JP2012116679A - Method for producing seed crystal holder and method for producing single crystal using the same - Google Patents

Abstract

A method for producing a seed crystal holder capable of forming a single crystal having high quality and sufficiently suppressing the generation of voids, and a method for producing a single crystal using the same.
A method for producing a seed crystal holding body 8 comprising a base material 9 and a seed crystal 10 joined to the base material 9 via a joint portion 11, comprising a vapor phase method on the base material 9. To form a polycrystalline body made of the same material as the seed crystal 10 as the joint portion 11, and to reduce the surface roughness of the surface to be joined to join the seed crystal 10 in the joint portion 11, thereby smoothing the surface. A joint surface roughness reducing step to be obtained, and a seed crystal joining step of joining the seed crystal 10 to the smoothed surface of the joint 11.
[Selection] Figure 4

Description

  The present invention relates to a seed crystal support and a method for producing a single crystal using the seed crystal support.

  Since compound semiconductors such as silicon carbide and aluminum nitride have a wide band gap, they are expected to be used for light emitting devices, high voltage / high frequency power supply ICs, and the like. In particular, an aluminum nitride single crystal has a small lattice mismatch with gallium nitride of 2.4%, and thus is expected as a growth substrate when growing a gallium nitride semiconductor.

  Various methods for producing such a compound semiconductor single crystal are known, and among them, the sublimation method is generally used as an effective method for producing a bulk crystal because of its generally high growth rate. It has been. In the sublimation method, the growth vessel is heated, a temperature difference is provided between the bottom and the lid of the growth vessel, the raw material placed on the bottom is sublimated, and the sublimation gas is fixed to the lid having a lower temperature than the bottom. This is a method of growing a crystal by recrystallization from the crystal.

  As a method for fixing the seed crystal to the lid of the growth vessel, a method is known in which the seed crystal is fixed to the lid via a metal that is stable under the conditions of crystal growth and its silicide, carbide, or nitride ( Patent Document 1) below.

  After placing a metal material between the seed crystal and the graphite pedestal, placing a pressure member on the seed crystal, and heat-treating the metal material at a temperature above its melting point while pressing the seed crystal with the pressure member A method of fixing a seed crystal to a graphite pedestal by cooling is also known (Patent Document 2 below).

  Furthermore, a method is also known in which a seed crystal is fixed to the lid member by providing the lid member with a silicon carbide seed crystal through a polycrystalline layer made of silicon carbide (Patent Document 3 below). In this method, the seed crystal is mechanically held in a non-adhering manner by a hook-like member provided on the lid-like member.

Japanese National Patent Publication No. 11-510781 JP-A-2005-247681 JP 2002-201097 A

  However, in the above Patent Documents 1 to 3, the following problems occur in the obtained single crystal.

  That is, in the methods described in Patent Documents 1 and 2, strains and cracks may occur in the obtained single crystal, and a high-quality single crystal could not be obtained.

  Further, in the method described in Patent Document 3, voids may occur in the obtained single crystal.

  The present invention has been made in view of the above circumstances, and a method for producing a seed crystal holding body capable of forming a single crystal having high quality and sufficiently suppressing generation of voids, and a single crystal using the same It aims at providing the manufacturing method of.

  In order to solve the above-mentioned problems, the present inventors have examined the causes of the above-mentioned problems in Patent Documents 1 to 3. First, in the inventions described in Patent Documents 1 and 2, the seed crystal and the metal bonded thereto are made of different materials, and their thermal expansion coefficients are different. Therefore, when growing a crystal from a seed crystal, if the metal or the like is heated to a high temperature, the seed crystal is distorted, and as a result, the growth crystal provided in the seed crystal may be distorted. They thought.

  In the invention described in Patent Document 3, since the seed crystal is mechanically held by the hook-like member on the lid-like member without adhesion, a gap is likely to be generated between the lid-like member and the polycrystalline layer. From this, when growing a single crystal, the temperature of the lid-like member is lower than that of the polycrystalline layer, so that sublimation occurs from the back surface of the polycrystalline layer toward the lid-like member. We thought that it would continue to the grown crystal, resulting in voids in the grown crystal. Therefore, as a result of intensive studies, the present inventors have found that the above-described problems can be solved by the following invention.

