JP2015160772A - Crystal production apparatus, and crystal production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal production apparatus capable of improving quality of a growing crystal.SOLUTION: A crystal production apparatus 1 includes a cylindrical heater 15 open upward and downward, a first crucible 8 disposed inside the heater 15 and having a recess 9 open upward, an insulation member 10 composed of a first insulation part 11 arranged on the bottom face of the recess 9 of the first crucible 8 and a second insulation part 12 arranged on the inner face of the recess 9, and a second crucible 6 disposed inside the recess 9 of the first crucible 8 via the insulation member 10 and holding a solution 5 for growing a crystal 2. The amount of heat conduction through the first insulation part 11 is larger than the amount of heat conduction through the second insulation part 12. The quality of the growing crystal 2 is thus improved.

Description

  The present invention relates to a crystal manufacturing apparatus for growing a crystal by a solution growth method and a crystal manufacturing method using the crystal manufacturing apparatus.

  At present, silicon carbide crystals, which have a wider band gap than silicon and have a high electric field strength leading to dielectric breakdown, are attracting attention as a substrate material for forming devices such as transistors. It is known that silicon carbide crystals are manufactured by, for example, a solution growth method. For example, in Patent Document 1, a heat insulating material is arranged around a crucible arranged in a cylindrical heating device, and the thickness of the heat insulating material arranged on the bottom surface of the crucible is larger than the thickness of the heat insulating material arranged on the side surface of the crucible. Describes that silicon carbide crystals are produced using a larger crystal production apparatus.

JP 2012-101960 A

  In the invention disclosed in Patent Document 1, in the planar direction, the temperature in the vicinity of the side portion (container wall) of the solution crucible tends to be higher than the temperature in the central portion of the crucible. As a result, the temperature gradient in the planar direction of the solution increases, and the variation in the degree of growth on the crystal growth surface tends to increase. For this reason, there is a problem that the quality of the crystal may be deteriorated.

  The present invention has been devised in view of such circumstances, and an object thereof is to provide a crystal manufacturing apparatus capable of improving the quality of crystals.

  A crystal manufacturing apparatus according to an embodiment of the present invention includes a cylindrical heating device that is open up and down, a first crucible that is disposed inside the heating device and has a recess that is open on an upper surface, and the first crucible. A heat retaining member comprising a first heat retaining portion disposed on the bottom surface of the concave portion of the crucible and a second heat retaining portion disposed on the inner surface of the concave portion, and in the concave portion of the first crucible via the heat retaining member And a second crucible for holding a solution for growing a crystal, and a heat amount of heat conduction by the first heat retaining portion is larger than a heat amount of heat conduction by the second heat retaining portion.

  According to the crystal manufacturing apparatus according to the embodiment of the present invention, the second heat of the solution whose temperature is likely to be increased by making the amount of heat conduction by the first heat retaining unit larger than the amount of heat conduction by the second heat retaining unit. The temperature rise in the vicinity of the side portion of the crucible can be suppressed, and the temperature rise in the central portion of the second crucible of the solution whose temperature tends to be low can be promoted. As a result, since the temperature gradient in the planar direction of the solution can be reduced, variation in the degree of growth on the crystal growth surface can be reduced. Therefore, the quality of the grown crystal can be improved.

It is sectional drawing which shows the outline of the crystal manufacturing apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the modification of the crystal manufacturing apparatus which concerns on one Embodiment of this invention.

<Crystal production equipment>
Hereinafter, a crystal manufacturing apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The present invention is not limited to these embodiments, and various changes and improvements can be made without departing from the scope of the present invention.

  FIG. 1 shows an outline of a crystal manufacturing apparatus according to an embodiment of the present invention, and shows a cross section of the crystal manufacturing apparatus cut in the vertical direction. FIG. 2 shows a modification of the crystal manufacturing apparatus according to one embodiment of the present invention, and shows a cross section of the crystal manufacturing apparatus cut in the vertical direction.

  The crystal manufacturing apparatus 1 is an apparatus for manufacturing a silicon carbide crystal 2 used for a semiconductor component or the like. As shown in FIG. 1, the crystal manufacturing apparatus 1 mainly includes a seed crystal 3, a holding member 4 that holds the seed crystal 3, a solution 5, and a crucible 6 that stores (holds) the solution 5 (hereinafter referred to as a second type). Crucible 6). The crystal manufacturing apparatus 1 moves the seed crystal 3 into the second crucible 6 via the holding member 4, and brings the lower surface of the seed crystal 3 into contact with the solution 5 in the second crucible 6, whereby the seed crystal 3 Crystal 2 is grown on the lower surface of the substrate.

