JP2013071870A - Apparatus for growing crystal and method for growing crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for growing a crystal, capable of inhibiting separation of a seed crystal from a holding member.SOLUTION: The apparatus for growing the crystal grows a silicon carbide crystal by bringing the lower surface 4B of the seed crystal 4 comprising silicon carbide fixed to the lower end surface 2A of the holding member 2 through an adhesive member 3 into contact with the fused liquid of silicon carbide in a crucible to grow the crystal of silicon carbide on the lower surface 4B from the fused liquid, wherein the holding member 2 comprises carbon, while the adhesive member 3 includes carbon and a material whose boiling point is lower than the melting point of silicon carbide, and the lower end surface 2A of the holding member 2 is a rough surface having a 5-30 μm arithmetic average roughness Ra. The method for growing the crystal comprises a step for bringing the lower end surface 2A of the holding member 2 to be the rough surface, a step for applying the adhesive 3 to the lower end surface 2A and a step for fixing the seed crystal 4 to the lower end surface 2A of the holding member 2 through the adhesive 3 by bringing the seed crystal 4 into contact with the adhesive 3.

Description

  The present invention relates to a crystal growth apparatus and a crystal growth method for growing a silicon carbide crystal.

  As a crystal currently attracting attention, there is silicon carbide (SiC) which is a compound of carbon and silicon. Silicon carbide has a wider band gap than silicon, has a high electric field strength that leads to dielectric breakdown (good withstand voltage characteristics), high thermal conductivity, high heat resistance, and excellent chemical resistance. In addition, it attracts attention because of various advantages such as excellent radiation resistance. Fields in which silicon carbide is focused are wide, for example, heavy electricity including nuclear power, transportation including automobiles and aviation, home appliances, and space. A single crystal of silicon carbide is manufactured by a solution growth method as described in Patent Document 1, for example.

JP 2000-264790 A

  In research and development of crystal growth made of silicon carbide, when a crystal is enlarged by a solution growth method, it is difficult to fix the grown single crystal to a holding member. The present invention has been devised in view of such circumstances, and an object thereof is to provide a crystal growth apparatus and a crystal growth method capable of stably fixing a crystal to be grown.

The crystal growth apparatus according to the present invention contacts a silicon carbide melt in a crucible with a lower surface of a seed crystal made of silicon carbide fixed to a lower end surface of a holding member via an adhesive, and the melt is applied to the lower surface. In the crystal growing apparatus for growing silicon carbide crystals from a liquid, the holding member is made of carbon, and the adhesive includes a material having a boiling point lower than the melting point of the silicon carbide and carbon particles, and the holding member The lower end surface is a rough surface having an arithmetic average roughness Ra of 5 μm or more and 30 μm or less.

Further, in the crystal growth method of the present invention, the lower surface of the seed crystal fixed to the lower end surface of the holding member is brought into contact with the silicon carbide melt in the crucible, and the holding member is pulled upward, In the crystal growth method for growing a silicon carbide crystal from the melt on the lower surface of the seed crystal, a step of making the lower end surface of the holding member a rough surface with a predetermined roughness, and the roughened surface The seed crystal is brought into contact with the adhesive after applying the adhesive including a material having a boiling point lower than the melting point of the silicon carbide and carbon particles on the lower end surface and applying the adhesive. And a step of fixing the seed crystal to the lower end surface of the holding member via the adhesive.

  According to the crystal growing apparatus of the present invention, since the lower end surface of the holding member is rough, it is included in the adhesive by fixing the lower end surface and the upper surface of the seed crystal via the adhesive. The carbon particles can enter the concave portion of the rough surface and improve the adhesive strength with the adhesive. As a result, separation of the seed crystal from the holding member can be suppressed, and the silicon carbide crystal grown on the seed crystal and the lower surface of the seed crystal can be stably fixed to the holding member.

  Moreover, since the crystal growth method of the present invention includes a step of roughening the lower end surface of the holding member, the seed crystal can be made difficult to peel from the holding member. As a result, the crystal can be greatly grown on the lower surface of the seed crystal.

