Low-defect-density silicon carbide crystal, substrate, growth device and growth method

Abstract

The invention belongs to the technical field of silicon carbide crystal growth, and particularly relates to a low-defect-density silicon carbide crystal, a substrate, a growth device and a growth method. The small pits or cavities on the low-defect-density silicon carbide crystals are round or hexagonal under an optical microscope, and the diameter of the small pits or cavities is less than 10 microns; the number of the small pits or holes is smaller than or equal to 0.5 cm <-2 > within the radius range from the center of the crystal and the center of the substrate as the circle center to the wafer, and the number of the small pits or holes is smaller than or equal to 1 cm <-2 > in the annular area from the outside of the radius range to the edge of the wafer. The low-defect-density silicon carbide crystal provided by the invention is obtained through growth of the growth device provided with the partition plate, and the partition plate blocks contact between steam and the seed crystal in the heating stage, so that erosion damage of the steam to the seed crystal and formation of liquid drops on the surface of the seed crystal are prevented, and the defect that the silicon carbide crystal forms high density in the initial growth stage is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon carbide crystal growth, and in particular relates to a low-defect density silicon carbide crystal, a substrate, a growth device, and a growth method. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Compared with the PVT method, the crystals prepared by the liquid phase method are larger in size, have lower dislocation density and are easier to dope with p-type, and are expected to become a better method for preparing crystals such as silicon carbide. Taking the growth of silicon carbide as an example, in the PVT method, silicon carbide powder is placed under the crucible, and the seed crystal is bonded to the crucible cover. The powder is heated and sublimated to decompose into gas phase components such as Si, Si2C, and SiC2. With gas convection, it is transported to the end of the seed crystal, and SiC crystals are crystallized on the seed crystal to achieve single crystal growth. In the liquid phase method, an open graphite crucible is used as a reactor. By adding a co-solvent to the molten pure silicon, its solubility in carbon is increased; in the high-temperature area near the wall of the crucible, carbon dissolves in the molten silicon; and at the silicon carbide seed crystal with a lower temperature in the center of the crucible, the solubility of carbon decreases, forming a supersaturated solution; at this time, the carbon in the solution combines with silicon and grows epitaxially on the surface of the seed crystal.

[0004] Since the melting point of silicon carbide is as high as 2700℃, silicon carbide powder will not melt and produce steam in the PVT method, but will directly sublimate and decompose into gas phase components, and the gas phase components will directly crystallize into SiC crystals at the seed crystal end. By controlling the pressure in the growth chamber, the sublimation and decomposition of silicon carbide powder can be regulated. The gas phase components produced by sublimation and decomposition will not have adverse effects such as erosion on the seed crystal, and there is no need to consider the impact of the powder heating stage on the seed crystal and crystal. In the heating stage of the liquid phase method, silicon material and other added co-solvents will melt to form a silicon-rich solution, and the free liquid surface of the solution will evaporate to produce steam. Due to the influence of temperature gradient and concentration gradient, the steam will be transmitted upward. There are seed crystals and seed crystal axes on the transmission path. The steam will condense on the colder seed crystal surface to form small droplets of solution. Although the gas phase components produced in the PVT method also contain Si components, the Si and C ratio of the gas phase components is close to 1:1. The gas phase Si component reaches the surface of the seed crystal and can be deposited as SiC together with the gas phase SiC2. In the liquid phase method, however, the vapor formed by the silicon-rich solution contains no carbon or very little carbon, and the droplets formed by its condensation are highly corrosive to the seed crystal. In the process from the melting of the silicon material to the temperature reaching the growth temperature, the surface of the seed crystal is in an evaporating gas atmosphere, and the vapor and droplets will gradually erode and destroy the surface of the seed crystal at high temperature, forming corrosion pits. In addition, when the seed crystal with vapor condensation droplets comes into contact with the surface of the solution, bubbles are easily formed in the gaps between the droplets, forming high-density defects in the early stage of growth. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the present invention provides a low defect density silicon carbide crystal, a substrate, a growth device, and a growth method. The low defect density silicon carbide crystal provided by the present invention is grown by a growth device provided with a partition, and the partition blocks the contact between steam and seed crystal during the heating stage, thereby preventing steam from corroding and damaging the seed crystal and forming droplets on the surface of the seed crystal, thereby avoiding the formation of high-density defects in the silicon carbide crystal at the initial growth stage.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In the first aspect, the present invention provides a low defect density silicon carbide crystal, wherein the small pits or holes on the low defect density silicon carbide crystal appear circular or hexagonal under an optical microscope, and the diameter of the small pits or holes is less than 10 μm; within the radius range from the center of the crystal and the substrate to the wafer, the number of small pits or holes is ≤ 0.5 cm -2， The number of small pits or holes in the annular area outside the radius range to the edge of the wafer is ≤ 1 cm -2 .

