JP2015120605A - Production method of silicon carbide single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a silicon carbide single crystal having high crystallinity by clarifying a proper heating method as a method for heating a seed crystal fixative.SOLUTION: A production method of a silicon carbide single crystal includes steps for: preparing a pedestal 20 having a first plane (third principal plane 20A), a seed substrate 10 loaded on the first plane (third principal plane 20A) of the pedestal 20, and an adhesive 30 for allowing the pedestal 20 to adhere to the seed substrate 10; laminating the seed substrate 10 onto the first plane (third principal plane 20A) of the pedestal 20 via the adhesive 30; and curing the adhesive 30 by a heat treatment. A temperature gradient in the radial direction of the seed substrate 10 in the curing step is 1°C/mm or less. A coating film 11 containing carbon may be formed of an organic resin on a principal plane 10B of the seed substrate 10, and the organic resin may be composed of a photosensitive resin to be bridged or decomposed by action of light.

Description

  The present invention relates to a method for manufacturing a silicon carbide single crystal, and more particularly to a method for manufacturing a silicon carbide single crystal capable of improving crystal quality.

  In recent years, the use of silicon carbide (SiC) as a semiconductor material has been actively studied. The large band gap of silicon carbide can contribute to improving the performance of the semiconductor device. The manufacture of a silicon carbide semiconductor usually requires a silicon carbide single crystal substrate. A silicon carbide single crystal substrate (wafer) can be formed by slicing a silicon carbide single crystal (ingot).

  The silicon carbide single crystal is manufactured using a sublimation recrystallization method. In this method, a silicon carbide single crystal is grown on the surface of a seed crystal fixed on a pedestal. If the seed crystal is not uniformly fixed to the pedestal at this time, the quality of the single crystal grown on the seed crystal may be lowered. For this reason, the seed crystal fixing agent for fixing a seed crystal uniformly to a base is examined.

  Japanese Patent Application Laid-Open No. 2012-250865 discloses a method for producing a single crystal using a sublimation recrystallization method, which is difficult by heating as a seed crystal fixing agent used to fix a seed substrate on a pedestal. A method for producing a single crystal is described in which a high-quality crystal can be grown on a seed crystal by using a fixing agent composed of a resin that becomes graphitized carbon and diamond fine particles. Specifically, by heating the seed crystal fixing agent when the back surface of the seed crystal is fixed, the volume increases due to the change from diamond fine particles to graphite fine particles, and the volume decreases due to the change from resin to non-graphitizable carbon. It is described that the generation of pores is suppressed by offsetting. As a result, JP 2012-250865 A discloses that the temperature of the seed substrate can be made more uniform during crystal growth.

JP 2012-250865 A

  However, as a result of diligent research by the inventors of the present application, it was confirmed that the seed crystal and the pedestal may not be fixed uniformly in the joint surface depending on the method and conditions for heating the seed crystal fixing agent. . In this case, during the growth of the single crystal, the temperature of the seed crystal fixed by the seed crystal fixing agent becomes non-uniform in the plane, so that it becomes difficult to grow a silicon carbide single crystal having high crystallinity.

  The present invention has been made to solve the above-described problems. The main object of the present invention is to clarify a heating method suitable as a method for heating a seed crystal fixing agent, and to provide a method for producing a silicon carbide single crystal having high crystallinity.

  A method for manufacturing a silicon carbide single crystal according to the present invention includes a pedestal having a first surface, a seed substrate mounted on the first surface of the pedestal, and an adhesive for bonding the pedestal and the seed substrate. A step of bonding the seed substrate to the first surface of the pedestal via an adhesive, and a step of curing the adhesive by heat treatment, in the radial direction of the seed substrate in the step of curing The temperature gradient is 1 ° C./mm or less.

  According to the present invention, a silicon carbide single crystal having high crystallinity can be obtained.

It is a flowchart of the manufacturing method of the single crystal which concerns on this Embodiment. It is a side view for demonstrating the manufacturing method of the single crystal which concerns on this Embodiment. It is a side view for demonstrating the manufacturing method of the single crystal which concerns on this Embodiment. In the manufacturing method of the single crystal which concerns on this Embodiment, it is a graph showing each temperature increase rate of a seed substrate and a base. It is a side view for demonstrating the manufacturing method of the single crystal which concerns on this Embodiment. It is sectional drawing for demonstrating the manufacturing method of the single crystal which concerns on this Embodiment. It is sectional drawing for demonstrating the modification of the heating member in the manufacturing method of the single crystal which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

[Description of Embodiment of Present Invention]
First, the outline of the embodiment of the present invention will be enumerated.