It is sectional drawing which shows an example of embodiment of the crystal growth apparatus based on this invention. It is a figure which shows a part of crystal growth apparatus shown in FIG. 1, (a) is sectional drawing which expanded a part, (b) is sectional drawing which expanded the part further. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part. It is a figure which shows the modification of the crystal growth apparatus of FIG. 1, and is the expanded sectional view which expanded a part.

<Crystal growth device>
An embodiment of a crystal growth apparatus according to the present invention will be described with reference to the drawings. The crystal growing apparatus 1 is mainly composed of a holding member 2, an adhesive 3, a seed crystal 4 and a melt 5. Below, the outline of the crystal growth apparatus 1 is demonstrated, referring FIG.

  The crucible 6 is disposed inside the crucible container 7. The crucible container 7 has a function of holding the crucible 6. A heat insulating material 8 is disposed between the crucible container 7 and the crucible 6. This heat insulating material 8 surrounds the crucible 6. The heat insulating material 8 suppresses heat radiation from the crucible 6 and contributes to keeping the temperature of the crucible 6 stable.

  The crucible 6 has a function as a vessel for internally melting a raw material of silicon carbide single crystal to be grown. In the present embodiment, the single crystal raw material (carbon and silicon) is melted in the crucible 6 and stored as the melt 5. In this embodiment, a solution growth method is employed, and crystals are grown by creating a thermal equilibrium state inside the crucible 6.

  The crucible 6 is heated by the heating mechanism 10. The heating mechanism 10 of the present embodiment employs an electromagnetic heating method in which the crucible 6 is heated by electromagnetic waves, and includes a coil 11 and an AC power supply 12. The crucible 6 is made of, for example, carbon (graphite).

  Inside the crucible 6, the melt 5 is arranged. In the melt 5, carbon and silicon, which are elements constituting the silicon carbide crystal to be grown, are melted as a solvent. The solubility of the element that becomes the solute increases as the temperature of the element that becomes the solvent increases. For this reason, when the melt 5 in which many solutes are dissolved in a solvent at a high temperature is cooled, the solutes are deposited on the boundary of thermal equilibrium. In the solution growth method employed in the present embodiment, the crystal is grown on the lower surface 4B of the seed crystal 4 by utilizing precipitation due to this thermal equilibrium.

  The coil 11 is formed of a conductor and is wound so as to surround the periphery of the crucible 6. The AC power supply 12 is for flowing an AC current through the coil 11, and the heating time up to the set temperature in the crucible 6 can be shortened by using an AC current having a high frequency.

  In the present embodiment, the crucible 6 is heated as follows. First, an electric current is passed through the coil 11 using the AC power source 12 to generate an electromagnetic field in the space including the heat insulating material 8. Next, an induced current flows through the crucible 6 by this electromagnetic field. The induced current flowing through the crucible 6 is converted into thermal energy by various losses such as Joule heat generation due to electric resistance and heat generation due to hysteresis loss. That is, the crucible 6 is heated by the heat loss of the induced current. The electromagnetic field may generate heat by causing an induced current to flow through the melt 5 itself. Thus, when making the melt 5 itself heat | fever-generate, it is not necessary to heat the crucible 6 itself.

  In the present embodiment, an electromagnetic heating method is employed as the heating mechanism 10, but heating may be performed using other methods. The heating mechanism 10 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 mechanism is employed, a heating resistor is disposed (between the crucible 6 and the heat insulating material 8).

  A single crystal seed crystal 4 is supplied to the melt 5 of the crucible 6 by the transport mechanism 13. The transport mechanism 13 also has a function of carrying out crystals grown from the melt 5. The transport mechanism 13 includes a holding member 2 and a power source 14. The holding member 2 carries in and out the seed crystal 4 and the single crystal grown on the lower surface 4B of the seed crystal 4. The seed crystal 4 is attached to the lower end surface 2A of the holding member 2, and the movement of the holding member 2 is controlled in the vertical directions D1 and D2 by the power source 14. In the present embodiment, the D1 direction means a downward direction on the physical space, and the D2 direction means an upward direction on the physical space.

