A method for preparing aluminum nitride single crystal substrate

Abstract

The present invention relates to the technical field of ceramic materials, and in particular to a method for preparing an aluminum nitride single crystal substrate, comprising the following steps: S1: coating a copolymer on the surface of the aluminum nitride single crystal substrate to obtain a copolymer layer; S2: coating a crosslinked material on the surface of the copolymer layer to obtain a crosslinked material layer; S3: sputtering silver ions on the surface of the crosslinked material layer to obtain an aluminum nitride single crystal substrate. The present invention provides a method for preparing an aluminum nitride single crystal substrate, and the obtained aluminum nitride single crystal film layer has good crystal quality.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, and in particular to a method for preparing an aluminum nitride single crystal substrate. Background Art

[0002] The wide bandgap characteristics of the third-generation semiconductors give the devices based on them a series of advantages, such as high voltage resistance, breakdown resistance, radiation resistance, wide optical window, etc. It can be seen that the development of new wide bandgap semiconductors and even ultra-wide bandgap semiconductor materials will become an important factor in the further development of the electronics and device fields in the future. Aluminum nitride is called the next generation of ultra-wide bandgap semiconductors because of its bandgap width of up to 6.2eV. The deep ultraviolet band photodiodes based on it have already occupied a place in the field of sterilization and disinfection. Whether it can be further developed and applied to a wider range of power electronics and optoelectronics depends directly on the crystal quality of its materials. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a method for preparing an aluminum nitride single crystal substrate, and the obtained aluminum nitride single crystal film layer has good crystal quality.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for preparing an aluminum nitride single crystal substrate comprises the following steps:

[0006] S1: coating a copolymer on the surface of an aluminum nitride single crystal substrate to obtain a copolymer layer;

[0007] S2: coating a cross-linked material on the surface of the copolymer layer to obtain a cross-linked material layer;

[0008] S3: Silver ion sputtering is then performed on the surface of the cross-linked layer to obtain an aluminum nitride single crystal substrate.

[0009] Preferably, the step S3 further includes the following step: thinning the substrate from the side of the substrate away from the surface of the cross-linked material layer where the silver ion sputtering is performed.

[0010] Preferably, the preparation method of the copolymer specifically comprises the following steps:

[0011] Mix 10% by mass of ammonium persulfate, monomer acrylic acid and isopropanol, heat to 60-75°C, stir for 20 minutes, continue to heat to 80-90°C and stir for 1-2 hours, keep warm for 1 hour, and finally cool to room temperature to obtain a copolymer.

[0012] Preferably, the weight ratio of the ammonium persulfate, the monomer acrylic acid and the isopropyl alcohol is 5:1:2.

[0013] Preferably, the preparation method of the cross-linked product specifically comprises the following steps:

[0014] Dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile and octadecyl acrylate are reacted at 80°C for 4-6 hours, and then ethylene glycol diacrylate and copper oxide are added and reacted at 90°C for 1-2 hours to obtain a cross-linked product.

[0015] Preferably, the weight ratio of dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile, octadecyl acrylate, ethylene glycol diacrylate and copper oxide is 200:1:2:50:20:7:5:1.

[0016] Preferably, the silver ion sputtering in step S3 specifically includes the following steps: performing silver ion sputtering on the surface of the cross-linked layer by an ion sputtering instrument, with a current density of 40-50 mA / cm2 and a sputtering time of 1-3 min.

[0017] Preferably, the thinning process is specifically to thin the substrate by plasma bombardment.

[0018] Preferably, the energy of the plasma bombardment is 150-250 keV.

[0019] Preferably, after the thinning process, the thickness ratio of the single crystal substrate layer, the copolymer layer and the cross-linked layer is 2:1:1.

[0020] The copolymer layer and the cross-linked material layer of the present invention are added to achieve dense distribution on the substrate surface, so as to introduce molecular stress and reduce dislocation generation. Then, silver ions are sputtered to produce coupling effect to improve the crystal quality of the aluminum nitride single crystal film layer, and finally an aluminum nitride single crystal composite substrate with high crystal quality is obtained. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. In addition, it is specifically stated that the raw materials and equipment of the present invention can be obtained from commercial sources, and no longer listed one by one. Among them, the raw materials of the present invention can be obtained from commercial sources and are well known to those skilled in the art. Embodiment 1:

[0022] A method for preparing an aluminum nitride single crystal substrate comprises the following steps:

[0023] S1: coating a copolymer on the surface of an aluminum nitride single crystal substrate to obtain a copolymer layer, wherein the preparation method of the copolymer specifically comprises the following steps: mixing 10% by mass of ammonium persulfate, monomer acrylic acid and isopropanol in a weight ratio of 5:1:2, heating to 60°C, stirring at this temperature for 20 minutes, heating to 80°C and stirring for 1 hour, reacting at this temperature for 1 hour, and finally cooling to room temperature to obtain a copolymer;

[0024] S2: coating a crosslinked material on the surface of the copolymer layer to obtain a crosslinked material layer, wherein the preparation method of the crosslinked material specifically comprises the following steps: reacting dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile and octadecyl acrylate at 80°C for 4 hours, then adding ethylene glycol diacrylate and copper oxide, and reacting at 90°C for 1 hour to obtain a crosslinked material, wherein the weight ratio of dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile, octadecyl acrylate, ethylene glycol diacrylate and copper oxide is 200:1:2:50:20:7:5:1;

[0025] S3: silver ion sputtering is performed on the surface of the cross-linked layer by an ion sputtering instrument, with a current density of 40 mA / cm2 and a sputtering time of 1 min.

[0026] S4: The substrate is thinned by plasma bombardment from the side of the substrate away from the cross-linked layer surface where silver ions are sputtered, and the energy of the plasma bombardment is 150 keV, to obtain an aluminum nitride single crystal substrate, wherein the thickness ratio of the single crystal substrate layer, the copolymer layer and the cross-linked layer after the thinning treatment is 2:1:1, and the thickness of the substrate can be 500 μm. Embodiment 2:

[0027] A method for preparing an aluminum nitride single crystal substrate comprises the following steps:

[0028] S1: coating a copolymer on the surface of an aluminum nitride single crystal substrate to obtain a copolymer layer, wherein the preparation method of the copolymer specifically comprises the following steps: mixing 10% by mass of ammonium persulfate, monomer acrylic acid and isopropanol in a weight ratio of 5:1:2, heating to 75°C, stirring at this temperature for 20 minutes, heating to 90°C and stirring for 2 hours, reacting at this temperature for 1 hour, and finally cooling to room temperature to obtain a copolymer;

[0029] S2: coating a crosslinked material on the surface of the copolymer layer to obtain a crosslinked material layer, wherein the preparation method of the crosslinked material specifically comprises the following steps: reacting dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile and octadecyl acrylate at 80°C for 6 hours, then adding ethylene glycol diacrylate and copper oxide, and reacting at 90°C for 2 hours to obtain a crosslinked material, wherein the weight ratio of dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile, octadecyl acrylate, ethylene glycol diacrylate and copper oxide is 200:1:2:50:20:7:5:1;

[0030] S3: silver ion sputtering is performed on the surface of the cross-linked layer by an ion sputtering instrument, with a current density of 50 mA / cm2 and a sputtering time of 3 min.

[0031] S4: The substrate is thinned by plasma bombardment from the side of the substrate away from the cross-linked layer surface where silver ions are sputtered, and the energy of the plasma bombardment is 250 keV, to obtain an aluminum nitride single crystal substrate, wherein the thickness ratio of the single crystal substrate layer, the copolymer layer and the cross-linked layer after the thinning treatment is 2:1:1, and the thickness of the substrate can be 600 μm. Embodiment 3:

[0032] A method for preparing an aluminum nitride single crystal substrate comprises the following steps:

[0033] S1: coating a copolymer on the surface of an aluminum nitride single crystal substrate to obtain a copolymer layer, wherein the preparation method of the copolymer specifically comprises the following steps: mixing 10% by mass of ammonium persulfate, monomer acrylic acid and isopropanol in a weight ratio of 5:1:2, heating to 70°C, stirring at this temperature for 20 minutes, heating to 85°C and stirring for 1.5 hours, reacting at this temperature for 1 hour, and finally cooling to room temperature to obtain a copolymer;

[0034] S2: coating a crosslinked material on the surface of the copolymer layer to obtain a crosslinked material layer, wherein the preparation method of the crosslinked material specifically comprises the following steps: reacting dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile and octadecyl acrylate at 80°C for 5 hours, then adding ethylene glycol diacrylate and copper oxide, and reacting at 90°C for 1.5 hours to obtain a crosslinked material, wherein the weight ratio of dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile, octadecyl acrylate, ethylene glycol diacrylate and copper oxide is 200:1:2:50:20:7:5:1;

[0035] S3: silver ion sputtering is performed on the surface of the cross-linked layer by an ion sputtering apparatus, with a current density of 45 mA / cm2 and a sputtering time of 2 min.

