JP2018140884A - Single crystal production apparatus, and single crystal production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal production apparatus and a single crystal production method capable of producing a high quality single crystal of silicon carbide or the like at a lower cost than in the past.SOLUTION: A quartz tube 1 is used as a chamber and an induction heating coil 7 is wound around the outside of the quartz tube 1 for high-frequency induction heating. A top flange 2 and a base flange 3 are installed at the upper part and the lower part of the quartz tube 1 respectively for sealing the quartz tube 1. A carbon crucible 4 is set in the quartz tube 1. An insulation lid 5 and an insulation cylinder 6 are arranged so as to enclose the carbon crucible. A takeout rod 15 for drawing the carbon crucible 4 upward in the quartz tube 1 has a joint 16 for linking the takeout rod 15 and carbon crucible 4. The joint 16 is designed so that the takeout rod 15 is attachable to and detachable from the carbon crucible 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a single crystal manufacturing apparatus and a single crystal manufacturing method for manufacturing a single crystal such as silicon carbide by a sublimation method.

  Silicon carbide (SiC) is known as a semiconductor material that has excellent characteristics that are thermally and chemically stable and that has a forbidden band width that is larger than that of silicon (Si), and that has excellent characteristics electrically. . In particular, 4H-type silicon carbide has already been put into practical use as a semiconductor material substrate for power devices because of its high electron mobility and saturated electron velocity.

  Currently, an improved Rayleigh method (sublimation method) is used as a method for producing a silicon carbide single crystal for use as a semiconductor substrate, and substrates up to 6 inches in diameter are commercially available. In the sublimation method, the raw material is sublimated at a high temperature in a crucible, diffused, re-precipitated on a seed crystal placed at a temperature controlled at a lower temperature than the raw material, and recrystallized to recrystallize the single crystal. It is a way to grow.

Patent Document 1 discloses that when SiC sublimates in a carbon crucible made of graphite, active species such as Si, Si ₂ C, and SiC ₂ are generated, and sublimation occurs in a state where the partial pressure of Si is higher than the partial pressure of C; A method for producing a high-quality single crystal by providing a structure for controlling the components of the sublimated source gas and its flow is described. Further, in Patent Document 2, in an induction heating type single crystal manufacturing apparatus, a molded heat insulating material provided below a crucible and a graphite cylindrical heat insulating material provided between the crucible and the molded heat insulating material are provided. A method for stabilizing the crystal growth conditions is described.

Japanese Patent No. 469394 JP2013-35705A

  The current silicon carbide single crystal substrate has a problem of high crystal defect density and high price. In order to put the silicon carbide single crystal substrate into practical use for a wider range of applications, the crystal defect density must be lowered. There is a need to reduce manufacturing costs by improving performance and mass productivity. In order to manufacture a silicon carbide single crystal substrate at low cost, it is required to shorten the time required for manufacturing while maintaining the crystal quality. In the production of a silicon carbide single crystal by the sublimation method, in order to increase the crystal growth rate, the temperature difference between the raw material and the seed crystal must be increased. However, if the temperature difference is too large, the vapor pressure of Si in the vicinity of the raw material tends to be larger than the saturated vapor pressure of Si in the vicinity of the seed crystal, resulting in a problem that the crystal quality is greatly deteriorated.

  In the conventional single crystal manufacturing apparatus described above, the chamber of the crystal growth furnace is composed of a double quartz tube that can be cooled, and the crucible after the crystal growth and the installation of the crucible containing the raw material in a predetermined place in the quartz tube Is taken out using a crucible lifting / lowering device provided at the bottom of the quartz tube. In this case, a crucible covered with a heat insulating material is installed on the upper end of the crucible lifting device, and when the crucible is taken in and out, the surrounding heat insulating material also moves together.

