Crucible and device for silicon carbide single crystal growth and method for growing silicon carbide single crystal

Abstract

The present invention provides a crucible for silicon carbide single crystal growth, the crucible comprises a crucible cover and a crucible body, the upper surface side of the crucible cover is provided with a groove, the groove gradually inclines towards the lower surface side of the crucible cover from one end to the other end, a silicon carbide seed crystal wafer is fixed on the lower surface of the crucible cover, and the silicon carbide seed crystal wafer is fixed on the crucible cover. And at least part of the silicon carbide seed crystal wafer is located in an area corresponding to the inclined surface of the groove. The invention further provides a device for producing the silicon carbide single crystals. Furthermore, the invention also provides a method for growing the silicon carbide single crystal. According to the crucible provided by the invention, the groove with the inclined surface is formed in the upper surface side of the crucible cover, so that the radial temperature gradient is increased, the temperature of a growth surface is reduced, the crystal surface type is favorably adjusted, and the crystal phase change is reduced; and the crucible cover is simple in structure and wide in applicability, and can realize the growth of high-quality single crystals with different sizes and different crystal forms.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon carbide single crystal preparation, and in particular to a crucible for silicon carbide single crystal growth, a device for silicon carbide single crystal growth and a method for growing silicon carbide single crystal. BACKGROUND

[0002] Silicon carbide (SiC) single crystal has a wide band gap, is often referred to as the third generation of wide band gap semiconductor material, has high thermal conductivity, high carrier saturation drift speed and low dielectric constant, can be used to prepare high-temperature, high-frequency and high-power devices, and can also be used as a substrate material for GaN-based light emitting diodes, and has great application potential in optoelectronics and the like.

[0003] SiC single crystal has more than 200 polytypes, and the most common and mature production technology is 6H-SiC and 4H-SiC. Different polytypes have different physical properties, especially in terms of semiconductor properties. Different polytypes have similar growth temperatures, and the growth of 4H silicon carbide single crystal is often accompanied by the occurrence of 6H or 15R polytypes.

[0004] With the gradual improvement of silicon carbide single crystal growth technology, polytype is gradually becoming the main defect affecting the quality of silicon carbide single crystal. At present, the radial temperature gradient and the axial temperature gradient are reduced by controlling the growth parameters and improving the temperature field structure, so as to ensure the stability and consistency of the growth interface temperature. However, slight changes in the growth surface temperature will still lead to the generation of different crystal types, and polytype defects often occur on the growth facets. Therefore, it is of great significance to provide an effective method for controlling polytype defects. SUMMARY

[0005] The technical problem solved by the present application is to provide a crucible for silicon carbide single crystal growth. The crucible provided in the present application can reduce the generation of facet polytype silicon carbide and improve the quality of silicon carbide single crystal due to the provision of the crucible cover.

[0006] Therefore, the present application provides a crucible for silicon carbide single crystal growth, which comprises a crucible cover and a crucible body. A groove is provided on the upper surface side of the crucible cover. The groove gradually inclines from one end to the other end to the lower surface side of the crucible cover. A silicon carbide seed wafer is fixed to the lower surface of the crucible cover. At least part of the silicon carbide seed wafer is in the region corresponding to the inclined surface of the groove.

[0007] Preferably, the angle between the inclined surface and the horizontal plane is 0-30° and ≠ 0°.

[0008] Preferably, the maximum circumference of the side wall of the groove is 50-150mm for growing a 4-inch silicon carbide single crystal; the maximum circumference of the side wall of the groove is 75-225mm for growing a 6-inch silicon carbide single crystal; the maximum circumference of the side wall of the groove is 100-300mm for growing a 8-inch silicon carbide single crystal.

[0009] Preferably, the depth of the groove decreases from the growth surface of the silicon carbide single crystal to the vice positioning edge.

[0010] Preferably, the center of the maximum circumference of the side wall of the groove is different from the center of the crucible cover, or the center of the maximum circumference of the side wall of the groove is concentric with the center of the crucible cover.

[0011] The application also provides a device for growing a silicon carbide single crystal, comprising a crucible and a heating device; the crucible is the above-mentioned crucible.

[0012] The application also provides a method for growing a silicon carbide single crystal, comprising the following steps:

[0013] S1) fixing a silicon carbide seed wafer on a crucible cover; the crucible cover is the above-mentioned crucible cover in the above-mentioned crucible;

[0014] S2) sealingly assembling the crucible cover and a crucible body with silicon carbide growth raw materials placed therein;

[0015] S3) placing the crucible obtained in step S2) into a PVT single crystal growth furnace, and then growing a silicon carbide single crystal to obtain the silicon carbide single crystal.

[0016] Preferably, inert gas is introduced into the single crystal growth furnace, and the pressure is 200-1000Pa.

