JP2007230846A - Crucible for single crystal producing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crucible for a single crystal producing apparatus, which can make the temperature distribution in a raw material powder provided therein uniform, sublimate the raw material powder stably, enhance crystal growth speed, and improve crystal quality. <P>SOLUTION: The crucible for the single crystal producing apparatus for growing a single crystal on a seed crystal substrate 7 is equipped with: a seed crystal attaching part 25 which is provided on a cap part 5 of a crucible body 24 and to which the seed crystal substrate 7 comprising a single crystal is attached; a conical flange 6 in which the opening part at the raw material powder 4 side is larger than that at the seed crystal substrate 7 side and which consolidates the gas sublimated from the raw material powder 4 to the vicinity of the seed crystal substrate 7; a heat insulating material 23 for covering the whole crucible body; and a high frequency coil 8 which is arranged at the outside of the heat insulating material 23 arranged at the periphery of the whole crucible body to heat the seed crystal and the raw material. The thickness of the side wall of the crucible body 24 of a heat conductor is continuously changed within a range from the bottom part of the crucible body 24 to a position between the surface of the raw material powder 4 accommodated in the crucible body 24 and the lower end of the conical flange 6 so as to make the thermal conduction to the raw material powder 4 uniform. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a crucible for a single crystal manufacturing apparatus, and can be suitably used particularly for manufacturing a silicon carbide single crystal.

Conventionally, a sublimation method has been widely used as a method for growing a silicon carbide single crystal. The sublimation method is also called the modified Rayleigh method. A cylindrical graphite crucible filled with a seed crystal substrate composed of a silicon carbide single crystal and a raw material powder composed of polycrystalline silicon carbide is heated to become a sublimation gas when moving to the seed crystal substrate. The single crystal grows by being cooled and solidified near the seed crystal substrate at a temperature lower than the raw material powder. In order to produce a high quality single crystal, it is generally said that the temperature difference between the seed crystal substrate and the raw material surface is preferably 20 to 30 ° C. Since this crystal growth process is a chemical reaction, the crucible is sometimes called a reaction furnace. The composition of the sublimation gas generated when silicon carbide is used as a raw material is Si, SiC ₂ , Si ₂ C, Si ₂ , Si _3, etc. Especially, Si, SiC ₂ , Si ₂ C have a large equilibrium partial pressure and are important. It is believed that.

  A general sublimation silicon carbide single crystal manufacturing apparatus and manufacturing method will be described with reference to FIGS. 20 and 17 (see, for example, Patent Document 1). For convenience of explanation, the graphite crucibles shown in these drawings are referred to as Prior Art 1, and the graphite crucible is simply referred to as a crucible.

  The crucible 24 of the prior art 1 in FIG. 17 is a cylindrical container in which the crucible side wall 2 provided with the conical flange 6 is placed on the crucible bottom plate 3 and opened on one side, and the crucible upper lid 5 is fitted into the opening. The appearance is cylindrical. A raw material powder 4 is filled in the lower portion of the crucible, and a seed crystal substrate 7 made of a silicon carbide single crystal is attached to a seed crystal attachment portion 25 of the crucible upper lid. The conical flange is used for the purpose of gas flow control for collecting the sublimation gas generated from the raw material on the seed crystal substrate. The single crystal grows in a single crystal growth space 26 formed surrounded by the crucible, the raw material powder 4 and the seed crystal substrate 7.

  Most of the materials used for the crucible are graphite, but some materials other than graphite, such as high melting point materials and high melting point material-coated graphite, are partially used. Although silicon carbide powder is generally used as the raw material powder 4, silicon, carbon, or a dopant may be added to silicon carbide depending on the purpose.

  FIG. 20 shows the entire single crystal device. The crucible 24 is surrounded by a heat insulating material 23 and placed on the support base 9. Then, there is a high-frequency coil 8 spirally wound outside the heat insulating material, and by passing a high-frequency current of 20 kHz, for example, several hundreds A, the graphite in the crucible is induction-heated to a high temperature of 2000 ° C. or higher. . Using a non-contact thermometer, move the support base up and down so that the crucible lower part is 2200-2500 ° C. and the crucible upper lid outer surface temperature is 100-200 ° C. lower than the crucible lower part temperature. adjust. However, the essential temperature information that determines the crystal growth quality is not the temperature outside the crucible where the temperature can be measured, but the temperature distribution in the single crystal growth space. As described above, in order to grow a good quality single crystal, the temperature of the seed crystal substrate is sometimes 20-30 ° C. lower than the surface of the raw material, but this is a phenomenon inside the crucible and cannot be measured with a non-contact thermometer. was there. Therefore, the temperature distribution inside the crucible is generally visualized by a thermal fluid simulation technique such as a finite element method. Then, by utilizing the simulation, the relationship between the high frequency coil position and the temperature distribution in the single crystal growth space is analyzed, and the appropriate relative position between the high frequency coil and the crucible and the coil current value are determined. In this way, if the temperature gradient between the raw material surface and the seed crystal substrate is controlled to 20 to 30 ° C., the sublimation gas is stably transported from the raw material powder to the seed crystal substrate, and as shown in FIG. The crystal 27 grows stably.