  FIG. 6 is a cross-sectional view schematically showing a configuration of an example of a single crystal manufacturing apparatus for manufacturing a conventional silicon carbide single crystal, and FIG. 6 (a) shows a case where a crucible is installed in the chamber. (B) is a figure which each shows a mode when the crucible is taken out from the inside of a chamber. In FIG. 6, this single crystal manufacturing apparatus 20 uses a water-cooled double quartz tube 21 as a chamber of a crystal growth furnace, and an induction heating oscillator ( An induction heating coil 27 connected to (not shown) is wound. A top flange 22 is provided at the upper part of the water-cooled double quartz tube 21 and a base flange 23 is provided at the lower part to seal the water-cooled double quartz tube 21, and a carbon crucible 24 and a heat insulating material lid as a heat insulating material so as to surround it. 25 and a cylindrical heat insulating material 26 are installed. The top flange 22 is water-cooled and at the same time serves as a seal for preventing water leakage of the water-cooled double quartz tube 21, so that the top flange 22 cannot be easily removed. The top flange 22 and the base flange 23 are provided with a water inlet 28 and a water outlet 29 for water cooling, and further, a gas inlet 31 and a gas outlet for introducing atmospheric gas into the water-cooled double quartz tube 21. 32 is provided. A base seal 33 is inserted between the water-cooled double quartz tube 21 and the base flange portion 23, and the base flange 23 is removable.

  As shown in FIG. 6 (b), the mechanism for lowering the carbon crucible 24 together with the heat insulating material lid 25, the cylindrical heat insulating material 26 and the base flange 23 by using a crucible lifting / lowering device at the time of material addition after crystal growth and before crystal growth. The carbon crucible 24 is lowered to a position where it can be taken out, the heat insulating material cover 25 is opened, and the carbon crucible 24 is taken out.

  As described above, in the conventional single crystal growth apparatus, since the heat insulating material is also pulled out when the crucible is taken in and out, the position in the furnace is likely to be shifted every time the crystal is grown, and a large amount of adjustment is required to obtain temperature control reproducibility. There was a problem that it took a long time. Or there was a problem that the reproducibility of the temperature control was insufficient and the crystal quality was likely to vary. Therefore, it has been difficult for the conventional single crystal manufacturing apparatus to shorten the time required for manufacturing while maintaining the crystal quality. In addition, since it is necessary to secure a moving length necessary for taking out the crucible below the chamber and to install the crucible lifting device, the price of the device is also expensive.

  Accordingly, the present invention has been made to solve such problems, and a single crystal manufacturing apparatus and a single crystal manufacturing method capable of manufacturing a high-quality single crystal such as silicon carbide at a lower cost than conventional ones. The purpose is to provide.

  In a first aspect, the single crystal production apparatus of the present invention comprises a crucible composed of a cylindrical crucible body having a bottom surface and a disc-shaped upper lid, a chamber for housing the crucible, and means for heating the crucible. And a heat insulating material disposed below and above the crucible and between the crucible and the chamber, and sublimating the raw material stored in the crucible by heating the crucible by the heating means, Thus, in a single crystal production apparatus for producing a single crystal by growing a seed crystal arranged on the lower side of the upper lid of the crucible, a takeout rod for pulling out the crucible above the chamber, the takeout rod, and the A connecting portion for connecting the crucible to the crucible, and the connecting portion is configured such that the take-out rod can be attached to and detached from the crucible.

