peripheral space 169 that communicates with the heating chamber 14. The outer peripheral space 169 is disposed on the outer periphery of the crucible group 160 and functions as an outer peripheral heat conducting section that conducts heat supplied from the heat source 140 to the crucibles 160. The outer peripheral space 169 is cylindrical and has a width w in the horizontal direction. In FIG. 1, the upper surface of the outer peripheral space 169 is aligned with the upper surface of the crucibles 160, but they may not be aligned. Specifically, the depth of the outer peripheral space 169 is arbitrary.

[0032] The heat insulating section 161 includes an outer peripheral sidewall 166. The outer peripheral sidewall 166 is arranged on the outer periphery of the plurality of crucibles (crucible group) 160. The outer peripheral sidewall 166 is also made of a heat insulating material. The outer peripheral space 169 may be isolated from the heating chamber 14 by a heat insulating material or an extension of the crucible common base. The degree of heating from the periphery of the crucible group can also be adjusted by transporting heat from the heating chamber 14 to the outer peripheral space 169 via this partition.

[0033] The heat insulating section 161 includes a plurality of cylindrical sections 167 corresponding to the plurality of crucibles 160. Each cylindrical section 167 has a through-hole (heat channel) 164.

[0034] The heating chamber 14 further includes a heat insulating portion 141. The heat insulating portion 141 is disposed around and below the heat source 140. The heat insulating portion 141 is connected to the heat insulating portion 161.

[0035] The chamber 12 includes a temperature measurement hole 121 for measuring the temperature of the crucible 160 .

[0036] 2, the plurality of crucibles 160 include one central crucible 1600, six first outer crucibles 1601 arranged on the periphery of the central crucible 1600, six second outer crucibles 1602 and six third outer crucibles 1603 arranged on the periphery of the first outer crucible 1601. The distance between the second outer crucible 1602 and the central crucible 1600 is shorter than the distance between the third outer crucible 1603 and the central crucible 1600. In other words, the second outer crucible 1602 is closer to the central crucible 1600 than the third outer crucible 1603.

[0037] The insulating material is made of carbon fiber, expanded graphite, or flexible graphite, or a combination of at least two of these. The carbon fiber insulating material may be in the form of, for example, felt or sheet. This type of insulating material has a thermal conductivity of 3.0 W / mK or less at 2000°C. Alternatively, it may be molded carbon fiber insulating material obtained by impregnating carbon fiber insulating material with resin, molding it, and then graphitizing it. This type of insulating material has a thermal conductivity of 1.0 W / mK or less at 2000°C. The expanded graphite insulating material may be in the form of, for example, bulk, flake, or granule. Alternatively, it may be an insulating material made of flexible graphite obtained by compression molding expanded graphite. The flexible graphite insulating material may be in the form of, for example, bulk or sheet. This type of insulating material has a thermal conductivity of 10 W / mK or less in the thickness direction at room temperature (25°C).

[0038] <Chamber> The chamber 12 is airtight and capable of controlling the pressure under reduced pressure while supplying various gases such as argon, helium, and nitrogen. All components (heat source 140, crucible 160, heat insulating section 161, and heat insulating section 141) are housed within the chamber 12. The chamber 12 can be divided into upper and lower halves to allow for easy access to these internal components. The chamber 12 may be opened and closed by raising the upper side of the chamber 12, lowering the lower side, or performing both actions simultaneously. Alternatively, the chamber 12 may be opened and closed by rotating the upper and / or lower sides of the chamber 12. The dividing plane of the chamber 12 may be vertical rather than horizontal. If the dividing plane is vertical, the chamber 12 can be divided horizontally (left and right). The chamber 12 is made of stainless steel such as SUS316, 304, or 430. To prevent the intrusion of foreign matter, the inner surface of the chamber is preferably polished to a mirror finish by mechanical or electrolytic polishing.

[0039] The surface temperature of the heat insulating material in the heating chamber 14 and the growth chamber 16 can reach 300 to 500°C, and the temperature at the top of the heat channel 164 can reach 1000°C. Therefore, it is preferable that the back surface of the inner wall of the chamber 12 is water-cooled, and it is even more preferable that an outer wall of the chamber 12 is provided and the gap between the inner wall and the outer wall is a water-cooled jacket.

