CN102618930B - A kind of preparation method of AlN crystal - Google Patents

Abstract

A method for preparing AlN crystals relates to a method for preparing crystals. The present invention aims to solve the problem that in the existing method for preparing AlN single crystal by using the PVT method, the lattice mismatch between the heterogeneous seed crystal and the AlN crystal is relatively large, and the obtained AlN crystal has a high defect density. Method: 1. Put the AlN powder in the crucible, fix the seed crystal on the top of the crucible, raise the temperature to 1800-2000°C in a nitrogen atmosphere, and keep it warm for 1-5 hours; 2. Put the pre-sintered AlN powder in a nitrogen atmosphere Heating in medium temperature to 2150-2300°C, keeping it warm for 8-20 hours, and cooling down to room temperature. Zero-micropipe SiC as a heterogeneous seed can reduce the defect density of AlN crystals, and at the same time due to the off-angle SiC seed deviates from At a certain angle, the probability of defect inheritance will also be significantly reduced, thereby ultimately reducing the adverse effects of defects on device performance. The AlN crystal of the present invention is used in semiconductor devices.

Description

A kind of preparation method of AlN crystal

technical field

The invention relates to a method for preparing crystals.

Background technique

AlN crystal is one of the typical representatives of the third-generation semiconductor materials, with wide bandgap (6.2eV), high thermal conductivity (330W/m K), high resistivity, good ultraviolet transmittance, high electron saturation mobility and Higher radiation resistance, so it is more suitable for the manufacture of high temperature, high frequency, radiation resistance and high power devices, such as high energy efficiency optoelectronic devices, high power electronic devices, solid state laser detectors, high density solid state memory and so on.

Currently, methods for growing AlN crystals mainly include: hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE), metal organic vapor phase epitaxy (MOCVD) and physical vapor transport (PVT). The HVPE method has a high growth rate (up to 100 μm/h), has the self-cleaning effect of impurities, and can prepare AlN films with a large thickness; the MBE method has a slow growth rate (about 1 μm/h), and the growth process is easy to control. This technology can prepare AlN single crystal thin films with dozens of atomic layers; the MOCVD method has low deposition temperature and wide growth temperature range, which is suitable for mass production. AlN thin films can be prepared by this method; Evaporate in the low temperature zone, use the diffusion of steam and the transport of gas phase, and grow into crystals in the low temperature zone. Using this method, the crystal raw material can be used to nucleate spontaneously to grow a single crystal, and the seed crystal can also be used to sublimate the crystal raw material and deposit it on the seed crystal to grow a single crystal. The PVT method has the advantages of fast growth rate and good crystal integrity. A large number of studies have proved that the PVT method is one of the most effective ways to prepare large-sized AlN crystals.

In general, PVT growth of AlN crystals requires selection of a suitable seed crystal, which should take into account the lattice matching between the seed crystal and the AlN crystal (wurtzite structure: ), thermal matching (thermal expansion coefficient α _a =4.15x10 ^-6 /K, α _c =5.27×10 ^-6 /K) and other factors. Obviously, using AlN as a homogeneous seed crystal to grow AlN single crystal will achieve a very ideal effect, because there is no lattice mismatch and thermal mismatch between the two. However, the research on AlN single crystals by relevant domestic and foreign institutions is still in the laboratory exploration stage. Only a few institutions such as Crystal IS in the United States and N-Crystals in Russia can prepare AlN single crystals with a diameter of 2 inches. Therefore, it is necessary to grow AlN crystals with heterogeneous seeds. A large number of studies have proved that AlN thin films or AlN bulk single crystals can be prepared using single crystal silicon, sapphire, and silicon carbide as substrates or seed crystals. Among them, single crystal silicon belongs to the diamond structure, which has a large lattice mismatch with AlN, and its thermal expansion coefficient (α=2.59×10 ^-6 K) is also quite different from AlN; sapphire has a wurtzite structure ( ), thermal expansion coefficient (α _a =8.5x10 ^-6 /K, α _c =7.3×10 ^-6 /K) and AlN also have large lattice mismatch and thermal mismatch; silicon carbide (6H-SiC) Cell parameters( ), thermal expansion coefficient (α _a =4.3×10 ^-6 /K, α _c =4.7×10 ^-6 /K) are relatively close to AlN. In comparison, SiC is more conducive to the growth of AlN crystals, and can be used as a seed crystal material for growing AlN crystals by PVT method.