  In the single crystal manufacturing apparatus of the present invention, as in the past, a heat insulating material is arranged around the crucible and the crucible is heated by heating means, thereby controlling the temperature gradient in the crucible necessary for crystal growth by the sublimation method. I do. However, the present invention does not require a conventional crucible elevating device, and the crucible is taken out above the chamber by the take-out bar as described above. In this case, since the take-out rod is configured to be attached to and detached from the crucible by the coupling portion, after the crucible is placed in a predetermined position, the take-out rod is removed and crystal growth is performed. It couple | bonds with a coupling | bond part and takes out a crucible upwards. At this time, the heat insulating material on the upper side of the crucible is pulled out together with the crucible by the take-out rod, but the heat insulating material arranged around the cylindrical surface of the crucible and the heat insulating material arranged on the lower side of the crucible do not need to move. It is placed in the furnace as it is. In addition, since the crucible is always placed on the fixed lower heat insulating material, the possibility of displacement in the furnace every time the crystal is grown is reduced, and adjustment for obtaining temperature control reproducibility is unnecessary. Become. This improves the problem of variation in crystal quality due to insufficient temperature control reproducibility. Further, the crucible lifting / lowering device only needs to have a function of adjusting the installation positions of the crucible and the heat insulating material in the first furnace, so that it can be constituted by an inexpensive device.

  As described above, according to the present invention, a single crystal manufacturing apparatus capable of manufacturing a high-quality single crystal such as silicon carbide at a lower cost than the conventional one can be obtained.

  In the present invention, various forms are conceivable as the coupling portion for coupling the take-out bar and the crucible. For example, a hook-like structure is provided at the tip of the take-out bar, and a structure to be hooked on the crucible itself or attached to the crucible. A configuration in which a notch and a groove are provided so as to be combined by inserting and rotating, a screw structure is provided at the lower end of the take-out bar, and a screw hole that fits into the screw structure is provided in the upper surface of the upper cover of the crucible.

  Parts other than the above of the single crystal manufacturing apparatus in the present invention can be configured in the same manner as in the past, for example, using a carbon crucible as a crucible, using an induction heating coil as a heating apparatus, and a lid structure that can be opened and closed at the upper end of the chamber. It is possible to provide a vacuum evacuation unit, a gas introduction unit, and an evacuation unit of the chamber so that the chamber can be grown in a reduced pressure argon atmosphere. Further, as a heat insulating material arranged around the crucible, a heat insulating cylinder made of carbon felt may be used, and only a lid portion at the top of the heat insulating cylinder may be configured to be detachable so as to be pulled out together with the take-out rod. Note that the single crystal manufacturing apparatus and single crystal manufacturing method of the present invention can be applied not only to silicon carbide single crystals but also to the manufacture of single crystals such as aluminum nitride and gallium oxide by a sublimation method.

  In a second aspect, the present invention provides the single crystal manufacturing apparatus according to the first aspect, wherein the coupling portion is formed at a screw hole formed on an upper surface of the upper cover of the crucible and at a lower end of the take-out bar. It has a screw structure that can be fitted into the screw hole. As a result, the coupling portion can be configured with a simple configuration and sufficient strength.

  In a third aspect, the present invention provides the single crystal manufacturing apparatus according to the first or second aspect, wherein the crucible is a carbon crucible in which the crucible body and the upper lid are made of graphite, and the lower surface of the upper lid Further, a carbon sheet having a thickness of 0.1 to 2 mm inserted between the upper lid and the seed crystal is provided. Commonly used carbon crucibles are usually composed of a graphite molding material including an upper lid. On the other hand, the carbon sheet is composed of a flexible graphite sheet that is specially processed from natural graphite and molded without using a binder. The thermal conductivity of the carbon crucible is 100 W / mK, whereas the thermal conductivity of the carbon sheet is The rate is as small as 10 W / mK in the thickness direction. Therefore, the temperature of the seed crystal can be controlled by the number of carbon sheets, and the seed crystal can be controlled to an optimum temperature. Moreover, since the carbon sheet is softer than graphite, it is easy to peel off. Thereby, according to the invention of this aspect, the installation and removal of the seed crystal from the upper lid and the temperature control of the seed crystal are facilitated. The carbon sheet can be attached to the upper lid by adhesion.

  In a fourth aspect, the present invention provides the single crystal manufacturing apparatus according to the third aspect, wherein an outer shape of the single crystal is provided between an upper end of the raw material storage portion in the crucible and an installation portion of the seed crystal. It has a conical guide portion for control, and the guide portion is made of a carbon material having a thickness of 0.1 to 10 mm. By installing this guide part, the flow of the sublimated material gas can be controlled, and the shape of the single crystal to be grown can be controlled.