  In the crucible of such prior art 1, as described above, the temperature gradient of the single crystal growth space must be controlled around 20-30 ° C. while the entire crucible is at a high temperature of 2000 ° C. or higher. There is a technical problem. FIG. 17 is also a vector diagram showing the flow of heat from the crucible to the raw material powder. The raw material powder located at the lower part of the crucible receives heat 19 from the crucible side wall and heat 22 from the crucible bottom plate and is uniformly heated. However, since there is only the heat source 19 from the crucible side wall on the surface of the raw material, the temperature distribution on the raw material surface is higher as the crucible side wall is lowered toward the crucible central axis, and the temperature variation is large. According to the thermal fluid simulation, when the raw material powder is approximately 2200 ° C., the temperature difference between the raw material powder near the central axis on the raw material surface and the raw material powder in contact with the inner wall of the crucible is about 2.2 ° C. Considering that the temperature gradient of the single crystal growth space must be controlled around 20-30 ° C., it can be seen that the temperature difference of 2.2 ° C. cannot be ignored.

  Since the sublimation phenomenon of the raw material powder increases as the temperature rises, in the crucible of the prior art 1, sublimation starts from the crucible side wall and the crucible bottom plate according to the temperature variation and expands to the whole. A hatching region 21 in FIG. 17 represents a place where the sublimation of the raw material powder is large, and is an image of the fact that the sublimation is large near the crucible side wall and the crucible bottom plate.

  However, since the raw material powder that has been sublimated changes into a bowl-like powder with large heat insulation properties, the heat conduction from the crucible side wall and the crucible bottom plate to the crucible center decreases, and the raw material in the crucible center is not heated sufficiently, and the crystal growth process It may remain without sublimation until the end of. That is, sublimation of the raw material powder does not extend to the entire raw material. Therefore, in order to sublime all the raw material powder filled in the crucible, the temperature distribution of the whole raw material powder in the crucible is made uniform and sublimated at the same time. is important.

Therefore, in the prior art 2 described in Patent Document 2, in order to make the temperature distribution of the raw material powder uniform, a heat conductor 18 using graphite is arranged in the center of the crucible as shown in FIG. Since other configurations are the same as those of the prior art 1, description thereof is omitted. By doing so, since the central portion of the raw material is heated by the heat 20 from the thermal conductor shown in FIG. 18, the temperature gradient in the radial direction of the raw material powder is improved as compared with the prior art 1. The hatched area 21 in FIG. 18 is an image of the temperature distribution in the crucible center portion being uniform and the sublimation of the raw material powder being increased in the crucible center portion.
JP 05-32496 A Japanese Patent Laid-Open No. 05-58774

  However, the conventional configuration has a problem that desired temperature uniformity cannot be obtained. FIG. 21 shows the analysis result of the conventional thermofluid simulation.

  In FIG. 21, the temperature distribution in the radial direction on the surface of the raw material is improved from the prior art 1, but the temperature distribution in the radial direction at the center of the raw material is worse than that of the prior art 1, and the total value of the variation between the surface of the raw material and the center of the raw material is also Prior art 2 is greater than prior art 1. Here, the center of the raw material is a height that is ½ of the height of the raw material powder. Therefore, as a result of the thermal fluid simulation, it has become clear that the prior art 2 is equivalent to or worse than the prior art 1.

  According to FIG. 21, when the temperature of the raw material powder at the central axis of the raw material powder surface is approximately 2200 ° C., the temperature variation at the raw material surface is 2.2 ° C. and the temperature variation at the central portion of the raw material is 3. 0 ° C. In the prior art 2, the temperature variation on the surface of the raw material is 2.1 ° C., and the temperature variation at the center of the raw material is 3.3 ° C.

  In order to effectively use the raw material powder filled in the crucible, it is necessary to stably sublime the raw material powder all at once. For that purpose, it is indispensable to make temperature variation smaller than at least prior art 1 and prior art 2. In addition, the latest literatures and academic societies have reports that discuss the causal relationship between temperature variations of raw materials and crystal defects, and it is desirable to suppress the temperature variations of raw material powders to 2 ° C. or lower based on these reports.

