Low-base plane dislocation P-type silicon carbide crystal, substrate, growth equipment and growth method

Abstract

The invention belongs to the technical field of crystal growth, and particularly relates to a low-base plane dislocation P-type silicon carbide crystal, a substrate, growth equipment and a growth method. The low-base plane dislocation density P-type silicon carbide crystal has no ridge plane dislocation, BPD is in the [11-20] direction, the BPD included angle is smaller than 60 degrees, the BPD density is smaller than or equal to 50 cm <-2 >, the BPD distance is larger than or equal to 0.1 mm, the in-plane density change rate is smaller than or equal to 10%, the rocking curve full width at half maximum of the (0004) plane is smaller than 20 arcsec, the in-plane average value deviation is smaller than 3 arcsec, and the base plane deflection angle lt is achieved. 0.2 degree; the Raman spectrum longitudinal optical phonon and plasmon coupling mode has a full width at half maximum of 10-17 cm <-1 >. According to the invention, the seed crystal with the convex structure is mechanically connected with the seed crystal support, so that thermal stress generated in crystal growth and cooling stages due to non-uniformity of a carbon adhesive or different thermal expansion coefficients between a graphite material and silicon carbide is avoided, and the low-base plane dislocation density P-type silicon carbide crystal is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal growth, and in particular relates to a low basal plane dislocation P-type silicon carbide crystal and a substrate as well as 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] Silicon carbide (SiC) single crystal has the advantages of wide bandgap, high thermal conductivity, high breakdown field strength, high saturated electron drift rate, etc. It is suitable for the development of high-voltage and high-current power devices and is widely used in 5G communications, electric vehicles, photovoltaic energy storage, rail transportation, smart grids and other fields. It is the core basic material supporting the future digital and low-carbon industry. Especially in the field of high-voltage and high-power applications above 10kV, low-resistance, high-quality P-type 4H-SiC substrate materials have better commercial application prospects.

[0004] Because the mobility of electrons in SiC materials is higher than that of holes, in theory, N-channel SiC IGBTs will have better conduction characteristics than P-channel SiC IGBTs. The preparation of N-channel SiC IGBTs requires a low-resistance, high-quality P-type SiC substrate material, and the currently commercialized P-type 4H-SiC substrate has a relatively high resistance value (2.5Ω·cm), which is two orders of magnitude larger than that of N-type SiC substrates. Aluminum (Al) is usually used as a dopant to grow P-type SiC crystals, but in the preparation of P-type SiC substrates by the PVT method, there are problems of Al source inclusions and Al source depletion in the early growth stage. The use of aluminum carbide (Al4C3) and the like as Al sources also has problems such as uneven Al doping in the radial direction of the crystal and resistance values ​​that are difficult to meet the use requirements. In the liquid phase method, since the growth environment of the SiC crystal is in a stable solution, the growth process is closer to a state of equilibrium, and higher quality SiC crystals can be obtained.

[0005] In the process of growing silicon carbide crystals by liquid phase method, in order to immerse the seed crystals in the solution or pull them out of the solution after growth, it is generally necessary to connect the seed crystals and the graphite shaft, and control the position and rotation of the seed crystals by the movement of the graphite shaft. The connection between the seed crystals and the graphite shaft is generally carried out by bonding, directly pasting the silicon carbide seed crystals to the graphite through glue, or by adding graphite paper between the seed crystals and the graphite to achieve the connection between the seed crystals and the graphite. Due to the different thermal conductivity and thermal expansion coefficients of graphite materials and silicon carbide crystals, thermal stress will be generated at the bonding interface and in the growing crystal. And when the glue is unevenly applied, bubbles and cavities will be generated, which will also lead to uneven heat conduction on the seed crystals and then stress, causing defects in the crystal growth layer. Studies have shown that thermal stress is the main cause of basal plane dislocations. Driven by thermal stress, basal plane dislocations (BPD) will also slip along the slip plane. After the crystal grows thicker, the stress at the crystal bonding will bring new BPD to the crystal as a whole, causing an increase in dislocation density. Based on thermal stress calculation, the critical shear stress for edge dislocation is 8MPa. Since stress mainly exists at the edge of the crystal, edge dislocation is mainly distributed in the edge area, and the central area is basically zero. It is generally distributed within 5-10mm from the edge of the crystal. The two groups of edge dislocations generally present an angle of 60°. The main reason is that the main slip system of BPD is (0001) plane, [11-20] direction, and other slip systems include: (1-100) plane, [11-20] direction; (01-10) plane, [2-1-10] direction; (10-10) plane, [-12-10] direction.