  That is, the present invention is a method for producing a seed crystal holder comprising a base material and a seed crystal bonded to the base material via a joint portion, wherein the seed crystal is formed on the base material by a vapor phase method. A joining portion forming step of forming a polycrystalline body made of the same material as the crystal as the joining portion, and a joining portion that obtains a smoothed surface by reducing the surface roughness of a joining planned surface for joining the seed crystal in the joining portion A method for producing a seed crystal holding body, comprising: a surface roughness reducing step; and a seed crystal bonding step of bonding the seed crystal to the smoothed surface of the bonding portion.

  According to this invention, since the joining portion is obtained by being formed on the base material by a vapor phase method, the joining portion is formed densely and the adhesion between the joining portion and the base material is improved. It is sufficiently prevented that voids are generated in the joint portion. In addition, the seed crystal is made smooth by reducing the surface roughness of the joint planned surface of the joint, and then joined to the smooth surface of the joint. For this reason, it becomes possible to make the clearance gap between a seed crystal and a junction part small enough. For this reason, when the seed crystal holder obtained by the above manufacturing method is installed in a growth vessel containing a single crystal raw material, and the single crystal raw material is sublimated in the growth vessel, crystals from the seed crystal of the seed crystal holder are obtained. Will grow. At this time, the adhesion between the bonded portion and the base material is improved, and the occurrence of voids in the bonded portion is sufficiently prevented. In addition, since the seed crystal is smoothed by reducing the surface roughness of the joint planned surface of the joint, and then joined to the smoothed surface of the joint, the seed crystal is bonded between the seed crystal and the joint. The gap can be made sufficiently small. For this reason, sublimation of the seed crystal from the substrate side is sufficiently prevented, and generation of voids in the seed crystal is also sufficiently prevented. As a result, voids are sufficiently prevented from occurring in the grown crystal grown from the seed crystal. Further, since the joint portion is composed of a polycrystal made of the same material as the seed crystal, the difference in thermal expansion coefficient between the joint portion and the seed crystal is sufficiently small. For this reason, even if the junction is heated, the strain applied to the seed crystal can be made sufficiently small, and the strain can be made sufficiently small even in the obtained grown crystal. As a result, a high quality single crystal can be obtained.

  In the manufacturing method, between the joint surface roughness reducing step and the seed crystal joining step, the smoothness surface is reduced by reducing the surface roughness of the surface to be joined to the joint portion of the seed crystal. It is preferable to further include a seed crystal surface roughness reducing step to be obtained.

  In this case, since both the bonding scheduled surface of the bonded portion and the planned bonding surface of the seed crystal are smoothed, the adhesion between the bonded portion and the seed crystal can be further improved. Therefore, the generation of sublimation gas in the seed crystal is more sufficiently prevented, and the generation of voids in the seed crystal can be more sufficiently suppressed. As a result, generation of voids due to sublimation can be more sufficiently suppressed in the obtained single crystal.

  The present invention also provides a seed crystal holder installation step in which the seed crystal holder obtained by the above production method is placed in a growth vessel containing a single crystal raw material; And a crystal growth step for growing the crystal from the seed crystal.

  According to this invention, since the seed crystal holder described above is used as the seed crystal holder, the seed crystal is sufficiently prevented from sublimating from the substrate side during the single crystal growth, and the seed crystal It is sufficiently prevented that voids are generated therein. As a result, voids are sufficiently prevented from occurring in the grown crystal grown from the seed crystal. Further, since the joint portion is composed of a polycrystal made of the same material as the seed crystal, the difference in thermal expansion coefficient between the joint portion and the seed crystal is sufficiently small. For this reason, even if the junction is heated, the strain applied to the seed crystal can be made sufficiently small, and the strain can be made sufficiently small even in the obtained grown crystal. As a result, a high quality single crystal can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the seed crystal holding body which can form the high quality and the single crystal which generation | occurrence | production of a space | gap is fully suppressed, and the manufacturing method of a single crystal using the same are provided.

