JP2015189626A - Method of manufacturing crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a crystal capable of manufacturing a high-quality silicon carbide crystal.SOLUTION: A method of manufacturing a crystal includes: a preparation step for preparing a silicon carbide seed crystal 3 having an undersurface recessed gradually from an edge part to a central part in a microscopic view, a crucible 5 having a recessed part 8 opened in an upward direction, and a solution 6 that is obtained by dissolving carbon in a silicon solvent and is held in the recessed part 8 of the crucible 5; a contact step for bringing the seed crystal 3 into contact with the central part of the surface of the solution 6; and a crystal growth step for growing a crystal of silicon carbide on the undersurface of the seed crystal 3 by pulling up the seed crystal 3 in contact with the solution 6. In the crystal growth step, the solution 6 is accelerated at the undersurface of the seed crystal 3 or the undersurface of the growing crystal by rotating the seed crystal 3, thus, the solution 6 is caused to flow downward along the wall of the crucible 6 and upward toward the undersurface of the seed crystal 3, and a crystal is grown while making the flow of the solution 6 abut against the central part of the undersurface of the seed crystal 3 or the central part of the undersurface of the growing crystal.

Description

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

  At present, silicon carbide is attracting attention as a substrate material for forming electronic components such as transistors, which has a wider band gap than silicon and has a high electric field strength leading to dielectric breakdown. It is known that a silicon carbide crystal serving as a substrate is manufactured by a solution method (solution growth method) as described in Patent Document 1 below, for example. The solution method is a method of manufacturing a crystal by supplying a crystal raw material from a solution to a seed crystal and pulling it up while growing the crystal on the seed crystal.

JP 2010-184849 A

  In the solution method, when the silicon carbide crystal is pulled up while being grown, the crystal may grow extremely in a portion where it is easy to grow if the crystal is grown only in the vertical direction. As a result, a groove is formed on the lower surface of the grown crystal, and the quality of the grown crystal may be deteriorated.

  The present invention has been devised in view of such circumstances, and an object of the present invention is to provide a crystal manufacturing method capable of manufacturing a silicon carbide crystal with improved quality.

  A method for producing a crystal according to an embodiment of the present invention includes a seed crystal of silicon carbide having a lower surface gradually concaved from an edge to a central portion microscopically, a crucible having a concave portion opened upward, and the crucible of the crucible A preparation step of preparing a solution in which carbon is dissolved in a silicon solvent, which is held in the recess, a contact step of bringing the seed crystal into contact with a liquid surface center portion of the solution, and the seed crystal in contact with the solution A crystal growth step of growing a silicon carbide crystal on the lower surface of the seed crystal by pulling up the seed crystal, and rotating the seed crystal in the crystal growth step or the lower surface of the seed crystal to grow By accelerating the solution, the flow of the solution descends along the wall of the crucible and rises toward the lower surface of the seed crystal, and grows at the center of the lower surface of the seed crystal or grows. Above Growing said crystal while applying the flow of the solution in the central portion of the lower surface of the crystal.

  In the method for producing a crystal according to an embodiment of the present invention, a seed crystal having a lower surface gradually concaved from the edge to the center is used microscopically, and the flow of the solution is applied to the center of the lower surface of the seed crystal. While growing the crystal. As a result, the solution flows along the lower surface of the seed crystal from the center of the lower surface toward the edge of the lower surface. As a result, since the flow of the solution generated along the lower surface of the seed crystal hits the inside of the dent on the lower surface of the seed crystal, it becomes easy to grow the crystal from the edge toward the center on the lower surface of the seed crystal. Therefore, the crystal growth in the lateral direction can be promoted at the center of the lower surface of the seed crystal or the center of the lower surface of the growing crystal, so that the quality of the grown crystal is improved compared to the case where the crystal grows only in the vertical direction. Can be made.

It is sectional drawing which shows an example of the crystal manufacturing apparatus used for the manufacturing method of the crystal which concerns on one Embodiment of this invention. It is sectional drawing which shows an example of a part of crystal manufacturing apparatus used for the manufacturing method of the crystal which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows an example of a part of crystal manufacturing apparatus used for the manufacturing method of the crystal which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows an example of a part of crystal manufacturing apparatus used for the manufacturing method of the crystal which concerns on one Embodiment of this invention. It is sectional drawing which shows 1 process of the manufacturing method of the crystal | crystallization which concerns on one Embodiment of this invention.