At the same time, since there is a certain lattice mismatch and thermal mismatch between the SiC seed crystal and AlN, this unfavorable factor can be greatly alleviated by epitaxially growing an AlN buffer layer on the SiC substrate. The SiC/AlN composite seed crystal is prepared by epitaxially growing an AlN buffer layer on a SiC substrate by metal-organic chemical vapor deposition (MOCVD).

CN102046857A discloses a method for producing AlN bulk single crystals; the method is specifically disclosed as follows: a step of providing AlN bulk single crystals by growing AlN single crystals on the surface of a hexagonal single crystal material serving as a seed crystal by using a sublimation method, The surface is a crystal plane inclined at an angle of 10° to 80° relative to the C plane; the hexagonal single crystal material is AlN, SiC, GaN or ZnO; the hexagonal single crystal is a SiC substrate and the SiC substrate The surface is the (01-15) plane; the growth plane of the provided AlN bulk single crystal is the (10-12) plane.

Contents of the invention

The purpose of the present invention is to solve the problem that in the existing method of preparing AlN single crystal by physical vapor transport (PVT), when heterogeneous seed crystals are used, the lattice mismatch between heterogeneous seed crystals and AlN crystals is large, and the obtained AlN To solve the problem of high density of crystal defects, the present invention provides a method for preparing AlN crystals.

The present invention adopts physical vapor transport method to prepare AlN single crystal, and the preparation method of AlN crystal is realized through the following steps:

1. Put the AlN powder in the crucible, and then fix the seed crystal on the top of the crucible. The distance between the seed crystal and the AlN powder is not more than 10mm, and then put the crucible in the single crystal growth furnace, and pass nitrogen gas into the crucible. Under a nitrogen atmosphere of 1 atmospheric pressure, heat up to 1800°C to 2000°C at a heating rate of 50°C/h to 200°C/h, and keep it warm for 1 to 5 hours to complete the pre-sintering of the AlN powder;

2. Heat the pre-sintered AlN powder in the crucible to 2150°C to 2500°C at a heating rate of 50°C/h to 200°C/h under a high-purity nitrogen atmosphere of 1 atmosphere pressure, and perform a heat preservation reaction for 8~ 20 hours, and then lowered to room temperature at a cooling rate of 50°C/h to 200°C/h to obtain AlN crystals;

The seed crystal described in step 1 is a zero micropipe off-angle SiC seed crystal or a SiC/AlN composite seed crystal, wherein the crystal form of the zero micropipe off-angle SiC seed crystal is 6H-, and the off-angle means that SiC deviates from The angle of the surface is 0°～8°.

The physical vapor transport method described in the preparation method of the AlN crystal of the present invention is common knowledge of those skilled in the art. A crystal growth furnace known to those skilled in the art can be used.

The preparation method of the AlN crystal of the present invention adopts the physical vapor phase transport method to prepare the AlN crystal, by placing the AlN powder on the bottom of the crucible, placing the seed crystal on the top of the crucible, first gradually raising the temperature for pre-sintering, removing the impurities of the AlN powder, and then using the pre-treated The sintered AlN powder is used as the starting material, under a certain pressure of nitrogen atmosphere, the temperature is raised, and the AlN crystal is deposited on the seed crystal through the sublimation of the AlN powder and the transport of the gas phase. The prepared AlN crystal has excellent characteristics such as low defect density and large diameter span, and the AlN crystal is applied to various types of semiconductor devices.