  The crystal 2 is processed into a wafer after being manufactured, and becomes a part of the semiconductor component through a semiconductor component manufacturing process. The crystal 2 is made of, for example, a single crystal of silicon carbide. Crystal 2 is a lump of silicon carbide crystals grown on the lower surface of seed crystal 3. The crystal 2 is formed in a columnar shape, for example.

  The seed crystal 3 becomes a seed of the crystal 2 grown by the crystal manufacturing apparatus 1. The seed crystal 3 is formed in a flat plate shape having, for example, a circular or polygonal planar shape. The seed crystal 3 is a crystal made of the same material as the crystal 2. That is, in the present embodiment, the seed crystal 3 made of a silicon carbide crystal is used to produce the silicon carbide crystal 2. The seed crystal 3 is made of, for example, a single crystal or a polycrystal.

  The seed crystal 3 is fixed to the lower surface of the holding member 4. The seed crystal 3 is fixed to the holding member 4 by, for example, an adhesive (not shown) containing carbon. The seed crystal 3 can be moved in the vertical direction (Z-axis direction) by the holding member 4.

  The holding member 4 holds the seed crystal 3 and carries the seed crystal 3 in and out of the solution 5. Specifically, the holding member 4 has a function of bringing the seed crystal 3 into contact with the solution 5 and keeping the crystal 2 away from the solution 5. The holding member 4 is fixed to a moving mechanism (not shown) that is a part of the moving device 7. The moving mechanism moves the holding member 4 fixed to the moving mechanism in the vertical direction using, for example, a motor. As a result, the holding member 4 moves in the vertical direction by the moving device 7. Therefore, the seed crystal 3 moves in the vertical direction as the holding member 4 moves.

  The holding member 4 is formed in a columnar shape, for example. The holding member 4 is made of, for example, a polycrystal of carbon or a fired body obtained by firing carbon. The holding member 4 may be fixed to the moving device 7 so as to be rotatable around a vertical axis.

  The solution 5 is stored inside the second crucible 6, and supplies the raw material of the crystal 2 to the seed crystal 3 to grow the crystal 2. Solution 5 contains the same material as crystal 2. That is, since the crystal 2 is a silicon carbide crystal, the solution 5 contains carbon and silicon. In the present embodiment, in the solution 5, a solute made of carbon is dissolved in a solvent made of silicon. In addition, the solution 5 may contain metal materials, such as chromium, in order to improve the solubility of carbon.

In this embodiment, a solution growth method is used as a method for growing the silicon carbide crystal 2.
In the solution growth method, the temperature of the seed crystal 3 is maintained while keeping the solution 5 in a metastable state (a state that is very close to a stable state in which the precipitation and elution of crystals are balanced thermodynamically) on the lower surface of the seed crystal 3. The crystal 2 is grown on the lower surface of the seed crystal 3 by controlling the conditions so that the precipitation of the crystal 2 proceeds slightly more than the elution. That is, in the solution 5, carbon (solute) is dissolved in silicon (solvent), and the solubility of carbon increases as the temperature of the solvent increases. Here, when the solution 5 heated to a high temperature is cooled by contact with the seed crystal 3, the dissolved carbon becomes supersaturated, and the vicinity of the seed crystal 3 of the solution 5 is locally metastable. Then, the solution 5 precipitates as a silicon carbide crystal 2 on the lower surface of the seed crystal 3 in an attempt to shift to a stable state (thermodynamic equilibrium state). As a result, the crystal 2 grows on the lower surface of the seed crystal 3.

  The second crucible 6 stores the solution 5 and heats the solution 5. For example, the second crucible 6 is formed in a concave shape in order to store the solution 5. The second crucible 6 is made of, for example, graphite. In the present embodiment, the second crucible 6 melts silicon in the raw material of the crystal 2 in the second crucible 6 to be a solvent, and a part (carbon) of the second crucible 6 is dissolved in the silicon solvent. Thus, the solution 5 contains carbon and silicon.

The outer shape of the second crucible 6 is formed in a columnar shape having, for example, a circular shape or a polygonal planar shape. In the present embodiment, the outer shape of the second crucible 6 is formed in a cylindrical shape. The area of the bottom surface outside the second crucible 6 is set to, for example, 3000 mm ² or more and 20000 mm ² or less. The height of the second crucible 6 is set to, for example, 60 mm or more and 200 mm or less.