<Crystal production equipment>
Below, an example of the crystal manufacturing apparatus used for the manufacturing method of the crystal which concerns on one Embodiment of this invention is demonstrated, referring FIGS. 1-4. Note that the present invention is not limited to the present embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention.

  FIG. 1 shows an outline of the crystal manufacturing apparatus of this example. FIG. 2 shows a part of the crystal manufacturing apparatus of this example, and shows a cross section of a seed crystal which is a part of the crystal manufacturing apparatus. 3 and 4 show a part of the crystal manufacturing apparatus of this example, and are enlarged sectional views microscopically showing the lower surface of the seed crystal that is a part of the crystal manufacturing apparatus.

  The crystal manufacturing apparatus 1 is an apparatus for manufacturing a silicon carbide crystal 2 used for a semiconductor component or the like. The crystal 2 is grown on the lower surface of the seed crystal 3 to manufacture the crystal 2. The crystal production apparatus 1 includes a holding member 4 and a crucible 5 as shown in FIG. The seed crystal 3 is fixed and held on the holding member 4, and the solution 6 is stored in the crucible 5. The crystal manufacturing apparatus 1 causes the lower surface of the seed crystal 3 to contact the solution 6 to grow the crystal 2 on the lower surface of the seed crystal 3.

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

  The width of the crystal 2 is set to, for example, 25 mm or more and 150 mm or less. The width of the crystal 2 can be measured using, for example, a caliper. The width of the crystal 2 refers to the diameter of the crystal 2 when the crystal 2 is cylindrical. Further, when the crystal 2 has a polygonal column shape, the maximum straight line among the linear lengths between one end of the lower surface of the crystal 2 and the other end facing the one end with the center portion of the planar shape interposed therebetween. Say length. In the following description, the definition of the width and the measurement of the width are the same as described above unless otherwise specified.

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

The lower surface of the seed crystal 3 is gradually concaved microscopically from the edge to the center. That is, when viewed with the naked eye, the lower surface of the seed crystal 3 appears flat as shown in FIG. 2, but when enlarged and viewed more finely, as shown in FIG. The lower surface of the seed crystal 3 is gradually recessed from the edge to the center. FIG. 3 is an enlarged cross-sectional view microscopically showing a cross section of the seed crystal 3. Of the seed crystal 3, a half from the central portion (left side in the figure) to one end (right side in the figure) of the seed crystal 3. Is shown. Moreover, the cross section shown in FIG. 3 is a cross section when the seed crystal 3 is cut upward from the lower surface.

  Specifically, the lower surface of the seed crystal 3 of the present embodiment has a stepped shape that is stepped toward the center. That is, microscopically, as shown in FIG. 3, the lower surface of the seed crystal 3 alternately includes a plurality of terraces 31 that are surfaces along the plane direction and a plurality of steps 32 that are surfaces along the vertical direction. It has a staircase shape. The state in which the lower surface of the seed crystal 3 is stepped can be observed, for example, with an atomic force microscope. In the present embodiment, the lower surface of the crystal 2 that grows on the lower surface of the seed crystal 3 also has a stepped shape so as to be gradually dented from the edge to the center.

  The width of the seed crystal 3 of this embodiment is set to 25 mm or more and 150 mm or less, for example. The length (width) (L) along the planar direction (basically the horizontal direction) of the terrace 31 of the seed crystal 3 of the present embodiment is set to, for example, 10 nm or more and 10 μm or less. The length (height) (H) along the vertical direction (basically in the vertical direction) of step 32 of the seed crystal 3 of the present embodiment is set to 0.5 nm or more and 2 nm or less, for example. Moreover, the depth of the most concave part of the lower surface of the seed crystal 3 is set to 1 μm or more and 100 μm or less, for example. Each of the length along the planar direction of the terrace 31 and the length along the vertical direction of the step 32 can be measured using, for example, an atomic force microscope.

