Nano-patterned sapphire substrate and its preparation method and application

Abstract

The present invention discloses a nano-patterned sapphire substrate and a preparation method and application thereof. The preparation method comprises: processing the surface of the sapphire substrate to form a plurality of defects; performing high temperature annealing treatment on the sapphire substrate at a temperature above 1000°C to form a nano-pattern on the surface of the sapphire substrate. The preparation method of the nano-patterned sapphire substrate provided by the present invention is simple and easy to operate, has low cost, and has little damage to the crystal quality. The pattern morphology and size of the prepared nano-patterned sapphire substrate are easy to control, and the periodicity, uniformity and repeatability are good, which is conducive to batch preparation.

Description

Technical Field

[0001] The invention relates to a method for preparing a patterned substrate, in particular to a nano-patterned sapphire substrate and a preparation method and application thereof, belonging to the technical field of epitaxial growth of semiconductor materials. Background Art

[0002] At present, compound semiconductor thin film materials are usually grown epitaxially on substrates using metal organic vapor phase epitaxy (MOCVD). Due to its large size, low price, and mature growth process, sapphire substrates are the best choice for compound semiconductors, especially for epitaxy of III-nitride thin films such as gallium nitride and aluminum nitride. However, due to the lattice mismatch between the substrate and the epitaxial material, the epitaxially grown crystals have problems such as warping, cracking, and high dislocation density. The use of sapphire patterning can effectively reduce a series of problems caused by lattice mismatch. The patterned sapphire substrate helps promote the three-dimensional nucleation growth of nitride thin films, thereby accelerating dislocation annihilation and stress relaxation, thereby improving the quality of thin film crystals and improving the overall performance of the device. Summary of the invention

[0003] The main purpose of the present invention is to provide a nano-patterned sapphire substrate and a preparation method and application thereof, so as to overcome the deficiencies in the prior art.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0005] The embodiment of the present invention provides a method for preparing a nano-patterned sapphire substrate, comprising:

[0006] Processing the surface of the sapphire substrate to form a plurality of defects;

[0007] The sapphire substrate is subjected to high temperature annealing treatment at a temperature above 1000° C., so that a nano pattern is formed on the surface of the sapphire substrate.

[0008] In some more specific embodiments, the preparation method specifically comprises:

[0009] Performing a first annealing treatment on the sapphire substrate in the presence of a reducing gas at a temperature of 800-1300° C., so as to partially decompose at least a surface layer of the sapphire substrate to form a plurality of defects;

[0010] The sapphire substrate after the first annealing treatment is etched by wet etching;

[0011] The etched sapphire substrate is subjected to a second annealing treatment at a temperature above 1000° C. in a protective atmosphere or vacuum condition, so that a nano pattern is formed on the surface of the sapphire substrate.

[0012] In some more specific embodiments, the preparation method specifically comprises:

[0013] Performing a first annealing treatment on the sapphire substrate in the presence of a reducing gas at a temperature of 800-1300° C., so as to partially decompose at least a surface layer of the sapphire substrate to form a plurality of defects;

[0014] The sapphire substrate after the first annealing treatment is etched by wet etching;

[0015] The etched sapphire substrate is subjected to a second annealing treatment at a temperature above 1000° C. in a protective atmosphere or vacuum condition, so that a nano pattern is formed on the surface of the sapphire substrate.

[0016] In some more specific embodiments, the preparation method specifically comprises:

[0017] The surface of the sapphire substrate is etched by wet etching or plasma etching to form a plurality of defects;

[0018] The etched sapphire substrate is annealed in a protective atmosphere or vacuum at a temperature above 1000° C. to form a nano pattern on the surface of the sapphire substrate.

[0019] In some more specific embodiments, the preparation method specifically comprises:

[0020] First, a group III nitride material layer is formed by epitaxial growth on the surface of a sapphire substrate, and then the group III nitride material layer is completely etched away by wet etching. Thereafter, the sapphire substrate is annealed in air at a temperature above 1000° C. to form a nano-pattern on the surface of the sapphire substrate.

[0021] The embodiment of the present invention also provides a nano-patterned sapphire substrate prepared by the preparation method.

[0022] The embodiment of the present invention also provides the use of the nano-patterned sapphire substrate in preparing semiconductor devices.