  As shown in FIG. 1, the second crucible 6 is disposed inside an outer crucible 8 (hereinafter referred to as a first crucible 8). The first crucible 8 has a function of receiving heat from the heating device 15 that heats the first crucible 8 and transmitting the heat to the second crucible 6 by holding the second crucible 6 inside. The first crucible 8 has a recess 9 opened on the upper surface in order to accommodate the second crucible 6. The second crucible 6 is disposed in the first crucible 8 so as to be positioned at the center of the first crucible 8 when viewed in plan. Since the second crucible 6 is arranged at the center of the first crucible 8, the heat from the first crucible 8 can be easily transferred to the second crucible 6.

The outer shape of the first crucible 8 is formed in a columnar shape having, for example, a circular or polygonal planar shape. In the present embodiment, the outer shape of the first crucible 8 is formed in a cylindrical shape. The area of the outer bottom surface of the first crucible 8 is set to, for example, 5000 mm ² or more 40000 mm ² or less. The height of the first crucible 8 is set to, for example, 120 mm or more and 300 mm or less.

The concave portion 9 of the first crucible 8 is formed in a shape similar to the outer shape of the first crucible 8. In this embodiment, the outer shape of the first crucible 8 is cylindrical, so that the concave portion 9 is cylindrical. Is formed. The opening area of the recess 9 is set to, for example, 4000 mm ² or more 32000Mm ² or less. The depth of the recessed part 9 is set to 110 mm or more and 290 mm or less, for example.

  A heat retaining member 10 is disposed between the first crucible 8 and the second crucible 6. That is, the heat retaining member 10 is disposed on the inner surface of the recess 9 of the first crucible 8, and the second crucible 6 is disposed in the recess 9 of the first crucible 8 via the heat retaining member 10.

  The heat retaining member 10 surrounds the second crucible 6 and heats the second crucible 6. The heat retaining member 10 includes a first heat retaining portion 11 disposed on the bottom surface of the concave portion 9 of the first crucible 8 and a second heat retaining portion 12 disposed on the inner surface of the concave portion 9 of the first crucible 8. The amount of heat conduction by the first heat retaining unit 11 is set to be larger than the amount of heat conduction by the second heat retaining unit 12. That is, the heat retaining member 10 is designed such that the product of the thermal conductivity and the thickness of the first heat retaining portion 11 is larger than the product of the thermal conductivity and the thickness of the second heat retaining portion 12.

  In the crystal manufacturing apparatus 1 of the present embodiment, since the crystal manufacturing apparatus 1 has the first heat retaining part 11 and the second heat retaining part 12, when heat is conducted from the first crucible 8 to the second crucible 6, The conducted heat is more easily transmitted to the bottom of the second crucible 6 than to the side of the second crucible 6. That is, the crystal manufacturing apparatus 1 can suppress the temperature increase in the vicinity of the side of the second crucible 6 of the solution 5 whose temperature is likely to be increased by the second heat retaining unit 12, and the temperature is likely to be decreased by the first heat retaining unit 11. An increase in temperature at the center of the solution 5 can be promoted. As a result, the temperature gradient in the planar direction of the solution 5 can be reduced, and the variation in the growth degree on the growth surface of the crystal 2 can be reduced. Therefore, the deterioration of the quality of the growing crystal 2 can be suppressed, and as a result, the quality of the grown crystal 2 can be improved.

  The first heat retaining portion 11 may be disposed only directly below the second crucible 6 so that the end of the second heat retaining portion 12 is in contact with the bottom surface of the concave portion 9 of the first crucible 8. In this case, heat conduction from the side of the first crucible 8 can be effectively reduced.

The 1st heat retention part 11 is formed in the plate shape which has the same planar shape as the bottom face of the 1st crucible 8, for example. In this embodiment, the 1st heat retention part 11 is formed in the disk shape. The area of the planar shape of the first retaining section 11 is set to, for example, 3000 mm ² or more 32000Mm ² or less. The thickness of the 1st heat retention part 11 is set to 10 mm or more and 20 mm or less, for example.

The second heat retaining unit 12 is formed in a shape similar to the side surface of the first crucible 8, for example. That is, the shape of the second heat retaining portion 12 is similar to the shape of the portion excluding the bottom from the first crucible 8. In the present embodiment, the second heat retaining unit 12 is formed in a cylindrical shape. Area of the outline of the planar shape of the second retaining section 12 is set to, for example, 4000 mm ² or more 32000Mm ² or less. The thickness of the 2nd heat retention part 12 is set to 12 mm or more and 30 mm or less, for example.