  (1) A method for manufacturing a silicon carbide single crystal according to the present embodiment includes a base 20 having a first surface (third main surface 20A) and a seed substrate mounted on the first surface of base 20. 10 and a step of preparing an adhesive 30 for bonding the pedestal 20 and the seed substrate 10 (S10), and a step of bonding the seed substrate 10 to the first surface of the pedestal 20 via the adhesive 30 (S20) and a step (S30) of curing the adhesive 30 by heat treatment, and the radial temperature gradient of the seed substrate 10 in the curing step (S30) is 1 ° C./mm or less.

  As a result of the diligent research conducted by the inventors of the present application, for example, when the adhesive 30 is heated and cured via the pedestal 20 by induction heating, the radial direction D of the seed substrate 10 on the pedestal 20 (see FIG. 2. The temperature gradient in the direction D) exceeds 1 ° C./min, and the adhesive 30 may not be uniformly cured in the radial direction D, and further, peeling may occur between the seed substrate 10 and the pedestal 20. Was confirmed. This is considered to be because when the adhesive 30 is heated via the pedestal 20 by induction heating, the pedestal 20 is heated from its surface portion, and thus a large temperature distribution is generated in the radial direction D in the pedestal 20. .

  On the other hand, when the adhesive 30 is cured by a heat treatment method (thermal conduction or thermal radiation) described later, the temperature gradient in the radial direction D of the seed substrate 10 and / or the pedestal 20 is 1 ° C./mm or less. It was confirmed that the adhesive 30 was uniformly cured in the radial direction and could prevent the seed substrate 10 and the pedestal 20 from being peeled off. Further, this confirmed that the temperature of the seed substrate 10 can be made uniform in the radial direction D during crystal growth, so that a silicon carbide single crystal having high crystallinity can be obtained.

  That is, according to the method for manufacturing a silicon carbide single crystal according to the present embodiment, seed substrate 10, pedestal 20, and adhesive 30 can be uniformly heated in radial direction D. It can be cured. As a result, a SiC single crystal with high crystallinity can be obtained.

  When the seed substrate 10 and the pedestal 20 are bonded together, a weight 51 or the like may be placed on the first main surface 10A of the seed substrate 10 as described later. It is difficult to directly measure the principal surface 10A. In this case, as a sample product of the seed substrate 10, for example, a small hole extending from the side surface to the center is passed through the same substrate as the seed substrate 10, and the temperature of the seed substrate 10 is measured through a thermocouple inside the hole. May be.

  (2) In the method for manufacturing a silicon carbide single crystal according to the present embodiment, the curing step (S30) may be performed by heat conduction from the heating member that contacts pedestal 20 to pedestal 20.

  In this way, compared to the case where the adhesive 30 is cured by induction heating, for example, the adhesive 30 can be heated uniformly through the pedestal 20 in the radial direction of the seed substrate 10. It can be cured without any problems. As a result, adhesive 30 can be uniformly cured in the radial direction to prevent peeling between seed substrate 10 and pedestal 20, and a silicon carbide single crystal having high crystallinity can be obtained.

  (3) In the method for manufacturing a silicon carbide single crystal according to the present embodiment, the heating member may be a hot plate.

  That is, in the curing step (S30), the pedestal 20 on which the seed substrate 10 is bonded via the adhesive 30 is disposed on the hot plate, and heat generated from the hot plate is transmitted to the pedestal 20 by heat conduction. Then, heat treatment may be performed. In this way, compared to the case where the adhesive 30 is cured by induction heating, for example, the adhesive 30 can be heated uniformly through the pedestal 20 in the radial direction of the seed substrate 10. It can be cured without any problems. As a result, adhesive 30 can be uniformly cured in the radial direction to prevent peeling between seed substrate 10 and pedestal 20, and a silicon carbide single crystal having high crystallinity can be obtained.

  (4) In the method for manufacturing a silicon carbide single crystal according to the present embodiment, the curing step is performed by thermal radiation from the heating member to at least one of base 20, seed substrate 10, and adhesive 30. Also good.