[0008] Preferably, the basal plane dislocation density in the front 1 / 3 region of one end of the low defect density silicon carbide crystal is ≤100cm -2, TSD density ≤ 100cm -2 , (0004) plane rocking curve half-height width ≤ 30 arcsec, in-plane average deviation ≤ 5 arcsec; basal plane dislocation density in the rear 2 / 3 region ≤ 50 cm -2 , TSD density ≤50cm -2 , the half-width of the rocking curve of the (0004) plane is ≤20arcsec, and the in-plane average deviation is ≤3arcsec.

[0009] Preferably, the number of pits or cavities is 0 cm -2 .

[0010] Preferably, the conductivity type of the low defect density silicon carbide crystal is p-type, semi-insulating type or n-type.

[0011] In a second aspect, the present invention provides a low defect density silicon carbide substrate obtained by processing the silicon carbide crystal as described in the first aspect.

[0012] In a third aspect, the present invention provides a low defect density silicon carbide crystal growth device, which is used to grow the low defect density silicon carbide crystal as described in the first aspect, comprising:

[0013] A crucible, wherein a heat-insulating material is arranged outside the crucible, the crucible is arranged on a crucible supporting shaft, and an upper heat-insulating port is arranged on the upper part of the crucible and the heat-insulating material;

[0014] A heating coil, wherein the heating coil is arranged outside the heat-insulating material;

[0015] A seed crystal shaft, one end of which is connected to the water-cooled shaft, and the other end of which is connected to the seed crystal;

[0016] A movable partition is used to prevent the steam generated in the crucible from contacting the seed crystal.

[0017] Preferably, the material of the separator is one or more of graphite, alumina and high temperature resistant metals, and the high temperature resistant metals include tungsten, molybdenum, tantalum, niobium, vanadium, chromium, titanium, zirconium or alloys thereof.

[0018] Preferably, the partition is connected to a lifting shaft, and the lifting shaft is arranged on the top wall of the growth device and is parallel to the water-cooling shaft.

[0019] Preferably, the partition is disposed through a side wall of the growth device, and the partition is disposed above the upper heat-insulating port and can move radially along the growth device.

[0020] Preferably, the area of ​​the partition is larger than the upper insulation port.

[0021] Preferably, graphite felt is provided on the upper portion of the partition.

[0022] In a fourth aspect, the present invention provides a method for growing a low defect density silicon carbide crystal, which is used to grow the low defect density silicon carbide crystal as described in the first aspect, using the growth device as described in the third aspect, comprising the following steps:

[0023] The raw materials are placed in a crucible, the seed crystal is connected to the seed crystal axis, the growth device is evacuated and then an inert gas is introduced, a partition is moved to cover the seed crystal, the raw materials are heated to melt to form a solution, and the temperature is continuously raised to a predetermined growth temperature;

[0024] The partition is moved away from the seed crystal, and the seed crystal is lowered until it contacts the liquid surface of the solution, and then the crystal grows;

[0025] After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is taken out after cooling.

[0026] Preferably, after the crystal growth is completed, the crystal is pulled to separate from the solution, and the crystal is continued to be pulled to above the upper insulation port, the partition and the seed crystal axis are moved to make the crystal contact with the graphite felt, and after contact, the partition is moved away from the crystal, the crystal is lowered to the upper insulation port, and the crystal is taken out after cooling.

[0027] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0028] The low defect density silicon carbide crystals obtained by the present invention avoid defects caused by steam droplets during the growth process, the diameter and number of small pits or voids are greatly reduced, the quality of the low defect density silicon carbide crystals is improved, which is conducive to the preparation of high-quality substrates. The low-defect high-quality substrates avoid the decrease in stability caused by the increase in leakage current, and further improve the yield of downstream applications.