[0040] During crystal growth, the surface temperature of the heat source 140 installed in the heating chamber 14, the temperatures of the top, bottom, or side of the crucible 160, and other temperatures are measured as needed. A radiation thermometer is used to measure these temperatures. Therefore, an airtight window made of quartz glass or the like is preferably installed as the temperature measurement hole 121 on the top surface of the chamber 12. Airtight windows are also preferably installed on the bottom and side surfaces of the chamber 12. To suppress external factors during temperature measurement, a graphite pipe with both ends open may be installed penetrating from the temperature measurement hole 121 to the interior of the chamber 12. Furthermore, when crystal growth is continued over a long period of time, accumulation of dirt on the surface of the airtight window can cause a decrease in the reading of the radiation thermometer and lead to temperature measurement errors. Therefore, it is preferable that the airtight window be removable. Alternatively, a wiper for cleaning dirt from the inner surface or a shutter for hiding the inner surface of the airtight window to prevent dirt from accumulating when not measuring the temperature may be installed.

[0041] <Heating chamber> The heating chamber 14 is a space covered by a heat insulating section 141, excluding the heat channel 164 and the inlet section of the heat source 140. To promote the flow of heat in the direction of the heat channel 164, it is preferable that the escape of heat toward the outer periphery of the chamber 12 via the heat insulating section 141 is sufficiently suppressed to maintain the temperature. There are no particular restrictions on the material, thickness, or shape of the heat insulating section 141 used, but general graphite felt or its molded body can be suitably used, and the required thickness of the heat insulating section 141 on the chamber surface is, for example, 100 mm or more, more preferably 150 mm or more.

[0042] The heat source 140 installed in the heating chamber 14 is not particularly limited as long as it can achieve a surface temperature of 2100 to 2500°C, and high-frequency induction heating, resistance heating, infrared heating, gas heating, arc heating, laser heating, or a combination of these can also be used.

[0043] The surface of the heat insulating section 141 facing the heating chamber 14 is easily worn away by being exposed to high temperatures for a long time. Furthermore, a small amount of sublimation gas containing Si and C leaking from the crucible 160 may reach the interior of the heat insulating section 141 and precipitate as SiC or Si at a temperature where it can be precipitated, thereby reducing the heat insulating performance. Therefore, it is preferable that the surface layer, which is easily worn away, be replaceable. It is even more preferable to cover the surface of the heat insulating section 141 with a flexible graphite sheet or the like to provide resistance to the penetration of sublimation gas. The surface of a graphite sheet has a higher reflectivity to radiant light than graphite felt or the like, and is therefore advantageous in that it can efficiently guide radiant heat from the heat source 140 to the heat channel 164.

[0044] <Growth room> The growth chamber 16 is disposed on a heat flow path (heat channel 164) extending upward from the heating chamber 14. The heat channels 164 are separated by insulating sections 161, which restrict the horizontal transport of heat between the crucibles 160. The thickness of the insulating sections 161 disposed in the vertical direction within the heat channels 164 is thinner than the portions other than the heat channels 164, reducing the resistance to heat transport. As a result, the heat generated in the heating chamber 14 is transported upward from the boundary with the heating chamber 14 through the heat channels 164, ideally evenly, and is absorbed from the top as mainly radiant light by the cooled inner wall of the chamber 12.

[0045] A crucible 160, which is the growth site for the SiC single crystal, is installed within the heat channel 164. The crucible 160 may be suspended from the top of the chamber 12 or may be mounted on a pedestal extending from the bottom of the chamber 12. A pedestal may be installed for each heat channel 164, or a single common pedestal may cross all of the heat channels 164. The material of the pedestal is not particularly limited, but graphite is preferred, and extruded graphite, which has excellent thermal conductivity in the vertical direction, is more preferred. Furthermore, since the weight of the pedestal increases as the number of crucibles 160 increases, a molded carbon fiber plate (Carbon Fiber Rainforced Carbon Composite Material: CCM), which has higher bending strength, may be used. This material has thermal conductivity in the horizontal direction (parallel to the pedestal surface) equivalent to that of general graphite, but its thermal conductivity in the vertical direction (perpendicular to the pedestal surface) is approximately 1 / 10 to 1 / 100 of that of general graphite. Therefore, in order to efficiently supply heat from the heating chamber 14 into the crucible 160, a through-hole may be present in the pedestal surface that contacts the crucible 160. A material with excellent vertical thermal conductivity may be disposed in place of a portion of the pedestal surface that contacts the crucible 160. The crucible 160 may be held in such a way that the lower part of the crucible 160 protrudes from the lower surface of the pedestal toward the heating chamber 14.