[0017] Preferably, the growth temperature is 1900-2300℃, and the time is 30-150h.

[0018] Preferably, the thickness of the silicon carbide single crystal is 10-35mm, the silicon carbide seed is a 4H-4° seed, and the silicon carbide single crystal is an N-type doped conductive type crystal.

[0019] The application provides a crucible for silicon carbide single crystal growth, which comprises a crucible cover and a crucible body, wherein a groove is arranged on the upper surface side of the crucible cover, the groove is gradually inclined from one end to the other end to the lower surface side of the crucible cover, and a silicon carbide seed wafer is fixed on the lower surface of the crucible cover, and at least part of the silicon carbide seed wafer is in the region corresponding to the inclined surface of the groove. The crucible provided by the application increases the radial temperature gradient of the silicon carbide single crystal growth surface by arranging the crucible cover with the inclined surface and the silicon carbide seed wafer, reduces the temperature of the growth surface, thereby reducing the generation of silicon carbide facet polymorphism, and improving the quality of the silicon carbide single crystal. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A schematic diagram of the device for silicon carbide single crystal growth of the application;

[0021] Figure 2 A top view of the crucible cover for silicon carbide single crystal growth provided by embodiment 1 of the application;

[0022] Figure 3 A physical photo of the silicon carbide single crystal produced by embodiment 1 of the application;

[0023] Figure 4 A top view of the crucible cover for silicon carbide single crystal growth provided by embodiment 2 of the application;

[0024] Figure 5 A physical photo of the silicon carbide single crystal grown by embodiment 2 of the application. DETAILED DESCRIPTION

[0025] In order to further understand the application, the preferred embodiments of the application are described below in combination with the embodiments, but it should be understood that these descriptions are only for further illustrating the features and advantages of the application, and are not limitations on the claims of the application.

[0026] In view of the problem of silicon carbide single crystal polymorphism defects and polymorphism occurring in the growth facet in the prior art, the application provides a crucible for silicon carbide single crystal growth, which increases the radial temperature gradient of the silicon carbide single crystal growth surface by introducing a crucible cover with a special structure, thereby reducing the generation of facet polymorphism and improving the quality of the silicon carbide single crystal. The schematic diagram of the device for silicon carbide single crystal growth provided by the application is as follows: Figure 1As shown in the figure, wherein 1 is an induction coil, 2 is a heat preservation graphite felt, 3 is a crucible body, 4 is a SiC growth raw material, 5 is a silicon carbide seed crystal, 6 is a crucible cover, 7 is a groove, the related parameters of the groove 7 include a diameter D, an inclined surface angle θ and an inclined surface height H, the position of the inclined surface can be controlled according to requirements, and 8 is a heating body. Specifically, the embodiment of the present application discloses a crucible for silicon carbide single crystal growth, which comprises a crucible cover and a crucible body, the upper surface side of the crucible cover is provided with a groove, one end of the groove is gradually inclined to the lower surface side of the crucible cover, and the lower surface of the crucible cover is fixed with a silicon carbide seed crystal wafer, and at least part of the silicon carbide seed crystal wafer is in the region corresponding to the inclined surface of the groove.

[0027] In the crucible for silicon carbide single crystal growth provided in the present application, the crucible body is a structure known to those skilled in the art, and the present application does not particularly limit the structure thereof, and the cooperation of the crucible cover and the crucible body needs to realize sealing and the growth of silicon carbide single crystal.

[0028] In the present application, the crucible cover comprises an upper surface and a lower surface, and a groove is arranged on the upper surface side, and the groove forms an inclined surface gradually inclined to the lower surface side from one end to the other end; the crucible cover is the same as the crucible cover in the prior art except for the arranged groove, and the present application does not particularly limit this.

[0029] In the present application, the lower surface of the crucible cover is fixed with a silicon carbide seed crystal wafer, and the size of the silicon carbide seed crystal wafer is greater than the region corresponding to the inclined surface of the groove, or the size of the silicon carbide seed crystal wafer is smaller than the region corresponding to the inclined surface of the groove, or the size of the silicon carbide seed crystal wafer is equal to the region corresponding to the inclined surface of the groove, that is, at least part of the silicon carbide seed crystal wafer is in the region corresponding to the inclined surface of the groove.