[0006] The application scenario of P-type substrate is 10kV UHV power devices, during which the BPD density in the substrate is extremely high. During the epitaxial process, more than 99% of the BPD in the substrate will be converted into through-edge dislocations, but there will still be a small amount of unconverted BPD that continues into the epitaxial layer. The BPD in the epitaxial layer is extremely harmful in UHV devices. For the application of UHV, under ideal conditions, the BPD in the grown silicon carbide crystal needs to be zero, that is, a BPD Free crystal. Summary of the invention

[0007] In order to solve the deficiencies of the prior art, the present invention provides a low basal plane dislocation P-type silicon carbide crystal and substrate and a growth device and a growth method. The present invention obtains a low basal plane dislocation density P-type silicon carbide crystal by mechanically connecting a seed crystal with a seed crystal holder using a convex structure to avoid thermal stress generated during the crystal growth and cooling stages due to uneven carbon adhesive or different thermal expansion coefficients between graphite material and silicon carbide.

[0008] The present invention is achieved through the following technical solutions:

[0009] In the first aspect, the present invention provides a P-type silicon carbide crystal with low basal plane dislocation density, wherein the P-type silicon carbide crystal with low basal plane dislocation density has no facet dislocation, the BPD presents a [11-20] direction, the BPD angle is less than 60°, and the BPD density is ≤50cm -2 , BPD spacing ≥ 0.1mm, in-plane density change rate ≤ 10%.

[0010] Preferably, the rocking curve half-width of the (0004) plane of the low basal plane dislocation density P-type silicon carbide crystal is less than 20 arcsec, the in-plane average deviation is less than 3 arcsec, and the basal plane deviation angle is less than 0.2°; the Raman spectrum longitudinal optical phonon and plasmon coupling mode (LOPC) half-width (FWHM) is 10-17 cm -1 . Wherein, the average deviation within the surface = maximum or minimum value - average value.

[0011] Preferably, the BPD angle is less than 30° and the BPD density is ≤10cm -2 .

[0012] Preferably, the Al doping concentration is ≥5E19 cm -3 , resistivity ≤0.5Ω·cm.

[0013] Further preferably, the Al doping concentration is ≥1E20 cm -3 , resistivity ≤0.1Ω·cm.

[0014] Further preferably, the Raman spectrum LOPC mode half-width is 13 to 15 cm -1 .

[0015] Preferably, the size of the low basal plane dislocation density P-type silicon carbide crystal is 2 to 12 inches, and the crystal type includes 4H-SiC, 3C-SiC or 6H-SiC.

[0016] In a second aspect, the present invention provides a growth device for a low basal plane dislocation density P-type silicon carbide crystal, which is used to grow and comprises a crucible, a heat preservation material, a heating coil, a crucible support shaft, a water-cooled shaft, a seed crystal shaft, a seed crystal holder and a seed crystal;

[0017] The seed crystal holder is a concave structure, and the side wall is provided with a first connection structure for connecting the seed crystal;

[0018] The seed crystal is a convex structure consisting of an upper boss and a lower truncated cone. The diameter of the upper boss is smaller than that of the lower truncated cone. The side wall of the upper boss is provided with a second connection structure that cooperates with the first connection structure.

[0019] Preferably, the first connection structure comprises a positioning pin, a first positioning plate or a first positioning ring, the first connection structure is integrally arranged with the seed crystal holder or connected via a detachable connection piece, and the first connection structure and the detachable connection piece are made of silicon carbide;

[0020] When the first connecting structure is a positioning pin, the second connecting structure is a positioning hole;

[0021] When the first connection structure is a first positioning plate or a first positioning ring, the second connection structure is a positioning groove.