1 is a cross-sectional end view illustrating an example of a manufacturing apparatus that performs a method for manufacturing a single crystal according to the present invention. It is a cut surface end view showing an example of a joined part manufacture device for forming a joined part on a substrate by a sublimation method. It is sectional drawing which shows the laminated body of a base material and a junction part. It is sectional drawing which shows the seed crystal holding body obtained by the manufacturing method of the seed crystal holding body which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, an example of a manufacturing apparatus for carrying out the method for manufacturing a single crystal according to the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional end view showing a single crystal manufacturing apparatus according to the present invention. As shown in FIG. 1, an aluminum nitride single crystal manufacturing apparatus (hereinafter simply referred to as “manufacturing apparatus”) 100 includes a growth vessel 2 containing a raw material 1 of an aluminum nitride single crystal and a reaction surrounding the growth vessel 2. The tube 3 and a heating device 4 provided around the reaction tube 3 are configured.

  The reaction tube 3 is connected to a cylindrical reaction tube main body 3a and a side surface of the reaction tube main body 3a, and introduces a dilution gas for diluting the gas discharged from the growth vessel 2 into the reaction tube main body 3a. And an introduction pipe 3b. The reaction tube 3 is made of, for example, graphite, tungsten, or tantalum carbide. The dilution gas only needs to be able to dilute the gas discharged from the growth vessel 2, and examples of such dilution gas include nitrogen gas and argon gas.

  The growth vessel 2 includes a cylindrical raw material container 2a, an annular member 2c that protrudes from the outer peripheral surface of the raw material container 2a and forms a groove 2b, and a dome-shaped cap member 2d that covers the raw material container 2a. Have.

  A crucible 5 for accommodating the aluminum nitride single crystal raw material 1 is accommodated in the raw material accommodating portion 2a. In addition, a gas introduction pipe 2 f for introducing nitrogen gas passes through the main body 3 a of the reaction tube 3 and is connected to the raw material accommodation part 2 a in the raw material accommodation part 2 a. A gas introduction port 2h is formed at the tip of the gas introduction pipe 2f.

  The cap member 2d is formed with an insertion port 2g for inserting the seed crystal holding body 8 fixed to the tip of the support member 7. Here, the seed crystal holding body 8 includes a base material 9 fixed to the support member 7, a seed crystal 10, and a joint portion 11 that joins the base material 9 and the seed crystal 10. Here, the support member 7 and the base material 9 are made of, for example, graphite or tungsten. The seed crystal 10 is usually composed of an aluminum nitride single crystal, but may be composed of silicon carbide or a silicon carbide single crystal grown on an aluminum nitride single crystal film. The junction 11 is made of a polycrystalline body made of the same material as the seed crystal 10, for example. A polycrystal is an aggregate of aluminum nitride single crystals.

  The cap member 2d is capable of inserting the upper end portion of the raw material storage portion 2a inside thereof. The end of the cap member 2d can be inserted into the groove 2b of the annular member 2c. And by inserting the upper end part of the raw material accommodating part 2a inside the cap member 2d and inserting the end part of the cap member 2d into the groove 2b of the annular member 2c, the single crystal growth region 6 is formed, and the gas A discharge path 2e is formed.

  Here, the gas discharge path 2e is provided at a position where the outlet of the gas discharge path 2e is closer to the heating device 4 than the inlet. That is, the gas discharge path 2e is provided outside the raw material container 2a. For this reason, in the gas discharge path 2e, the temperature increases from the inlet toward the outlet.

  The single crystal growth region 6 is formed by the upper end of the raw material storage portion 2a and the inner wall surface of the cap member 2d, and is provided above the gas discharge path 2e and the raw material storage portion 2a. And the gas discharge path 2e is arrange | positioned in the position higher than the crucible (raw material arrangement | positioning part) 5 in which a raw material is arrange | positioned, and lower than the single crystal arrangement | positioning area | region 6. FIG. That is, the gas discharge path 2 e is arranged between the crucible 5 and the single crystal arrangement region 6.