  In a fifth aspect, the present invention provides a method for producing a single crystal characterized by producing a single crystal using the single crystal production apparatus of the first to fourth aspects. In the method for producing a single crystal of the present invention, it is possible to produce a high-quality single crystal such as silicon carbide at a lower cost than in the past by using the single crystal production apparatus of the present invention having the above-described characteristics. A single crystal manufacturing method is obtained.

  In a sixth aspect, the present invention provides a single crystal manufacturing method for manufacturing a single crystal using the single crystal manufacturing apparatus according to the third or fourth aspect, wherein the single crystal is manufactured between the upper lid and the crucible body. After providing the carbon sheet and storing the raw material in the crucible, the crucible is sealed by fixing between the upper lid and the carbon sheet and between the carbon sheet and the crucible body with a carbon adhesive. It is characterized by that. Since the carbon sheet is softer and more easily peeled than graphite, which is a crucible material, the crystal after growth can be easily taken out.

  In a seventh aspect, the present invention provides a single crystal manufacturing method for manufacturing a single crystal using the single crystal manufacturing apparatus according to the third or fourth aspect, wherein the seed crystal has a thickness of 0.1 to The growth is performed in a radial direction using a 1.0 mm seed crystal. When a seed crystal is directly attached to an upper lid made of graphite, crystal nuclei are randomly generated on the graphite simultaneously with the growth of the seed crystal, and polycrystalline growth occurs. On the other hand, the carbon sheet has a heat insulating effect, hardly causes a temperature difference from the seed crystal, and is less likely to grow on the surface than graphite. Therefore, in the single crystal manufacturing method of this aspect, the growth on the seed crystal is performed preferentially, the crystal growth in the radial direction proceeds, and the effect that the polycrystalline growth hardly occurs is obtained.

  In an eighth aspect, the present invention relates to the method for producing a single crystal according to the fifth to seventh aspects, wherein when the single crystal is continuously produced, the raw material remaining in the crucible in the previous production process is obtained. More than half of the upper part is taken out, and the remaining raw material is placed on an unused raw material and used as a recycled raw material. Thereby, a raw material can be used efficiently and manufacturing cost can be further reduced. The lower side of the remaining raw material cannot be reused because silicon is removed and the carbon content is high, but the upper side can be reused.

  As described above, according to the present invention, a single crystal manufacturing apparatus and a single crystal manufacturing method capable of manufacturing a high-quality single crystal such as silicon carbide at a lower cost than in the past can be obtained.

It is sectional drawing which shows typically the structure of the single crystal manufacturing apparatus which concerns on Example 1, FIG.1 (a) when a crucible is installed in a chamber, FIG.1 (b) is a mode when taking out a crucible from a chamber. FIG. Sectional drawing which shows typically the structure of the crucible used for Example 1, the heat insulating material arrange | positioned in the circumference | surroundings, and a taking-out stick | rod. 1 is an external view photograph of the silicon carbide single crystal ingot obtained in Example 1. FIG. 2 is an appearance photograph of the silicon carbide single crystal ingot obtained in Example 2. FIG. It is a figure which shows an experimental result, and is a figure which shows the relationship between the numerical value of growth temperature / pressure, and a micropipe defect area. It is sectional drawing which shows typically the structure of an example of the manufacturing apparatus of the conventional silicon carbide single crystal, when Fig.5 (a) installed the crucible in the chamber, FIG.5 (b) took out the crucible from the chamber. The figure which shows each state of time.

  Hereinafter, the single crystal manufacturing apparatus and single crystal manufacturing method of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description thereof is omitted.