  In the present embodiment, the slope of the straight line connecting the upper end of one step 32 with the seed crystal 3 and the edge on the edge side of the terrace 31 connected to the lower end of the step 32 is centered from the lower edge of the seed crystal 3. It is getting smaller as you go to. More specifically, as shown in FIG. 4, for example, a straight line connecting the upper end of step 32 at the edge of the lower surface of the seed crystal 3 and the edge on the edge side of the terrace 31 is a straight line L1, and the lower surface of the seed crystal 3 is The straight line connecting the upper end of step 32 and the end of the edge of terrace 31 at the intermediate part between the edge and the center is a straight line L2 and the upper end of step 32 and the edge of terrace 31 at the center of the lower surface of seed crystal 3 Is defined as a straight line L3, the slopes of the straight line L1, the straight line L2, and the straight line L3 become smaller in the order of the straight line L1, the straight line L2, and the straight line L3. The maximum inclination of the straight line connecting the upper end of one step 32 with the seed crystal 3 and the edge on the edge side of the terrace 31 connected to the lower end of the step 32 is the height of the step 32 at that time (H ) Is divided by the width (L) of the terrace 31 (H / L), for example, it is set to 0.015 or more and 0.15 or less.

  The slope of a straight line connecting the upper end of one step 32 with the seed crystal 3 and the end on the edge side of the terrace 31 connected to the lower end of the step 32 is determined by using, for example, an atomic force microscope. The length (L) along the plane direction of 31 and the length (H) along the vertical direction of step 32 can be obtained by measurement. FIG. 4 is an enlarged view showing a cross section of the seed crystal 3, and shows a half from the central portion (left side in the figure) to one end (right side in the figure) of the seed crystal 3 as in FIG. Moreover, the cross section shown in FIG. 4 is a cross section when the seed crystal 3 is cut upward from the lower surface as in FIG.

  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 is held by a holding member 4 so as to be movable in the vertical direction.

The holding member 4 holds the seed crystal 3 and carries the seed crystal 3 into and out of the solution 6. Specifically, the holding member 4 has a function of bringing the seed crystal 3 into contact with the solution 6 and keeping the crystal 2 away from the solution 6. As shown in FIG. 1, the holding member 4 is fixed to a moving mechanism (not shown) of the moving device 7. The moving device 7 has a moving mechanism that moves the holding member 4 fixed to the moving device 7 in the vertical direction using, for example, a motor. Therefore, the holding member 4 is moved in the vertical direction by the moving device 7. 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 attached to the moving device 7 so as to be rotatable around an axis extending in the vertical direction.

  The solution 6 is stored (held) in the crucible 5, and the crystal 2 is grown by supplying the raw material of the crystal 2 to the seed crystal 3 or the growing crystal 2. Solution 6 contains the same material as crystal 2. That is, since the crystal 2 is a silicon carbide crystal, the solution 6 contains carbon and silicon. In this embodiment, the solution 6 is obtained by dissolving carbon (solute) in a silicon liquid (solvent). The solution 6 may contain a metal material such as chromium, for example, in order to improve the solubility of carbon.

  The crucible 5 stores the solution 6. The crucible 5 has a concave portion 8 opened upward to store the solution 6. The crucible 5 has a function as a vessel for melting the raw material of the crystal 2 inside. The crucible 5 is made of graphite, which is a material made of carbon, for example. In the present embodiment, the crucible 5 is obtained by melting silicon out of the raw material of the crystal 2 in the crucible 5 to use as a solvent, and by dissolving a part of the crucible 5 (carbon) in the silicon solvent, Solution 6 containing

  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 solution 6 is locally metastable on the lower surface of the seed crystal 3 (thermodynamically non-equilibrium, but temporarily stable in that state). The crystal 2 is deposited on the lower surface of the seed crystal 3. That is, in the solution 6, carbon (solute) is dissolved in silicon (solvent), and the solubility of carbon (solute) in the solution 6 increases as the temperature of silicon (solvent) increases. Here, when the solution 6 heated to a high temperature is cooled by contact with the seed crystal 3, the dissolved carbon becomes supersaturated, and the solution 6 is locally metastable. Then, the solution 6 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 crucible 5 is arranged inside the crucible container 9. The crucible container 9 has a function of holding the crucible 5. A heat insulating material 10 is disposed between the crucible container 9 and the crucible 5. This heat insulating material 10 surrounds the crucible 5. The heat insulating material 10 suppresses heat radiation from the crucible 5 and stably maintains the temperature of the crucible 5. The crucible 5 may be arranged inside the crucible container 9 in a rotatable state.

  The crucible 5 is heated by the heating device 11. The heating device 11 according to the present embodiment includes a coil 12 and an AC power source 13 and heats the crucible 5 by an electromagnetic induction heating method using electromagnetic induction, for example. The heating device 11 may employ other methods such as a method of transferring heat generated by a heating resistor such as carbon. When this heat transfer type heating device is employed, a heating resistor is disposed (between the crucible 5 and the heat insulating material 10).