[0029] The present invention arranges a partition in the growth device, which blocks the contact between steam and seed crystal in the heating stage, thereby preventing steam from corroding and damaging the seed crystal and forming droplets on the surface of the seed crystal, thereby avoiding the formation of high-density defects in the early stage of crystal growth.

[0030] The present invention further arranges graphite felt on the upper part of the partition to absorb residual droplets on the surface of the crystal after growth, thereby preventing shear stress from being generated on the surface of the crystal and defects caused by the shear stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0032] Figure 1 is a schematic diagram of the structure of the growth device in Example 1;

[0033] Figure 2is a schematic diagram of the structure of the growth device in Example 2;

[0034] Figure 3 is a schematic diagram of the structure of the growth device in Example 3;

[0035] In the figure, 1 is a crucible, 2 is a heat-insulating material, 3 is a crucible supporting shaft, 4 is a heating coil, 5 is a seed crystal shaft, 6 is a water-cooling shaft, 7 is a seed crystal, 8 is a partition, 9 is a lifting shaft, and 10 is a graphite felt. DETAILED DESCRIPTION

[0036] As described in the background technology, during the liquid phase method, the raw materials are heated to form a free liquid surface of the solution, which will evaporate and produce steam. The contact of the steam with the seed crystal will corrode and destroy the seed crystal, and form droplets on the surface of the seed crystal. The gaps between the droplets are prone to form bubbles, thus forming high-density defects in the early stage of growth.

[0037] To solve the above problems, embodiments of the present invention provide a low defect density silicon carbide crystal, a substrate, a growth device, and a growth method.

[0038] In an embodiment of the present invention, a low defect density silicon carbide crystal is provided, wherein the small pits or holes on the low defect density silicon carbide crystal appear to be circular or hexagonal under an optical microscope, and the diameter of the small pits or holes is less than 10 μm; within the radius range from the center of the crystal and the substrate to the wafer, the number of small pits or holes is ≤0.5 cm -2 , the number of small pits or holes in the annular area outside the radius to the edge of the wafer is ≤1cm -2 .

[0039] In some embodiments of the present invention, the basal plane dislocation density of 1 / 3 region at one end of the low defect density silicon carbide crystal is ≤100cm -2 , TSD density ≤ 100cm -2 , (0004) plane rocking curve half-height width ≤ 30 arcsec, in-plane average deviation ≤ 5 arcsec; basal plane dislocation density in the rear 2 / 3 region ≤ 50 cm -2 , TSD density ≤50cm -2 , the half-width of the rocking curve of the (0004) plane is ≤20arcsec, and the in-plane average deviation is ≤3arcsec.

[0040] It should be noted that, in some embodiments of the present invention, the end of the low defect density silicon carbide crystal refers to the end in contact with the seed crystal during growth.

[0041] In some embodiments of the present invention, the number of small pits or holes is 0 cm -2 .

[0042] In some embodiments of the present invention, the conductivity type of the low defect density silicon carbide crystal is p-type, semi-insulating type or n-type.

[0043] An embodiment of the present invention provides a low defect density silicon carbide substrate, which is obtained by processing the silicon carbide crystal as described above.

[0044] An embodiment of the present invention provides a low defect density silicon carbide crystal growth device, which is used to grow the low defect density silicon carbide crystal as described above, comprising:

[0045] A crucible, wherein a heat-insulating material is arranged outside the crucible, the crucible is arranged on a crucible supporting shaft, and an upper heat-insulating port is arranged on the upper part of the crucible and the heat-insulating material;

[0046] A heating coil, wherein the heating coil is arranged outside the heat-insulating material;

[0047] A seed crystal shaft, one end of which is connected to the water-cooled shaft, and the other end of which is connected to the seed crystal;

[0048] A movable partition is used to prevent the steam generated in the crucible from contacting the seed crystal.