[0022] Preferably, the first connection structure comprises an internal thread, an external thread or a groove provided inside the side wall of the seed crystal holder;

[0023] When the first connection structure is an internal thread, the second connection structure is an external thread;

[0024] When the first connection structure is an external thread, the second connection structure is an internal thread;

[0025] When the first connection structure is a groove, the second connection structure is a second positioning plate or a second positioning ring.

[0026] Preferably, the seed crystal holder is made of graphite or silicon carbide, and the thickness of the seed crystal is ≥3 mm.

[0027] In a third aspect, the present invention provides a method for growing a low basal plane dislocation density P-type silicon carbide crystal, using the growth device as described in the second aspect, comprising the following steps:

[0028] Put the raw materials into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft;

[0029] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0030] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0031] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0032] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0033] The separated seed crystals are surface treated and then used again as seed crystals.

[0034] In a fourth aspect, the present invention provides a low basal plane dislocation density P-type silicon carbide substrate obtained by processing the low basal plane dislocation density P-type silicon carbide crystal as described in the first aspect.

[0035] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0036] The low basal plane dislocation density P-type silicon carbide crystal obtained by the present invention has no edge dislocation, and the BPD angle and density are greatly reduced and the spacing is improved. The low BPD of the P-type silicon carbide crystal can avoid the adverse effects such as device leakage current generation, insulation breakdown, and performance degradation. Processing it into a P-type substrate can be further applied to ultra-high voltage power devices, and improve device yield and device performance.

[0037] The present invention uses a convex seed crystal composed of an upper boss and a lower truncated cone to grow a low basal plane dislocation density P-type silicon carbide crystal. The upper boss is used to connect with the seed crystal holder, and the lower truncated cone is used for crystal growth. When the crystal grows, the stress effect caused by the connection between the upper boss and the seed crystal holder can be avoided. The seed crystal after crystal growth can be separated from the crystal and can be reused after surface processing again, thereby improving the utilization rate of the seed crystal.

[0038] The present invention cooperates with the first connection structure on the seed crystal holder and the second connection structure on the upper boss of the seed crystal to change the connection mode between the seed crystal and the seed crystal holder and the seed crystal shaft from bonding to mechanical connection, thereby avoiding the thermal stress generated during the crystal growth and cooling stages due to uneven carbon adhesive or different thermal expansion coefficients between graphite material and silicon carbide. It is also convenient to separate the seed crystal from the seed crystal holder after the crystal growth is completed, which is conducive to the reuse of the seed crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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.

[0040] Figure 1 Schematic diagram of the cross-sectional structure of the seed crystal shaft, seed crystal holder and seed crystal in Example 1;

[0041] Figure 2 Schematic diagram of the cross-sectional structure of the seed crystal shaft, seed crystal holder and seed crystal in Example 2;

[0042] Figure 3 Schematic diagram of the cross-sectional structure of the seed crystal shaft, seed crystal holder and seed crystal in Example 3;

[0043] Figure 4 Schematic diagram of the cross-sectional structure of the seed crystal shaft, seed crystal holder and seed crystal in Example 4;

[0044] Figure 5 Schematic diagram of the cross-sectional structure of the seed crystal axis, seed crystal holder and seed crystal in Comparative Example 1;

[0045] Figure 6Schematic diagram of the cross-sectional structure of the seed crystal axis, seed crystal holder and seed crystal in Comparative Example 2;

[0046] In the figure, 1 is a seed crystal shaft, 2 is a seed crystal holder, 3 is a seed crystal, 21 is a first connection structure, 22 is a detachable connection member, 31 is an upper boss, 32 is a lower frustum, and 33 is a second connection structure. DETAILED DESCRIPTION

[0047] As described in the background technology, when the silicon carbide seed crystal is directly attached to the graphite by glue, or the connection between the seed crystal and the graphite is achieved by adding graphite paper between the seed crystal and the graphite to grow P-type silicon carbide by the liquid phase method, due to the different thermal expansion coefficients of the graphite material and the seed crystal, thermal stress will be generated during the growth of silicon carbide to induce BPD. And when the glue is unevenly applied, bubbles and cavities will be generated, which will also cause uneven thermal conductivity on the seed crystal and generate stress, causing defects in the crystal growth layer. The BPD in the crystal is too high to be processed into a P-type substrate for 10kV ultra-high voltage power devices.