[0046] The temperatures of the top and bottom surfaces of the crucible 160 and the temperature difference between them are important factors that affect the crystal growth rate. These temperatures and the temperature difference can be controlled by the position and thickness of the heat insulating portion 161 disposed within the heat channel 164. That is, by disposing a heat insulating material between the heating chamber 14 and the bottom surface of the crucible 160, the temperature region at the bottom of the crucible 160 can be lowered. Conversely, by disposing the heat insulating portion 161 between the top surface of the crucible 160 and the top surface of the heat channel 164, the temperature region within the crucible 160 can be raised. Furthermore, by making the heat insulating portion 161 disposed here thinner, the temperature difference between the top and bottom of the crucible 160 increases; conversely, by making the heat insulating portion 161 thicker, the temperature difference between the top and bottom of the crucible 160 decreases. This allows the sublimation rate of the SiC raw material 162 and the growth rate of the SiC single crystal to be adjusted.

[0047] <Effects of the First Embodiment> According to the first embodiment, the heat channel 164 flows heat supplied from the heat source 140 upward through the crucible 160. The temperature difference between the top and bottom of the heat channel 164, including the crucible 160, changes along with the ratio of the heat flowing through the heat channel 164 to the heat from the heat source 140, depending on the ratio of the thermal resistance between the heat channel 164 and the thermal insulation 161. That is, as the thermal resistance of the heat channel 164 becomes smaller than the thermal resistance of the thermal insulation 161, the ratio of the heat flowing through the heat channel 164 increases. Accordingly, the temperature difference between the top and bottom of the crucible 160 in the heat channel 164 also increases, thereby increasing the growth rate of the SiC single crystal. Furthermore, the presence of thermal insulation between the multiple crucibles 160 prevents heat transfer between the multiple crucibles 160. As a result, the temperatures in the multiple crucibles 160 can be controlled independently of each other by utilizing the position and thickness of the thermal insulation 161. Furthermore, since the heat insulating section 161 includes the outer peripheral sidewall 166 disposed on the outer periphery of the crucible group 160, the insulating material constituting the outer peripheral sidewall 166 prevents heat from escaping laterally from the crucible group 160. The higher the insulating performance of the outer peripheral sidewall 166, the less likely heat from the crucible group 160 to escape laterally. Therefore, the lower the thermal conductivity of the outer peripheral sidewall 166 and the thicker the outer peripheral sidewall 166, the more likely heat will flow upward through the heat channel 164. However, if the insulating performance of the outer peripheral sidewall 166 is insufficient, heat from the crucible group 160 will easily escape laterally, and the outer crucibles 1601, 1602, and 1603 will tend to be significantly lower in temperature than the central crucible 1600.

[0048] Here, when the heat insulating section 161 has the outer peripheral space 169, heat is transferred from the heating chamber 14 into the outer peripheral space 169, and even if there is no heat source on the periphery of the crucible group 160, heat is transferred from the periphery to the crucible group 160. As a result, it is possible to suppress a decrease in temperature inside the second outer peripheral crucible 1602 and the third outer peripheral crucible 1603. In this way, by providing the outer peripheral space 169 with a high temperature inside the heat insulating section 161, heat from the outer peripheral space 169 flows laterally, but heat from the crucible group 160 is less likely to flow laterally.

[0049] The surface temperature of the insulating material facing the outer peripheral space 169 can be adjusted by the radial width and height of the outer peripheral space 169, i.e., the horizontal cross-sectional area and volume of the outer peripheral space 169, or the degree of opening at the point where it connects to the heating chamber 14. The surface temperature of the insulating material can also be changed by the shape and structure of the surface, including the unevenness of the surface of the outer peripheral space 169. In addition, the outer peripheral space 169 and the heating chamber 14 can be isolated by extending the insulating material or the crucible common base, which allows the surface temperature of the insulating material to be adjusted.