(Example of single crystal production apparatus)
FIG. 1 is a cross-sectional view schematically showing a configuration of a single crystal manufacturing apparatus according to Example 1. FIG. 1 (a) shows a crucible installed in the chamber when FIG. 1 (a) is installed in the chamber. It is a figure which shows a mode when taking out. FIG. 2 is a cross-sectional view schematically showing the structure of the crucible used in the present embodiment, the heat insulating material disposed around the crucible, and the take-out rod. In FIG. 1, in the single crystal manufacturing apparatus 10 of the present embodiment, a quartz tube 1 is used as a chamber of a crystal growth furnace, and an induction heating oscillator (not shown) is provided outside the quartz tube 1 for heating by a high frequency induction heating method. ) Is connected to the induction heating coil 7. The height of the quartz tube 1 is 1.2 to 1.8 m. In order to seal the quartz tube 1, a top flange 2 is installed at the upper part of the quartz tube 1 and a base flange 3 is installed at the lower part. Inside the quartz tube 1, a carbon crucible 4 and a heat insulating material lid 5 and a cylindrical heat insulating material 6 arranged so as to surround the carbon crucible 4 are installed. Furthermore, it has a take-out bar 15 for pulling out the carbon crucible 4 above the quartz tube 1, and a coupling part 16 that couples the take-out bar 15 and the carbon crucible 4. Attachment and removal to the carbon crucible 4 are possible.

  In the present embodiment, the top flange 2 is separated from the carbon crucible 4 serving as the heating unit by 50 cm or more, so that water cooling like the top flange 22 of the conventional apparatus shown in FIG. 6 is unnecessary. Therefore, the top flange 2 is light in weight and can be easily removed. The base flange 3 is also 50 cm or more away from the carbon crucible 4 serving as a heating unit, so that water cooling is not required. In order to introduce atmospheric gas into the quartz tube 1, a gas inlet 11 is provided in the top flange 2, and a gas outlet 12 is provided in the base flange 3. Although not shown, a vacuum pump for evacuating the quartz tube 1 is connected. At the time of crystal growth, the atmosphere in the quartz tube 1 is not used at 1 atm or higher, so that the weights of the top flange 2 and the quartz tube 1 can be obtained simply by providing the sealing silicon rubber sheets 13 at the upper and lower ends of the quartz tube 1. By this, the sealing of the quartz tube 1 is maintained. In addition, the weight of the top flange 2 used for a present Example is about 7 kg.

The carbon crucible 4 is made of isotropic graphite because it is necessary to have conductivity and heat resistance at high temperature because it is heated using induction heating by high frequency. The density of isotropic graphite is about 1.9 g / cm ³ . The heat insulating material lid 5 and the cylindrical heat insulating material 6 are manufactured by impregnating a felt heat insulating material with a resin, and the density thereof is 0.1 g / cm ³ .

  As shown in FIG. 2, the carbon crucible 4 includes a cylindrical crucible body 8 having a bottom surface and a disc-shaped upper lid 9. Furthermore, in the present embodiment, as the coupling portion 16, a screw hole 9 a is formed on the upper surface of the upper lid 9, and a screw portion 15 a that can be fitted into the screw hole 9 a is formed on the lower end of the take-out bar 15. After the carbon crucible 4 is installed at a predetermined position in the cylindrical heat insulating material 6, the take-out rod 15 is rotated counterclockwise to be removed from the screw hole 9 a and pulled upward through the insertion hole 5 a of the heat insulating material lid 5. After the crystal growth is completed, the take-out rod 15 is again inserted into the insertion hole 5a, rotated to the right, and coupled to the screw hole 9a to take out the carbon crucible 4 upward. Here, when the carbon crucible 4 is installed in the cylindrical heat insulating material 6 and pulled out, the heat insulating material lid 5 is taken in and out together with the carbon crucible 4. However, since the cylindrical heat insulating material 6 does not need to be moved and is arranged in the furnace as it is, and the carbon crucible 4 is always housed in the fixed cylindrical heat insulating material 6, there is a positional shift in the furnace every time the crystal is grown. The possibility of occurring is reduced and no adjustment is necessary to obtain the reproducibility of the temperature control. This improves the problem of variation in crystal quality due to insufficient temperature control reproducibility. Further, the crucible lifting / lowering device only needs to have a function of adjusting the installation positions of the crucible and the heat insulating material in the first furnace, so that it can be constituted by an inexpensive device.