  The heating device 4 can set the temperature of the gas discharge path 2 e higher than that of the single crystal growth region 6. Specifically, as shown in FIG. 1, the heating device 4 includes a plurality of independent ring-shaped heaters 4a, 4b, and 4c. The plurality of heaters 4a, 4b, and 4c are sequentially arranged from the lower portion to the upper portion of the growth vessel 2, and the amount of heat generated in each heater 4a, 4b, and 4c can be adjusted independently. Each of the heaters 4a, 4b, 4c is preferably meandering. Each of the heaters 4a, 4b, 4c may be divided into a plurality (for example, two). Here, the heater 4 a is for adjusting the temperature of the raw material 1. Therefore, the heater 4 a is arranged so as to surround the crucible 5. The heater 4b is for adjusting the temperature of the gas discharge path 2e. Accordingly, the heater 4b is disposed so as to surround the gas discharge path 2e. The heater 4c is for heating the single crystal growth region 6. Therefore, the heater 4 c is arranged so as to surround the single crystal arrangement region 6. Therefore, if the heat generation amount of the heater 4b is made larger than the heat generation amount of the heater 4c, the temperature of the gas discharge path 2e can be made higher than the temperature of the single crystal growth region 6.

  In addition, the raw material accommodating part 2a and the cap member 2d are normally comprised with graphite. However, the inner wall surfaces of the raw material container 2a and the cap member 2d are tantalum carbide (TaC), zirconium nitride (ZrN), tungsten nitride (WN) from the viewpoint of suppressing corrosion by aluminum gas generated during sublimation of the raw material 1. ), Tantalum nitride (TaN), etc., and it is preferable to coat with tantalum carbide because it is particularly excellent in corrosion resistance against aluminum gas.

  Next, a method for manufacturing a single crystal using the manufacturing apparatus 100 will be described.

  First, a method for manufacturing the seed crystal support 8 fixed to the tip of the rod-shaped support member 7 will be described. As described above, the seed crystal support 8 includes the base material 9 fixed to the tip of the support member 7, the seed crystal 10, and the joint portion 11 that joins the base material 9 and the seed crystal 10. .

(Joint formation process)
First, a polycrystalline body is formed on the substrate 9 by a vapor phase method. Examples of vapor phase methods include sublimation method, hydride deposition method (HVPE), MOCVD method, thermal evaporation method, vacuum evaporation method, electron beam evaporation method, laser ablation method, plasma method and sputtering method. It is done. Of these, the sublimation method is preferably used because of the high growth rate of the single crystal. The thickness of the polycrystal is usually 1 to 5000 μm, preferably 20 to 500 μm.

  2 is a cross-sectional end view showing an example of a joint manufacturing apparatus for forming a joint on a substrate by a sublimation method, FIG. 3 is a cross-sectional view showing a laminate of the substrate and the joint, and FIG. FIG. 3 is a cross-sectional view showing a seed crystal holder. As shown in FIG. 2, the joint manufacturing apparatus 20 includes a heating element 14, a heat insulating material 13 that surrounds the heating element 14, and a heating coil 16 that is wound around the heat insulating body 13. The heating element 14 includes a raw material container 14a that stores the raw material 15 and a lid body 14b that seals the raw material container 14a. The heat insulating material 13 also has a heat insulating material main body 13a and a lid 13b provided on the heat insulating material main body 13a. Further, the heat insulating material 13 has a through hole 13c formed so as to expose the lid 14b of the heating element 14, and a through hole 13d formed so as to expose the bottom part of the raw material accommodating portion 14a of the heating element 14. Is formed. The through-hole 13c is for inserting a radiation thermometer and measuring the temperature of the lid 14b by infrared rays radiated from the lid 14b. The through-hole 13d is for inserting a radiation thermometer and measuring the temperature of the bottom by infrared rays radiated from the bottom of the raw material container 14a.

  And in the junction manufacturing apparatus 20, the cover 13b of the heat insulating material 13 is removed, and the cover 14b of the heating element 14 is removed. And the base material 9 is fixed to the surface which opposes the raw material 15 when the raw material accommodating part 14a is sealed with the cover body 14b at the cover body 14b of the heat generating body 14. FIG. The base material 9 is fixed, for example, by placing the base material 9 on the heating element 14 as a lid 14b of the heating element 14 or by mechanically fitting it on the lid 14b of the heating element 14. Can be done by.