  The thickness of the first heat retaining unit 11 may be smaller than the thickness of the second heat retaining unit 12. In this case, the heat conduction heat amount of the first heat retaining unit 11 can be effectively made larger than the heat conduction heat amount of the second heat retaining unit 12.

  The heat conductivity of the first heat retaining unit 11 may be larger than the heat conductivity of the second heat retaining unit 12. In this case, the heat conduction heat amount of the first heat retaining unit 11 can be effectively made larger than the heat conduction heat amount of the second heat retaining unit 12.

  The 1st heat retention part 11 is formed with the felt which knitted carbon fiber, for example. The second heat retaining portion 12 is also formed of a felt knitted with carbon fibers, for example. In such a case, the heat conductivity of the 1st heat retention part 11 and the 2nd heat retention part 12 can be adjusted with the knitting method of carbon fiber. The thermal conductivity of the first heat retaining unit 11 is set to 0.4 W / (m · K) or more and 1 W / (m · K) or less. The thermal conductivity of the second heat retaining unit 12 is set to 0.3 W / (m · K) or more and 0.5 W / (m · K) or less. The thermal conductivity of the first heat retaining unit 11 or the second heat retaining unit 12 can be measured by, for example, a flash method or a probe method.

  The thermal conductivity of the first thermal insulation unit 11 may be made smaller than the thermal conductivity of the second thermal insulation unit 12, and the thickness of the first thermal insulation unit 11 may be made smaller than the thickness of the second thermal insulation unit 12. In this case, the heat conduction heat amount of the first heat retaining unit 11 can be more effectively increased than the heat conduction heat amount of the second heat retaining unit 12.

  The first heat retaining part 11 may have a through hole 13 located at the bottom center part of the second crucible 6. Since the first heat retaining portion 11 has the through-hole 13, heat is transmitted from the bottom surface of the first crucible 8 to the bottom center portion of the second crucible 6 by radiation, and the bottom center portion of the second crucible 6 is effective. To increase the temperature at the center of the solution 5.

The planar shape of the through hole 13 is, for example, a circular shape. The opening area of the through-hole 13 is set to, for example, 2400 mm ² or more 26000Mm ² or less. The opening area of the through hole 13 is, for example, at least 1/2 times as large as the bottom surface of the first crucible 8.

  As shown in FIG. 2, the first crucible 8 may have a convex portion 14 at the center of the bottom surface of the concave portion 9. Since the first crucible 8 has the convex portion 14, the distance between the first crucible 8 and the second crucible 6 at the center of the bottom surface of the second crucible 6 can be reduced. Thus, heat can be easily transferred to the center of the bottom surface of the second crucible 6.

The convex part 14 is formed in plate shape, for example. The planar shape of the convex portion 14 is, for example, a shape similar to the bottom surface of the second crucible 6. The thickness of the convex part 14 is set to 10 mm or more and 20 mm or less, for example. The area of the upper surface of the convex portion 14 is set to, for example, 2400 mm ² or more 26000Mm ² or less. The area of the upper surface of the convex portion 14 is set, for example, at least 1/2 times the bottom surface of the first crucible 8.

  The convex part 14 of the first crucible 8 may be located in the through hole 13 of the first heat retaining part 11. That is, the convex portion 14 may enter the through hole 13. In this case, the heat retaining member 10 does not exist between the convex portion 14 and the bottom surface of the second crucible 6, and heat can be easily transferred from the bottom surface of the first crucible 8 to the center of the bottom surface of the second crucible 6.

  The convex portion 14 of the first crucible 8 may be in contact with the bottom surface of the second crucible 6. In this case, heat can be easily transferred from the bottom surface of the first crucible 8 to the bottom surface of the second crucible 6 by the convex portion 14. In addition, the convex part 14 at this time is formed so that the 2nd crucible 6 may be supported.

  Since the first crucible 8 is heated by the heating device 15 as described above, it is disposed inside the heating device 15 and heated. Specifically, the heating device 15 is formed in a cylindrical shape opened up and down, and the first crucible 8 is arranged inside the tube of the heating device 15. The heating device 15 of the present embodiment includes a coil 16 and an AC power source 17 and heats the second crucible 6 by, for example, an electromagnetic heating method using electromagnetic waves. Note that the heating device 15 may employ other methods such as a resistance heating method for transferring heat generated by a heating resistor such as carbon.