SiC is one of the most mature third-generation semiconductor materials. SiC crystals with large sizes (2, 3, and 4 inches) and low defect density (zero micropipes) have been industrialized. Using zero micropipe off-angle SiC seed crystal or SiC/AlN composite seed crystal to grow AlN crystal will help to obtain high-quality AlN crystal, which is shown in: 1. Micropipe defect is a typical defect of SiC crystal. During the AlN crystal growth process of the seed crystal, the SiC seed crystal with micropipe defects will cause crystal defects such as dislocations and stacking faults in the AlN crystal, which seriously affects the quality of the AlN crystal. Therefore, if SiC with zero micropipes is selected as the seed crystal, it can Effectively reduce the defect density of AlN crystal. 2. Using a zero micropipe SiC seed, the If the AlN crystal is grown on the surface, the defects (such as dislocations, stacking faults, etc.) in the SiC seed crystal will be largely inherited to the AlN crystal along the growth plane. If the SiC seed crystal deviates from If the surface is at a certain angle (ranging from 0-8°), the probability of defect inheritance will be significantly reduced, so that the quality of AlN crystals will be further improved. 3. The SiC/AlN composite seed crystal prepared from SiC seed crystal with zero micropipe and off-angle, its AlN buffer layer will effectively alleviate the thermal mismatch and lattice mismatch between SiC and AlN, which is beneficial to reduce the defects of AlN crystal density.

The AlN crystal prepared by the invention is applied to various types of semiconductor devices.

Description of drawings

Fig. 1 is the schematic diagram of the test device used in the present invention, wherein 1 is the outer wall of the reaction chamber, 2 is the induction coil, 3 is the insulation material, 4 is the crucible, 5 is the ALN powder, and 6 is the seed crystal.

Detailed ways

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific implementation mode 1: The preparation method of AlN crystal in this implementation mode is realized through the following steps:

1. Put the AlN powder in the crucible, and then fix the seed crystal on the top of the crucible. The distance between the seed crystal and the AlN powder is not more than 10mm, and then put the crucible in the single crystal growth furnace, and pass nitrogen gas into the crucible. Under a nitrogen atmosphere of 1 atmospheric pressure, heat up to 1800°C to 2000°C at a heating rate of 50°C/h to 200°C/h, and keep it warm for 1 to 5 hours to complete the pre-sintering of the AlN powder;

2. Heat the pre-sintered AlN powder in the crucible to 2150°C to 2500°C at a heating rate of 50°C/h to 200°C/h under a high-purity nitrogen atmosphere of 1 atmosphere pressure, and perform a heat preservation reaction for 8~ 20 hours, and then lowered to room temperature at a cooling rate of 50°C/h to 200°C/h to obtain AlN crystals;

The seed crystal described in step 1 is a zero micropipe off-angle SiC seed crystal or a SiC/AlN composite seed crystal, wherein the crystal form of the zero micropipe off-angle SiC seed crystal is 6H-, and the off-angle means that SiC deviates from The angle of the surface is 0°～8°.

SiC is one of the most mature third-generation semiconductor materials. SiC crystals with large sizes (2, 3, and 4 inches) and low defect density (zero micropipes) have been industrialized. In this embodiment, using zero micropipe off-angle SiC seed crystals or SiC/AlN composite seed crystals to grow AlN crystals will help to obtain high-quality AlN crystals, which will be beneficial to obtain high-quality AlN crystals, which are shown in: 1 .Micropipe defects are typical defects of SiC crystals. During the growth process of AlN crystals with SiC as seeds, SiC seed crystals with micropipe defects will cause crystal defects such as dislocations and stacking faults in AlN crystals, which seriously affect AlN crystals. Therefore, if SiC with zero micropipes is selected as the seed crystal, the defect density of AlN crystal can be effectively reduced. 2. Using a zero micropipe SiC seed, the If the AlN crystal is grown on the surface, the defects (such as dislocations, stacking faults, etc.) in the SiC seed crystal will be largely inherited to the AlN crystal along the growth plane. If the SiC seed crystal deviates from If the surface is at a certain angle (ranging from 0-8°), the probability of defect inheritance will be significantly reduced, so that the quality of AlN crystals will be further improved. 3. The SiC/AlN composite seed crystal prepared from the SiC seed crystal with zero micropipe off-angle, its AlN buffer layer will effectively alleviate the thermal mismatch and lattice mismatch between SiC and AlN, which is beneficial to reduce the defect density of AlN crystal .

Embodiment 2: This embodiment is different from Embodiment 1 in that: in step 1, the distance between the seed crystal and the AlN powder is controlled to be 5-9 mm. Others are different from the first embodiment.

Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that in Step 1, the SiC/AlN composite seed crystal is epitaxially grown AlN on a SiC substrate with zero micropipe off-angle by metal-organic chemical vapor deposition. The buffer layer is prepared. Others are the same as in the first or second embodiment.