[0036] S4: The substrate is thinned by plasma bombardment from the side of the substrate away from the cross-linked layer surface where silver ions are sputtered, and the energy of the plasma bombardment is 200 keV to obtain an aluminum nitride single crystal substrate, wherein the thickness ratio of the single crystal substrate layer, the copolymer layer and the cross-linked layer after the thinning treatment is 2:1:1, and the thickness of the substrate can be 550 μm.

[0037] Comparative Example 1:

[0038] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that no crosslinking layer coating and sputtering are performed, specifically:

[0039] A method for preparing an aluminum nitride single crystal substrate comprises the following steps:

[0040] S1: coating a copolymer on the surface of an aluminum nitride single crystal substrate to obtain a copolymer layer, wherein the preparation method of the copolymer specifically comprises the following steps: mixing 10% by mass of ammonium persulfate, monomer acrylic acid and isopropanol in a weight ratio of 5:1:2, heating to 60°C, stirring at this temperature for 20 minutes, heating to 80°C and stirring for 1 hour, reacting at this temperature for 1 hour, and finally cooling to room temperature to obtain a copolymer;

[0041] S2: The substrate is thinned by plasma bombardment from the side of the substrate away from the surface of the copolymer layer. The energy of the plasma bombardment is 150 keV to obtain an aluminum nitride single crystal substrate. The thickness ratio of the single crystal substrate layer and the copolymer layer after the thinning treatment is 2:1, and the thickness of the substrate can be 500 μm.

[0042] The following tests were conducted on Examples 1-3, the commercially available aluminum nitride single crystal substrate produced by Jingyue Semiconductor Co., Ltd., and the comparative example 1.

[0043] Performance Testing:

[0044] Bending strength: The bending strength was tested by the three-point bending strength method.

[0045] Crystalline rocking curve half-width: measured by X-ray diffraction rocking curve test.

[0046] Table 1: Test data of aluminum nitride single crystal substrates of Examples 1-3, commercially available single crystal substrates and Comparative Example 1

[0047]

[0048] It can be seen from the above table that the aluminum nitride substrates prepared in Examples 1-3 have higher strength and better crystal quality than those in the comparative example.

[0049] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an aluminum nitride single crystal substrate, characterized in that: The following steps are involved: S1: coating a copolymer on the surface of an aluminum nitride single crystal substrate to obtain a copolymer layer; S2: coating a cross-linked material on the surface of the copolymer layer to obtain a cross-linked material layer; S3: performing silver ion sputtering on the surface of the cross-linked layer to obtain an aluminum nitride single crystal substrate; The step S3 further includes the following steps: thinning the substrate from the side of the substrate away from the surface of the cross-linked material layer subjected to silver ion sputtering; The preparation method of the copolymer specifically comprises the following steps: Mix 10% ammonium persulfate, acrylic acid and isopropanol, heat to 60-75°C, stir for 20 minutes, heat to 80-90°C, stir for 1-2 hours, heat for 1 hour, and finally cool to room temperature to obtain a copolymer. The weight ratio of the ammonium persulfate, the monomer acrylic acid and the isopropyl alcohol is 5:1:2; The preparation method of the cross-linked product specifically comprises the following steps: Dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile and octadecyl acrylate are reacted at 80°C for 4-6 hours, and then ethylene glycol diacrylate and copper oxide are added and reacted at 90°C for 1-2 hours to obtain a cross-linked product; The weight ratio of dimethyl sulfoxide, azobisisobutyronitrile, acrylic acid, methyl acrylate, acrylonitrile, octadecyl acrylate, ethylene glycol diacrylate and copper oxide is 200:1:2:50:20:7:5:1; The silver ion sputtering in step S3 specifically includes the following steps: silver ion sputtering is performed on the surface of the cross-linked material layer by an ion sputtering instrument at a current density of 40-50 mA / cm 2 , sputtering time 1-3min; The thinning process specifically comprises thinning the substrate by plasma bombardment; The energy of the plasma bombardment is 150-250keV; After the thinning process, the thickness ratio of the single crystal substrate layer, the copolymer layer and the cross-linked material layer is 2:1:1.

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