  And after accommodating the raw material 15 in the raw material accommodating part 14a, the raw material accommodating part 14a is sealed with the cover body 14b. Subsequently, the heat insulating body 13a is sealed with the lid 13b.

  The heating element 14 is heated by applying a current to the heating coil 16 to generate a magnetic field. At this time, a radiation thermometer is inserted into each of the through holes 13c and 13d of the heat insulating material 13 to measure the temperature of the lid 14b of the heating element 14 and the bottom of the raw material accommodating part 14a of the heating element 14, while the raw material 15 The raw material 15 is heated to a temperature for sublimation. At this time, the temperature of the lid 14b of the heating element 14 is set to be lower than the temperature of the bottom of the raw material container 14a of the heating element 14. Then, the raw material 15 is sublimated, and a polycrystalline body made of the same material as the seed crystal 10 is deposited on the surface of the base material 9 by the sublimated gas. In this way, the joining part 11 is formed on the base material 9, and the laminated body of the base material 9 and the joining part 11 is obtained (FIG. 3).

  Next, the cover 13b of the heat insulating material 13 is removed, and then the cover 14b of the heating element 14 is removed. And the laminated body of the base material 9 and the junction part 11 is removed from the cover body 14b.

(Joint surface roughness reduction process)
Next, the smoothened surface is formed by reducing the surface roughness of the bonding planned surface of the bonding portion 11. Here, in order to reduce the surface roughness of the surface to be bonded of the bonding portion 11, for example, grinding or polishing may be performed on the surface to be bonded of the bonding portion 11. Among them, grinding is preferable because the processing speed is high, but since the surface roughness is lower in polishing, both may be used in combination. Moreover, it is preferable to reduce the surface roughness of the joining plan surface of the junction part 11 until the arithmetic surface roughness Ra of the smoothed surface is 0.05 to 2 μm, and more preferably to 0.2 to 1 μm.

  On the other hand, a seed crystal 10 is prepared. As the seed crystal 10, aluminum nitride (AlN) is usually used, but silicon carbide (SiC) can also be used. The thickness of the seed crystal 10 is usually 100 to 2000 μm, preferably 200 to 1000 μm.

  And the seed crystal 10 is piled up on the smooth surface of the junction part 11 of the said laminated body, and the junction part 11 and the seed crystal 10 are heat-processed in this state. In this way, the joining part 11 and the seed crystal 10 are joined, and the seed crystal holding body 8 is obtained (FIG. 4). At this time, the temperature of the heat treatment may be a temperature at which the joint 11 and the seed crystal 10 are joined, but is usually 1800 to 2100 ° C., preferably 1900 to 2000 ° C. Moreover, it is preferable to perform heat processing of the junction part 11 and the seed crystal 10, pressurizing. In this case, the seed crystal 10 can be firmly bonded to the bonding portion 11 as compared with the case where the heat treatment is performed without applying pressure. The pressure applied at this time is usually 5 to 200 kPa, preferably 10 to 50 kPa.

(Seed crystal surface roughness reduction process)
In addition, before heat-treating the joint part 11 and the seed crystal 10, it is preferable to reduce the surface roughness of the surface to be joined to the joint part 11 of the seed crystal 10 to form a smoothed surface. In this case, the adhesion between the joint portion 11 and the seed crystal 10 can be further improved.

  In order to reduce the surface roughness of the planned joining surface of the seed crystal 10, for example, grinding or polishing may be performed on the scheduled joining surface of the seed crystal 10. Among these, grinding is preferable because of its high processing speed. In addition, the surface roughness of the surface to be bonded of the seed crystal 10 is preferably 0.05 to 2 μm, more preferably 0.2 to 1 μm, with the calculated surface roughness Ra of the smoothed surface.

  After the seed crystal holder 8 is obtained in this way, as shown in FIG. 1, first, in the growth vessel 2, the aluminum nitride single crystal raw material 1 is accommodated in the crucible 5 disposed in the raw material accommodating portion 2 a.