[0048] In order to solve the above technical problems, the present invention provides a low basal plane dislocation P-type silicon carbide crystal and substrate, as well as a growth device and a growth method.

[0049] The embodiment of the present invention provides a low basal plane dislocation density P-type silicon carbide crystal, wherein the low basal plane dislocation density P-type silicon carbide crystal has no edge dislocation, the BPD presents a [11-20] direction, the BPD angle is less than 60°, and the BPD density is ≤50cm -2 , BPD spacing ≥ 0.1mm, in-plane density change rate ≤ 10%.

[0050] In an embodiment of the present invention, the rocking curve half-width of the (0004) plane of the low basal plane dislocation density P-type silicon carbide crystal is less than 20 arcsec, the in-plane average deviation is less than 3 arcsec, and the basal plane deviation angle is less than 0.2°; the half-width (FWHM) of the Raman spectrum longitudinal optical phonon and plasmon coupling mode (LOPC) is 10 to 17 cm -1 . Wherein, the average deviation within the surface = maximum or minimum value - average value.

[0051] In the embodiment of the present invention, the BPD angle is less than 30° and the BPD density is ≤10cm -2 .

[0052] In the embodiment of the present invention, the Al doping concentration is ≥ 5E19 cm -3 , resistivity ≤0.5Ω·cm.

[0053] In some embodiments of the present invention, the Al doping concentration is ≥1E20 cm -3 , resistivity ≤0.1Ω·cm.

[0054] In some embodiments of the present invention, the half-width of the Raman spectrum LOPC mode is 13-15 cm -1 .

[0055] In an embodiment of the present invention, the size of the low basal plane dislocation density P-type silicon carbide crystal is 2 to 12 inches, and the crystal type includes 4H-SiC, 3C-SiC or 6H-SiC.

[0056] An embodiment of the present invention provides a growth device for a low basal plane dislocation density P-type silicon carbide crystal, which is used to grow and comprises a crucible, a heat-insulating material, a heating coil, a crucible support shaft, a water-cooled shaft, a seed crystal shaft, a seed crystal holder and a seed crystal;

[0057] The seed crystal holder is a concave structure, and the side wall is provided with a first connection structure for connecting the seed crystal;

[0058] The seed crystal is a convex structure consisting of an upper boss and a lower truncated cone. The diameter of the upper boss is smaller than that of the lower truncated cone. The side wall of the upper boss is provided with a second connection structure that cooperates with the first connection structure.

[0059] The seed crystal is composed of an upper boss and a lower cone. The lower cone is used for crystal growth, and the upper boss is used to connect with the seed crystal holder and prevent stress from affecting the crystal. The first connection structure on the seed crystal holder and the second connection structure on the upper boss of the seed crystal are matched to change the connection mode between the seed crystal and the seed crystal holder and the seed crystal axis from bonding to mechanical connection, which can avoid thermal stress generated during the crystal growth and cooling stages due to uneven carbon adhesive or different thermal expansion coefficients between graphite material and silicon carbide.

[0060] In an embodiment of the present invention, the first connection structure comprises a positioning pin, a first positioning plate or a first positioning ring, the first connection structure is integrally arranged with the seed crystal holder or connected via a detachable connection piece, and the first connection structure and the detachable connection piece are made of silicon carbide;

[0061] When the first connecting structure is a positioning pin, the second connecting structure is a positioning hole;

[0062] When the first connection structure is a first positioning plate or a first positioning ring, the second connection structure is a positioning groove.

[0063] A protruding first connection structure such as a positioning pin, a first positioning plate or a first positioning ring is arranged on the side wall of the seed crystal holder, and cooperates with the positioning hole and positioning groove formed on the seed crystal to connect the seed crystal to the seed crystal holder. Compared with the first connection structure integrated with the seed crystal holder, connecting the first connection structure to the seed crystal holder through a detachable connection piece is more conducive to avoiding thermal stress caused by different thermal expansion coefficients of the seed crystal, the seed crystal holder and the first connection structure. In addition, the material of the first connection structure and the detachable connection piece is set to silicon carbide, which further avoids thermal stress caused by different thermal expansion coefficients from the root. The detachable connection piece can be a bolt, a pin, a buckle or other structure.