[0049] By setting a movable partition, the seed crystal is shielded during the raw material heating stage to prevent the generated steam from adhering to the seed crystal and causing erosion and forming droplets. The size of the partition is sufficient to completely cover the seed crystal, that is, the area of ​​the partition is larger than the area of ​​the seed crystal. The partition can be moved manually, mechanically, electrically, etc., and can be moved by a rotating shaft, a lifting rod, etc., to meet the requirements of seed crystal shielding and crystal growth.

[0050] In some embodiments of the present invention, the material of the separator is one or more of graphite, alumina and high temperature resistant metals, and the high temperature resistant metals include tungsten, molybdenum, tantalum, niobium, vanadium, chromium, titanium, zirconium or alloys thereof.

[0051] In some embodiments of the present invention, the partition is connected to a lifting shaft, and the lifting shaft is arranged on the top wall of the growth device and is parallel to the water-cooling shaft.

[0052] In some embodiments of the present invention, the partition is disposed through a side wall of the growth device, and the partition is disposed above the upper heat preservation port and is movable along a radial direction of the growth device.

[0053] In some embodiments of the present invention, the area of ​​the partition is larger than the upper heat-insulating port.

[0054] When the area of ​​the partition is larger than the upper insulation port, the partition can be used to completely cover the upper insulation port to completely block the steam and the seed crystal.

[0055] In some embodiments of the present invention, graphite felt is disposed on the upper portion of the separator.

[0056] After the crystal grows, when the crystal is separated from the solution, due to the wettability of the solution and the effect of surface tension, droplets of the solution will adhere to the surface of the crystal. During the cooling process, when the temperature is about to drop below a certain temperature, the droplets will gradually solidify into a solid, forming a connection between the solidified droplets of the solution and the surface of the crystal. Due to the difference in thermal conductivity between the droplets and the crystal, expansion and contraction effects occur during the cooling process, which will generate shear stress on the surface of the crystal. On the one hand, it promotes the expansion of basal plane dislocations on the surface of the crystal due to shear stress. On the other hand, when the deformation caused by stress exceeds the upper limit of elastic deformation, plastic deformation will occur and cracks will be generated. Therefore, a graphite felt is further arranged on the partition to absorb and eliminate the residual droplets of the solution after the crystal growth.

[0057] In an embodiment of the present invention, a method for growing a silicon carbide crystal with low defect density is provided, which is used to grow the silicon carbide crystal with low defect density as described above, using the growth device as described above, and comprises the following steps:

[0058] The raw materials are placed in a crucible, the seed crystal is connected to the seed crystal axis, the growth device is evacuated and then an inert gas is introduced, a partition is moved to cover the seed crystal, the raw materials are heated to melt to form a solution, and the temperature is continuously raised to a predetermined growth temperature;

[0059] The partition is moved away from the seed crystal, and the seed crystal is lowered until it contacts the liquid surface of the solution, and then the crystal grows;

[0060] After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is taken out after cooling.

[0061] In some embodiments of the present invention, after the crystal growth is completed, the crystal is pulled to separate from the solution, and the crystal is continued to be pulled to above the upper insulation port, the partition and the seed crystal axis are moved to make the crystal contact with the graphite felt, and after contact, the partition is moved away from the crystal, the crystal is lowered to the upper insulation port, and the crystal is taken out after cooling.

[0062] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0063] Example 1

[0064] like Figure 1 As shown, a growth device for low defect density silicon carbide crystal comprises:

[0065] A crucible 1, a heat-insulating material 2 is arranged outside the crucible 1, the crucible 1 is arranged on a crucible supporting shaft 3, and an upper heat-insulating port is arranged on the upper part of the crucible 1 and the heat-insulating material 2;

[0066] A heating coil 4, which is arranged outside the heat-insulating material 2;

[0067] A seed crystal shaft 5, one end of the seed crystal shaft 5 is connected to the water-cooled shaft 6, and the other end is connected to the seed crystal 7;

[0068] A movable partition 8 is used to prevent the steam generated in the crucible 1 from contacting the seed crystal 7 . The partition 8 is connected to a lifting shaft 9 . The lifting shaft 9 is arranged on the top wall of the growth device and is parallel to the water-cooling shaft 6 .