[0023] Compared with the prior art, the advantages of the present invention include:

[0024] 1) A method for preparing a nano-patterned sapphire substrate provided in an embodiment of the present invention does not require expensive mask lithography and etching equipment, thereby reducing production costs and technical barriers;

[0025] 2) The method for preparing the nano-patterned sapphire substrate provided by the present invention is simple and easy to operate, has low cost, causes little damage to the crystal quality, and the pattern morphology and size of the prepared nano-patterned sapphire substrate are easy to control, and has good periodicity, uniformity and repeatability, which is conducive to batch preparation;

[0026] 3) The method for preparing a nano-patterned sapphire substrate provided in an embodiment of the present invention uses an annealing process during the preparation process, and no amorphous layer is introduced during the crystal recrystallization process, so the damage to the crystal quality is relatively small; BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a surface morphology image of a nano-patterned sapphire substrate prepared in Example 1 of the present invention;

[0028] Figure 2 This is a surface morphology image of a nano-patterned sapphire substrate prepared in Example 4 of the present invention;

[0029] Figure 3 This is a surface morphology image of a nano-patterned sapphire substrate prepared in Example 7 of the present invention;

[0030] Figure 4 The (10-12) plane XRD rocking curves of an AlN film epitaxially grown using a patterned substrate provided in a typical implementation case of the present invention and an AlN film epitaxially grown without using the patterned substrate. DETAILED DESCRIPTION

[0031] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0032] In view of the shortcomings of the existing technology for preparing patterned substrates, the embodiments of the present invention provide a simple, reliable and suitable method for preparing nanoscale patterned substrates, which is used to solve the problems of amorphous layers, poor uniformity and uncontrollable patterns in the prior art.

[0033] To achieve the above object, an embodiment of the present invention provides a method for preparing a nano-patterned substrate, and the method for preparing a nano-patterned substrate mainly comprises the following steps:

[0034] Providing a sapphire substrate with a certain bevel angle, the bevel angle is 0.5-10°;

[0035] The sapphire substrate is heated to 800°C-1300°C and a reducing gas such as H2 is introduced to partially decompose the sapphire substrate in the high-temperature reducing atmosphere to form point defects;

[0036] The sapphire substrate is corroded by wet etching for 5 minutes to 10 hours. The etching solution used in the wet etching can be a KOH solution, a NaOH solution, or a mixed solution of KOH and NaOH and an H3PO4 solution. The concentration of the etching solution is 0.1 to 10 mol / L, and the temperature of the etching solution is 25-90° C. The main purpose of the wet etching is to fully expand the point defects generated by the previous annealing treatment.

[0037] The sapphire substrate is annealed again and a protective gas is introduced (the protective gas can be any one of N2, an inert gas (such as Ar), NH3, or a combination of two or more). The purpose of the annealing treatment is to slowly repair the defects on the surface of the sapphire substrate. During the repair process, a uniform submicron or nanometer-scale graphic structure is formed on the surface of the sapphire substrate.

[0038] Specifically, the morphology and size of the submicron or nanometer-scale graphic structure can be controlled by adjusting the annealing conditions and etching conditions. The nano-graphics with different morphologies and sizes obtained under different annealing conditions and different etching conditions are respectively as follows: Figure 2 and Figure 3 shown.

[0039] The embodiment of the present invention provides a method for preparing a nano-patterned sapphire substrate, comprising:

[0040] Processing the surface of the sapphire substrate to form a plurality of defects;

[0041] The sapphire substrate is subjected to high temperature annealing treatment at a temperature above 1000° C., so that a nano pattern is formed on the surface of the sapphire substrate.

[0042] In some more specific embodiments, the preparation method specifically comprises:

[0043] Performing a first annealing treatment on the sapphire substrate in the presence of a reducing gas at a temperature of 800-1300° C., so as to partially decompose at least a surface layer of the sapphire substrate to form a plurality of defects;

[0044] The sapphire substrate after the first annealing treatment is etched by wet etching;

[0045] The etched sapphire substrate is subjected to a second annealing treatment at a temperature above 1000° C. in a protective atmosphere or vacuum condition, so that a nano pattern is formed on the surface of the sapphire substrate.