[0064] In an embodiment of the present invention, the first connection structure includes an internal thread, an external thread or a groove provided inside the side wall of the seed crystal holder;

[0065] When the first connection structure is an internal thread, the second connection structure is an external thread;

[0066] When the first connection structure is an external thread, the second connection structure is an internal thread;

[0067] When the first connection structure is a groove, the second connection structure is a second positioning plate or a second positioning ring.

[0068] The second positioning plate or the second positioning ring may be arranged to protrude from the side wall of the upper boss, or may be formed by carving on the side wall of the upper boss.

[0069] In an embodiment of the present invention, the seed crystal holder is made of graphite or silicon carbide, and the thickness of the seed crystal is ≥3 mm.

[0070] In order to further avoid thermal stress caused by the different thermal expansion coefficients of the seed crystal and the seed crystal holder, the seed crystal holder is made of silicon carbide.

[0071] The thicker the seed crystal, the less likely it is that the stress generated on the top of the seed crystal will cause the growing crystal. During the crystal growth process, using thick seed crystals can also effectively avoid the solution from contacting the back of the seed crystal caused by the traditional connection method, causing the solution to enter the back of the seed crystal to produce silicon carbide polycrystals.

[0072] An embodiment of the present invention provides a method for growing a P-type silicon carbide crystal with a low basal plane dislocation density, using the growth device as described above, comprising the following steps:

[0073] Put the raw materials into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft;

[0074] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0075] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0076] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0077] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0078] The separated seed crystals are surface treated and then used again as seed crystals.

[0079] An embodiment of the present invention provides a low basal plane dislocation density P-type silicon carbide substrate, which is obtained by processing the low basal plane dislocation density P-type silicon carbide crystal as described above.

[0080] 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.

[0081] Example 1

[0082] The growth equipment of low basal plane dislocation density P-type silicon carbide crystal comprises a crucible, a heat preservation material, a heating coil, a crucible support shaft, a water cooling shaft, a seed crystal shaft 1, a seed crystal holder 2 and a seed crystal 3. Figure 1 As shown, the seed crystal shaft 1 is connected to the seed crystal holder 2; the seed crystal holder 2 is a concave structure, and the side wall is provided with a first connection structure 21 for connecting the seed crystal 3; the seed crystal 3 is a convex structure composed of an upper boss 31 and a lower truncated cone 32, the diameter of the upper boss 31 is smaller than the lower truncated cone 32, and the side wall of the upper boss 31 is provided with a second connection structure 33 that cooperates with the first connection structure 21. The thickness of the seed crystal 3 is 5mm. The first connection structure 21 is a first positioning ring, which is connected to the side wall of the seed crystal holder 2 through a detachable connection member 22, and the first connection structure 21, the detachable connection member 22 and the seed crystal holder 2 are made of silicon carbide. The second connection structure 33 is a positioning groove, and the first positioning ring extends into the positioning groove to realize the connection between the seed crystal holder 2 and the seed crystal 3.

[0083] The growth of low basal plane dislocation density P-type silicon carbide crystals using the above equipment is performed as follows:

[0084] Put raw materials (Si, Cr, Al) into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft;

[0085] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0086] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0087] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0088] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0089] The separated seed crystals are surface treated and then used again as seed crystals.

[0090] The obtained P-type silicon carbide crystal has no facet dislocation, the BPD is in the [11-20] direction, the BPD angle is less than 30°, and the BPD density is ≤10cm -2 , BPD spacing ≥ 0.1 mm, in-plane density variation ≤ 10%, (0004) plane rocking curve half-height width less than 20 arcsec, in-plane average deviation < 3 arcsec, base plane deviation angle < 0.2°. Al doping concentration ≥ 1E20 cm -3 , resistivity ≤≤0.1Ω·cm. Raman spectrum LOPC mode half-height width is 13~15cm -1 .