[0069] The growth device is used to grow a low defect density silicon carbide crystal, and the steps are as follows:

[0070] The raw materials (Si, Cr) are placed in a crucible 1 (the crucible 1 is a graphite crucible), the seed crystal 7 is connected to the seed crystal shaft 5, the growth device is evacuated and then an inert gas is introduced, the partition 8 is moved to cover the seed crystal 7, the raw materials are heated to melt to form a solution, and the temperature is continuously raised to a predetermined growth temperature;

[0071] The movable partition 8 deviates from the seed crystal 7, and the seed crystal 7 is lowered until it contacts the liquid surface of the solution, and then the crystal grows;

[0072] After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is taken out after cooling.

[0073] The small pits or holes on the low defect density silicon carbide crystal grown in this embodiment appear to be circular or hexagonal under an optical microscope, and the diameter of the small pits or holes is less than 10 μm; the number of small pits or holes within the radius range from the center of the crystal and the substrate to the wafer is ≤0.5 cm -2 , the number of small pits or holes in the annular area outside the radius to the edge of the wafer is ≤1cm -2 ; The basal plane dislocation density in the front 1 / 3 region of the crystal close to the seed crystal is ≤100cm -2 , TSD density ≤ 100cm -2 The half-height width of the (0004) plane rocking curve is ≤30 arcsec, the average deviation in the plane is ≤5 arcsec; the basal plane dislocation density in the rear 2 / 3 region of the crystal close to the seed crystal is ≤50 cm -2 , TSD density ≤50cm -2 , the half-width of the rocking curve of the (0004) plane is ≤20arcsec, and the in-plane average deviation is ≤3arcsec.

[0074] Example 2

[0075] like Figure 2 As shown, a growth device for low defect density silicon carbide crystal comprises:

[0076] A crucible 1, a heat-insulating material 2 is arranged outside the crucible 1, the crucible 1 is arranged on a crucible supporting shaft 3, and an upper heat-insulating port is arranged on the upper part of the crucible 1 and the heat-insulating material 2;

[0077] A heating coil 4, which is arranged outside the heat-insulating material 2;

[0078] A seed crystal shaft 5, one end of the seed crystal shaft 5 is connected to the water-cooled shaft 6, and the other end is connected to the seed crystal 7;

[0079] A movable partition 8 is used to prevent the steam generated in the crucible 1 from contacting the seed crystal 7. The partition 8 is arranged through the side wall of the growth device. The partition 8 is arranged above the upper insulation port and can move radially along the growth device.

[0080] The growth device is used to grow a low defect density silicon carbide crystal, and the steps are as follows:

[0081] The raw materials (Si, Cr) are placed in a crucible 1 (the crucible 1 is a graphite crucible), the seed crystal 7 is connected to the seed crystal shaft 5, the growth device is evacuated and then an inert gas is introduced, the partition 8 is moved to cover the seed crystal 7, the raw materials are heated to melt to form a solution, and the temperature is continuously raised to a predetermined growth temperature;

[0082] The movable partition 8 deviates from the seed crystal 7, and the seed crystal 7 is lowered until it contacts the liquid surface of the solution, and then the crystal grows;

[0083] After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is taken out after cooling.

[0084] The small pits or holes on the low defect density silicon carbide crystal grown in this embodiment appear to be circular or hexagonal under an optical microscope, and the diameter of the small pits or holes is less than 10 μm; the number of small pits or holes within the radius range from the center of the crystal and the substrate to the wafer is ≤0.5 cm -2 , the number of small pits or holes in the annular area outside the radius to the edge of the wafer is ≤1cm -2 ; The basal plane dislocation density in the front 1 / 3 region of the crystal close to the seed crystal is ≤100cm -2 , TSD density ≤ 100cm -2 The half-height width of the (0004) plane rocking curve is ≤30 arcsec, the average deviation in the plane is ≤5 arcsec; the basal plane dislocation density in the rear 2 / 3 region of the crystal close to the seed crystal is ≤50 cm -2 , TSD density ≤50cm -2 , the half-width of the rocking curve of the (0004) plane is ≤20arcsec, and the in-plane average deviation is ≤3arcsec.