  In this way, compared to the case where the adhesive 30 is cured by induction heating, for example, the adhesive 30 can be heated uniformly through the pedestal 20 in the radial direction of the seed substrate 10. It can be cured without any problems. As a result, adhesive 30 can be uniformly cured in the radial direction to prevent peeling between seed substrate 10 and pedestal 20, and a silicon carbide single crystal having high crystallinity can be obtained.

  (5) In the method for manufacturing a silicon carbide single crystal according to the present embodiment, the heating member includes a heating furnace that holds pedestal 20 on which seed substrate 10 is bonded via adhesive 30 inside. Also good.

  That is, in the curing step (S30), the base 20 on which the seed substrate 10 is bonded via the adhesive 30 is placed in a heating furnace (for example, a resistance heating furnace), and the inside of the heating furnace is heated to form the base 20 In contrast, heat treatment may be performed by heat radiation. In this way, compared to the case where the adhesive 30 is cured by induction heating, for example, the adhesive 30 can be heated uniformly through the pedestal 20 in the radial direction of the seed substrate 10. It can be cured without any problems. As a result, adhesive 30 can be uniformly cured in the radial direction to prevent peeling between seed substrate 10 and pedestal 20, and a silicon carbide single crystal having high crystallinity can be obtained.

  (6) In the method for manufacturing a silicon carbide single crystal according to the present embodiment, in the curing step (S30), the seed substrate 10 may be heat-treated at a rate of temperature increase of 5 ° C./min or less.

  In the curing step (S30), for example, by setting the heating rate of the heating member to 5 ° C./min or less, all of the seed substrate 10, the pedestal 20, and the adhesive 30 are heated at 5 ° C./min or less. Can be. If it does in this way, it can control that reaction which hardens adhesive 30 advances rapidly, and adhesive 30 can be hardened in the diameter direction of seed substrate 10 uniformly. Further, even when the seed substrate 10 and the pedestal 20 are warped or undulated, the adhesive 30 that fills the gap generated between the seed substrate 10 and the pedestal 20 when they are bonded together. However, it can be cured without unevenness. As a result, even in the above case, a SiC single crystal with high crystallinity can be obtained.

[Details of the embodiment of the present invention]
Next, details of the embodiment of the present invention will be described.

  First, a method for manufacturing a silicon carbide (SiC) single crystal according to the present embodiment will be described with reference to FIGS. The method for manufacturing a silicon carbide single crystal according to the present embodiment includes a step (S10) of preparing seed substrate 10, pedestal 20, and adhesive 30, and third main surface 20A as the first surface of pedestal 20. A step of bonding the seed substrate 10 on the adhesive 30 via the adhesive 30 (S20), a step of curing the adhesive 30 by heat treatment (S30), and a fixing layer 31 formed by curing the adhesive 30. A step (S40) of growing a single crystal on the seed substrate 10 fixed on the third main surface 20A.

  First, the seed board | substrate 10, the base 20, and the adhesive agent 30 are prepared (process (S10)). The seed substrate 10 is a crystal made of SiC, and the crystal structure is preferably a hexagonal system. The crystal polymorph is preferably 4H or 6H. In this case, the surface orientation of the seed substrate 10 (the orientation of the lower surface in the drawing) preferably has an off angle smaller than 15 ° with respect to {0001}, and more preferably has an off angle smaller than 10 °.

  A coating film 11 containing carbon may be formed on the second main surface 10B of the seed substrate 10. The covering film 11 is an organic film in the present embodiment. This organic film is preferably formed from an organic resin. As the organic resin, for example, various resins such as an acrylic resin, a phenol resin, a urea resin, and an epoxy resin can be used, and a resin that is formed as a photosensitive resin that is crosslinked or decomposed by the action of light can also be used. it can. As the photosensitive resin, a positive type or negative type photoresist used for manufacturing a semiconductor device can be used, and since a coating technique by spin coating is established for these, the coating film 11 is used. Can be easily controlled. The spin coating method is performed as follows, for example.

  First, the seed substrate 10 is adsorbed to a holder (not shown). The seed substrate 10 is rotated by rotating the holder at a predetermined rotation speed. After the photoresist is dropped on the rotating seed substrate 10, the photoresist is applied thinly and uniformly by continuing the rotation for a predetermined time. In order to ensure uniformity over the entire surface of the seed substrate 10, for example, the rotation speed is 1000 rotations / minute to 10,000 rotations / minute, the time is 10 seconds to 100 seconds, and the coating thickness is 0.1 μm or more. .