[0091] Example 2

[0092] The growth equipment of low basal plane dislocation density P-type silicon carbide crystal comprises a crucible, a heat preservation material, a heating coil, a crucible support shaft, a water cooling shaft, a seed crystal shaft 1, a seed crystal holder 2 and a seed crystal 3. Figure 2 As shown, the seed crystal shaft 1 is connected to the seed crystal holder 2; the seed crystal holder 2 is a concave structure, and the side wall is provided with a first connection structure 21 for connecting the seed crystal 3; the seed crystal 3 is a convex structure composed of an upper boss 31 and a lower cone 32, the diameter of the upper boss 31 is smaller than the lower cone 32, and the side wall of the upper boss 31 is provided with a second connection structure 33 that cooperates with the first connection structure 21. The thickness of the seed crystal 3 is 5mm. The first connection structure 21 is two symmetrical positioning pins integrated with the seed crystal holder 2, and the material of the first connection structure 21 and the seed crystal holder 2 is silicon carbide. The second connection structure 33 is two symmetrical positioning holes, and the positioning pins extend into the positioning holes to realize the connection between the seed crystal holder 2 and the seed crystal 3.

[0093] The growth of low basal plane dislocation density P-type silicon carbide crystals using the above equipment is performed as follows:

[0094] Put raw materials (Si, Cr, Al) into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft;

[0095] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0096] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0097] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0098] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0099] The separated seed crystals are surface treated and then used again as seed crystals.

[0100] The obtained P-type silicon carbide crystal has no facet dislocation, the BPD is in the [11-20] direction, the BPD angle is less than 40°, and the BPD density is ≤20cm -2 , BPD spacing ≥ 0.1mm, in-plane density variation ≤ 10%, (0004) plane rocking curve half-height width less than 20arcsec, in-plane average deviation < 3arcsec, base plane deviation angle < 0.2°. Al doping concentration ≥ 9E19 cm -3 , resistivity ≤ 0.2Ω·cm. Raman spectrum LOPC mode half-width is 13~15cm -1 .

[0101] Example 3

[0102] The growth equipment of low basal plane dislocation density P-type silicon carbide crystal comprises a crucible, a heat preservation material, a heating coil, a crucible support shaft, a water cooling shaft, a seed crystal shaft 1, a seed crystal holder 2 and a seed crystal 3. Figure 3 As shown, the seed crystal shaft 1 is connected to the seed crystal holder 2; the seed crystal holder 2 is a concave structure, and the side wall is provided with a first connection structure 21 for connecting the seed crystal 3; the seed crystal 3 is a convex structure composed of an upper boss 31 and a lower cone 32, the diameter of the upper boss 31 is smaller than the lower cone 32, and the side wall of the upper boss 31 is provided with a second connection structure 33 that cooperates with the first connection structure 21. The material of the seed crystal holder 2 is graphite. The thickness of the seed crystal 3 is 5mm. The first connection structure 21 is a groove opened on the inner side of the side wall of the seed crystal holder 2. The second connection structure 33 is a second positioning ring, and the second positioning ring extends into the positioning groove to realize the connection between the seed crystal holder 2 and the seed crystal 3.

[0103] The growth of low basal plane dislocation density P-type silicon carbide crystals using the above equipment is performed as follows:

[0104] Put raw materials (Si, Cr, Al) into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft;

[0105] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0106] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0107] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0108] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0109] The separated seed crystals are surface treated and then used again as seed crystals.

[0110] The obtained P-type silicon carbide crystal has no facet dislocation, the BPD is in the [11-20] direction, the BPD angle is less than 50°, and the BPD density is ≤30cm -2 , BPD spacing ≥ 0.1mm, in-plane density variation ≤ 10%, (0004) plane rocking curve half-height width less than 20arcsec, in-plane average deviation < 3arcsec, base plane deviation angle < 0.2°. Al doping concentration ≥ 7E19 cm -3 , resistivity ≤ 0.3Ω·cm. Raman spectrum LOPC mode half-width is 12~14cm -1 .