  The crucible shape of the prior art 1 studied in this thermal fluid simulation has a crucible inner wall radius of 30 mm, a crucible outer wall radius of 45 mm, an overall height from the bottom surface of the crucible bottom plate to the surface of the crucible upper lid, and the thickness of the crucible bottom plate is 15 mm. The height h1 of the raw material powder filled in the crucible is 92 mm, the height h2 from the bottom surface of the crucible bottom plate to the conical flange is 115 mm, the single crystal growth space from the raw material surface to the seed crystal substrate is 40 mm, and the thickness of the seed crystal substrate Is 1 mm. The crucible shape of prior art 2 is the above shape, and the radius of the heat conductor is 5 mm, and the upper end of the heat conductor is 5 mm from the raw material surface.

  The lower end of the conical flange starts at a distance of 23 mm from the surface of the raw material and has a conical shape that narrows toward the seed crystal. The conical shape at this time is 20 mm in the height direction. The seed crystal attachment portion and the conical flange are provided with a 1 mm gap in the radial direction.

  The temperature variation shown in Table 1 was defined by the ratio of the raw material powder temperature on the inner wall of the crucible to the raw material powder temperature at the center of the crucible based on Equation 5. Also shown in FIG. 8a is the location of the source surface and the center of the source. The temperature variation is determined by the ratio between the temperature of the raw material powder in contact with the inner wall of the crucible side wall and the temperature of the raw material powder on the crucible central axis. That is, | (temperature of the raw material powder in contact with the inner wall of the crucible side wall) / (temperature of the raw material powder on the crucible central axis) | -1 is calculated. From this equation, if the raw material powder temperature at the crucible central axis and the raw material powder temperature at the inner wall surface of the crucible are the same, the temperature variation is zero.

  In the structure of the prior art 2, since the heat conductor is arranged in the center of the crucible, the filling amount of the raw material powder is smaller than that of the prior art 1, and the single crystal that can be manufactured is also small. Therefore, after the first growth process is completed, it is necessary to refill the raw material powder and perform the second growth process, and the time required to make a single crystal of the same size as the prior art 1 becomes longer. Therefore, there is a problem that the crystal growth rate is lowered. In the future, the existence of a heat conductor at the center of the crucible will also include a problem that it becomes difficult to cope with the increase in size and length of single crystals.

  The present invention solves the above-mentioned problems of the prior art 1 and the prior art 2, and can uniformly sublimate and consume the raw material by increasing the temperature distribution of the raw material powder, and can increase the filling amount of the raw material. An object is to provide a crucible for a single crystal manufacturing apparatus. Therefore, the temperature variation at the raw material surface and the raw material center is suppressed to 2 ° C. or less. By solving these problems, it is possible to provide a crucible for a single crystal manufacturing apparatus capable of improving the crystal growth rate.

  In order to solve the above-mentioned conventional problems, the crucible for a single crystal production apparatus of the present invention accommodates a raw material powder for growing a single crystal in a crucible of a cylindrical container, and sublimates the single crystal raw material powder by heating. In a crucible for a single crystal growth apparatus, which is supplied on a seed crystal substrate made of crystals and grows a single crystal on the seed crystal substrate, a seed for installing the seed crystal substrate made of a single crystal on the lid inside the crucible A crystal mounting portion, a conical flange having an opening larger than the seed crystal substrate side on the raw material powder side for concentrating the sublimation gas from the raw material powder in the vicinity of the seed crystal substrate with respect to the seed crystal substrate, and the crucible body A heat insulating material covering the whole, and a high-frequency coil disposed outside the heat insulating material disposed around the entire crucible body for heating the seed crystal and the raw material, and a side wall of the crucible of the heat conductor The raw material powder The thickness from the bottom of the crucible to the position between the surface of the raw material powder stored in the crucible and the bottom of the conical flange is continuously changed in order to make the heat conduction to the uniform uniform Thus, the uniformity of the temperature of the raw material powder in the crucible can be improved.

  According to the crucible for a single crystal production apparatus of the present invention, the temperature distribution of the raw material powder in the crucible can be made uniform so that the raw material powder can be stably sublimated and consumed, and the crystal growth rate can be improved.

  Before explaining the embodiments of the present invention, the pre-examined crucible for single crystal manufacturing apparatus will be described with reference to FIGS. 8a, 8b, 10, 11, 15, 15a, 15b, and 16. FIG.