  The coil 12 is formed of a conductor and surrounds the crucible 5. The coil 12 is arranged around the crucible 5 so as to surround the crucible 5 in a cylindrical shape. That is, the heating device 11 having the coil 12 has a cylindrical heating region formed by the coil 12. The AC power supply 13 is for flowing an AC current through the coil 12, and the heating time to the set temperature in the crucible 5 can be shortened by increasing the AC current.

In the present embodiment, the AC power supply 13 and the moving device 7 are connected to the control device 14 and controlled. That is, in the crystal manufacturing apparatus 1, the heating and temperature control of the solution 6 and the loading / unloading of the seed crystal 3 are controlled by the control device 14 in conjunction with each other. The control device 14 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 with reference to FIG. FIG. 5 is a cross-sectional view for explaining one step of the method for producing a crystal according to one embodiment of the present invention, and shows a state in which the crystal 2 is grown by bringing the seed crystal 3 into contact with the solution 6.

  The crystal manufacturing method includes a preparation process, a contact process, a crystal growth process, and a separation process. Note that the present invention is not limited to the present embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention.

(Preparation process)
A crucible 5 and a solution 6 in which carbon is dissolved in a silicon solvent, which are accumulated in the recess 8 of the crucible 5, are prepared. Specifically, first, a crucible 5 having a recess 8 is prepared. Next, silicon particles as a raw material of silicon are put into the recess 8 of the crucible 5 and the crucible 5 is heated to a melting point of silicon (1420 ° C.) or higher. At this time, carbon (solute) forming the crucible 5 is dissolved in silicon (solvent) melted and liquefied. As a result, a solution 6 containing carbon and silicon can be prepared in the crucible 5. In the solution 6, carbon may be dissolved simultaneously with melting silicon by adding carbon particles as a raw material in advance.

  The heating device 11 is prepared, and the crucible 5 is accommodated in the heating device 11. In the present embodiment, the crucible 5 is accommodated in the heating device 11 by being disposed in the crucible container 9 surrounded by the coil 12 of the heating device 11 via the heat insulating material 10. The solution 6 may be prepared by housing the crucible 5 in the heating device 11 and heating the crucible 5 with the heating device 11. Alternatively, the crucible 5 may be placed in the heating device 11 after the crucible 5 is heated outside the crystal production device 1 to form the solution 6 in advance. Alternatively, after the solution 6 is formed in a container other than the crucible 5, the solution 6 may be poured into the crucible 5 installed in the heating device 11.

  A seed crystal 3 is prepared. As the seed crystal 3, for example, a silicon carbide crystal lump manufactured by a solution growth method or the like is processed into a flat plate shape. In addition, processing to flat form is performed by cutting the lump of silicon carbide by, for example, machining.

  The seed crystal 3 to be prepared is prepared such that the lower surface is microscopically recessed from the edge to the center. The lower surface of the seed crystal 3 is prepared by, for example, preparing a solution 6 in which carbon is unsaturated, rotating the seed crystal 3 by bringing the seed crystal 3 into contact with the center of the liquid surface of the solution 6 and rotating the seed crystal 3. Can be processed by generating a flow that rises toward the lower surface of the seed crystal 3. That is, by applying the flow of the solution 6 to the center of the lower surface of the seed crystal 3, the surface of the center of the lower surface of the seed crystal 3 is dissolved. At this time, the flow that hits the center of the lower surface of the seed crystal 3 flows from the center of the lower surface of the seed crystal 3 toward the edge of the lower surface. As a result, the flow of the solution 6 in which carbon is most unsaturated hits the center of the lower surface of the seed crystal 3, and flows from the center of the lower surface of the seed crystal 3 toward the edge while dissolving the seed crystal 3. The lower surface of 3 can be microscopically dented from the edge to the center.