  In the crystal growing apparatus 1, the AC power source 12 of the heating mechanism 10 and the power source 14 of the transport mechanism 13 are connected to the control unit 15 and controlled. That is, in the crystal growing apparatus 1, the heating and temperature control of the melt 5 and the carry-in / out of the seed crystal 4 are controlled by the control unit 15 in conjunction with each other. The control unit 15 includes a central processing unit and a storage device such as a memory, and is composed of, for example, a known computer.

  In this way, the lower surface 4B of the seed crystal 4 fixed to the lower end surface 2A of the holding member 2 via the adhesive 3 can be brought into contact with the melt 5 to grow a crystal on the lower surface 4B.

  Next, portions for fixing crystals such as the seed crystal 4 and the holding member 2 will be described in detail.

  As shown in FIG. 2A, the holding member 2 has a seed crystal 4 fixed to the lower end surface 2 </ b> A via an adhesive 3. Here, FIG. 2A is an enlarged view of a portion including the seed crystal 4, the adhesive 3, and the holding member 2. The holding member 2 only needs to have a lower end surface 2A, and the lower end surface 2A has a polygonal shape such as a square shape or a circular shape in plan view. The holding member 2 has a three-dimensional shape, for example, a rod shape or a rectangular parallelepiped shape.

  The lower end surface 2A of the holding member 2 may have an area larger than the upper surface 4A of the seed crystal 4 or an area smaller than the upper surface 4A of the seed crystal 4. In the present embodiment, the lower end surface 2A of the holding member 2 is smaller than the area of the upper surface 4A of the seed crystal 4. When the area of the lower end surface 2A of the holding member 2 is equal to or larger than the area of the upper surface 4A of the seed crystal 4, the entire upper surface 4A of the seed crystal 4 can be fixed via the adhesive material 3. . Therefore, it is possible to further suppress the seed crystal 4 from being detached from the holding member 2.

  The holding member 2 is made of carbon. The holding member 2 should just be comprised with the material which has carbon as a main component. The carbon of the holding member 2 is made of, for example, a polycrystalline carbon or a fired body obtained by firing carbon. Thus, the porosity in the holding member 2 is high because the holding member 2 is constituted by a carbon polycrystal or a fired body. The porosity inside the holding member 2 can be changed, for example, by adjusting the firing conditions. As a method for calculating the porosity (%), for example, a calculation formula of “porosity (%) = volume ÷ mass × 100” can be used as a calculation method for simple measurement.

  Furthermore, the lower end surface 2A of the holding member 2 is a rough surface. The rough surface of the holding member 2 should just have even a part. That is, the rough surface of the holding member 2 may be provided over the entire lower end surface 2A or may be provided only in part. The rough surface of the holding member 2 can be provided so as to be, for example, 30% or more with respect to the entire area of the lower end surface 2A.

  When the entire lower end surface 2A of the holding member 2 is rough, for example, the carbon contained in the adhesive 3 is carbonized over the entire lower end surface 2A that has become a rough surface. For this reason, it is possible to make it difficult for the adhesive 3 to peel from the lower end surface 2A of the holding member 2.

  The rough surface of the lower end surface 2 </ b> A of the holding member 2 is composed of a plurality of recesses 9. The rough surface of the lower end surface 2A has an arithmetic average roughness Ra of, for example, 5 μm or more and 30 μm or less. The surface roughness (arithmetic average roughness Ra) of the lower end surface 2A of the holding member 2 can be confirmed, for example, according to JIS B0601-2001. One recess 9 is set to have a depth of, for example, 5 μm or more and 60 μm or less.

  The adhesive 3 includes carbon particles 3a as shown in FIG. 2 (b). The particle size of the carbon particles 3a can be set to 0.7 μm or more and 40 μm or less, for example. By making the adhesive material 3 contain carbon particles having a smaller particle diameter than the surface roughness Ra of the lower end surface 2A of the holding member 2, the carbon particles 3a can easily enter the recesses 9 constituting the rough surface. it can.