    FIG. 10 is a diagram showing a cross section of the crucible 24 of the single crystal manufacturing apparatus that was preliminarily studied, and expressed as β = h3 ÷ (h2−h1) using the dimensions h1, h2, and h3 as the shape factor β. Is. In the crucible 24 having a cylindrical shape, a crucible side wall 2 provided with a conical flange 6 is placed on the crucible bottom plate 3 and opened upward. It is a configuration. A seed crystal substrate mounting portion 25 is provided on the crucible upper lid, and the seed crystal substrate 7 is bonded thereto. The raw material powder 4 is filled up to the position of the v-groove 28 in the crucible, and the single crystal growth space 26 becomes a space between the raw material surface and the seed crystal substrate. The v-groove is formed simultaneously when the crucible side wall is turned.

  The conical flange is provided for the purpose of concentrating the sublimation gas from the raw material powder in the vicinity of the seed crystal substrate. The lower end of the shape starts from a position 23 mm away from the surface of the raw material and narrows toward the seed crystal in a conical shape. At this time, the conical shape is 20 mm in the height direction. The seed crystal attachment portion and the conical flange are provided with a 1 mm gap in the radial direction.

  Although omitted in FIG. 10, the outer side of the crucible is surrounded by a heat insulating material 23, and the high-frequency coil 8 is spirally arranged outside the crucible as in the prior art 1. When the crucible is heated by passing a current of several hundreds A through the high frequency coil, the raw material becomes high temperature and sublimation gas is generated, and the single crystal 27 grows on the seed crystal substrate.

  Compared with the crucible of prior art 1, the major difference is that a stepped side wall 17 is provided outside the crucible side wall. The problem of the prior art 1 is that the vicinity of the surface of the raw material powder is only heated from the crucible side wall, so that there is temperature variation where the vicinity of the crucible side wall is high temperature and the vicinity of the crucible central axis is low temperature. Therefore, by providing a stepped portion at the lower part of the crucible side wall and increasing the heat flow from the lower part of the crucible toward the raw material surface, heating from the crucible side wall can be relatively suppressed, so that the raw material powder is heated in a balanced manner. According to this configuration, the temperature variation of the raw material surface can be improved as compared with the prior art 1. Compared with the prior art 2, since there is no heat conductor 18, it can be filled with much raw material powder.

  The approximate dimensions of the crucible are as follows: the crucible inner wall radius r00 is 30 mm, the crucible outer wall radius r30 is 45 mm, and the other outer wall radius r10 = 38 mm. The total height from the lower surface of the crucible bottom plate to the surface of the crucible upper lid is 150 mm, and the plate thickness of the crucible bottom plate is h0 = 15 mm. The height h1 of the raw material powder filled in the crucible is 92 mm, the height h2 from the bottom surface of the crucible bottom plate to the conical flange is 115 mm, the distance from the raw material surface to the seed crystal substrate (crystal growth space 26) is 40 mm, the seed crystal The thickness of the substrate is 1 mm.

  The crucible shapes of the prior art 1 and the prior art 2 are as described in “Problems to be solved by the invention”.

  FIG. 11 compares the shape factor β of the stepped side wall with the actual crucible shape. If β = −1.6, the height of the stepped side wall is half of the height direction of the raw material powder. When β = 0, the height of the stepped side wall is the same as the surface of the raw material powder, and when β = 0.5, the height of the stepped side wall is in the middle between the raw material surface and the root of the conical flange. When β = 1, the height of the stepped side wall is the same height as the root of the conical flange. Therefore, when β takes a large negative value, the crucible side wall has a thickness (r10-r00) of prior art 1, and when β takes a large positive value, the crucible side wall has a thickness (r20-r00). Similar to the crucible of prior art 1.

  FIG. 15a is a result of thermal analysis of the raw material surface temperature along the radial direction using a thermofluid simulation for the crucible having the stepped side wall, and a result of changing several coefficients β representing the shape of the stepped side wall. The results of Conventional Technology 1 and Conventional Technology 2 are compared. Similarly, FIG. 15B shows the result of thermal analysis along the radial direction with respect to the center of the raw material. In both cases, the horizontal axis represents the radius, and the vertical axis represents the temperature ratio at each radius with respect to the raw material powder temperature at radius = 0. In both figures, if the temperature ratio is close to 1, the temperature distribution is uniform. 8a and 8b show the positions of the surface of the raw material and the center of the raw material subjected to the thermal analysis. The center of the raw material indicates a half place in the height direction of the raw material powder.

  According to FIG. 15a, as is conventional, the temperature distribution of the two prior arts is such that the inner wall surface of the crucible (radius 15 mm) is the highest temperature, and the temperature decreases toward the crucible central axis (radius 0 mm). In contrast, in a crucible having a stepped side wall, if the shape factor β is positive, the inner wall surface of the crucible is hotter, but if the shape factor β is negative, the inner wall surface of the crucible becomes lower. It can also be seen from FIG. 15a that the temperature distribution on the raw material surface is most uniform when the shape factor β = 0.