[0030] The angle θ between the inclined surface and the horizontal surface in the groove of the crucible cover is 0-30° and ≠0°, more specifically, the angle θ between the inclined surface and the horizontal surface is 0-8° and ≠0°, for example, the angle between the inclined surface and the horizontal surface is 1°, 2°, 3°, 4°, 5°, 6°, 7° or 8°. The angle between the inclined surface and the horizontal surface is adjusted according to the bias angle of the silicon carbide seed crystal. The diameter D of the groove is the diameter of the largest circumference surrounded by the side wall of the groove, and the largest circumference surrounded by the side wall of the groove is the diameter of the upper surface circumference of the groove according to the structure of the crucible cover of the present application. The diameter of the groove is adjusted according to the diameter and bias angle of the silicon carbide seed crystal, specifically, for growing a 4-inch silicon carbide single crystal, the diameter of the largest circumference surrounded by the side wall of the groove is 50-150 mm; for growing a 6-inch silicon carbide single crystal, the diameter of the largest circumference surrounded by the side wall of the groove is 75-225 mm; for growing an 8-inch silicon carbide single crystal, the diameter of the largest circumference surrounded by the side wall of the groove is 100-300 mm; more specifically, for growing a 4-inch silicon carbide single crystal, the diameter of the largest circumference surrounded by the side wall of the groove is 80-120 mm; for growing a 6-inch silicon carbide single crystal, the diameter of the largest circumference surrounded by the side wall of the groove is 95-175 mm; for growing an 8-inch silicon carbide single crystal, the diameter of the largest circumference surrounded by the side wall of the groove is 120-230 mm. The maximum depth H of the groove is the height H of the inclined surface, which gradually decreases from the silicon carbide single crystal growth surface to the auxiliary positioning edge, and the thickness of the crucible cover at the growth surface is thin, the heat dissipation capacity is large, and the growth surface temperature is low.

[0031] In the present application, the position of the inclined surface of the crucible cover can be adjusted according to the interface temperature variation, i.e. the center of the largest circumference surrounded by the side wall of the groove is not concentric with the center of the crucible cover (specifically as shown in Figure 4 ), or the center of the largest circumference surrounded by the side wall of the groove is concentric with the center of the crucible cover (specifically as shown in Figure 2 ).

[0032] The present application also provides a device for growing a silicon carbide single crystal, which comprises a crucible and a heating device, wherein the crucible is as described above, and the heating device can be an induction heating coil or other heating element; specifically, the structure diagram of the device is as shown in Figure 1 , wherein 1 is an induction coil, 2 is a heat preservation graphite felt, 3 is a crucible body, 4 is a SiC growth raw material, 5 is a silicon carbide seed crystal, 6 is a crucible cover, 7 is a groove, and 8 is a heating body.

[0033] The specific steps of the above-mentioned device for silicon carbide single crystal growth are as follows: the powder 4 for growing silicon carbide crystals is placed in the crucible body 3; the heating element 8 heats up in the magnetic field provided by the induction coil 1 to provide the temperature required for silicon carbide crystal growth; the heat-insulating graphite felt 2 is used to maintain the high temperature of the silicon carbide single crystal growth system; the crucible body 3 is screwed tightly to the crucible cover 6 by threads; and a silicon carbide seed crystal 4 is set on the lower surface of the crucible cover 6 so as to grow silicon carbide crystals on the seed crystal 4.

[0034] Furthermore, this application also provides a method for growing silicon carbide single crystals, comprising the following steps:

[0035] S1) Fix the silicon carbide seed crystal wafer onto the crucible cover; the crucible cover is the crucible cover in the crucible described in the above scheme;

[0036] S2) Seal and assemble the crucible lid and the crucible body containing the silicon carbide growth raw material;

[0037] S3) Place the crucible obtained in step S2) into the PVT single crystal growth furnace and then perform silicon carbide single crystal growth to obtain silicon carbide single crystal.

[0038] During the growth of silicon carbide single crystals, an inert gas is introduced into the single crystal growth furnace at a pressure of 200~1000Pa, specifically 300~900Pa; the growth temperature of the silicon carbide single crystal is 1900~2300℃, and the growth time is 30~150h; specifically, the growth temperature of the silicon carbide single crystal is 2100~2300℃, and the growth time is 50~120h.

[0039] Since the formation temperatures of various crystal forms of silicon carbide single crystals are relatively similar, the preparation of single crystals often results in the generation of different crystal forms. This invention provides a crucible for silicon carbide single crystal growth, comprising a crucible lid and a crucible body. A groove is provided on the upper surface of the crucible lid, and the groove gradually slopes from one end to the other towards the lower surface of the lid. A silicon carbide seed crystal wafer is fixed to the lower surface of the crucible lid in the area corresponding to the slope of the groove. This invention increases the radial temperature gradient by creating a groove on the upper surface of the crucible lid, thereby reducing the temperature of the growth surface, adjusting the crystal shape, and minimizing crystal phase transitions. Furthermore, the crucible lid has a simple structure, wide applicability, and can achieve the growth of high-quality single crystals of different sizes and crystal forms. The crucible provided in this application can grow single crystals with a thickness of 10-35 mm, and the absence of polymorphism can be determined by observing the crystal surface state.