  Next, the applied photoresist is dried to be solidified. Any method can be adopted as the drying method. The drying temperature and time can be appropriately selected depending on the photoresist material and the coating thickness. Preferably, the drying temperature is from 100 ° C. to 400 ° C., and the drying time is from 5 minutes to 60 minutes. For example, when the drying temperature is 120 ° C., the time required for volatilization is, for example, 15 minutes at a thickness of 5 μm, 8 minutes at a thickness of 2 μm, and 3 minutes at a thickness of 1 μm. Note that the coating film 11 can be formed by performing the above-described steps of application and drying once, but a thicker coating film 11 may be formed by repeating this process. In this way, the seed substrate 10 having the second main surface 10B covered with the coating film 11 can be prepared.

  The pedestal 20 is configured as a lid of a crucible 60 described later, for example. The material constituting the pedestal 20 is, for example, a carbon material, and more specifically, for example, graphite. The pedestal 20 is bonded to the second main surface 10B of the seed substrate 10 in a step (S20) to be described later, and a third main surface 20A disposed toward the inside of the crucible 60, and a third main surface 20A and a fourth main surface 20B located on the opposite side.

  The adhesive 30 includes, for example, a resin that becomes non-graphitizable carbon when heated, diamond fine particles, and a solvent. Non-graphitizable carbon is carbon having an irregular structure that suppresses the development of a graphite structure when heated in an inert gas. Examples of the resin that becomes non-graphitizable carbon when heated include novolac resin, phenol resin, and furfuryl alcohol resin. The amount of diamond fine particles is preferably smaller than the amount of resin based on the number of moles of carbon atoms. The particle diameter of the diamond fine particles is, for example, not less than 0.1 μm and not more than 10 μm. The adhesive 30 may further include graphite fine particles in addition to the diamond fine particles. As the solvent, a solvent capable of dissolving and dispersing the above resin and carbohydrate is appropriately selected. The solvent is not limited to a single type of liquid, and may be a mixed liquid of a plurality of types of liquid. For example, a solvent containing alcohol that dissolves carbohydrates and cellosolve acetate that dissolves resin may be used. The adhesive 30 is provided to be curable at a predetermined temperature (for example, 1000 ° C. or higher).

  Next, referring to FIG. 2, seed substrate 10 is bonded to third main surface 20 </ b> A as the first surface of pedestal 20 via adhesive 30 (step (S <b> 20)). Specifically, the fifth main surface 11B of the coating film 11 formed on the second main surface 10B of the seed substrate 10 and the third of the pedestal 20 via the adhesive 30 (seed crystal fixing agent). The main surface 20A is connected. Preferably, this step (S20) is performed at a temperature of 50 ° C. or higher and 120 ° C. or lower and a pressure of 0.01 Pa or higher and 1 MPa or lower so that the two are pressed against each other. The heat treatment in this step (S20) may be performed by any heating method, but is performed on the hot plate 40, for example. The pressurizing process may be performed by an arbitrary method. For example, the pressurizing process is performed by placing a weight 51 having a predetermined mass on the first main surface 10A of the seed substrate 10 via the protective sheet 50. In this step (S20), the adhesive 30 is not cured, and the seed substrate 10 and the base 20 are not fixed. Conversely, the adhesive 30 is softened by being heated at the above temperature. Thereby, in the case where warpage or the like occurs in the second main surface 10B of the seed substrate 10 or the third main surface 20A of the pedestal 20, the gap generated between both surfaces is filled with the adhesive 30. Can be pasted together.

  Next, the adhesive 30 is cured by heat treatment (step (S30)). This step (S30) includes a step (S32) of performing the first heat treatment in a predetermined temperature region, a step (S33) of performing the second heat treatment in a higher temperature region following the step (S32), and including.

  Specifically, first, a first heat treatment is performed in a predetermined temperature range (step (S32)). This step (S32) is performed using the hot plate 40 so that the temperature gradient in the radial direction D (see FIG. 2) in the seed substrate 10 and the pedestal 20 is 1 ° C./mm or less. The heat conducted from the hot plate 40 to the pedestal 20 is conducted to the adhesive 30 and the seed substrate 10 disposed on the third main surface 20A through the pedestal 20, and heats the adhesive 30 and the seed substrate 10. To do.