  Therefore, the adhesive material 3 can be made difficult to peel from the lower end surface 2A. The carbon particles 3a exhibit the effects of the present invention as long as the particle size is set smaller than the depth of the rough concave portion 9. In the adhesive 3, it is considered that the carbon particles 3 a contained therein are chemically bonded by carbonizing the surface of the lower end surface 2 A of the holding member 2 and the surface of the upper surface 4 A of the seed crystal 4. .

  In the present embodiment, the carbon particles 3a of the adhesive 3 enter the concave portion 9 of the rough surface of the lower end surface 2A. Thus, since the rough surface of the lower end surface 2 and the adhesive material 3 are bonded together, it is possible to suppress the adhesive material 3 from peeling from the holding member 4.

  Since the lower end surface of the conventional holding member was flat, there were few places where the lower end surface and the carbon particle 3a contacted, and the adhesive strength was weak. As a result, the adhesive was easy to peel off from the holding member, and it was difficult to increase the size of the crystal grown on the lower surface of the seed crystal.

(Variation 1 of crystal growth apparatus)
The adhesive material 3 may include a material having a boiling point lower than the melting point of silicon carbide (hereinafter referred to as a vaporized material). Here, as the “melting point of silicon carbide”, for example, when the silicon carbide melt 5 contains titanium or chromium, for example, the temperature of the melt 5 may be used. By including titanium or chromium in the silicon carbide melt 5, the ratio of carbon contained in the melt 5 can be increased, and the growth rate of the silicon carbide crystal grown on the lower surface 4 </ b> B of the seed crystal 4 is improved. Can be made.

  The vaporizing material of the adhesive 3 is specifically a material lower than the melting point of silicon carbide (melting point: 2545 ° C.), for example, heat of phenol resin (boiling point: about 380 ° C.), epoxy resin, polyimide resin, polyester resin, etc. Contains curable material. In addition, when it is difficult to measure the boiling point of the thermosetting material, for example, a decomposition temperature may be used. This is because gas is considered to be generated during decomposition.

  In this modification, a vaporized material having a boiling point lower than the melting point of silicon carbide is contained inside the adhesive material 3. Therefore, when the seed crystal 4 is brought close to the melt 5, for example, the temperature of the adhesive 3 is increased by being transmitted through the seed crystal 4, so that the vaporized material existing inside the adhesive 3 is gas and As a result, bubbles are generated. Here, since the lower end surface 2A is a rough surface, the surface area of the lower end surface 2A is large, and bubbles generated inside the adhesive 3 are easily removed from the holding member.

  As described above, since the bubbles generated inside the adhesive 3 are less likely to stay inside the adhesive 3, it is possible to suppress a decrease in the adhesive strength of the adhesive 3. Therefore, even if a crystal made of silicon carbide is greatly grown on the lower surface 4B of the seed crystal 4 and the weight of the crystal grown on the lower surface 4B of the seed crystal 4 and the seed crystal 4 is increased, the crystal is peeled off from the holding member 2. Can be suppressed. As a result, the crystal grown on the lower surface 4B of the seed crystal 4 can be enlarged, and the productivity of the crystal can be improved.

  Since the conventional seed crystal is fixed to the holding member on the flat lower end surface via an adhesive, the adhesive is easily peeled off due to a large number of small bubbles generated inside the adhesive. For this reason, since the seed crystal easily falls off the holding member, it is difficult to increase the size of the crystal grown on the lower surface of the seed crystal.

(Variation 2 of crystal growth apparatus)
As shown in FIG. 3, the lower end surface 2 </ b> A of the holding member 2 may be inclined with respect to a horizontal plane L <b> 1 perpendicular to the vertical direction. An angle D1 formed by the lower end surface 2A and the horizontal plane L1 can be set to be 0.5 ° or more and 45 ° or less, for example. As a method of inclining the lower end surface 2A from the horizontal plane L1 in this manner, for example, a method of roughening the surface with the lower end surface 2A of the holding member 2 inclined can be exemplified. As a roughening method, for example, a polishing method or the like can be used as described later.