[0040] To further understand the present invention, the method for growing silicon carbide single crystals provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0041] Example 1 This example describes the growth of a 4-inch conductive silicon carbide single crystal, including the following steps:

[0042] 1) A groove is provided on the upper part of the crucible lid: the diameter of the crucible lid is Φ130mm, the diameter of the groove is Φ80mm, the inclination angle is 4°, the depth at both ends of the inclination is 5.6mm at one end and 0mm at the other end, and the center of the groove is concentric with the center of the crucible lid. Figure 2 As shown, Figure 2 6 is a top view of the crucible lid, and 7 is a top view of the groove;

[0043] 2) Fix a Φ100mm 4H-4° seed crystal under the crucible lid;

[0044] 3) Take a graphite crucible containing SiC powder and assemble the crucible lid with seed crystals as described above for later use.

[0045] 4) Place the assembled crucible system into the PVT single crystal growth furnace and perform a furnace cleaning operation;

[0046] 5) Argon and nitrogen gases are introduced, the pressure is controlled at 700 Pa, the temperature is 2100~2300℃, and after 100 hours of growth, high-quality silicon carbide single crystals are obtained with no polymorphic defects on the crystal surface, such as... Figure 3 As shown.

[0047] Example 2 This example describes the growth of a 6-inch conductive silicon carbide single crystal, including the following steps:

[0048] 1) A groove is provided on the upper part of the crucible lid, with the following dimensions: crucible lid diameter Φ210mm, groove diameter Φ175mm, inclined surface angle 1°, depth at one end of the inclined surface 3mm, and depth at the other end 0mm. The center of the groove is not concentric with the center of the crucible lid. Figure 4 As shown, Figure 4 6 is a top view of the crucible lid, and 7 is a top view of the groove;

[0049] 2) Fix a Φ150 4H-4° seed crystal under the crucible lid;

[0050] 3) Take a graphite crucible containing SiC powder and assemble the crucible lid with seed crystals as described above for later use.

[0051] 4) Place the assembled crucible system into the PVT single crystal growth furnace and perform a furnace cleaning operation;

[0052] 5) Argon and nitrogen gases are introduced, the pressure is controlled at 400 Pa, the temperature is 2100~2300℃, and after 80 hours of growth, high-quality silicon carbide single crystals are obtained with no polymorphic defects on the crystal surface, such as... Figure 5 As shown.

[0053] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0054] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A crucible for silicon carbide single crystal growth comprising a crucible lid and a crucible body, characterized in that, The upper surface side of the crucible cover is provided with a groove, one end to the other end of the groove gradually inclines to the lower surface side of the crucible cover, and the lower surface of the crucible cover is fixed with a silicon carbide seed wafer, at least the silicon carbide seed wafer is partially in the region corresponding to the inclined surface of the groove.

2. The crucible of claim 1, wherein The angle between the inclined surface and the horizontal plane is 0-30° and ≠0°.

3. The crucible of claim 1, wherein The maximum circumference of the side wall of the groove is 50-150mm in diameter for growing a 4-inch silicon carbide single crystal; the maximum circumference of the side wall of the groove is 75-225mm in diameter for growing a 6-inch silicon carbide single crystal; the maximum circumference of the side wall of the groove is 100-300mm in diameter for growing an 8-inch silicon carbide single crystal.

4. The crucible of claim 1, wherein The depth of the groove decreases from the growth surface of the silicon carbide single crystal to the vice positioning edge.

5. The crucible of claim 1, wherein The center of the maximum circumference of the side wall of the groove and the center of the crucible cover are not concentric, or the center of the maximum circumference of the side wall of the groove and the center of the crucible cover are concentric.

6. An apparatus for growing a silicon carbide single crystal, comprising a crucible, a heating device; the crucible is the crucible of any one of claims 1-5.

7. A method for growing a silicon carbide single crystal, comprising the following steps: S1) fixing a silicon carbide seed wafer on a crucible cover; the crucible cover is the crucible cover in the crucible of any one of claims 1-5; S2) sealingly assembling the crucible cover and the crucible body with silicon carbide growth raw materials placed therein; S3) placing the crucible obtained in step S2) into a PVT single crystal growth furnace, and then growing a silicon carbide single crystal to obtain a silicon carbide single crystal.

8. The method of claim 7, wherein, Inert gas is introduced into the single crystal growth furnace, and the pressure is 200-1000Pa.

9. The method of claim 7, wherein, The growth temperature is 1900-2300℃, and the time is 30-150h.

10. The method of claim 7, wherein, The thickness of the silicon carbide single crystal is 10-35mm, the silicon carbide seed crystal is a 4H-4° seed crystal, and the silicon carbide single crystal is an N-type doped conductive type crystal.

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