  The heating temperature in this step (S32) is a temperature at which the solvent contained in the adhesive 30 can be evaporated to some extent, for example, a predetermined temperature of 100 ° C. or higher and 400 ° C. or lower.

  At this time, the heating rate of the hot plate 40 is controlled so that the heating rate of the seed substrate 10 and the pedestal 20 is 5 ° C./min or less. Alternatively, the heating rate of the hot plate 40 may be 5 ° C./min or less. FIG. 4 is a graph showing the temperature increase rates of the seed substrate 10 and the pedestal 20. The vertical axis in FIG. 4 indicates temperature (unit: ° C.), and the horizontal axis indicates heating time (unit: minutes). Referring to FIG. 4, when the temperature is raised to the above heating temperature, the temperature difference d between the seed substrate 10 and the pedestal 20 in the region facing each other through the adhesive 30 is the seed substrate 10. L / 2 ° C. or less when the outer diameter is Lmm (see FIG. 2). As a result, the temperature gradient in the radial direction D (see FIG. 2) in the seed substrate 10 and the pedestal 20 can be set to 1 ° C./mm or less.

  The heat treatment time is, for example, not less than 5 minutes and not more than 60 minutes after reaching a predetermined temperature. In this way, the adhesive 30 can be temporarily cured.

  Next, the second heat treatment is performed in a higher temperature region continuously with the step (S32) (step (S33)). Specifically, it is carried out by a heat treatment method that enables heating to a predetermined temperature of, for example, 1000 ° C. or higher, preferably 2000 ° C. or higher. This step (S33) is performed using, for example, a lamp annealing apparatus. This heating is preferably performed in an inert gas. In this step (S33), the temperature gradient in the radial direction D may exceed 1 ° C./min. Further, the rate of temperature increase may be over 5 ° C./min.

  By this step (S33), the coating film 11 is carbonized into the carbon film 12 as shown in FIG. That is, the second main surface 10 </ b> B of the seed substrate 10 is a surface covered with the carbon film 12. Further, the adhesive 30 becomes the fixed layer 31 when the solvent contained in the adhesive 30 is evaporated and cured. As a result, referring to FIG. 5, seed substrate 10 is fixed on third main surface 20 </ b> A of pedestal 20 via fixing layer 31.

  Next, a single crystal is grown on the first main surface 10A of the seed substrate 10 fixed on the pedestal 20 via the fixed layer 31 (step (S40)). When a silicon carbide single crystal is manufactured using the silicon carbide seed substrate 10, a sublimation recrystallization method can be used as the formation method.

  That is, referring to FIG. 6, first, base 20 is attached to crucible 60 such that seed substrate 10 faces inside crucible 60. The crucible 60 is configured including, for example, a carbon raw material. A raw material 61 is stored in the crucible 60. Raw material 61 is, for example, silicon carbide powder. The crucible 60 is provided so as to be heated to a predetermined temperature, which will be described later, by a heating unit (not shown) disposed around the crucible 60.

  Next, the single crystal 70 can be grown by depositing a sublimate on the seed substrate 10 by sublimating the raw material 61. The temperature in this sublimation recrystallization method is, for example, 2100 ° C. or higher and 2500 ° C. or lower. The pressure in the sublimation recrystallization method is preferably 1.3 kPa or more and atmospheric pressure or less, and more preferably 13 kPa or less in order to increase the growth rate. As described above, SiC single crystal 70 according to the present embodiment can be obtained.

  Next, the effect of the method for manufacturing a silicon carbide single crystal according to the present embodiment will be described. In the method for manufacturing a silicon carbide single crystal according to the present embodiment, the step of curing adhesive 30 (S30) is performed by two-stage heat treatment at different heating temperatures, and the first heat treatment performed first is performed. The step (S32) is performed such that the temperature gradient in the radial direction D of the seed substrate 10 and the pedestal 20 is 1 ° C./mm or less. Thereby, since the adhesive 30 can be heated uniformly through the pedestal 20 in the radial direction of the seed substrate 10, the adhesive 30 is cured without unevenness in the step of performing the second heat treatment (S 33). 31. As a result, since the seed substrate 10 and the pedestal 20 are fixed with good adhesion via the fixed layer 31, the SiC single crystal 70 having high crystallinity can be grown on the seed substrate 10.