[0111] Example 4

[0112] The growth equipment of low basal plane dislocation density P-type silicon carbide crystal comprises a crucible, a heat preservation material, a heating coil, a crucible support shaft, a water cooling shaft, a seed crystal shaft 1, a seed crystal holder 2 and a seed crystal 3. Figure 4 As shown, the seed crystal shaft 1 is connected to the seed crystal holder 2; the seed crystal holder 2 is a concave structure, and the side wall is provided with a first connection structure 21 for connecting the seed crystal 3; the seed crystal 3 is a convex structure composed of an upper boss 31 and a lower truncated cone 32, the diameter of the upper boss 31 is smaller than the lower truncated cone 32, and the side wall of the upper boss 31 is provided with a second connection structure 33 matched with the first connection structure 21. The thickness of the seed crystal 3 is 5mm. The material of the seed crystal holder 2 is graphite. The first connection structure 21 is an external thread, and the second connection structure 33 is an internal thread, so as to realize the connection between the seed crystal holder 2 and the seed crystal 3.

[0113] The growth of low basal plane dislocation density P-type silicon carbide crystals using the above equipment is performed as follows:

[0114] Put raw materials (Si, Cr, Al) into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft;

[0115] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0116] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0117] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0118] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0119] The separated seed crystals are surface treated and then used again as seed crystals.

[0120] The obtained P-type silicon carbide crystal has no facet dislocation, the BPD is in the [11-20] direction, the BPD angle is less than 60°, and the BPD density is ≤50cm -2 , BPD spacing ≥ 0.1 mm, in-plane density variation ≤ 10%, (0004) plane rocking curve half-height width less than 20 arcsec, in-plane average deviation < 3 arcsec, base plane deviation angle < 0.2°. Al doping concentration ≥ 5E19 cm -3 , resistivity ≤ 0.5Ω·cm. Raman spectrum LOPC mode half-width is 10~12cm -1 . .

[0121] Comparative Example 1

[0122] The growth equipment of P-type silicon carbide crystal includes a crucible, a heat preservation material, a heating coil, a crucible support shaft, a water cooling shaft, a seed crystal shaft 1, a seed crystal holder 2 and a seed crystal 3. Figure 5 As shown, the seed crystal shaft 1 is connected to the seed crystal holder 2; the seed crystal holder 2 is a concave structure, and the side wall is provided with a first connection structure 21 for connecting the seed crystal 3; the seed crystal 3 is cylindrical, and the side wall is provided with a second connection structure 33 that cooperates with the first connection structure 21. The thickness of the seed crystal 3 is 5mm. The first connection structure 21 is two symmetrical positioning pins integrated with the seed crystal holder 2, and the material of the first connection structure 21 and the seed crystal holder 2 is graphite. The second connection structure 33 is two symmetrical positioning holes, and the positioning pins extend into the positioning holes to realize the connection between the seed crystal holder 2 and the seed crystal 3.

[0123] The growth of P-type silicon carbide crystals using the above equipment is carried out in the following steps:

[0124] Put raw materials (Si, Cr, Al) into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft;

[0125] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0126] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0127] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0128] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0129] The separated seed crystals are surface treated and then used again as seed crystals.

[0130] The obtained p-type silicon carbide crystal BPD density is ≥50cm -2 , Al doping concentration ≥ 1E19cm -3 , resistivity ≥ 0.5Ω·cm, rocking curve half-width greater than 20arcsec, and in-plane average deviation greater than 3arcsec.

[0131] Comparative Example 2

[0132] The growth equipment of P-type silicon carbide crystal includes a crucible, a heat preservation material, a heating coil, a crucible supporting shaft, a water cooling shaft, a seed crystal shaft 1 and a seed crystal 3. Figure 6 As shown, the seed crystal shaft 1 is bonded to the seed crystal shaft 3; the seed crystal 3 is a convex structure composed of an upper boss 31 and a lower truncated cone 32, and the diameter of the upper boss 31 is smaller than that of the lower truncated cone 32. The thickness of the seed crystal 3 is 5 mm. The seed crystal shaft 1 is a graphite shaft.

[0133] The growth of P-type silicon carbide crystals using the above equipment is carried out in the following steps:

[0134] Put raw materials (Si, Cr, Al) into a graphite crucible, connect the seed crystal to the seed crystal axis, and then connect the seed crystal axis to the water-cooled axis;

[0135] After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature;

[0136] Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal;

[0137] After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled;

[0138] After the crystal is taken out, the grown crystal is separated from the seed crystal;

[0139] The separated seed crystals are surface treated and then used again as seed crystals.