  Further, in this embodiment, as shown in FIG. 2, a carbon sheet 14 having a thickness of 0.1 to 2 mm inserted between the upper lid 9 and the seed crystal 18 is provided on the lower surface of the upper lid 9 of the carbon crucible 4. A conical guide portion made of a carbon material having a thickness of 0.1 to 10 mm between the upper end of the storage portion of the raw material 19 and the installation portion of the seed crystal 18. 17 is installed. The flow of the material gas sublimated by this guide part 17 can be controlled, and the shape of the single crystal to be grown can be controlled.

  Here, as an example of a specific shape of each component, the carbon crucible 4 has an outer diameter of 115 mm, an inner diameter of 100 mm, a depth of 130 mm, the upper lid 9 has an outer diameter of 115 mm, a thickness of 10 mm, and the carbon sheet 14 has a thickness of 0.2 mm. The seed crystal 18 can have an outer diameter of 76 mm, a thickness of 0.3 mm, and the distance between the raw material 19 and the seed crystal 18 can be 45 mm.

(Example of single crystal manufacturing method)
Next, an embodiment of a single crystal manufacturing method according to the present invention using the single crystal manufacturing apparatus 10 of the above embodiment will be described.

  In order to grow a silicon carbide single crystal, a 3N GC abrasive comprising a high-purity silicon carbide powder was used as a raw material. 1500 g of the raw material was filled in the crucible body 8 of the carbon crucible 4 and heat-treated in a high-pressure vacuum furnace at 2000 ° C. or higher and a reduced pressure argon atmosphere of about 10 Torr for 1 hour or longer. A 6H type silicon carbide seed crystal having an outer diameter of 76 mm and a thickness of 0.3 mm was previously attached to the upper lid 9 via a carbon sheet 14. The upper lid 9 was fixed to the crucible body 8 after the heat treatment with a carbon adhesive and sealed. In this embodiment, the outer diameter of the carbon sheet 14 previously applied to the upper lid 9 is set to the same size as the outer diameter of the crucible body 8 and is applied to the entire lower surface of the upper lid 9. The crucible body 8 was adhered and sealed to the upper end. Since the carbon sheet is easy to peel off, it becomes easy to take out crystals after growth.

  Next, crystal growth was performed according to the following procedure. With the heat insulating material lid 5 placed on the carbon crucible 4, the screw portion 15 a of the take-out bar 15 is screwed into the screw hole 9 a of the upper cover 9 to hold the whole as shown in FIG. Then, the take-out bar 15 is rotated leftward to remove the screw and pull it upward. Thereafter, the top flange 2 is attached, the quartz tube 1 is evacuated, and the pressure in the quartz tube 1 is reduced to 1 Torr or less. The quartz tube 1 is filled with an inert gas and kept at 600 Torr. In this embodiment, argon gas is used as the inert gas to be filled, but other inert gases can also be used. While maintaining the pressure in the quartz tube 1 at 600 Torr, the temperature at the bottom of the carbon crucible 4 is heated by induction heating over 4 hours until it reaches 2500 ° C., which is the crystal growth temperature of silicon carbide. The induction heating frequency was 9 kHz.

  Thereafter, after holding for 1 hour, the pressure in the quartz tube 1 is reduced to 50 Torr which is the crystal growth pressure of silicon carbide while keeping the temperature of the carbon crucible 4. When the pressure in the carbon crucible 4 reaches this crystal growth pressure, the growth of a silicon carbide single crystal on the seed crystal starts. The growth time of the single crystal was 50 hours. During crystal growth, the temperature at the bottom of the carbon crucible 4 was kept constant at 2500 ° C., and the temperature at the top of the carbon crucible 4 was almost constant at 2350 ° C. Further, the output of the induction heating oscillator was kept almost constant at 15 kW.