[0050] A heat-conducting member may be embedded in all or part of the peripheral space 169. While the peripheral space 169 conducts heat by radiant light, the heat-conducting member conducts heat by itself. While there are no particular restrictions on the material of the heat-conducting member, graphite is a suitable material. This also creates a thermal environment similar to that of a lateral heat source, and it is possible to control the time delay during temperature rise and fall depending on the thermal capacity of the heat-conducting member. Furthermore, this heat-conducting member may include a heat insulating material. This allows for the adjustment of heat transport from the heating chamber 14 to the crucible group via the heat-conducting member.

[0051] As shown in Fig. 3, the heat insulating portion 161 around the crucible group 160 excluding the outer peripheral side wall 166 may be circular in plan view, or may be approximately hexagonal as shown in Fig. 4. In the case of the hexagonal heat insulating portion 161, the thickness of the heat insulating material around the outermost crucibles 160 (1602, 1603) is approximately the same.

[0052] <Embodiment 2> As shown in FIG. 5 , in the SiC single crystal manufacturing apparatus 10 according to the second embodiment, the heat insulating section 161 does not extend between the multiple crucibles 160. That is, the heat insulating section 161 does not need to be present between the multiple crucibles 160. Instead, the heat insulating section 161 includes a heat insulating material 170. The heat insulating material 170 is cylindrical and is installed so that its outer peripheral surface contacts the inner peripheral surface of the outer peripheral side wall 166. The outer peripheral space 169 of the heat insulating section 161 is disposed on the outer periphery of the crucible group 160 and communicates with the heating chamber 14, but in the second embodiment, it is located between the outer peripheral surface of the outermost crucible 160 (1602, 1603) of the crucible group 160 and the inner peripheral surface of the heat insulating material 170.

[0053] As described above, the growth chamber 16 includes individual spaces 171. The individual spaces 171 are arranged around each crucible 160 and conduct heat supplied from the heat source 140 to the crucible 160. That is, the heat insulating section 161 has not only the peripheral space 169 but also the individual spaces 171. However, a portion of the individual space 171 around the outermost crucible 160 overlaps with the peripheral space 169.

[0054] As shown in Fig. 6, the heat insulating material 170 may be cylindrical, but as shown in Fig. 7, the inner surface of the heat insulating material 170 may be substantially hexagonal in plan view. When the inner surface is hexagonal, the distance between the outermost crucible 160 (1602, 1603) and the heat insulating material 170 becomes substantially the same.

[0055] 8, the heat insulating material 170 may be installed away from the outer peripheral side wall 166. In this case, another outer peripheral space 169 exists between the outer peripheral side wall 166 and the heat insulating material 170.

[0056] 9, the heat insulating material 170 may be a hexagonal tube. In this case, the distance between the outermost crucible 160 (1602, 1603) and the heat insulating material 170 is approximately the same.

[0057] <Embodiment 3> 10 , in the SiC single crystal manufacturing apparatus 10 according to the third embodiment, the heat insulating portion 161 extends between the plurality of crucibles 160 as a cylindrical portion 167. That is, the heat insulating portion 161 is also present between the plurality of crucibles 160. The heat insulating portion 161 has an outer peripheral space 169 and individual spaces 171.

[0058] In this example, the cylindrical portion 167 is in contact with the crucible 160, but it may be separated from the crucible 160. In this case, a space exists not only around the outer periphery of the heat insulating material 170 but also around the inner periphery.

[0059] As shown in Fig. 11, adjacent cylindrical portions 167 may be in contact with each other, but as shown in Fig. 12, if the cylindrical portions 167 are thin, the cylindrical portions 167 may be spaced apart. In this case, the individual spaces 171 communicate with the outer circumferential space 169. Conversely, as shown in Fig. 13, if the cylindrical portions 167 are sufficiently thick, the cylindrical portions 167 may be in contact with each other through interference. In this case, the individual spaces 171 do not communicate with the outer circumferential space 169. Furthermore, each individual space 171 does not communicate with the other individual spaces 171.

[0060] 14, a heat insulating material 170 having a substantially hexagonal cylindrical shape may be provided around the crucible group 160.

[0061] <Embodiment 4> 15, in the SiC single crystal manufacturing apparatus 10 according to the fourth embodiment, similarly to the second embodiment, the heat insulating section 161 includes a heat insulating material 170. Also, similarly to the third embodiment, the heat insulating section 161 has an outer circumferential space 169 and an individual space 171.