  According to FIG. 15b, the temperature of the raw material powder in contact with the inner wall surface of the crucible is higher than the temperature of the raw material powder located on the crucible central axis with all the shape factors β. In addition, comparing the crucible having the stepped side wall and the two prior art crucibles, except for β = 0.87, the crucible having the stepped side wall has a large temperature difference between the raw material powder at the crucible inner wall surface and the crucible central axis. .

  FIG. 16 is a summation of the results of FIGS. 15a and 15b by Equation 5, and the overall tendency can be easily grasped. From this result, the crucible of the stepped side wall was a result opposite to the expectation. That is, it has been found that the temperature variation is larger than that of the prior art and the above technical problem cannot be solved. However, through this approach, it became clear that the outer wall shape of the crucible has a great influence on the temperature distribution of the raw material powder, and it was found that there is a high possibility that the temperature variation can be improved by appropriately controlling the outer wall shape of the crucible.

  Accordingly, the shape of the outer wall of the crucible was examined, and the inventors found a crucible shape that can improve the temperature variation of the raw material powder. The embodiment of the crucible for a single crystal manufacturing apparatus of the present invention will be described below in detail with reference to the drawings. To do.

  FIG. 1 shows a cross section of a crucible for a single crystal manufacturing apparatus according to a first embodiment of the present invention. In the crucible 24 having a cylindrical shape, the crucible side wall 2 provided with the conical flange 6 on the inner wall side is placed on the crucible bottom plate 3, and the crucible side wall is open upward and fits into the opening. It is the structure by which the crucible upper cover 5 was arrange | positioned. The crucible is placed on a support base 9. A seed crystal substrate mounting portion 25 is provided on the crucible upper lid, and the seed crystal substrate 7 is bonded thereto. The raw material powder 4 is filled up to the position of the v-groove 28 in the crucible, and the single crystal growth space 26 becomes a space between the raw material surface and the seed crystal substrate. The v-groove is formed simultaneously when turning the crucible side wall.

  The outer side of the crucible is surrounded by a heat insulating material 23, and the high-frequency coil 8 is arranged on the outer side. When the crucible is heated by passing a current of several hundreds of A through the high-frequency coil, the raw material powder becomes high temperature and sublimation gas is generated, and the gas is transported toward the seed crystal substrate, and the single crystal is made into a single crystal substrate. Crystal 27 grows. Since this crystal growth process is performed by a chemical reaction, the crucible is sometimes referred to as a reaction furnace.

  The conical flange is provided for the purpose of concentrating the sublimation gas from the raw material powder in the vicinity of the seed crystal substrate. The lower end of the shape starts from a position 23 mm away from the surface of the raw material and narrows toward the seed crystal in a conical shape. At this time, the conical shape is 20 mm in the height direction. The seed crystal attachment portion and the conical flange are provided with a 1 mm gap in the radial direction.

  Compared with the crucible of the prior art 1, the major difference is that a taper 1 is provided on the outside of the crucible side wall so that the thickness of the crucible side wall continuously decreases from the crucible lower part toward the crucible upper part. This is the contents described in claims 1 and 2. The crucible bottom plate and the crucible side wall become a heater that heats the raw material powder by induction heating, but if the taper configuration is adopted, as shown in FIG. 2, the heat flow 11 from the crucible side wall to the raw material becomes weaker as it goes above the crucible, The heat flow 12 from the crucible bottom plate becomes relatively strong, and the raw material powder is heated in a balanced manner. Therefore, the temperature distribution of the raw material powder becomes uniform as compared with the prior art 1, and the raw material powder can be sublimated and consumed evenly. The hatched region 10 in FIG. 2 is an image of the fact that the temperature distribution of the entire raw material powder is uniform as compared with the prior art 1, and the sublimation of the raw material powder is increased even in the crucible central axis portion. As shown in FIG. 5, even if the taper is not a strict linear shape, the effect of the present invention can be obtained even if the taper is a gentle curved shape 13.

  Further, since there is no thermal conductor 18 as compared with the prior art 2, it can be filled with a large amount of raw material powder, the crystal growth rate is fast, and there is an effect that it is advantageous for increasing the size and length of a single crystal.

  The schematic dimensions of the crucible in Example 1 will be described with reference to FIG. The crucible inner wall radius r00 is 30 mm, the crucible outer wall radius r10 is 45 mm, the total height from the lower surface of the crucible bottom plate to the surface of the crucible upper lid is 150 mm, and the thickness of the crucible bottom plate is h0 = 15 mm. The height h1 of the raw material powder filled in the crucible is 92 mm, the height h2 from the bottom surface of the crucible bottom plate to the conical flange is 115 mm, the single crystal growth space from the raw material surface to the seed crystal substrate is 40 mm, and the thickness of the seed crystal substrate Is 1 mm.