[0046] Furthermore, the first annealing treatment specifically includes: placing the sapphire substrate in a reaction chamber, and introducing a reducing gas into the reaction chamber at a flow rate of 1-10L / min, and heating the temperature of the sapphire substrate to 800-1300°C and keeping it warm for more than 5 minutes, preferably 5-20 minutes.

[0047] Furthermore, the reducing gas includes hydrogen, but is not limited thereto.

[0048] Furthermore, the etching treatment specifically includes: immersing the sapphire substrate after the first annealing treatment in a corrosion solution at 25-90° C. for 5 minutes to 10 hours.

[0049] Furthermore, the etching solution includes any one of KOH solution, NaOH solution, and H3PO4 solution, or a combination of two or more thereof.

[0050] Furthermore, the etching solution comprises a mixed solution of KOH and NaOH, and the mass ratio or molar ratio of KOH to NaOH in the mixed solution is 0.1-10:1.

[0051] Furthermore, the concentration of the corrosive solution is 0.1-10 mol / L.

[0052] Furthermore, the second annealing treatment specifically includes: placing the etched sapphire substrate in a reaction chamber, and introducing a protective gas into the reaction chamber at a flow rate of 1-20L / min, and heating the temperature of the sapphire substrate to above 1000°C and keeping it warm for more than 1h, preferably 1-3h.

[0053] Furthermore, the protective gas includes any one of nitrogen, ammonia, oxygen, air and inert gas or a mixture of two or more thereof, but is not limited thereto.

[0054] Furthermore, the vacuum degree of the vacuum condition is 1×10 -5 -1×10 -2 Pa.

[0055] In some more specific embodiments, the preparation method specifically comprises:

[0056] The surface of the sapphire substrate is etched by wet etching or plasma etching to form a plurality of defects;

[0057] The etched sapphire substrate is annealed in a protective atmosphere or vacuum at a temperature above 1000° C. to form a nano pattern on the surface of the sapphire substrate.

[0058] Furthermore, the preparation method specifically includes: immersing the sapphire substrate in a corrosive solution at 25-90° C. for 5 min-10 h to perform etching on the surface of the sapphire substrate to form multiple defects.

[0059] Furthermore, the etching solution includes any one of KOH solution, NaOH solution, and H3PO4 solution, or a combination of two or more thereof.

[0060] Furthermore, the etching solution comprises a mixed solution of KOH and NaOH, and the mass ratio or molar ratio of KOH to NaOH in the mixed solution is 0.1-10:1.

[0061] Furthermore, the concentration of the corrosive solution is 0.1-10 mol / L.

[0062] Furthermore, the plasma used in the plasma etching includes one or any combination of SF6 / CHF3 / He / Cl2 / BCl3, and the plasma etching time is 1-30 minutes and the power is 100-1500w.

[0063] Furthermore, the preparation method specifically includes: placing the etched sapphire substrate in a reaction chamber, and introducing a protective gas into the reaction chamber at a flow rate of 1-20L / min, and heating the temperature of the sapphire substrate to above 1000°C and keeping it warm for more than 1h, preferably 1-3h.

[0064] Furthermore, the protective gas includes any one of nitrogen, ammonia, oxygen, air and inert gas or a mixture of two or more thereof, but is not limited thereto.

[0065] Furthermore, the vacuum degree of the vacuum condition is 1×10 -5 -1×10 -2 Pa.

[0066] In some more specific embodiments, the preparation method specifically comprises:

[0067] First, a group III nitride material layer is formed by epitaxial growth on the surface of a sapphire substrate, and then the group III nitride material layer is completely etched away by wet etching. Thereafter, the sapphire substrate is annealed in air at a temperature above 1000° C. to form a nano-pattern on the surface of the sapphire substrate.

[0068] Furthermore, the thickness of the III-nitride material layer is 5-100 nm, preferably 5-20 nm.

[0069] Furthermore, the material of the III-nitride material layer includes AlN or GaN.

[0070] Furthermore, the preparation method specifically includes: immersing a sapphire substrate having a group III nitride material layer grown on the surface in a 25-90° C. etching solution until the nitride buffer layer is completely removed.

[0071] Furthermore, the etching solution includes any one of KOH solution, NaOH solution, and H3PO4 solution, or a combination of two or more thereof, but is not limited thereto.