[0062] In the fourth embodiment, as shown in FIG. 16, the heat insulating material 170 is cylindrical and is installed so that its outer circumferential surface contacts the inner circumferential surface of the outer circumferential side wall 166.

[0063] Furthermore, as shown in FIG. 17, in addition to the cylindrical heat insulating material 170, a heat insulating material 170 having a substantially hexagonal cylindrical shape may be provided around the crucible group 160.

[0064] <Other embodiments> In particular, when an insulating material is placed in contact with the top surface of the crucible 160, it is possible to freely control the horizontal temperature distribution in the single crystal growth section so that the temperature increases from the central axis to the periphery by either thinning the thickness of the insulating material near the central axis of the crucible 160, or by thickening the thickness of the insulating material near the periphery of the crucible 160, or by doing both.

[0065] For example, from the vertical position corresponding to the bottom surface of the crucible 160 to the vertical position corresponding to the surface of the SiC source material 162 loaded in the crucible 160, or to the position corresponding to the lowest end of the crystal boule at the time when the SiC single crystal growth is completed, no insulating material may be provided between the heat channels 164 (Embodiment 4), or the thickness of the insulating material may be thin (Embodiments 5 and 6). This allows heat to be transported between the SiC source materials 162 in different heat channels 164, which may improve the sublimation efficiency of the SiC source material 162. Therefore, the lower part of the crucible 160 where the SiC source material 162 is present may be arranged to protrude from the growth chamber 16 toward the heating chamber 14.

[0066] For example, from the vertical position corresponding to the top surface of crucible 160 to the vertical position where SiC seed crystal 163 is disposed within crucible 160, no insulating material may be disposed between heat channels 164, or the thickness of the insulating material may be thin. This allows heat to be transported between SiC growth crystals in different heat channels 164, which may reduce the variation in the growth rate of SiC single crystals between heat channels 164.

[0067] The inner wall of the water-cooled chamber 12 is preferably made of stainless steel, and since the outer surface temperature of the top surface of the heat channel 164 is adjusted to 1000°C or less, it is preferable that at least a portion of the top surface of the heat channel 164 is covered with an insulating material to adjust the outer surface temperature. [Example]

[0068] To confirm the effects of the above-described embodiment, a simulation of the temperature distribution during steady-state heating was performed using "Femtet" software manufactured by Murata Software Co., Ltd. Hereinafter, 19 crucibles 160 with a diameter of 200 mm (corresponding to a grown crystal diameter of 150 mm) were arranged. Specifically, one central crucible 1600 was arranged around it, and six first outer crucibles 1601 were arranged around it, and 12 crucibles 1602 and 1603 were arranged around them. Of these, six crucibles located closest to the central crucible 1600 were designated as second outer crucibles 1602, and six crucibles located farther from the central crucible 1600 were designated as third outer crucibles 1603. The vertical thermal conductivity of the crucibles 160 was set to 85 W / mK, and the horizontal thermal conductivity was set to 43 W / mK. Both thermal conductivities are those at 2000°C, and the same applies to the following. The shortest distance between the crucibles 160 was 10 mm, and the distance between the centers of the crucibles 160 was set to 210 mm. The dashed dotted line in Figure 2 indicates the cross-sectional position where the simulation analysis was performed.

[0069] Example 1 As described in the first embodiment shown in FIG. 1, the heat insulating section 161 around the crucible group 160 is divided into an outer peripheral side wall 166 and an inner peripheral side wall (cylindrical section 167). Between the inner peripheral surface of the outer peripheral side wall 166 and the outer peripheral surface of the inner peripheral side wall 167, there is an outer peripheral space 169 that communicates with the heating chamber 14. The upper end of the outer peripheral space 169 is set to the same height as the upper surface of the crucible 160. The horizontal width w of the outer peripheral space 169 was changed to 20 mm, 35 mm, and 50 mm.

[0070] <Result> The simulation results of the above-mentioned Comparative Example and Example 1 are summarized in FIGS. 18 and 19 from the viewpoints of "growth index" and "crucible temperature variation index."

[0071] 18 indicates the difference between the temperature at the center of the bottom surface of the raw material in crucible 160 placed in the center of the furnace and the temperature at the center of the pedestal surface (hereinafter sometimes referred to as the "top surface") on which SiC seed crystal 163 is placed, and respectively indicates the temperature at the site of raw material sublimation and recrystallization, and the driving force for crystal growth. The temperature here is the result of the heat supply setting from heat source 140, and is not necessarily a value suitable for SiC crystal growth. A high displayed temperature indicates that there is a margin of heating capacity, meaning that the amount of heat supplied from heat source 140 can be reduced.