The crystal structure of silicon carbide is, for example, a triangular pyramid in which one silicon atom bonded to each of the four silicon atoms is located at the approximate center of the triangular pyramid while four silicon atoms are located at each vertex of the triangular pyramid. -Like unit cell. The seed crystal 3 is formed by bonding silicon atoms of one unit cell to carbon atoms of another unit cell while a plurality of unit cells are arranged in the same direction in the plane direction. Here, in the unit cell, the distance of one bond (first bond) is longer than the distance of the other three bonds (multiple second bonds), and the first bond is longer than the second bond. It is easy to be cut. Here, when the center part of the lower surface of the seed crystal 3 is melted, the first bond is cut and the seed crystal 3 is melted. Therefore, when the seed crystal 3 is melted, the terrace 31 along the plane direction is formed. It is formed. Therefore, the lower surface of the seed crystal 3 is formed in a stepped shape in which the step 32 and the terrace 31 are continuous.

  In addition, the principle which a flow produces in the solution 6 by rotating the seed crystal 3 is as follows. That is, by rotating the seed crystal 3, a part of the solution 6 adjacent to the seed crystal 3 is accelerated outward by centrifugal force as the seed crystal 3 rotates, and a part of the solution 6 is accelerated by the crucible 5. The above-mentioned flow can be generated in the solution 6 by being lowered along the wall portion. At this time, the rotation speed of the seed crystal 3 and the crystal 2 is set to, for example, 10 rpm or more and 1000 rpm or less.

  The holding member 4 is prepared, and the seed crystal 3 is fixed to the lower surface of the holding member 4. Specifically, after preparing the holding member 4, an adhesive containing carbon is applied to the lower surface of the holding member 4. Next, the seed crystal 3 can be arranged on the lower surface of the holding member 4 with the adhesive interposed therebetween, and the seed crystal 3 can be fixed to the lower surface of the holding member 4. In this embodiment, after fixing the seed crystal 3 to the holding member 4, the upper end of the holding member 4 is attached to the moving device 7. As described above, the attachment to the moving device 7 is performed such that the periphery of the axis can be rotated with the center line extending in the vertical direction including the center portion of the planar shape of the holding member 4 as the axis.

(Contact process)
The lower surface of the seed crystal 3 is brought into contact with the solution 6. As shown in FIG. 2, the seed crystal 3 is brought into contact with the solution 6 by moving the holding member 4 downward. In this embodiment, the seed crystal 3 is brought into contact with the solution 6 by moving the seed crystal 3 downward. However, the seed crystal 3 is brought into contact with the solution 6 by moving the crucible 5 upward. May be.

  It suffices that at least a part of the lower surface of the seed crystal 3 is in contact with the liquid surface of the solution 6. Further, the entire lower surface of the seed crystal 3 may be brought into contact with the solution 6, or the seed crystal 3 may be brought into contact with the solution 6 so that the side surface or the upper surface of the seed crystal 3 is immersed. When it is put in the solution 6 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 surely brought into contact with the solution 6 and the yield can be improved.

  As described in the preparation step, when the lower surface of the seed crystal 3 is processed by using the flow of the solution 6, the seed crystal 3 is once separated from the solution 6 and then brought into contact with the seed crystal 3 again. Alternatively, the lower surface of the seed crystal 3 may be kept in contact.

(Crystal growth process)
Crystal 2 is grown from solution 6 on the lower surface of seed crystal 3 brought into contact with solution 6 in the contacting step. The growth of the crystal 2 starts when the lower surface of the seed crystal 3 is brought into contact with the solution 6 in the above contact step. That is, by bringing the lower surface of the seed crystal 3 into contact with the solution 6, a temperature difference can be created between the lower surface of the seed crystal 3 and the solution 6 near the lower surface of the seed crystal 3. Then, due to the temperature difference, the carbon dissolved in the solution 6 becomes supersaturated, and the carbon and silicon in the solution 6 start to precipitate as the crystal 2 on the lower surface of the seed crystal 3.

  As described in the preparation step, when the lower surface of the seed crystal 3 is processed using the flow of the solution 6 and the seed crystal 3 is brought into contact with the solution 6 as it is, the heating temperature of the crucible 5 is set, for example. By making the temperature lower than the temperature at which the lower surface of the seed crystal 3 is dissolved, the solution 6 can be supersaturated.

The temperature of the solution 6 is set to be 1400 ° C. or higher and 2100 ° C. or lower, for example.
When the temperature of the solution 6 fluctuates, as the temperature of the solution 6, 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 6, for example, a method of directly measuring with a thermocouple or a method of measuring indirectly with a radiation thermometer can be used.