[0072] Furthermore, the etching solution comprises a mixed solution of KOH and NaOH, and the mass ratio or molar ratio of KOH to NaOH in the mixed solution is 0.1-10:1.

[0073] Furthermore, the concentration of the corrosive solution is 0.1-10 mol / L.

[0074] Furthermore, the preparation method specifically includes: placing the etched sapphire substrate in a reaction chamber, and introducing a protective gas into the reaction chamber at a flow rate of 1-20L / min, and heating the temperature of the sapphire substrate to above 1000°C and keeping it warm for more than 1h.

[0075] Furthermore, the annealing treatment time is 1-3h.

[0076] Furthermore, the protective gas includes any one of nitrogen, ammonia, oxygen, air and inert gas or a mixture of two or more thereof, but is not limited thereto.

[0077] Furthermore, the vacuum degree of the vacuum condition is 1×10 -5 -1×10 -2 Pa.

[0078] Furthermore, the nano-pattern includes a plurality of periodically distributed submicron or nano-scale pattern structures.

[0079] Furthermore, the submicron or nanometer-scale graphic structure includes a plurality of submicron or nanometer-scale protrusions and / or a plurality of submicron or nanometer-scale recesses distributed on the surface of the sapphire substrate.

[0080] Furthermore, there is a bevel angle of 0.5-10° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal.

[0081] Furthermore, the nano-pattern includes a plurality of submicron or nano-scale pattern structures distributed periodically.

[0082] Furthermore, the submicron or nanometer-scale graphic structure includes a plurality of submicron or nanometer-scale protrusions and / or a plurality of submicron or nanometer-scale recesses distributed on the surface of the sapphire substrate.

[0083] Furthermore, the submicron or nanometer-scale protrusions are triangular or fish-scale structures.

[0084] Furthermore, the submicron or nanometer-scale protrusion has a plurality of atomic layer steps arranged along the longitudinal direction, and the length of each atomic layer step in the lateral direction is 50-500 nm.

[0085] Furthermore, there is a bevel angle of 0.5-10° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal.

[0086] The embodiment of the present invention also provides a nano-patterned sapphire substrate prepared by the preparation method.

[0087] The embodiment of the present invention also provides the use of the nano-patterned sapphire substrate in preparing semiconductor devices.

[0088] The technical solution, its implementation process and principles will be further explained below in conjunction with specific implementation cases. Unless otherwise specified, the process conditions and parameters used in the embodiments of the present invention may be those known to those skilled in the art.

[0089] Example 1

[0090] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0091] a) selecting a sapphire substrate with a bevel angle, wherein a bevel angle of 4° exists between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0092] b) placing the sapphire substrate in a high temperature annealing furnace and introducing H2 at a flow rate of 1 L / min, heating the sapphire substrate to 800°C and keeping the temperature for 20 minutes;

[0093] c) After the first step of annealing is completed, the sapphire substrate is placed in a 90°C, 10 mol / L H3PO4 solution and immersed in corrosion for 5 minutes;

[0094] d) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then the second step of high-temperature annealing is performed: the sapphire substrate is placed in a tubular furnace, and high-purity nitrogen is introduced as a protective gas at a flow rate of 1L / min. At the same time, the furnace temperature is gradually raised to above 1000°C and kept at this temperature for 3 hours. After the annealing is completed, the sapphire substrate is taken out to obtain the following Figure 1 The patterned sapphire substrate shown;

[0095] e) epitaxial growth of AlN thin film was performed on the patterned sapphire substrate and the untreated sapphire substrate with the same bevel angle, and the high-resolution XRD rocking curve of the epitaxially grown AlN thin film was as follows: Figure 4 As shown, compared with the untreated sapphire substrate with the same bevel angle, the FWHM (half-maximum width) of the sapphire substrate (10-12) surface is reduced from the original 450 arc seconds to 244 arc seconds.