  About the taper shape provided in the crucible outer wall, it is the outer wall radius r11 in the range of 30 mm <r11 <45 mm and the height h3 from the raw material surface. For convenience, the inclination degree of the taper is represented by the shape factor α defined by α = (r11−r00) / (r10−r00) using the r10, r11, and r00. This shape factor α is an index representing what percentage of the original side wall plate thickness is. The height of the taper is expressed by a shape factor β defined by β = h3 ÷ (h2−h1) using h1, h2, and h3.

  FIG. 4 shows a comparison between the shape factor β of the taper and the actual crucible shape. If β = −1.6, the taper height is half of the height direction of the raw material powder. When β = 0, the height of the taper is the same height as the surface of the raw material powder, and when β = 0.5, the height of the taper is the middle between the raw material surface and the root of the conical flange. When β = 1, the height of the taper is the same as the root of the conical flange. If the shape factor α = 0, it is the same simple cylindrical crucible as the prior art 1 having no taper, and as the shape factor α increases, the inclination of the taper increases and the thickness of the side wall of the crucible decreases.

  FIG. 12A shows the result of thermal analysis of the raw material surface temperature along the radial direction using the thermal fluid simulation for the crucible of Example 1, and the shape factor β representing the shape in the height direction of the taper was fixed to 0.5. This is a comparison of the results obtained by changing some of the shape factor α under the conditions with the results of the prior art 1 and the prior art 2. Similarly, FIG. 12b shows the result of thermal analysis along the radial direction with respect to the center of the raw material. In both cases, the horizontal axis represents the radius, and the vertical axis represents the temperature ratio of the raw material powder at each radius to the temperature of the raw material powder located at radius = 0. In both figures, the temperature distribution is more uniform as the temperature ratio is closer to 1 even if the radius is increased. The positions of the raw material surface and the raw material center are shown in FIGS. 8a and 8b.

  FIG. 13a shows the result of changing several shape factors β and the results of prior art 1 and prior art 2 on the condition that the shape factor α representing the radial shape of the taper is fixed to 0.5 for the crucible of example 1. Is a comparison. Similarly, FIG. 13 b shows the result of thermal analysis along the radial direction with respect to the center of the raw material. In both cases, the horizontal axis represents the radius, and the vertical axis represents the temperature ratio of the raw material powder at each radius to the temperature of the raw material powder located at radius = 0.

  According to FIG. 12a, as usual, the temperature distribution of the raw material powders filled in the two conventional crucibles is the highest on the inner wall of the crucible (radius 15 mm), and the temperature decreases toward the crucible central axis (radius 0 mm). Become. Regarding the crucible of Example 1 having a taper, when the shape factor α is close to 0, the temperature ratio is also close to the result of the prior art 1, but as the shape factor α increases, the temperature ratio becomes far from the result of the prior art 1. The temperature variation of the raw material powder is the smallest when the shape factor α is around 0.5, and when α is larger than this, the temperature variation increases. On the other hand, according to FIG. 12b, the temperature distribution in the center of the raw material becomes smaller as the shape factor α increases.

  According to FIG. 13a, when the shape factor β is a positive value, the temperature variation of the raw material surface is small, but when the shape factor β is a negative value, the temperature variation increases. On the other hand, the temperature variation of the raw material powder at the center of the raw material is minimized when the shape factor β is near zero.

  FIG. 14a shows the temperature variation of the results of FIGS. 12a and 12b, calculated from the expression | (temperature of the raw material powder in contact with the inner wall of the crucible side wall) / (temperature of the raw material powder on the crucible central axis) | -1. To do. This is the sum of these equations, and the overall tendency can be easily grasped regarding the taper shape factor α and the temperature variation of the raw material powder. From this result, the tapered shape of Example 1 is effective for uniforming the temperature distribution of the raw material powder, and the temperature variation of the raw material powder can be made smaller than the crucibles of the prior art 1 and the prior art 2. In particular, 0.4 <α <0.6 is preferable.

  FIG. 14b is the sum of the results of FIG. 13a and FIG. Using FIG. 14b, the relationship between the taper shape factor β and the temperature variation of the raw material powder can be easily grasped. From this result, the tapered shape is effective for uniforming the temperature distribution of the raw material powder, and the temperature variation of the raw material powder can be made smaller than that of the crucibles of the prior art 1 and the prior art 2. In particular, 0.3 <β <0.6 is optimal.