(Seed crystal holder installation process)
On the other hand, the seed crystal holder 8 obtained as described above is fixed to the tip of the rod-like support member 7. At this time, the base material 9 of the seed crystal holder 8 is fixed to the tip of the support member 7. Then, the support member 7 that supports the seed crystal holder 8 is inserted into the insertion port 2g of the cap member 2d from the seed crystal holder 8 side. At this time, the seed crystal 10 is disposed in the single crystal growth region 6 in the growth vessel 2. Specifically, the seed crystal 10 is arranged in the single crystal growth region 6 so that the surface facing the raw material 1 side is arranged at a predetermined distance from the bottom surface 2i of the raw material container 2a.

  On the other hand, the heating device 4 is operated while introducing nitrogen gas into the growth vessel 2 through the gas inlet 2h of the gas inlet tube 2f. At this time, for example, the heat generation amount of the ring-shaped heater 4b is made larger than that of the heater 4a, and the heat generation amount of the heater 4a is made larger than that of the heater 4c. Thereby, the temperature of the gas exhaust path 2 e becomes higher than the temperature of the raw material 1 and the single crystal growth region 6, and the temperature of the raw material 1 becomes higher than the temperature of the single crystal growth region 6.

(Crystal growth process)
Thus, when the raw material 1 of the aluminum nitride single crystal is heated and sublimated by the heating device 4, the mixed gas of the sublimation gas sublimated from the raw material 1 and the nitrogen gas introduced from the gas inlet 2h is cooled in the seed crystal 10. As a result, it is recrystallized to become a solid phase, and a crystal 12 grows on the seed crystal 10. Thus, an aluminum nitride single crystal is obtained.

  According to the manufacturing method, since the joint portion 11 is obtained by being formed on the base material 9 by a vapor phase method, the joint portion 11 is formed densely and the joint portion 11 and the base material 9 Adhesion is improved, and a gap is sufficiently prevented from occurring in the joint portion 11. In addition, the seed crystal 10 is joined to the smoothed surface of the joint portion 11 after reducing the surface roughness of the joining planned surface of the joint portion 11 to be a smoothed surface. For this reason, it becomes possible to make the clearance gap between the seed crystal 10 and the junction part 11 small enough. For this reason, the seed crystal holder 8 obtained by the above manufacturing method is installed in the growth vessel 2 containing the aluminum nitride single crystal raw material 1, and the single crystal raw material 1 is contained in the growth vessel 2 and sublimated. Then, the crystal 12 grows from the seed crystal 10 of the seed crystal holder 8. At this time, the adhesion between the joint portion 11 and the base material 9 is improved, and a gap is sufficiently prevented from being generated in the joint portion 11. In addition, since the seed crystal 10 is made smooth by reducing the surface roughness of the joining planned surface of the joint 11 and then joined to the smoothed surface of the joint 11, the seed crystal 10 and the joint 11 can be sufficiently reduced. For this reason, it is possible to sufficiently prevent the seed crystal 10 from sublimating from the base material 9 side, and it is also sufficiently prevented that voids are generated in the seed crystal 10. As a result, the generation of voids is sufficiently prevented even in the grown crystal growing on the seed crystal 10. Moreover, since the junction part 11 is comprised with the polycrystal which consists of the same material as the seed crystal 10, the difference of the thermal expansion coefficient between the junction part 11 and the seed crystal 10 becomes small enough. For this reason, even if the junction 11 is heated, the strain applied to the seed crystal 10 can be sufficiently reduced, and the strain can be sufficiently reduced even in the obtained grown crystal. As a result, a high quality single crystal can be obtained.

  In particular, in the above-described embodiment, the surface of the bonding planned surface to be bonded to the bonding portion 11 of the seed crystal 10 after reducing the surface roughness of the bonding portion 11 and before bonding the seed crystal 10 to the bonding portion 11. When the smoothed surface is formed by reducing the roughness, both the planned joining surface of the joint 11 and the planned joining surface of the seed crystal 10 are smoothed, so that the adhesion between the joint 11 and the seed crystal 10 is improved. It can be improved further. Therefore, the generation of sublimation gas in the seed crystal 10 is more sufficiently prevented, and the generation of voids in the seed crystal 10 can be more sufficiently suppressed. As a result, generation of voids due to sublimation can be more sufficiently suppressed in the obtained single crystal.