  By inclining the lower end surface 2A of the holding member 2 with respect to the horizontal plane L1 in this way, the surface area of the lower end surface 2A that is a rough surface can be increased, and thus the adhesive strength with the adhesive 3 is improved. Can do. In addition, since the lower end surface 2A of the holding member 2 is inclined from the horizontal plane L1, it is possible to make it easier for bubbles that hit the lower end surface 2A to move along the inclined surface. Thus, since it becomes easy to move a bubble along an inclined surface, the bubble is easy to escape from the holding member 2.

(Modification 3 of the crystal growing apparatus)
The end of the lower end surface 2A may be positioned so as to contact the upper surface 4A of the seed crystal 4 as shown in FIG. That is, a part of the rough surface of the lower end surface 2 </ b> A is disposed so as to contact the upper surface 4 </ b> A of the seed crystal 4. With this arrangement, the heat from the seed crystal 4 can be easily removed from the holding member 2, and the heat transmitted from the upper surface 4 </ b> A of the seed crystal 4 to the adhesive 3 can be reduced. As a result, bubbles generated in the adhesive material 3 can be reduced.

  Further, since the end of the lower end surface 2A is positioned so as to contact the seed crystal 4A, bubbles generated inside the adhesive material 3 located inside the recess 9 pass through the inner surface of the recess 9. The bubbles generated in the adhesive 3 can be easily removed from the holding member 2. As a result, bubbles staying in the adhesive material 3 can be reduced, and the adhesive material 3 can be made difficult to peel off.

(Modification 4 of crystal growth apparatus)
As shown in FIG. 5, the holding member 2 may have a portion including the lower end surface 2 </ b> A made of polycrystalline 2 ′ made of silicon carbide. Since the portion including the lower end surface 2A is thus composed of the polycrystalline 2 ′ made of silicon carbide, it has a thermal expansion coefficient similar to that of the seed crystal 4, and the polycrystalline 2 ′ of the holding member 2 And the difference in thermal expansion coefficient between the portion and the seed crystal 4 can be reduced. As a result, it is possible to suppress the occurrence of stress due to the difference in thermal expansion coefficient between the polycrystal 2 ′ and the seed crystal 4 in the adhesive 3 and maintain the adhesive strength.

(Variation 5 of the crystal growth apparatus)
The adhesive material 3 may further contain silicon. By including silicon in the adhesive 3, the difference in thermal expansion coefficient with the seed crystal 4 can be reduced, and the stress generated between the two can be suppressed. As a result, the seed crystal 4 can be made difficult to peel from the holding member 2.

  In addition, by including silicon in the adhesive material 3 as described above, when the holding member 2, the adhesive material 3, and the seed crystal 4 are brought close to the melt 5, the carbon particles 3 a included in the adhesive material 3 and When silicon carbide is converted into silicon carbide by heat, the seed crystal 4 can be more firmly fixed. As a result, the difference in thermal expansion coefficient from the seed crystal 4 can be reduced, and the seed crystal 4 can be made more difficult to peel from the holding member 2.

  Furthermore, as shown in the modified example 4, when the portion including the lower end surface 2A is made of the polycrystalline 2 ′ made of silicon carbide, it is between the polycrystalline 2 ′, the seed crystal 4 and the adhesive 3 Since the difference in thermal expansion coefficient can be reduced, the seed crystal 4 can be further prevented from peeling from the holding member 2.

(Modification 6 of crystal growth apparatus)
As shown in FIG. 6, the adhesive 3 may be composed of a plurality of adhesive bodies 3 ′ that are fixed to a part of the lower end surface 2 </ b> A of the holding member 2 and a part of the upper surface 4 </ b> A of the seed crystal 4. As described above, the adhesive body 3 ′ is fixed in a plurality of islands by fixing a part of the lower end surface 2 </ b> A of the holding member 2 and a part of the upper surface 4 </ b> A of the seed crystal 4. There will be a space in between.