  These effects will be described when the raw material temperature in the vicinity of the central axis on the raw material surface is approximately 2200 ° C. In FIG. 14a, when α = 0.5, the temperature variation on the surface of the raw material is 0.3 ° C., and the temperature variation at the center of the raw material is 1.1 ° C. Compared with the prior art 1, it is improved from 2.2 ° C. at the surface of the raw material and 3.0 ° C. at the center of the raw material, and the target temperature variation within 2 ° C. is also achieved by the problem of the prior art. . Also in FIG. 14b, when β = 0.6, the temperature variation on the surface of the raw material is 0.3 ° C., the temperature variation at the center of the raw material is 0.9 ° C., and the temperature variation is improved from the prior art 1 and the prior art 2. And the target values set forth in the problems of the prior art have been achieved.

  Further, the tapered shape satisfying 0.4 <α <0.6 and 0.3 <β <0.6 further suppresses the heat 11 flowing from the crucible side wall to the raw material powder, and the heat flowing from the crucible bottom plate to the raw material powder. Since 12 can be relatively increased, the temperature distribution of the raw material powder becomes uniform and the raw material can be sublimated and consumed evenly.

  Moreover, even when there is no conical flange as shown in FIG. 9, the action of suppressing the heat 11 flowing from the crucible side wall to the raw material powder and relatively increasing the heat 12 flowing from the crucible bottom plate to the raw material powder is effective. Can be made more uniform than the prior art 1 and the prior art 2. Therefore, even in the crucible shape of FIG. 9, the raw material powder can be sublimated and consumed evenly, so that the crystal growth rate can be increased.

  FIG. 6 shows a cross-sectional view of a crucible for a single crystal production apparatus of Example 2 of the present invention. In FIG. 6, the difference from the configuration of the first embodiment is that a taper 14 is provided inside the crucible side wall 2 and that a conical flange 15 of the second form conventionally used is attached to the crucible side wall. .

  The approximate dimensions of the crucible of Example 2 are as follows: crucible inner wall radius r00 is 30 mm, crucible outer wall radius r10 is 45 mm, and the height direction is the same as in Example 1.

  The taper shape provided on the inner wall of the crucible is defined by the inner wall radius r20 in the range of 30 mm <r20 <45 mm and the height h3 from the raw material surface. For the sake of convenience, the degree of taper inclination is r20, r10, r00, and the shape factor α defined by α = (r10−r20) / (r10−r00), and the taper height is h1, h2, h3. Is represented by a shape factor β defined by β = h3 ÷ (h2−h1).

  The relationship between the shape factor α and the shape factor β and the temperature variation of the raw material powder is substantially the same as in Example 1. If 0.4 <α <0.6 and 0.3 <β <0.6, the raw material powder The temperature distribution can be made uniform.

  FIG. 7: shows sectional drawing of the crucible for single crystal manufacturing apparatuses of Example 3 of this invention. In FIG. 7, the difference from the configuration of the first embodiment is that the taper 1 and the taper 14 are provided on both sides of the crucible side wall, and the conical flange 16 of the third form conventionally used is attached to the crucible inner wall. That is.

  The outline dimensions of the crucible of the third embodiment are the same as those of the first embodiment in the crucible inner wall radius r00 of 30 mm, the crucible outer wall radius r10 of 45 mm, and the height direction.

  The degree of inclination of the taper provided on the inner wall of the crucible is represented by the shape factor α defined by α = (r11−r20) / (r10−r00) using the r20, r11, r10, and r00. The height of the taper is represented by a shape factor β defined by β = h3 ÷ (h2−h1) using h1, h2, and h3.

  The relationship between the shape factor α and the shape factor β and the temperature variation of the raw material powder is substantially the same as in Example 1. If 0.4 <α <0.6 and 0.3 <β <0.6, the raw material powder The temperature distribution can be made uniform.

  The crucible for a single crystal production apparatus according to the present invention is useful as a crucible capable of efficiently producing a high-quality silicon carbide single crystal substrate by simultaneously achieving uniform sublimation / consumption of the raw material powder and improving the crystal growth rate. is there.

    The crucible for a single crystal manufacturing apparatus according to the present invention can be applied to other material materials manufactured by a sublimation method.