  After completion of crystal growth, the quartz tube 1 was filled with argon gas, the pressure in the quartz tube 1 was increased to 600 Torr, and the carbon crucible 4 was gradually cooled to room temperature over about 8 hours. Thereafter, the top flange 2 was removed, the take-out rod 15 was attached to the carbon crucible 4, the carbon crucible 4 was taken out, and the silicon carbide single crystal formed by opening the upper lid 9 was taken out from the carbon crucible 4. The weight of the cylindrical heat insulating material 6 after the crystal growth process was not changed, and it was confirmed that there was no deterioration of the cylindrical heat insulating material 6, that is, the temperature and pressure were the optimum conditions.

FIG. 3 shows a photograph of the appearance of the silicon carbide single crystal ingot obtained in this example. The ingot had a height of 25 mm, a diameter of 80 mm, and a flat surface. After slicing this ingot, the molten KOH etching process is performed to obtain the density of micropipe defects. As a result, a small value of 10 / cm ² is obtained, and the full width at half maximum of the rocking curve by X-ray diffraction is about A value of very high quality of 16 seconds was obtained.

  In this example, the conical guide part 17 and the carbon sheet 14 in the carbon crucible 4 of the single crystal production apparatus 10 used in Example 1 are removed, and all other parts are the same as the single crystal production apparatus 10. Crystal growth was performed using a crystal manufacturing apparatus.

  A single crystal was produced under the same crystal growth conditions as in Example 1 for the single crystal production method. The output of the induction heating oscillator supplied to the induction heating coil 7 during crystal growth was also 15 kW, which was almost the same as the output of the induction heating oscillator in the crystal growth process of Example 1. Further, the temperature at the top of the carbon crucible 4 was almost the same as the crystal growth step in Example 1.

FIG. 4 shows a photograph of the appearance of the silicon carbide single crystal ingot obtained in this example. As shown in FIG. 4, the obtained silicon carbide single crystal had a convex central portion and a rough surface, and the density of micropipe defects was 200 / cm ² or more. The average of the full width at half maximum of the rocking curve by the X-ray diffraction method was about 20 seconds. The reason for the deterioration in quality compared to Example 1 is considered to be due to the decrease in the supply density of the sublimation raw material on the crystal surface because there is no guide portion 14. Further, since the seed crystal 14 is directly attached to the graphite top lid 9, a temperature distribution in the growth surface occurs, and the growth rate in the peripheral portion is about 0.3 mm / h faster than other portions, resulting in micropipe defects. The density seems to have increased. For this reason, a polycrystalline portion is generated in the outer peripheral portion, resulting in a decrease in quality.

  As described above, the effects of the conical guide portion 17 and the carbon sheet 14 in the carbon crucible 4 of the single crystal manufacturing apparatus 10 were confirmed by comparison between Example 1 and Example 2.

(Additional experiment results)
Further, using the single crystal manufacturing apparatus 10 of Example 1, an experiment was conducted in which the crystal was grown by changing the growth temperature and pressure and changing the growth rate, and the crystal quality was confirmed. FIG. 5 is a diagram showing the experimental results obtained, and is a diagram showing the relationship between the numerical value of the growth temperature / pressure and the micropipe defect area. Here, since the crystal growth rate is in a relationship that is substantially proportional to the temperature and inversely proportional to the pressure, the horizontal axis of FIG. 5 is a value corresponding to the growth rate. The micropipe defect area is a value obtained by multiplying the number of defects by the size of the defect. As shown in FIG. 5, it was found that the size of the micropipe defect increases and the quantity increases as the growth rate increases. In this experiment, it was confirmed that high-quality crystals were obtained at a growth rate of 0.5 mm / h or less.