Embodiment 4: This embodiment is different from Embodiment 1 to Embodiment 3 in that: the diameter of the seed crystal in step 1 is 1 inch, 2 inches or 3 inches. Others are the same as those in the first to third specific embodiments.

Specific embodiment five: the difference between this embodiment and one of the specific embodiments one to four is: the off angle of SiC with zero micropipe off angle described in step one refers to the deviation of SiC from 4 ° ~ 6 ° angle. Others are the same as one of the specific embodiments 1 to 4.

Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is that the zero micropipe deviation angle SiC deviation angle in step 1 refers to the deviation of SiC from 8° angle. Others are the same as one of the specific embodiments 1 to 5.

Embodiment 7: This embodiment is different from Embodiment 1 to Embodiment 6 in that: in step 2, the temperature is raised to 2200° C. to 2450° C., and the heat preservation reaction is carried out for 8 to 20 hours. Others are the same as one of the specific embodiments 1 to 6.

Embodiment 8: This embodiment differs from Embodiments 1 to 7 in that: in step 2, the temperature is raised to 2250° C. to 2400° C. for heat preservation reaction for 8 to 20 hours. Others are the same as one of the specific embodiments 1 to 7.

Embodiment 9: This embodiment is different from Embodiment 1 to Embodiment 8 in that: in step 2, the temperature is raised to 2300° C., and the heat preservation reaction is carried out for 8 to 20 hours. Others are the same as one of the specific embodiments 1 to 8.

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one:

The preparation method of AlN crystal in this embodiment is realized through the following steps:

1. Put 200g of AlN powder 5 at the bottom of the crucible 4, fix the seed crystal 6 on the top of the crucible 4 with epoxy AB glue, the distance between the seed crystal and the AlN powder is 5mm, and then put the crucible 4 in the single crystal growth furnace, Introduce high-purity nitrogen gas into the crucible 4, and heat up to 1800°C at a heating rate of 100°C/h under a nitrogen atmosphere of 1 atmosphere pressure, and heat it for 2 hours to complete the pre-sintering of the AlN powder; The above-mentioned seed crystal is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 1°;

2. Heat the pre-sintered AlN powder in the crucible to 2200°C at a heating rate of 100°C/h under a high-purity nitrogen atmosphere of 1 atmosphere pressure, and carry out a heat preservation reaction for 10 hours, and then heat it at a temperature of 100°C/h. The cooling rate is lowered to room temperature to obtain AlN crystals.

The volume percent purity of the high-purity nitrogen gas in this example is 99.999%, and the raw materials used are all commercially available products.

Embodiment two:

The preparation method of AlN crystal in this embodiment is realized through the following steps:

1. Place 200g of AlN powder 5 at the bottom of the crucible 4, fix the seed crystal 6 on the top of the crucible 4 with epoxy AB glue, the distance between the seed crystal and the AlN powder is 8mm, and then put the crucible 4 in the single crystal growth furnace, Introduce high-purity nitrogen gas into the crucible 4, and heat up to 1900°C at a heating rate of 50°C/h under a nitrogen atmosphere of 1 atmosphere pressure, and heat it for 2 hours to complete the pre-sintering of the AlN powder; The above-mentioned seed crystal is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 1°;

2. Heat the pre-sintered AlN powder in the crucible to 2250°C at a heating rate of 50°C/h under a high-purity nitrogen atmosphere of 1 atmosphere pressure, and conduct a heat preservation reaction for 8 hours, and then heat it at a temperature of 50°C/h The cooling rate is lowered to room temperature to obtain AlN crystals.

The volume percent purity of the high-purity nitrogen gas in this example is 99.999%, and the raw materials used are all commercially available products.

Embodiment three:

The preparation method of AlN crystal in this embodiment is realized through the following steps:

1. Put 200g of AlN powder 5 at the bottom of the crucible 4, fix the seed crystal 6 on the top of the crucible 4 with epoxy AB glue, the distance between the seed crystal and the AlN powder is 5mm, and then put the crucible 4 in the single crystal growth furnace, Introduce high-purity nitrogen into the crucible 4, and heat up to 2000°C at a heating rate of 150°C/h under a nitrogen atmosphere of 1 atmospheric pressure, and keep it warm for 1 hour to complete the pre-sintering of the AlN powder; The above-mentioned seed crystal is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 1°;

2. Heat the pre-sintered AlN powder in the crucible to 2500°C at a heating rate of 150°C/h under a high-purity nitrogen atmosphere of 1 atmosphere pressure, and conduct a heat preservation reaction for 8 hours. The cooling rate is lowered to room temperature to obtain AlN crystals.