The figure which shows typically the cross section of the single-crystal manufacturing apparatus in Example 1 of this invention. The figure for demonstrating typically the heat flow from a crucible to a raw material in the crucible for single crystal manufacturing apparatuses in Example 1 of this invention. The figure which shows the main dimensions of the crucible for single-crystal manufacturing apparatuses in Example 1 of this invention The figure for demonstrating the relationship between shape factor (beta) and a crucible shape in the crucible for single crystal manufacturing apparatuses in Example 1 of this invention. Sectional drawing of the crucible for other single crystal manufacturing apparatuses in Example 1 of this invention Sectional drawing of the crucible for single-crystal manufacturing apparatuses in Example 2 of this invention Sectional drawing of the crucible for single-crystal manufacturing apparatuses in Example 3 of this invention The figure for demonstrating the position of the thermofluid simulation of the temperature distribution of the crucible for single crystal manufacturing apparatuses Sectional drawing of the crucible for further another single crystal manufacturing apparatus in Example 1 of this invention Cross-sectional view of a crucible for a single crystal production apparatus, which was preliminarily studied before reaching the present invention The figure for demonstrating the relationship between the shape factor (beta) of the crucible for single crystal manufacturing apparatuses and the crucible shape which were preliminary examined before reaching this invention The figure which shows the relationship between the shape factor α and temperature distribution of the crucible for single crystal manufacturing equipment Figure showing the relationship between the shape factor β and temperature distribution of a crucible for a single crystal manufacturing device The figure which shows the relationship with the temperature variation of the raw material center and the raw material surface with respect to the shape factors (alpha) and (beta) of the crucible for single crystal manufacturing apparatuses. Figure showing the relationship between the shape factor β and the temperature distribution of the crucible for single crystal manufacturing equipment that was studied in advance The figure which shows the relationship with the temperature variation of the raw material center with respect to the shape factors (alpha) and (beta) of the crucible for single crystal manufacturing apparatuses examined preliminary. The figure for demonstrating typically the flow of the heat | fever from a crucible to a raw material in the crucible for conventional single crystal manufacturing apparatuses. The figure for demonstrating typically the flow of the heat | fever from a crucible to a raw material in the other conventional crucible for single crystal manufacturing apparatuses. Cross-sectional view of a conventional crucible for single crystal manufacturing equipment Sectional view of conventional single crystal manufacturing equipment The figure which shows the analysis result of the thermal fluid simulation of the conventional constitution

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Taper 2 Crucible side wall 3 Crucible bottom plate 4 Raw material powder 5 Crucible top cover 6, 15, 16 Conical flange 7 Seed crystal substrate 8 High frequency coil 9 Support stand 10 Area | region where there is much sublimation and consumption of raw material powder 11 Heat flow from crucible side wall to raw material powder 12 representing the heat flow from the crucible bottom plate to the raw material powder 13 curve shape 14 taper 17 stepped side wall 18 heat conductor 19 vector representing the heat flow from the crucible side wall to the raw material powder 20 heat flow from the heat conductor to the raw material powder 21 representing a region where the sublimation / consumption of the raw material powder is large 22 a vector representing a heat flow from the crucible bottom plate to the raw material powder 23 heat insulating material 24 crucible 25 seed crystal substrate mounting portion 26 single crystal growth space 27 single crystal 28 V groove

Claims (4)

The raw material powder for growing a single crystal is stored in a crucible of a cylindrical container, and the single crystal raw material powder is heated and sublimated and supplied onto a seed crystal substrate made of a single crystal, and the single crystal is grown on the seed crystal substrate. In a crucible for a single crystal growth apparatus,
A seed crystal mounting part for installing a seed crystal substrate made of a single crystal in the lid part inside the crucible;
A conical flange having a larger opening than the seed crystal substrate side on the source powder side for concentrating the sublimation gas from the source powder in the vicinity of the seed crystal substrate with respect to the seed crystal substrate;
A heat insulating material covering the entire crucible body;
A high-frequency coil disposed outside a heat insulating material disposed around the entire crucible body to heat the seed crystal and the raw material;
With
The side wall of the crucible of the heat conductor has a thickness from the bottom of the crucible to the position between the raw material powder surface stored in the crucible and the bottom of the conical flange in order to make the heat conduction to the raw material powder uniform. A crucible for a single crystal growth apparatus, characterized by continuously changing. The crucible for a single crystal production apparatus according to claim 1, wherein the side wall of the crucible is thicker at the bottom of the crucible than at the bottom of the conical flange. When the inner wall radius of the crucible is r00, the outer wall radius of the crucible bottom is r10, and the smallest outer wall radius r11 of the crucible is defined as α = (r10−r11) ÷ (r10−r00), 0.4 <α < The crucible for a single crystal manufacturing apparatus according to claim 1, wherein the crucible is 0.6. The height h1 from the bottom of the crucible to the raw material powder surface, the height h2 from the bottom of the crucible to the conical flange, the height h3 from the surface position of the raw material to the place where the crucible has the smallest outer wall radius r11, β = The crucible for a single crystal manufacturing apparatus according to claim 3, wherein 0.3 <β <0.6 when defined by h3 ÷ (h2-h1).

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