  Crystal growth is performed while pulling up the seed crystal 3. The crystal 2 can be grown in a columnar shape by pulling up the seed crystal 3. That is, the crystal 2 can be grown while maintaining a certain width or diameter by gradually pulling the seed crystal 3 upward while adjusting the growth rate of the crystal 2 in the lateral direction and downward. Note that the pulling speed of the seed crystal 3 can be set to, for example, 50 μm / h or more and 500 μm / h or less.

  In the crystal growth, as shown in FIG. 5, the seed crystal 3 is rotated to cause the solution 6 to flow upward toward the center of the lower surface of the seed crystal 3. Do it while guessing. Here, in the conventional solution growth method, when a silicon carbide crystal is grown, if the crystal is grown only in the vertical direction, the crystal may grow extremely in a portion where it is easy to grow. As a result, a groove is formed on the lower surface of the grown crystal, and the quality of the grown crystal may be deteriorated.

  In contrast, according to the present invention, during crystal growth, the seed crystal 3 having a lower surface gradually concaved from the edge to the center is used microscopically, and the flow of the solution 6 is changed to the lower surface of the seed crystal 3. The crystal 2 is grown while being applied to the center. At this time, the solution 6 flows along the lower surface of the seed crystal 3 from the center of the lower surface toward the edge of the lower surface. As a result, the flow generated along the lower surface of the seed crystal 3 hits the inside of the dent on the lower surface of the seed crystal 3, and the crystal 2 is easily grown from the edge of the lower surface toward the center. That is, the flow of the solution 6 flowing along the lower surface of the seed crystal 3 can be easily applied to the plurality of steps 32, and the crystal can be easily grown from the plurality of steps 32 toward the inside. Therefore, the crystal growth in the lateral direction can be promoted, and the quality of the grown crystal 2 can be improved.

  The seed crystal 3 prepared in the preparation step is preferably prepared such that the width of the seed crystal 3 is ½ or more of the width of the recess 8 of the crucible 5. That is, it is preferable that the contact area of the liquid surface of the solution 6 where the crystal 2 is in contact with the solution 6 is larger than the remaining area. By adjusting the contact area as described above, the amount of the solution 6 adjacent to the seed crystal 3 can be increased, and the flow of the solution 6 is easily generated.

  In the crystal growth step, it is preferable to grow the crystal 2 while cooling the side surface of the growing crystal 2 so that the lower surface of the growing crystal 2 is gradually recessed from the edge to the center. As a result, crystal growth in the direction along the lower surface of the growing crystal 2 can be promoted also on the lower surface of the growing crystal 2. Therefore, variation in the growth rate can be reduced, and the quality of the crystal 2 can be maintained while the crystal is growing.

(Separation process)
After the crystal 2 is grown, the grown crystal 2 is pulled away from the solution 6 to finish the crystal growth.

  As described above, the crystal 2 with improved quality can be manufactured using the crystal manufacturing apparatus 1.

DESCRIPTION OF SYMBOLS 1 Crystal manufacturing apparatus 2 Crystal 3 Seed crystal 31 Terrace 32 Step 4 Holding member 5 Crucible 6 Solution 7 Moving device 8 Recess 9 Crucible container 10 Insulating material 11 Heating device 12 Coil 13 AC power supply 14 Control device

Claims (3)

Microscopically, a silicon carbide seed crystal having a lower surface gradually recessed from the edge to the center, a crucible having a recess opened upward, and carbon dissolved in the silicon solvent held in the recess of the crucible Preparing a prepared solution; and
Contacting the seed crystal with the liquid surface center of the solution;
A crystal growth step of growing a silicon carbide crystal on a lower surface of the seed crystal by pulling up the seed crystal brought into contact with the solution;
In the crystal growth step, by rotating the seed crystal and accelerating the solution on the lower surface of the seed crystal or the lower surface of the growing crystal, the seed crystal descends to the solution along the wall of the crucible. A method for producing a crystal, wherein a flow that rises toward the lower surface of the crystal is generated, and the crystal is grown while the flow of the solution is applied to a lower surface central portion of the seed crystal or a lower surface central portion of the growing crystal.   The method for producing a crystal according to claim 1 or 2, wherein, in the preparation step, a seed crystal having a width of the seed crystal that is 1/2 or more times the width of the concave portion of the crucible is prepared.   In the crystal growth step, the side surface of the crystal to be grown is cooled, and the lower surface of the crystal to be grown is microscopically maintained in a state of being gradually depressed from an edge to a central portion, and the crystal is grown. A method for producing the crystal according to 1 or 2.

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