  For this reason, bubbles generated inside the adhesive 3 ′ are easily removed not only from the rough surface of the holding member 2 but also from the space between the adhesives 3 ′, and the seed crystal 4 is peeled off from the holding member 2. Can be made difficult.

(Variation 7 of crystal growth apparatus)
As shown in FIG. 7, the adhesive 3 may have a polycrystalline buffer layer 17 made of silicon carbide located between the lower end surface 2 </ b> A of the holding member 2 and the upper surface 4 </ b> A of the seed crystal 4. Good.

  The buffer layer 17 is located away from the lower end surface 2A of the holding member 2 and the upper surface 4A of the seed crystal 4. Therefore, the adhesive 3 is disposed between the upper surface 17A of the buffer layer 17 and the lower end surface 2A of the holding member 2, and between the lower surface 17B of the buffer layer 17 and the upper surface 4A of the seed crystal 4. The buffer layer 17 can be set so that the thickness is, for example, 1 μm or more and 3 μm or less.

  Since the buffer layer 17 is thus arranged inside the adhesive material 3, bubbles generated inside the adhesive material 3 can be taken into the buffer layer 17, and the seed crystal 4 is held by the holding member 2. It can be made more difficult to peel off.

(Variation 8 of crystal growth apparatus)
As shown in FIG. 8, the holding member 2 may have a contact portion 2 ″ that comes into contact with the seed crystal 4 at a part of the roughened lower end surface 2A. It is set so as to contact the upper surface 4A of the crystal 4. Therefore, the contact portion 2 ″ is higher on the seed crystal 4 side than the roughened lower end surface 2 A. That is, the contact portion 2 ″ is the lowermost end surface in the holding member 2. Note that the contact portion 2 ″ may be provided so that the lower end surface 2A of the holding member 2 surrounds the outer periphery of the contact portion 2 ″.

  Therefore, when the holding member 2 and the seed crystal 4 are fixed via the adhesive 3, both are fixed by the adhesive 3 positioned between the rough surface of the lower end surface 2 </ b> A and the upper surface 4 </ b> A of the seed crystal 4. At the same time, the adhesive 3 is less likely to enter between the contact portion 2 ″ and the upper surface 4A of the seed crystal 4. As a result, the adhesive 3 is less likely to be present near the center of the lower end surface 2A of the holding member 2. Therefore, bubbles are less likely to be generated inside the adhesive 3 near the center, and the seed crystal 4 can be prevented from being peeled off from the adhesive 3.

  Further, the contact portion 2 ″ may have a lower porosity than other portions of the holding member 2 and may be densely configured with carbon. That is, the contact portion 2 ″ is difficult to pass bubbles (gas). . As described above, since the contact portion 2 ″ is provided in the region including the center of the lower end surface 2A of the holding member 2, bubbles (gas) generated inside the adhesive 3 are unlikely to pass through the contact portion 2 ″. It has become. Therefore, even when the adhesive 3 enters between the contact portion 2 ″ and the upper surface 4A of the seed crystal 4 to generate bubbles, the bubbles travel along the surface of the contact portion 2 ″ (along the surface). ), It can move to the lower end surface 2A which has become a rough surface, and can be easily removed from the holding member 2.

(Variation 9 of crystal growth apparatus)
As shown in FIG. 9, the holding member 2 may be provided so that the rough surface of the lower end surface 2 </ b> A is concentric. Even in this case, the rough surface of the lower end surface 2A of the holding member 2 can be set so that the height Th is, for example, 5 μm or more and 30 μm or less, as shown in FIG.

  As for the rough surface of the lower end surface 2A, the length Td of the surface portion parallel to the horizontal plane L1 perpendicular to the thickness direction may be reduced as much as possible, but the length Td of the surface portion is rough as shown in FIG. If it is set to be smaller than the surface height Th, the effects of the present invention can be obtained. Therefore, the length of the surface portion Td can be set by the height Th of the rough surface, and can be set to be 60 μm or less, for example.