  Further, while the crystal 12 is grown, it is preferable to introduce a dilution gas into the reaction tube main body 3a from the gas introduction tube 3b. In this case, aluminum nitride in the gas discharged from the gas discharge path 2e of the growth vessel 2 can be diluted, and aluminum nitride particles can be prevented from precipitating on the inner wall of the reaction tube body 3a.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the aluminum nitride single crystal is manufactured in the growth vessel 2 that is not sealed, but the aluminum nitride single crystal may be manufactured in a closed growth vessel.

Moreover, although the said embodiment demonstrated the case where a single crystal was aluminum nitride, this invention is applicable also to single crystals, such as a silicon carbide. In this case, a silicon carbide polycrystal is used as the joint portion 11, and a silicon carbide single crystal is used as the seed crystal 10.
Furthermore, in the said embodiment, although the gas discharge path 2e is arrange | positioned in the position higher than the crucible (raw material arrangement | positioning part) 5 in which a raw material is arrange | positioned, and lower than the single crystal arrangement | positioning area | region 6, the gas discharge path 2e Is arranged between the crucible 5 and the single crystal arrangement region 6, and is arranged at a position lower than the crucible (raw material arrangement portion) 5 where the raw material is arranged and at a position higher than the single crystal arrangement region 6. May be.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Example 1
A base material made of graphite was prepared. Next, in the joint manufacturing apparatus 20 shown in FIG. 2, the cover 13b of the heat insulating material 13 was removed, and the cover 14b of the heating element 14 was removed. And the base material 9 was fixed by fitting the base material 9 in the cover body 14b of the heat generating body 14. FIG.

  And after accommodating the raw material 15 which consists of aluminum nitride in the raw material accommodating part 14a, the raw material accommodating part 14a was sealed with the cover body 14b. Subsequently, the heat insulating material main body 13a was sealed with a lid 13b.

  The heating element 14 was heated by applying a current to the heating coil 16 to generate a magnetic field while flowing nitrogen gas around the heat insulating material 13 at a flow rate of 500 sccm. The pressure inside the heating element 14 was 400 Torr. At this time, a radiation thermometer is inserted into each of the through holes 13c and 13d of the heat insulating material 13 to measure the temperature of the lid 14b of the heating element 14 and the bottom of the raw material accommodating part 14a of the heating element 14, while the raw material 15 The raw material 15 was heated to a temperature for sublimation. At this time, the temperature of the lid 14b of the heating element 14 is 2100 ° C., the temperature of the bottom of the raw material storage portion 14a of the heating element 14 is 2200 ° C., and the temperature of the lid 14b of the heating element 14 is It was made to become smaller than the temperature of the bottom part of the part 14a. This state was maintained for 20 hours.

  Thus, a polycrystalline body made of aluminum nitride was obtained on the surface of the substrate 9.

  Next, the lid 13b of the heat insulating material 13 was removed, and then the lid 14b of the heating element 14 was removed. And the laminated body of the base material 9 and the junction part 11 was removed from the cover body 14b.

  On the other hand, a seed crystal 10 was prepared. As the seed crystal 10, aluminum nitride (AlN) was used.

  Then, both the joint 11 and the seed crystal 10 were smoothed by grinding so that the arithmetic surface roughness Ra of the smoothed surface was 0.3 μm.

Then, after superposing the seed crystal 10 on the joint portion 11 of the laminate, a weight made of tungsten was placed on the seed crystal 10 so that a pressure of 2 × 10 ⁴ Pa was applied to the seed crystal 10. . And it heat-processed by hold | maintaining the junction part 11 and the seed crystal 10 at 2000 degreeC for 24 hours in nitrogen gas stream under atmospheric pressure. In this way, the joint 11 and the seed crystal 10 were joined to obtain the seed crystal holder 8.

  An aluminum nitride single crystal was produced by the production apparatus shown in FIG. 1 using the seed crystal holder 8 thus obtained. Specifically, the seed crystal holder 8 was fixed by mechanical fitting to the tip of the support member 7 in a state where the support member 7 made of graphite was inserted into the support portion insertion port 2g of the cap member 2d.