  Specifically, in the method for manufacturing a silicon carbide single crystal according to the present embodiment, the step (S32) of performing the first heat treatment is performed using hot plate 40 as a heating member, so The pedestal 20 placed on is heated by receiving heat conduction. At this time, for example, by controlling the heating rate of the hot plate 40 so that the heating rate of the pedestal 20 is 5 ° C./min or less, the seed substrate 10 and the pedestal 20 are opposed to each other through the adhesive 30. The temperature difference d can be set to L / 2 ° C. or less when the seed substrate 10 has an outer diameter Lmm (see FIG. 2). As a result, the temperature gradient in the radial direction D on the seed substrate 10 and the pedestal 20 can be 1 ° C./mm or less. As a result, a steep temperature change in the pedestal 20 can be suppressed, and the temperature gradient in the radial direction D can be reduced for each of the pedestal 20, the adhesive 30, and the seed substrate 10.

  In the step of performing the first heat treatment (S32), the adhesive 30 can be preliminarily cured by heating in the radial direction D with good uniformity. Therefore, when the heat treatment is further performed at a higher temperature in the subsequent step (S33), the temperature gradient in the radial direction D of the seed substrate 10 and the pedestal 20 exceeds 1 ° C./min, or the temperature rising rate is 5 ° C./min. Even if it exceeds the minute, the adhesive 30 can be cured without unevenness in the radial direction D. In other words, the fixed layer 31 can be formed without unevenness in the radial direction D.

  In the method for manufacturing a silicon carbide single crystal according to the present embodiment, the bonding step (S20) is heated to a temperature of 50 ° C. or higher and 120 ° C. or lower on hot plate 40 and 0.01 Pa or higher and 1 MPa or lower. Although it is performed so that both press each other with pressure, it is not limited to this. In the step (S20), these may be bonded together without heating and / or pressurizing the seed substrate 10, the pedestal 20, and the adhesive 30. In this case, after the step (S20) and before the step (S32) of performing the first heat treatment, the pedestal 20 on which the seed substrate 10 is placed via the adhesive 30 is replaced with a hot plate. The process (S31) arrange | positioned on 40 should just be provided. Even if it does in this way, there can exist an effect similar to the manufacturing method of the silicon carbide single crystal which concerns on this Embodiment.

  In the step of performing the first heat treatment (S32), any heating method can be employed using any heating member. For example, the heating member may be the resistance heating furnace 41 with reference to FIG. 7, or a lamp annealing apparatus or the like. When the induction heating method is adopted, the induction heating method from the side surface of the pedestal 20 is not preferable, and the pedestal 20 is sandwiched from the vertical direction (direction perpendicular to the third main surface 20A) by a pancake coil. Any induction heating method with a structure may be used.

(Example)
Next, examples of the method for manufacturing a silicon carbide single crystal according to the present embodiment will be described.

(Evaluation 1)
First, as the seed substrate 10, 30 seed crystals having a thickness of about 3 mm, a diameter of 60 mm, a polytype 4H, and a plane orientation (000-1) were prepared. The back surface (second main surface 10B) side of the seed substrate 10 was mechanically polished using a diamond slurry having a particle size of about 15 μm.

  Next, the seed substrate 10 was attached to the holder so that the back surface of the seed substrate 10 was exposed. Next, while the seed substrate 10 is rotated by rotating this holder at 1450 times / minute, about 20 mg of a resist solution containing ethyl lactate and butyl acetate is dropped on the second main surface 10B with a dropper. Then, the rotation was continued for 20 seconds. Thus, the resist solution was applied with a thickness of about 1 μm. Next, the coating film 11 was formed by drying at 350 ° C. for 20 minutes.

  Referring to FIG. 2, 30 graphite pedestals 20 having third main surface 20A to which seed substrate 10 is to be attached were prepared. Next, the third main surface 20A was polished with diamond slurry.

Next, an adhesive 30 containing a phenol resin, phenol, ethyl alcohol, formaldehyde, moisture, and a solid carbon component was prepared. The coating film 11 and the base 20 were brought into contact with each other through the adhesive 30. The application amount of the adhesive 30 was about 25 mg / cm ² and the thickness was about 40 μm. The contact was performed on the hot plate 40 by heating to a temperature of 100 ° C. and applying a pressure of 0.1 MPa so as to press the seed substrate 10 and the pedestal 20 against each other.