The volume percent purity of the high-purity nitrogen gas in this example is 99.999%, and the raw materials used are all commercially available products.

Embodiment four:

The preparation method of AlN crystal in this embodiment is realized through the following steps:

1. Put 200g of AlN powder 5 on the bottom of the crucible 4, fix the seed crystal 6 on the top of the crucible 4 with epoxy AB glue, the distance between the seed crystal and the AlN powder is 6mm, and then put the crucible 4 in the single crystal growth furnace, Introduce high-purity nitrogen into the crucible 4, and heat up to 2000°C at a heating rate of 150°C/h under a nitrogen atmosphere of 1 atmospheric pressure, and keep it warm for 2 hours to complete the pre-sintering of the AlN powder; The above-mentioned seed crystal is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 2°;

2. Heat the pre-sintered AlN powder in the crucible to 2400°C at a heating rate of 150°C/h under a high-purity nitrogen atmosphere of 1 atmosphere pressure, and carry out a heat preservation reaction for 8 hours, and then heat it at a temperature of 150°C/h. The cooling rate is lowered to room temperature to obtain AlN crystals.

The volume percent purity of the high-purity nitrogen gas in this example is 99.999%, and the raw materials used are all commercially available products.

Embodiment five:

The preparation method of AlN crystal in this embodiment is realized through the following steps:

1. Place 200g of AlN powder 5 at the bottom of the crucible 4, fix the seed crystal 6 on the top of the crucible 4 with epoxy AB glue, the distance between the seed crystal and the AlN powder is 3 mm, and then put the crucible 4 in the single crystal growth furnace, Introduce high-purity nitrogen gas into the crucible 4, and heat up to 1900°C at a heating rate of 150°C/h under a nitrogen atmosphere of 1 atmosphere pressure, and keep it warm for 2 hours to complete the pre-sintering of AlN powder, in which the seed crystal The distance from the AlN powder is 0-10 mm; the seed crystal described in step 1 is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 3.4°;

2. Heat the pre-sintered AlN powder in the crucible to 2300°C at a heating rate of 150°C/h under a high-purity nitrogen atmosphere of 1 atmosphere pressure, and carry out a heat preservation reaction for 12 hours. The cooling rate is lowered to room temperature to obtain AlN crystals.

The volume percent purity of the high-purity nitrogen gas in this example is 99.999%, and the raw materials used are all commercially available products.

Embodiment six:

The difference between this embodiment and Embodiment 5 is that the seed crystal described in step 1 is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Surface 3.5 °, others are identical with embodiment five.

Embodiment seven:

The difference between this embodiment and Embodiment 5 is that the seed crystal described in step 1 is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 4 °, other is identical with embodiment five.

Embodiment eight:

The difference between this embodiment and Embodiment 5 is that the seed crystal described in step 1 is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 6.5 °, others are identical with embodiment five.

Embodiment nine:

The difference between this embodiment and Embodiment 5 is that the seed crystal described in step 1 is a zero micropipe 6H-SiC seed crystal with a diameter of 2 inches, and the SiC deviates from Face 8 °, other is identical with embodiment five.

In the above-mentioned embodiment, using zero micropipe off-angle SiC seed crystal to grow AlN crystal will help to obtain high-quality AlN crystal, which is shown in: 1. Micropipe defect is a typical defect of SiC crystal, when SiC is used as seed crystal During the AlN crystal growth process, the SiC seed crystal with micropipe defects will cause crystal defects such as dislocations and stacking faults in the AlN crystal, which will seriously affect the quality of the AlN crystal. Therefore, if SiC with zero micropipes is selected as the seed crystal, it can effectively Reduce the defect density of AlN crystals. 2. Using a zero micropipe SiC seed, the If the AlN crystal is grown on the surface, the defects (such as dislocations, stacking faults, etc.) in the SiC seed crystal will be largely inherited to the AlN crystal along the growth plane. If the SiC seed crystal deviates from If the surface is at a certain angle (ranging from 0-8°), the probability of defect inheritance will be significantly reduced, so that the quality of AlN crystals will be further improved.