[0085] Example 3

[0086] like Figure 3 As shown, a growth device for low defect density silicon carbide crystal comprises:

[0087] A crucible 1, a heat-insulating material 2 is arranged outside the crucible 1, the crucible 1 is arranged on a crucible supporting shaft 3, and an upper heat-insulating port is arranged on the upper part of the crucible 1 and the heat-insulating material 2;

[0088] A heating coil 4, which is arranged outside the heat-insulating material 2;

[0089] A seed crystal shaft 5, one end of the seed crystal shaft 5 is connected to the water-cooled shaft 6, and the other end is connected to the seed crystal 7;

[0090] A movable partition 8 is used to prevent the steam generated in the crucible 1 from contacting the seed crystal 7. The partition 8 is connected to a lifting shaft 9. The lifting shaft 9 is arranged on the top wall of the growth device and is parallel to the water-cooling shaft 6. A graphite felt 10 is arranged on the upper part of the partition 8.

[0091] The growth device is used to grow a low defect density silicon carbide crystal, and the steps are as follows:

[0092] The raw materials (Si, Cr) are placed in a crucible 1 (the crucible 1 is a graphite crucible), the seed crystal 7 is connected to the seed crystal shaft 5, the growth device is evacuated and then an inert gas is introduced, the partition 8 is moved to cover the seed crystal 7, the raw materials are heated to melt to form a solution, and the temperature is continuously raised to a predetermined growth temperature;

[0093] The movable partition 8 deviates from the seed crystal 7, and the seed crystal 7 is lowered until it contacts the liquid surface of the solution, and then the crystal grows;

[0094] After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is continued to be pulled up to the top of the upper insulation port. The partition 8 and the seed crystal axis 5 are moved to make the crystal contact with the graphite felt 10. After contact, the partition 8 is moved away from the crystal, and the crystal drops to the upper insulation port. The crystal is taken out after cooling.

[0095] The small pits or holes on the low defect density silicon carbide crystal grown in this embodiment appear to be circular or hexagonal under an optical microscope, and the diameter of the small pits or holes is less than 10 μm; the number of small pits or holes within the radius range from the center of the crystal and the substrate to the wafer is ≤0.5 cm -2 , the number of small pits or holes in the annular area outside the radius to the edge of the wafer is ≤1cm -2 ; The basal plane dislocation density in the front 1 / 3 region of the crystal close to the seed crystal is ≤100cm -2 , TSD density ≤ 100cm -2 The half-height width of the (0004) plane rocking curve is ≤30 arcsec, the average deviation in the plane is ≤5 arcsec; the basal plane dislocation density in the rear 2 / 3 region of the crystal close to the seed crystal is ≤50 cm -2 , TSD density ≤50cm -2 , the half-width of the rocking curve of the (0004) plane is ≤20arcsec, and the in-plane average deviation is ≤3arcsec.

[0096] Comparative Example 1

[0097] A silicon carbide crystal growth device, comprising:

[0098] A crucible 1, a heat-insulating material 2 is arranged outside the crucible 1, the crucible 1 is arranged on a crucible supporting shaft 3, and an upper heat-insulating port is arranged on the upper part of the crucible 1 and the heat-insulating material 2;

[0099] A heating coil 4, which is arranged outside the heat-insulating material 2;

[0100] The seed crystal shaft 5 has one end connected to the water-cooled shaft 6 and the other end connected to the seed crystal 7 .

[0101] The growth device is used to grow silicon carbide crystals, and the steps are as follows:

[0102] The raw materials (Si, Cr) are placed in a crucible 1 (the crucible 1 is a graphite crucible), the seed crystal 7 is connected to the seed crystal axis 5, the growth device is evacuated and then an inert gas is introduced, the raw materials are heated and melted to form a solution, and the temperature is continuously raised to a predetermined growth temperature;

[0103] After the seed crystal 7 is lowered to contact with the liquid surface of the solution, crystal growth is performed;

[0104] After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is taken out after cooling.