[0072] 19 is a graph showing the temperature difference between the central crucible 1600 and the third outer crucible 1603, which are positioned rotationally symmetrically, at the center of the pedestal surface that contacts the SiC seed crystal 163 in the crucible 160. The horizontal axis represents the difference in temperature between the central crucible 1600 and the third outer crucible 1603, which are positioned rotationally symmetrically, and the vertical axis represents the absolute value of the difference between the maximum and minimum temperatures of the pedestal surface that contacts the SiC seed crystal 163 between the central crucible 1600 and the first and third outer crucibles 1601 and 1603, which are positioned rotationally symmetrically. The horizontal axis, which corresponds to the temperature variation in the horizontal direction between the crucibles 160, is an index of the variation in growth rate between the crucibles 160 of the single crystal growing in the crucibles 160. The smaller this index is, the better the mass production equipment is with uniform heating. Furthermore, the smaller the vertical axis representing the horizontal temperature distribution within each crucible 160, the smaller the horizontal temperature difference that occurs within the growing crystal, which can be said to be an excellent crystal growth environment that can suppress cracks and the introduction of defects due to thermal stress.

[0073] 18, in the comparative example, by setting the output of the heat source 140 to 80 kW, the bottom surface temperature of the central crucible 1600 was 2688°C, and the temperature difference between the bottom surface and the top surface was 196°C. In contrast, in Example 1, the top surface temperature and the bottom surface temperature of the central crucible 1600 decreased, and as a result of heat being transferred via the peripheral space 169, the high-temperature region moved closer to the outer surface of the heat insulating section 161, increasing the amount of heat loss, which means that extra heat supply is required to maintain the temperature of the crucible 160. Accordingly, the temperature difference between the bottom surface and the top surface of the central crucible 1600 also tends to decrease.

[0074] However, when looking at the temperature difference between the central crucible 1600 and the third outer crucible on the horizontal axis of Fig. 19, in the comparative example without the outer space 169, the center tends to be the highest and the third outer crucible 1603 the lowest, with the difference being 45°C. This is due to the phenomenon that heat escapes to the sides of the crucible group 160 when the heat source 140 is arranged only below the crucible group 160.

[0075] In contrast, in Example 1, as the width w of the peripheral space 169 increased, the temperature difference between the central crucible 1600 and the third peripheral crucible 1603 decreased. When the width w of the peripheral space 169 was 50 mm, the temperature of the central crucible 1600 was the lowest and the temperature of the third peripheral crucible 1603 was the highest, resulting in a temperature difference of -10°C. This means that a portion of the heat from the heat source 140 was transported to the peripheral space 169, heating the surface of the insulating material facing the peripheral space 169, thereby also heating the third peripheral crucible 1603, which is close to the insulating material surface. While this result depends on parameters such as the dimensions and thermal conductivity of this simulation model, it was found that the effect was due to the width w of the peripheral space 169, i.e., the ease of heat conduction in the peripheral space 169, and could be adjusted by the temperature of the insulating material surface facing the peripheral space 169. In order to obtain the same crystal growth rate in multiple crucibles 160, it is desirable to have a small temperature difference between the central crucible 1600 and the third outer crucible 1603, and from this perspective and considering the results of this study, it can be said that the width w of the outer space 169 is preferably about 40 mm.

[0076] 19 , when the difference between the maximum and minimum temperatures of the pedestal surface in contact with the SiC seed crystal 163 in each crucible 160 is examined, the difference initially decreases as the width w of the outer peripheral space 169 increases compared to the comparative example, and then the temperature difference tends to increase, particularly in the third outer peripheral crucible 1603. This is because, as described above, the temperature of the insulating material surface facing the outer peripheral space 169 increases, which also increases the temperature of the third outer peripheral crucible 1603. As described above, this result depends on the simulation conditions. However, in view of the present results from the viewpoint of suppressing uneven crystal growth in the multiple crucibles 160 installed, it can be said that the width w of the outer peripheral space 169 is preferably about 20 mm.