Embodiment ten:

The difference between this embodiment and Embodiment 5 is that the seed crystal described in step 1 is a zero-micropipe 6H-SiC/AlN composite seed crystal with a diameter of 1 inch, and the SiC deviates from Face 4°, the zero micropipe 6H-SiC/AlN composite seed crystal in this embodiment is prepared by epitaxially growing an AlN buffer layer on the zero micropipe 6H-SiC substrate by metal organic chemical vapor deposition (MOCVD). Others are the same as in Embodiment five.

Embodiment eleven:

The difference between the present embodiment and the fifth embodiment is that the seed crystal described in step 1 is a zero micropipe 6H-SiC/AlN composite seed crystal with a diameter of 2 inches, and the SiC deviates from 8°, the zero micropipe 6H-SiC/AlN composite seed crystal in this embodiment is prepared by epitaxially growing an AlN buffer layer on the zero micropipe 6H-SiC substrate by metal organic chemical vapor deposition (MOCVD). Others are the same as in Embodiment five.

Embodiment 12:

The difference between this embodiment and Embodiment 5 is that the seed crystal described in step 1 is a zero micropipe 6H-SiC/AlN composite seed crystal with a diameter of 3 inches, and the SiC deviates from 8°, the zero micropipe 6H-SiC/AlN composite seed crystal in this embodiment is prepared by epitaxially growing an AlN buffer layer on the zero micropipe 6H-SiC substrate by metal organic chemical vapor deposition (MOCVD). Others are the same as in Embodiment five.

In the above examples, the use of SiC/AlN composite seed crystals to grow AlN crystals will help to obtain high-quality AlN crystals. The SiC/AlN composite seed crystals prepared from SiC seed crystals with zero micropipes and off-angles have AlN buffer The layer will effectively alleviate the thermal mismatch and lattice mismatch between SiC and AlN, which is beneficial to reduce the defect density of AlN crystal.

Claims (4)

1. a preparation method for AlN crystal, adopts physical vapor transport to prepare AlN monocrystalline, it is characterized in that the preparation method of AlN crystal is realized by following steps:

One, AlN powder is placed in crucible, then seed crystal is fixed on crucible top, the distance of seed crystal and AlN powder is 5 ~ 9mm, again crucible is put in monocrystal growing furnace, in crucible, passes into nitrogen, under 1 atmospheric nitrogen atmosphere, with the temperature rise rate of 50 DEG C/h ~ 200 DEG C/h, be heated to 1800 DEG C ~ 2000 DEG C, and be incubated 1 ~ 5 hour, complete the presintering of AlN powder;

Two, by the AlN powder after presintering in crucible under 1 atmospheric high pure nitrogen atmosphere, with the temperature rise rate of 50 DEG C/h ~ 200 DEG C/h, be heated to 2200 DEG C ~ 2450 DEG C, carry out insulation reaction 8 ~ 20 hours, again with the rate of temperature fall of 50 DEG C/h ~ 200 DEG C/h, be down to room temperature, obtain AlN crystal;

Seed crystal described in step one is SiC/AlN compound seed crystal, wherein said SiC/AlN compound seed crystal is by metal-organic chemical vapor deposition equipment method, be prepared from zero microtubule inclination angle SiC substrate Epitaxial growth AlN buffer layer, and the crystal formation of zero described microtubule inclination angle SiC substrate is 6H-, inclination angle refers to that SiC departs from the angle that face is 4 ° ~ 6 °;

The diameter of seed crystal described in step one is 1 inch, 2 inches or 3 inches.

2. the preparation method of a kind of AlN crystal according to claim 1, is characterized in that the inclination angle of zero microtubule inclination angle SiC described in step one refers to that SiC departs from the angle of 8 °.

3. the preparation method of a kind of AlN crystal according to claim 1, is characterized in that being heated to 2250 DEG C ~ 2400 DEG C in step 2 carries out insulation reaction 8 ~ 20 hours.

4. the preparation method of a kind of AlN crystal according to claim 1, is characterized in that being heated to 2300 DEG C in step 2, carries out insulation reaction 8 ~ 20 hours.