[0105] The small pits or holes on the silicon carbide crystal grown in this comparative example appear to be circular or hexagonal under an optical microscope, and the diameter of the small pits or holes is greater than 10 μm; the number of small pits or holes within the radius of the wafer from the center of the crystal and the substrate is greater than 0.5 cm -2 , the number of small pits or holes in the annular area outside the radius to the edge of the wafer is > 1 cm -2 ; The basal plane dislocation density in the front 1 / 3 region of the crystal close to the seed crystal is > 100 cm -2 , TSD density>100cm -2 The half-height width of the (0004) plane rocking curve is greater than 30 arcsec, and the average deviation in the plane is greater than 5 arcsec; the basal plane dislocation density in the rear 2 / 3 region of the crystal close to the seed crystal is greater than 50 cm -2 , TSD density>50cm -2 The half-width of the rocking curve of the (0004) plane is greater than 20 arcsec, and the average deviation within the plane is greater than 3 arcsec.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low defect density silicon carbide crystal, characterized in that: The small pits or holes on the low defect density silicon carbide crystal appear circular or hexagonal under an optical microscope, and the diameter of the small pits or holes is less than 10 μm; within the radius range from the center of the crystal and the substrate to the wafer, the number of small pits or holes is ≤ 0.5 cm -2 , the number of small pits or holes in the annular area outside the radius to the edge of the wafer is ≤1cm -2 .

2. The low defect density silicon carbide crystal according to claim 1, characterized in that: The basal plane dislocation density of the front 1 / 3 region of one end of the low defect density silicon carbide crystal is ≤100cm -2 , TSD density ≤ 100cm -2 The half-height width of the (0004) plane rocking curve is ≤30 arcsec, the average deviation in the plane is ≤5 arcsec; the basal plane dislocation density in the rear 2 / 3 region of the crystal close to the seed crystal is ≤50 cm -2 , TSD density ≤50cm -2 , the half-width of the rocking curve of the (0004) plane is ≤20arcsec, and the in-plane average deviation is ≤3arcsec.

3. A low defect density silicon carbide substrate, characterized in that: Obtained by processing the silicon carbide crystal as claimed in claim 1 or 2.

4. A growth device for low defect density silicon carbide crystal, characterized in that: For growing a low defect density silicon carbide crystal as claimed in claim 1 or 2, comprising: A crucible, wherein a heat-insulating material is arranged outside the crucible, the crucible is arranged on a crucible supporting shaft, and an upper heat-insulating port is arranged on the upper part of the crucible and the heat-insulating material; A heating coil, wherein the heating coil is arranged outside the heat-insulating material; A seed crystal shaft, one end of which is connected to the water-cooled shaft, and the other end of which is connected to the seed crystal; A movable partition is used to prevent the steam generated in the crucible from contacting the seed crystal.

5. The growth device according to claim 4, characterized in that The material of the partition is one or more of graphite, alumina and high temperature resistant metals, wherein the high temperature resistant metals include tungsten, molybdenum, tantalum, niobium, vanadium, chromium, titanium, zirconium or alloys thereof, and the area of ​​the partition is larger than the upper insulation port.

6. The growth device according to claim 4, characterized in that The partition is connected to a lifting shaft, and the lifting shaft is arranged on the top wall of the growth device and is parallel to the water-cooling shaft.

7. The growth device according to claim 4, characterized in that The partition plate is arranged through the side wall of the growth device, and the partition plate is arranged above the upper heat preservation port and can move along the radial direction of the growth device.

8. The growth device according to claim 4, characterized in that Graphite felt is arranged on the upper part of the partition.

9. A method for growing a low defect density silicon carbide crystal, characterized in that: For growing the low defect density silicon carbide crystal as claimed in claim 1 or 2, using the apparatus as claimed in any one of claims 4 to 8, comprising the following steps: The raw materials are placed in a crucible, the seed crystal is connected to the seed crystal axis, the growth device is evacuated and then an inert gas is introduced, a partition is moved to cover the seed crystal, the raw materials are heated to melt to form a solution, and the temperature is continuously raised to a predetermined growth temperature; The partition is moved away from the seed crystal, and the seed crystal is lowered until it contacts the liquid surface of the solution, and then the crystal grows; After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is taken out after cooling.

10. The method according to claim 9, characterized in that After the crystal growth is completed, the crystal is pulled up to separate from the solution, and the crystal is continued to be pulled up to the top of the upper insulation port. The partition and the seed crystal axis are moved to make the crystal contact with the graphite felt. After contact, the partition is moved away from the crystal, and the crystal is lowered to the upper insulation port. The crystal is taken out after cooling.

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