[0140] The obtained P-type silicon carbide crystal BPD density is ≥50cm -2 , Al doping concentration ≥ 1E19cm -3 , resistivity ≥ 0.5Ω·cm, rocking curve half-width greater than 20arcsec, and in-plane average deviation greater than 3arcsec.

[0141] 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 basal plane dislocation density P-type silicon carbide crystal, characterized in that: The low basal plane dislocation density P-type silicon carbide crystal has no prism dislocation, the BPD presents a [11-20] direction, the BPD angle is less than 60°, and the BPD density is ≤50cm -2 , BPD spacing ≥ 0.1mm, in-plane density change rate ≤ 10%.

2. The low basal plane dislocation density P-type silicon carbide crystal according to claim 1, characterized in that: The rocking curve half-width of the (0004) plane of the low basal plane dislocation density P-type silicon carbide crystal is less than 20 arcsec, the average deviation in the plane is less than 3 arcsec, and the basal plane deviation angle is less than 0.2°; the half-width of the Raman spectrum longitudinal optical phonon and plasmon coupling mode is 10-17 cm -1 .

3. The low basal plane dislocation density P-type silicon carbide crystal according to claim 1, characterized in that: Al doping concentration ≥ 5E19 cm -3 , resistivity ≤0.5Ω·cm.

4. The low basal plane dislocation density P-type silicon carbide crystal according to claim 1, characterized in that: The size of the low basal plane dislocation density P-type silicon carbide crystal is 2 to 12 inches, and the crystal type includes 4H-SiC, 3C-SiC or 6H-SiC.

5. A growth device for low basal plane dislocation density P-type silicon carbide crystal, characterized in that: A method for growing a low basal plane dislocation density P-type silicon carbide crystal as claimed in any one of claims 1 to 4, comprising a crucible, a heat-insulating material, a heating coil, a crucible support shaft, a water-cooled shaft, a seed crystal shaft, a seed crystal holder and a seed crystal; The seed crystal holder is a concave structure, and the side wall is provided with a first connection structure for connecting the seed crystal; The seed crystal is a convex structure consisting of an upper boss and a lower truncated cone. The diameter of the upper boss is smaller than that of the lower truncated cone. The side wall of the upper boss is provided with a second connection structure that cooperates with the first connection structure.

6. The growth device according to claim 5, characterized in that The first connection structure includes a positioning pin, a first positioning plate or a first positioning ring, the first connection structure is integrated with the seed crystal holder or connected via a detachable connection piece, and the first connection structure and the detachable connection piece are made of silicon carbide; When the first connecting structure is a positioning pin, the second connecting structure is a positioning hole; When the first connection structure is a first positioning plate or a first positioning ring, the second connection structure is a positioning groove.

7. The growth device according to claim 5, characterized in that The first connection structure includes an internal thread, an external thread or a groove provided inside the side wall of the seed crystal holder; When the first connection structure is an internal thread, the second connection structure is an external thread; When the first connection structure is an external thread, the second connection structure is an internal thread; When the first connection structure is a groove, the second connection structure is a second positioning plate or a second positioning ring.

8. The growth device according to claim 5, characterized in that The seed crystal holder is made of graphite or silicon carbide, and the thickness of the seed crystal is ≥3 mm.

9. A method for growing a low basal plane dislocation density P-type silicon carbide crystal, characterized in that: Using the growth device according to any one of claims 5 to 8 comprises the following steps: Put the raw materials into the graphite crucible, connect the seed crystal to the seed crystal holder, and then connect the seed crystal shaft to the water-cooled shaft; After evacuating the vacuum chamber, an inert gas is filled into the growth chamber, the raw material is heated to melt, and the temperature is continued to rise to a predetermined growth temperature; Lowering the crystal to the surface of the solution, and pulling the crystal to form a meniscus after contacting the surface of the solution, so as to grow the crystal; After the crystal growth is completed, the water-cooled shaft is pulled until the crystal is separated from the solution and cooled; After the crystal is taken out, the grown crystal is separated from the seed crystal; The separated seed crystals are surface treated and then used again as seed crystals.

10. A P-type silicon carbide substrate with low basal plane dislocation density, characterized in that: The method is obtained by processing the low basal plane dislocation density P-type silicon carbide crystal as claimed in any one of claims 1 to 4.

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