  The coil 16 is formed of a conductor and surrounds the second crucible 6. The coil 16 is arranged around the second crucible 6 so as to surround the second crucible 6 in a cylindrical shape. The AC power source 17 is for flowing an AC current through the coil 16, and the heating time up to the set temperature in the second crucible 6 can be shortened by using an AC current having a high frequency.

  In the present embodiment, the AC power supply 17 and the moving device 7 are connected to the control device 18 and controlled. That is, in the crystal manufacturing apparatus 1, the heating and temperature control of the solution 5 and the carry-in / out of the seed crystal 3 are controlled by the control device 18 in conjunction with each other. The control device 18 includes a central processing unit and a storage device such as a memory, and is composed of, for example, a known computer.

<Crystal production method>
A method for producing a crystal according to an embodiment of the present invention will be described. The crystal manufacturing method of the present embodiment includes a preparation process, a contact process, a crystal growth, and a separation process.

(Preparation process)
A seed crystal 3 is prepared. As the seed crystal 3, for example, a silicon carbide crystal lump manufactured by a sublimation method, a solution growth method, or the like is processed into a flat plate shape by cutting or the like. In the present embodiment, the lower surface of the seed crystal 3 is a carbon surface.

  In addition, the holding member 4 is prepared, and the seed crystal 3 is fixed to the lower surface of the holding member 4. Specifically, an adhesive containing carbon is applied to the lower surface of the holding member 4. Thereafter, the seed crystal 3 is arranged on the lower surface of the holding member 4 with the adhesive interposed therebetween, and the seed crystal 3 is fixed to the holding member 4. As a result, the seed crystal 3 fixed to the lower surface of the holding member 4 can be prepared. In this embodiment, after fixing the seed crystal 3 to the holding member 4, the upper end of the holding member 4 is fixed to the moving device 7.

  Also, the first crucible 8 is prepared. The first crucible 8 is prepared, for example, by forming a recess 9 in a columnar graphite lump. Thereafter, the heat retaining member 10 is prepared and disposed on the inner surface of the recess 9 of the first crucible 8. Specifically, the first heat retaining portion 11 is laid on the bottom surface of the recess 9, and the second heat retaining portion 12 is disposed on the inner surface of the recess 9. In addition, at this time, as for the 1st heat retention part 11 and the 2nd heat retention part 12, the product of the heat conductivity and thickness of the 1st heat retention part 11 is more than the product of the heat conductivity and thickness of the 2nd heat retention part 12. Design to be large. When the through hole 13 is formed in the first heat retaining portion 11 of the heat retaining member 10, the through hole 13 is formed in the first heat retaining portion 11 in advance, and the first heat retaining portion 11 having the through hole 13 is placed in the recess 9. Lay down.

  A second crucible 6 is prepared and placed in the first crucible 8. The second crucible 6 is prepared in the same manner as the first crucible 8. The second crucible 6 is disposed in the first crucible via the heat retaining member 10. Further, the second crucible 6 is arranged so as to be fitted into the heat retaining member 10 arranged in a concave shape, and is fixed in the first crucible 8.

  And the solution 5 is prepared. The preparation of the solution 5 is performed by putting silicon particles as a silicon raw material in the second crucible 6 and heating the second crucible 6 to a melting point of silicon (1420 ° C.) or higher. At this time, carbon (solute) forming the second crucible 6 is dissolved in liquefied silicon (solvent). As a result, the solution 5 containing carbon and silicon can be prepared in the second crucible 6. Carbon contained in the solution 5 may be dissolved at the same time as silicon is melted by adding carbon particles as a raw material in advance.

  In the present embodiment, the second crucible 6 is installed in the first crucible 8 surrounded by the coil 16 of the heating device 15. And the solution 5 can be formed by heating the 2nd crucible 6 with the heating apparatus 15. FIG. Note that the second crucible 6 may be placed in the first crucible 8 after the second crucible 6 is heated outside the crystal production apparatus 1 to form the solution 5 in advance. Alternatively, after the solution 5 is formed in a container other than the second crucible 6, the solution 5 may be poured into the second crucible 6 installed in the first crucible 8.