  Needless to say, the present invention is not limited to the above-described embodiments, and can be changed according to the characteristics and shape of the target single crystal. The structure, shape, material, and the like of each part of the single crystal manufacturing apparatus can also be changed according to the characteristics and shape of the target silicon carbide crystal. It is also desirable to optimize crystal growth conditions such as the temperature of each part depending on the structure and shape of each part of the single crystal manufacturing apparatus to be used. Additives such as vanadium (V) and nitrogen (N) may be added to the silicon carbide single crystal in accordance with the purpose of use.

  The present invention can also be applied to the production of silicon carbide single crystals used for power devices that require high-quality crystals and heat sinks that require thermal conductivity comparable to aluminum nitride.

1 Quartz tube 2, 22 Top flange 3, 23 Base flange 4, 24 Carbon crucible 5, 25 Insulation cover 5a Insertion hole
6, 26 Cylindrical heat insulating material 7, 27 Induction heating coil 8 Crucible body 9 Upper lid 9a Screw hole 10, 20 Single crystal manufacturing apparatus 11, 31 Gas inlet 12, 32 Gas outlet 13 Silicon rubber sheet for sealing 14 Carbon sheet 15 Taking out Rod 15a Thread part 16 Coupling part 17 Guide part 18 Seed crystal 19 Raw material 21 Water-cooled double quartz tube 28 Water supply port 29 Water outlet 33 Base seal

Claims (8)

A crucible comprising a cylindrical crucible body having a bottom surface and a disc-shaped upper lid, a chamber for storing the crucible, means for heating the crucible, lower and upper sides of the crucible, and the crucible and the chamber A seed crystal disposed under the upper lid of the crucible by sublimating the raw material stored in the crucible by heating the crucible with the heating means. In a single crystal manufacturing apparatus for manufacturing a single crystal by growing
An extraction rod for pulling out the crucible above the chamber; and a coupling portion for coupling between the extraction rod and the crucible, the coupling portion being capable of attaching and detaching the extraction rod to the crucible. An apparatus for producing a single crystal, characterized by being configured.   The said coupling | bond part has the screw structure which can be fitted in the screw hole formed in the upper surface of the upper cover of the said crucible, and the said screw hole formed in the lower end of the said taking-out stick | rod. Single crystal manufacturing equipment.   The crucible is a carbon crucible in which the crucible body and the upper lid are made of graphite, and a carbon sheet having a thickness of 0.1 to 2 mm inserted between the upper lid and the seed crystal on the lower surface of the upper lid. The single crystal manufacturing apparatus according to claim 1, wherein the single crystal manufacturing apparatus is provided.   A conical guide part for controlling the outer shape of the single crystal is provided between an upper end of the raw material storage part in the crucible and the seed crystal installation part, and the guide part has a thickness of 0.1. The single crystal manufacturing apparatus according to claim 3, wherein the single crystal manufacturing apparatus is made of a carbon material of 10 mm.   A single crystal manufacturing method using the single crystal manufacturing apparatus according to claim 1 to manufacture a single crystal.   A single crystal manufacturing method for manufacturing a single crystal using the single crystal manufacturing apparatus according to claim 3, wherein a carbon sheet is provided between the upper lid and the crucible body, and the raw material is stored in the crucible. Thereafter, the crucible is sealed by fixing a gap between the upper lid and the carbon sheet and between the carbon sheet and the crucible body with a carbon adhesive.   A single crystal manufacturing method for manufacturing a single crystal using the single crystal manufacturing apparatus according to claim 3, wherein a seed crystal having a thickness of 0.1 to 1.0 mm is used as the seed crystal in a radial direction. A method for producing a single crystal, characterized in that growth is performed.   When continuously producing single crystals, more than half of the upper part of the raw material remaining in the crucible in the previous manufacturing process is taken out, and the remaining raw material is placed on an unused raw material and used as a recycled raw material. The method for producing a single crystal according to any one of claims 5 to 7, wherein:

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