[0077] As described above, under the simulation conditions, there is a difference between the width w of the outer peripheral space 169 that is preferable for obtaining the same crystal growth rate in multiple crucibles 160 and the width w of the outer peripheral space 169 that is preferable for suppressing uneven crystal growth among the multiple crucibles 160. This difference varies depending on the thickness of the cylindrical portion 167, i.e., the distance between the crucibles. However, in this furnace structure, the temperature difference between the central crucible 1600 and the third outer crucible 1603 can be controlled by the thickness of the vertical insulating material arranged in each heat channel 164 in which each crucible 160 exists. Therefore, it is desirable to adjust the width w appropriately based on the temperature measurement results during actual furnace operation.

[0078] Through the results of the above examples, it was confirmed that heating the crucible group 160 from the periphery via the peripheral space 169 around the crucible group 160 can suppress the temperature drop toward the periphery of the furnace, which is a phenomenon that tends to occur when the heat source 140 is placed below the crucible group 160, and that it can also suppress the temperature difference that occurs in the crystal growth field within each crucible 160. By understanding the role of the peripheral space 169, a similar effect can be obtained even when a peripheral heat conductive part made of graphite or the like is installed in at least a part of the peripheral space 169. This is because, when this part is an open space, heat is transferred by radiant light, whereas when a peripheral heat conductive part is present, heat is transferred by thermal conduction within the peripheral heat conductive part.

[0079] <Example 2> As described in the second embodiment shown in Fig. 5, there is a heat insulating material 170 on the inner periphery of the outer peripheral side wall 166, but there is no heat insulating material between the multiple crucibles 160, i.e., around each crucible 160. The thickness t1 of the heat insulating material 170 on the inner periphery of the outer peripheral side wall 166 was changed to 30 mm, 50 mm, and 60 mm.

[0080] In contrast, a model was prepared as Comparative Example 1 in which there was no heat insulating material 170 on the inner periphery of the outer peripheral side wall 166 (t1=0) and no heat insulating material 167 around each crucible 160 (t2=0). Also, a model was prepared as Comparative Example 2 in which there was no outer peripheral space 169 (w=0).

[0081] <Result> The simulation results of the above-mentioned Comparative Examples 1 and 2 and Example 2 are summarized in FIGS. 20 and 21 from the viewpoints of the "growth index" and the "crucible temperature variation index."

[0082] 20, Example 2 had a higher growth index than Comparative Example 1. Furthermore, the thicker the heat insulating material 170 on the inner periphery of the outer periphery side wall 166, the higher the growth index. This means that heat from the heating chamber 14 is easily transferred to the crucible 160 through the outer periphery space 169, but is blocked by the heat insulating material 170 and therefore does not easily escape to the outside.

[0083] 21, focusing on Example 2, the thicker the heat insulating material 170 on the inner periphery of the outer side wall 166, the smaller the temperature difference within each pedestal surface, and also the smaller the temperature difference between the central crucible 1600 and the third outer crucible 1603. In this example, particularly when the thickness t1 of the heat insulating material is 60 mm, the temperature difference between the central crucible 1600 and the third outer crucible 1603 becomes almost zero.

[0084] Example 3 As described in the third embodiment shown in Fig. 10, heat insulating materials 167 are provided between the multiple crucibles 160, i.e., around each crucible 160, and an outer peripheral space 169 is provided between the heat insulating materials 167 and the outer peripheral side wall 166. As shown in Figs. 22 to 24, the thickness t2 of the heat insulating materials 167 around each crucible 160 was varied to 5 mm, 10 mm, and 15 mm.

[0085] There are gaps 172 between three adjacent cylindrical portions (thermal insulation materials 167). The gaps 172 may be empty or may be filled with a core material.

[0086] <Result> The simulation results of the above-mentioned Comparative Examples 1 and 2 and Example 3 are summarized in FIGS. 25 and 26 from the viewpoints of the "growth index" and the "crucible temperature variation index."

[0087] 25, Example 3 had a higher growth index than Comparative Example 1. Furthermore, the thicker the insulating material 167 around each crucible 160, the higher the growth index. This means that the heat inside each crucible 160 is blocked by the insulating material 167 around it, making it difficult for the heat to escape to the surroundings.