(Contact process)
The lower surface of the seed crystal 3 is brought into contact with the solution 5. The seed crystal 3 is brought into contact with the solution 5 by moving the holding member 4 downward. In this embodiment, the seed crystal 3 is brought into contact with the solution 5 by moving the seed crystal 3 downward. However, the seed crystal 3 is brought into contact with the solution 5 by moving the second crucible 6 upward. You may let them.

  It suffices that at least part of the lower surface of the seed crystal 3 is in contact with the liquid surface of the solution 5. Therefore, the entire lower surface of the seed crystal 3 may be brought into contact with the solution 5, or the solution 5 may be brought into contact with the side surface or the upper surface of the seed crystal 3. When the solution 5 is immersed so that the side surface or the upper surface of the seed crystal 3 is immersed, the entire lower surface of the seed crystal 3 can be brought into contact with the solution 5 reliably, and the productivity of the crystal 2 can be improved.

(Crystal growth process)
The crystal 2 is grown from the solution 5 on the lower surface of the seed crystal 3 brought into contact with the solution 5 in the contact step. The growth of the crystal 2 starts when the lower surface of the seed crystal 3 is brought into contact with the solution 5 in the above contact step. That is, when the lower surface of the seed crystal 3 is brought into contact with the solution 5, a temperature difference is generated between the lower surface of the seed crystal 3 and the solution 5 near the lower surface of the seed crystal 3. Then, carbon is supersaturated by the temperature difference, and carbon and silicon in the solution 5 begin to precipitate on the lower surface of the seed crystal 3 as the silicon carbide crystal 2.

  Next, the seed crystal 3 is pulled up from the solution 5 to grow the crystal 2 in a columnar shape. At this time, since the heat insulating member 10 is arranged in the recess 9 of the first crucible 8 as described in the preparation step, the temperature of the bottom of the second crucible 6 is changed to the side of the second crucible 6. The temperature can be higher than Thereby, the temperature gradient in the planar direction of the solution 5 can be reduced, and the quality of the growing crystal 2 can be improved.

  By pulling up the seed crystal 3 little by little in the upward direction while adjusting the growth rate of the crystal 2 in the plane direction and downward, the crystal 2 can be grown while maintaining a constant diameter. Specifically, the pulling speed of the seed crystal 3 can be set to, for example, 50 μm / h or more and 150 μm / h or less.

  The temperature of the solution 5 is set to be 1400 ° C. or higher and 2000 ° C. or lower, for example. When the temperature of the solution 5 fluctuates, as the temperature of the solution 5, for example, a temperature obtained by averaging temperatures measured a plurality of times in a certain time can be used. As a method of measuring the temperature of the solution 5, for example, a method of directly measuring with a thermocouple or a method of measuring indirectly with a radiation thermometer can be used.

(Separation process)
After the crystal 2 is grown, the grown crystal 2 is pulled away from the solution 5 to finish the crystal growth.

DESCRIPTION OF SYMBOLS 1 Crystal manufacturing apparatus 2 Crystal 3 Seed crystal 4 Holding member 5 Solution 6 2nd crucible 7 Moving apparatus 8 1st crucible 9 Recessed part 10 Thermal insulation member 11 1st thermal insulation part 12 2nd thermal insulation part 13 Through-hole 14 Convex part 15 Heating apparatus 16 Coil 17 AC power supply 18 Control device

Claims (5)

A cylindrical heating device opened up and down;
A first crucible disposed inside the heating device and having a recess opened on the upper surface;
A heat retaining member comprising a first heat retaining portion disposed on the bottom surface of the concave portion of the first crucible and a second heat retaining portion disposed on the inner surface of the concave portion;
A second crucible for holding a solution for growing a crystal disposed in the recess of the first crucible through the heat retaining member;
A crystal manufacturing apparatus for growing a crystal by a solution growth method, wherein a heat quantity of heat conduction by the first heat insulation part is larger than a heat quantity of heat conduction by the second heat insulation part.   2. The crystal manufacturing apparatus according to claim 1, wherein the first heat retaining unit has a through hole located in a central portion of a bottom surface of the second crucible.   The said 1st crucible is a crystal manufacturing apparatus of Claim 2 which has the convex part located in the said through-hole in the center part of the bottom face of the said recessed part.   The crystal manufacturing apparatus according to claim 3, wherein the convex portion is in contact with a bottom surface of the second crucible.   Using the crystal production apparatus according to any one of claims 1 to 4, the temperature at the bottom of the second crucible is made higher than the temperature at the side of the second crucible and held in the second crucible. A method for producing a crystal, comprising growing the crystal from a solution.

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