  Next, the first heat treatment was performed on the 30 pairs of seed substrate 10 and pedestal 20 bonded together with the adhesive 30. Specifically, of the 30 pairs, 10 pairs were sequentially subjected to heat treatment on the hot plate 40 for 4 hours at 80 ° C., 4 hours at 120 ° C., and 1 hour at 200 ° C. Further, the other 10 pairs were sequentially subjected to heat treatment in the thermostat 41 at 80 ° C. for 4 hours, 120 ° C. for 4 hours, and 200 ° C. for 1 hour. The remaining 10 pairs were sequentially subjected to heat treatment in a resistance heating furnace at 80 ° C. for 4 hours, 120 ° C. for 4 hours, and 200 ° C. for 1 hour. At this time, the heating rate to each heating temperature was 5 ° C./min or less.

  Next, a second heat treatment was performed. Specifically, heat treatment was performed on the previous 30 pairs in an 80 kPa helium gas atmosphere at a heating temperature of 1150 ° C. and a heating time of 1 hour. As a result, the 30 pairs of the seed substrate 10 and the pedestal 20 were fixed via the fixed layer 31.

  Next, for each pair, the pedestal 20 was fixed and the seed substrate 10 was pulled with a force of 20 kg to evaluate whether the seed substrate 10 and the pedestal 20 were peeled off. As a result, none of the 30 pairs peeled off the seed substrate 10 and the pedestal 20.

  On the other hand, as a comparative example, peeling evaluation was carried out on 10 pairs in which the first heat treatment (step (S32)) was performed by the induction heating method to the side surface of the pedestal while being basically manufactured in the same manner as the above 30 pairs. . As a result, the three pairs of the seed substrate 10 and the pedestal 20 were peeled off. In addition, when the 1st heat processing (process (S32)) was performed by the induction heating system, the temperature gradient of the radial direction D of the base 20 at that time exceeded 1 degreeC / mm.

  Furthermore, as a comparative example, peeling evaluation was performed on 10 pairs that were manufactured in the same manner as the above 30 pairs, but were performed at a rate of temperature increase in the first heat treatment (step (S32)) exceeding 5 ° C./min. Carried out. As a result, among the 10 pairs, 5 pairs of the seed substrate 10 and the pedestal 20 were peeled off. In addition, when the temperature increase rate in the first heat treatment (step (S32)) was performed at a rate exceeding 5 ° C./min, the temperature gradient in the radial direction D of the pedestal 20 at that time exceeded 1 ° C./mm. .

  From the results of the examples, according to the method for manufacturing a silicon carbide single crystal according to the present embodiment, the fixed layer 31 can be formed without unevenness in the radial direction D, so that the seed substrate 10 and the pedestal 20 are adhered to each other. It was confirmed that it can be fixed well.

  Although the embodiments and examples of the present invention have been described above, the above-described embodiments can be variously modified. Further, the scope of the present invention is not limited to the above-described embodiments and examples. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

10 seed substrate 10A first main surface 10B second main surface 11 coating film 11B fifth main surface 12 carbon film 20 pedestal 20A third main surface 20B fourth main surface 30 adhesive 31 fixing layer 40 hot Plate 41 Resistance heating furnace 50 Protective sheet 51 Weight 60 Crucible 61 Raw material

Claims (6)

Preparing a pedestal having a first surface, a seed substrate mounted on the first surface of the pedestal, and an adhesive for bonding the pedestal and the seed substrate;
Bonding the seed substrate on the first surface of the pedestal via the adhesive;
Curing the adhesive by heat treatment,
The manufacturing method of the silicon carbide single crystal whose temperature gradient of the radial direction of the said seed substrate in the said hardening process is 1 degrees C / mm or less.   The method for producing a silicon carbide single crystal according to claim 1, wherein the curing step is performed by heat conduction from a heating member that contacts the pedestal to the pedestal.   The method for manufacturing a silicon carbide single crystal according to claim 2, wherein the heating member is a hot plate.   The method for producing a silicon carbide single crystal according to claim 1, wherein the curing step is performed by thermal radiation from a heating member to at least one of the pedestal, the seed substrate, and the adhesive.   The said heating member is a manufacturing method of the silicon carbide single crystal of Claim 4 containing the heating furnace which hold | maintains the said base by which the said seed substrate is bonded together through the said adhesive agent inside.   The method for producing a silicon carbide single crystal according to any one of claims 1 to 5, wherein, in the curing step, the heat treatment is performed at a temperature rising rate of the seed substrate of 5 ° C / min or less.

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