[0088] 26, focusing on Example 3, the thicker the heat insulating material 167 around each crucible 160, the smaller the temperature difference within each pedestal surface, and also the smaller the temperature difference between the central crucible 1600 and the third outer crucible 1603. In this example, particularly when the thickness t2 of the heat insulating material 167 was 15 mm, the temperature difference between the central crucible 1600 and the third outer crucible 1603 was minimized.

[0089] Example 4 As explained in the fourth embodiment shown in Fig. 15, the heat insulating material 170 is in contact with the inner periphery of the outer peripheral side wall 166, the heat insulating material 167 is also provided around each crucible 160, and further, the outer peripheral space 169 is provided between the heat insulating material 170 and the heat insulating material 167. In the fourth embodiment, the thickness t1 of the heat insulating material 170 on the inner periphery of the outer peripheral side wall 166 is fixed to 60 mm, and the thickness t2 of the heat insulating material 167 around each crucible 160 is varied between 5 mm and 10 mm.

[0090] <Result> The simulation results of the above-mentioned Comparative Examples 1 and 2 and Example 4 are summarized in FIGS. 27 and 28 from the viewpoints of the "growth index" and the "crucible temperature variation index."

[0091] 27, Example 4 had a higher growth index than Comparative Example 1. Furthermore, the thicker the insulating material 167 around each crucible 160, the higher the growth index. This means that the heat inside each crucible 160 is blocked by the insulating material 167 around it, making it difficult for the heat to escape to the surroundings.

[0092] As shown in Figure 28, focusing on Example 4, the thicker the insulation 167 around each crucible 160, the smaller the temperature difference within each pedestal surface, and the smaller the temperature difference between the central crucible 1600 and the third outer crucible 1603.

[0093] All the simulation results for the above Comparative Examples 1 and 2 and Examples 1 to 4 are summarized in FIGS. 29 and 30 from the viewpoints of "growth index" and "crucible temperature variation index."

[0094] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified within the scope of the claims. [Explanation of symbols]

[0095] 10: SiC single crystal manufacturing equipment 12: Chamber 14:Heating chamber 16:Growth room 140:Heat source 141: Insulation section 160: Crucible (crucible group) 161: Insulation section 162:SiC raw material 163:SiC seed crystal 164: Through hole (heat channel) 166: Peripheral side wall 167: Cylindrical part (insulation material) 169: Peripheral space 170: Heat insulation 171: Individual space 172: Gap

Claims

1. a chamber; a heating chamber disposed within the chamber and including a heat source; a growth chamber provided within the chamber and positioned above the heating chamber; The growth chamber comprises: a plurality of crucibles arranged side by side in a horizontal direction, into which a SiC raw material can be charged and into which a SiC seed crystal can be attached; a heat insulating section having a plurality of through holes corresponding to the plurality of crucibles, each of the through holes forming a heat channel for allowing heat supplied from the heat source to flow upward through the corresponding crucible; The growth chamber further comprises: a peripheral heat conduction section disposed on the outer periphery of the plurality of crucibles and conducting heat supplied from the heat source to the crucibles;

2. The SiC single crystal manufacturing apparatus according to claim 1, The SiC single crystal manufacturing apparatus, wherein the peripheral heat conduction section includes a peripheral space communicating with the heating chamber.

3. The SiC single crystal manufacturing apparatus according to claim 1, The growth chamber further comprises: The SiC single crystal manufacturing apparatus includes individual heat conduction portions disposed around each of the crucibles and conducting heat supplied from the heat source to the crucibles.

4. The SiC single crystal manufacturing apparatus according to claim 3, The individual heat conduction section includes an individual space communicating with the heating chamber.

5. The SiC single crystal manufacturing apparatus according to claim 1, The SiC single crystal manufacturing apparatus, wherein the heat insulating section extends from above the plurality of crucibles to between the plurality of crucibles.

6. The SiC single crystal manufacturing apparatus according to claim 1, The SiC single crystal manufacturing apparatus, wherein the heat insulating section includes a plurality of cylindrical sections corresponding to the plurality of crucibles.

7. The SiC single crystal manufacturing apparatus according to claim 6, The SiC single crystal manufacturing apparatus, wherein the heat insulating section includes gaps between three adjacent cylindrical sections among the plurality of cylindrical sections.

8. The SiC single crystal manufacturing apparatus according to claim 7, The heat insulating portion further comprises: A SiC single crystal manufacturing apparatus including a core material filled in the gap.

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