  Next, the raw material container 2a was covered with the cap member 2d. At this time, nitrogen gas was introduced from the gas introduction pipe 2f, and nitrogen gas was introduced as a dilution gas from the gas introduction pipe 3b. And crystal growth was performed by the sublimation method.

The conditions for crystal growth were as follows. That is, the pressure in the growth vessel 2, the growth time, the flow rate of nitrogen gas, the flow rate of dilution gas, the raw material part temperature, the intermediate part temperature, and the growth part temperature were as follows.

Pressure in the growth vessel 2: 200 Torr
Growth time: 300 hours Nitrogen gas flow rate: 1 SLM
Flow rate of dilution gas: 1 SLM
Raw material part temperature: 2300 ° C
Intermediate part temperature: 2350 ° C
Growth part temperature: 2200 ° C

(Comparative Example 1)
Production of a single crystal in the same manner as in Example 1 except that the seed crystal was prepared by fixing the seed crystal to the base material using a carbon-based adhesive (ST-201, manufactured by Nisshinbo Chemical Co., Ltd.). Went. The carbon adhesive was prepared by dissolving a phenol resin and carbon in a solvent.

(Comparative Example 2)
A single crystal was produced in the same manner as in Example 1 except that the seed crystal was prepared by fixing the seed crystal to the base material using an aluminum nitride-based adhesive. The aluminum nitride-based adhesive was prepared by dissolving aluminum nitride in a solvent made of water.

  The seed crystal holders obtained in Example 1, Comparative Example 1 and Comparative Example 2 were cut so as to cross the seed crystal and the base material, and the cross section was observed visually. The following results were obtained. .

  That is, in the seed crystal holder of Example 1, no voids were observed at each of the interface between the seed crystal and the joint and the interface between the joint and the substrate.

  On the other hand, in Comparative Example 1, sublimation of the back surface (base material side) of the seed crystal was significant. That is, the presence of large voids in the seed crystal was recognized. Also in Comparative Example 2, sublimation of the back surface (surface on the base material side) of the seed crystal was observed. That is, the presence of voids was observed in the seed crystal.

  Further, the obtained single crystal was cut and the cross section was visually observed to examine the presence or absence of voids in the grown crystal. The results are shown in Table 1.

Further, with respect to the obtained single crystal, the rocking curve of the (0002) plane of aluminum nitride was measured by X-ray diffraction, and the half width (FWHM) of the peak was obtained. The results are shown in Table 1.

  From the results shown in Table 1, in Example 1, it was found that the presence of voids was not observed in the obtained single crystal and the FWHM value was small, so that a crystal with high crystallinity was obtained.

  Therefore, according to the method for producing a seed crystal holder according to the present invention, it was confirmed that a single crystal having high quality and sufficiently suppressed generation of voids can be formed.

8 ... Seed crystal holder 9 ... Base material 10 ... Seed crystal 11 ... Joint part

Claims (3)

A substrate;
A seed crystal holding method comprising a seed crystal joined via a joint on a substrate,
A bonding part forming step of forming a polycrystalline body made of the same material as the seed crystal on the base material by a vapor phase method as the bonding part;
A joint surface roughness reducing step for obtaining a smoothed surface by reducing the surface roughness of the joint planned surface for joining the seed crystal in the joint; and
And a seed crystal bonding step of bonding the seed crystal to the smoothed surface of the bonding portion.   Between the joint surface roughness reducing step and the seed crystal joining step, a seed crystal surface roughness that obtains a smoothed surface by reducing the surface roughness of the joint planned surface to be joined to the joint portion of the seed crystal. The method for producing a seed crystal holder according to claim 1, further comprising a thickness reducing step. A seed crystal holder installation step of installing the seed crystal holder obtained by the method for producing a seed crystal holder according to claim 1 or 2 in a growth container containing a single crystal raw material;
A crystal growth step of sublimating the raw material and growing a crystal from the seed crystal of the seed crystal holder,
A method for producing a single crystal characterized by the above.

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