  Thus, by making the rough surface of the lower end surface 2A concentric, bubbles generated inside the adhesive 3 are likely to be present in the concave portions 9 forming the respective circumferences. Therefore, the locations where bubbles are generated can be evenly dispersed, and the generation of bubbles in a concentrated manner can be suppressed. Since the bubbles generated in the adhesive material 3 can be dispersed in this manner, the adhesive material 3 can be prevented from being peeled off.

  The lower end surface 2A having such a concentric recess 9 can be formed by processing the lower end surface 2A of the holding member 2 with a lathe, for example. The concentric rough surface may be, for example, a spiral shape or a spiral shape.

  In addition, when the lower end surface 2A having a concentric rough surface is in contact with the upper surface 4A of the seed crystal 4, the lower end surface 2A and the seed crystal 4 are concentric. It is possible to alleviate the concentration of thermal stress generated between the two and a portion of the heat stress. As a result, it is possible to further suppress the adhesive material 3 from being peeled off.

  As shown in FIG. 10, the lower end surface 2A having a concentric rough surface may be inclined toward the center (concentric). The inclination of the lower end surface 2A is set to have an angle D2 with respect to the horizontal plane from the center (concentric) of the lower end surface 2A. By inclining the lower end surface 2A in this manner, bubbles existing in the concave portion 9 on the outer circle can be easily moved to the concave portion 9 on the inner circle. It is possible to suppress the bubbles generated inside the adhesive material 3 from being concentrated on a part.

<Crystal growth method>
A crystal growth method according to an embodiment of the present invention will be described. In the crystal growth method of the present embodiment, the lower surface 4B of the seed crystal 4 fixed to the lower end surface 2A of the holding member 2 is brought into contact with the silicon carbide melt 5 in the crucible 6 so that the upper side of the holding member 2 is raised. The silicon carbide crystal is grown from the melt 5 on the lower surface 4B of the seed crystal 4.

  A single crystal made of silicon carbide can be manufactured by the crystal growth apparatus 1. The crystal growing apparatus 1 includes a crucible 6, a crucible container 7, a heating mechanism 10, a transport mechanism 13, and a control unit 15. In this crystal growth apparatus 1, a single crystal is grown using a solution growth method.

(Process of making the lower end surface of the holding member a rough surface with a predetermined roughness)
A step of roughening the lower end surface 2A of the holding member 2; As a method of making the lower end surface 2A of the holding member 2 a predetermined rough surface, for example, a chemical mechanical polishing method or a method using abrasive cloth can be used. In order to obtain a predetermined rough surface, for example, there is a method of polishing using polishing sand having a predetermined particle diameter. In this case, as the particle size of the polishing sand, one larger than the arithmetic average roughness Ra can be used, for example, one having 7 μm or more and 60 μm or less can be used. 2 A of lower end surfaces of the holding member 2 can be set so that arithmetic mean roughness Ra may become a rough surface 5 micrometers or more and 30 micrometers or less.

(Process of applying adhesive)
After the step of making the lower end surface 2A a rough surface, there is a step of applying the adhesive material 3 to the lower end surface 2A having a rough surface. The adhesive 3 is applied to the entire lower end surface 2A of the holding member 2. In the case where a plurality of adhesive bodies 3 ′ are provided between the seed crystal 4 and the lower end surface 2 </ b> A of the holding member 2 (in the case of Modification 4 of the crystal growth apparatus), for example, the adhesive 3 is used as the holding member 2. You may form by apply | coating to a part of lower end surface 14 of this.

(Step of fixing the seed crystal to the holding member via an adhesive)
After the step of applying the adhesive material 3, the seed crystal 4 is fixed to the lower end surface 2 </ b> A of the holding member 2 through the adhesive material 3 by bringing the seed crystal 4 into contact with the adhesive material 3. The seed crystal 4 is brought into contact with the adhesive 3 applied to the lower end surface 2A.

  The seed crystal 4 may be subjected to heat treatment, for example, while being in contact with the adhesive 3. By performing the heat treatment in this manner, the thermosetting material contained in the adhesive 3 can be cured and carbonized. Thereby, the seed crystal 4 and the holding member 2 can be firmly fixed via the adhesive 3.

  Such heat treatment of the adhesive 3 can be performed in a vacuum atmosphere or an inert gas atmosphere using a heating furnace (including a degreasing furnace, a baking furnace, and the like). The heating temperature can be set to, for example, 150 ° C. or higher and 800 ° C. or lower. Specifically, for example, after temporary heating at a temperature of 200 ° C. for 1 hour, followed by main heating at 700 ° C. for 3 hours, the inside of the furnace may be cooled to room temperature.

  Thus, by bringing the lower surface 4B of the seed crystal 4 fixed to the lower end surface 2A of the holding member 2 via the adhesive 3 into contact with the melt 5, a crystal made of silicon carbide is formed on the lower surface 4B of the seed crystal 4. Can be grown. Then, the crystal can be continuously grown on the lower surface 4B of the seed crystal 4 by pulling the holding member 2 upward little by little.

  In the conventional holding member, since the entire lower end surface is a dense surface with high porosity, bubbles generated inside the adhesive are likely to stay inside, and there is a problem that the adhesive is easily peeled off. there were.

  In this embodiment, since it has the process of roughening the lower end surface 2A of the holding member 2, it is possible to remove the dense surface having a high porosity, and therefore it is generated inside the adhesive material 3. Air bubbles (gas) can be easily removed from the rough surface. As a result, it is possible to reduce bubbles existing inside the adhesive material 3, and it is possible to make it difficult for the seed crystal 4 to be peeled off from the holding member 4.

DESCRIPTION OF SYMBOLS 1 Crystal growth apparatus 2 Holding member 2A Lower end surface 2 'Polycrystal 2 "Contact part 3 Adhesive material 3a Particle | grain 4 Seed crystal 4A Upper surface 4B Lower surface 5 Melt 6 Crucible 7 Crucible container 8 Heat insulating material 9 Recessed part
10 Heating mechanism
11 coils
12 AC power supply
13 Transport mechanism
14 Power source
15 Control unit
17 Buffer layer

Claims (8)

The silicon carbide melt in the crucible is brought into contact with the lower surface of a seed crystal made of silicon carbide fixed to the lower end surface of the holding member via an adhesive, and a silicon carbide crystal is grown from the melt on the lower surface. In the crystal growing apparatus
The holding member is made of carbon, and the adhesive includes a material having a boiling point lower than the melting point of the silicon carbide and carbon particles,
The crystal growth apparatus, wherein the lower end surface of the holding member is a rough surface having an arithmetic average roughness Ra of 5 μm to 30 μm.   The crystal growth apparatus according to claim 1, wherein the holding member has the lower end surface thereof as the rough surface.   The crystal growth apparatus according to claim 1, wherein the holding member has the lower end surface inclined with respect to a horizontal plane perpendicular to the vertical direction.   The crystal growth apparatus according to claim 1, wherein the holding member includes a polycrystal made of silicon carbide in a portion including the lower end surface.   The crystal growth apparatus according to claim 1, wherein the adhesive further contains silicon.   The crystal growth apparatus according to claim 1, wherein the adhesive material includes a plurality of adhesive bodies that fix a part of the lower end surface of the holding member and a part of the upper surface of the seed crystal.   The said adhesive material has the polycrystalline buffer layer which consists of a silicon carbide located between the said lower end surface of the said holding member, and the upper surface of the said seed crystal. Crystal growth equipment. The lower surface of the seed crystal fixed to the lower end surface of the holding member is brought into contact with the silicon carbide melt in the crucible, and the holding member is pulled upward to bring the lower surface of the seed crystal from the melt. In a crystal growth method for growing a silicon carbide crystal,
Making the lower end surface of the holding member a rough surface with a predetermined roughness;
Applying an adhesive containing carbon and a material having a boiling point lower than the melting point of the silicon carbide to the roughened lower end surface;
After the step of applying the adhesive, the crystal is grown by contacting the seed crystal with the adhesive to fix the seed crystal to the lower end surface of the holding member via the adhesive Method.

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