[0096] Example 2

[0097] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0098] a) selecting a sapphire substrate with a bevel angle, wherein a bevel angle of 4° exists between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0099] b) placing the sapphire substrate in a high temperature annealing furnace and introducing H2 at a flow rate of 10 L / min, heating the sapphire substrate to 1300°C and keeping the temperature for 5 minutes;

[0100] c) After the first step of annealing is completed, the sapphire substrate is placed in a 25° C., 0.1 mol / L NaOH solution for immersion and corrosion for 10 hours;

[0101] d) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then the second step of high-temperature annealing is performed: the sapphire substrate is placed in a tube furnace, and high-purity argon is introduced as a protective gas at a flow rate of 20L / min. At the same time, the furnace temperature is gradually raised to above 1000℃ and kept at this temperature for 1h. After the annealing is completed, the sapphire substrate is taken out. The surface morphology of the patterned sapphire substrate is similar to that of the Figure 1 The basic consistency shown is

[0102] e) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0103] Example 3

[0104] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0105] a) selecting a sapphire substrate with a bevel angle, wherein a bevel angle of 4° exists between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0106] b) placing the sapphire substrate in a high temperature annealing furnace and introducing H2 at a flow rate of 3 L / min, heating the sapphire substrate to 1000°C and keeping the temperature for 10 minutes;

[0107] c) After the first step of annealing is completed, the sapphire substrate is placed in a mixed solution of KOH and NaOH at 85° C. and 3 mol / L (the molar ratio of KOH to NaOH in the mixed solution is 0.1-10:1) for immersion and etching for 2 hours;

[0108] d) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then the second step of high-temperature annealing is performed: the sapphire substrate is placed in a tubular furnace, and high-purity ammonia gas is introduced as a protective gas at a flow rate of 20L / min. At the same time, the furnace temperature is gradually raised to above 1000°C and kept warm for 2h. After the annealing is completed, the sapphire substrate is taken out. The surface morphology of the patterned sapphire substrate is similar to that of the Figure 1 The basic consistency shown is

[0109] e) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0110] Example 4

[0111] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0112] a) selecting a sapphire substrate with a bevel angle, wherein there is a bevel angle of 0.5° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0113] b) placing the sapphire substrate in a mixed solution of KOH and NaOH at 25° C. and 0.1 mol / L for 10 hours, wherein the molar ratio of KOH to NaOH in the mixed solution is 10:1;

[0114] c) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a tube furnace, high-purity nitrogen is introduced as a protective gas at a flow rate of 1L / min, and the furnace temperature is raised to 1100°C in stages and kept at this temperature for 3 hours. After annealing is completed, the sapphire substrate is taken out to obtain the following Figure 2 The patterned sapphire substrate shown;

[0115] d) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0116] Example 5

[0117] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0118] a) selecting a sapphire substrate with a bevel angle, wherein there is a bevel angle of 0.5° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0119] b) The sapphire substrate was placed in a 90°C, 5 mol / L KOH solution for 4 hours of immersion corrosion;

[0120] c) After etching, the sapphire substrate was thoroughly cleaned with ultrapure water, and then placed in a tube furnace, and air was introduced as a protective gas at a flow rate of 20L / min. At the same time, the furnace temperature was raised to 1300℃ in stages and kept warm for 2h. After annealing, the sapphire substrate was taken out. The surface morphology of the patterned sapphire substrate was similar to that of the Figure 2 The basic consistency shown is

[0121] d) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0122] Example 6

[0123] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0124] a) selecting a sapphire substrate with a bevel angle, wherein there is a bevel angle of 0.5° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0125] b) The sapphire substrate was placed in a mixed solution of 10 mol / L NaOH at 60°C and immersed in the solution for corrosion for 8 hours;

[0126] c) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a tube furnace, high-purity ammonia is introduced as a protective gas at a flow rate of 1L / min. At the same time, the furnace temperature is gradually raised to 1400℃ and kept at this temperature for 1h. After annealing is completed, the sapphire substrate is taken out. The surface morphology of the patterned sapphire substrate is similar to that of the Figure 2 The basic consistency shown is

[0127] d) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0128] Example 7

[0129] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0130] a) selecting a sapphire substrate with a bevel angle, wherein there is a bevel angle of 10° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0131] b) etching the sapphire substrate with a Cl2 / BCl3 plasma at a power of 100 W for 30 min;

[0132] c) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a tube furnace, high-purity nitrogen is introduced as a protective gas at a flow rate of 1-20L / min, and the furnace temperature is raised to above 1000°C in stages and kept at this temperature for 1-3 hours. After annealing is completed, the sapphire substrate is taken out to obtain the following Figure 3 The patterned sapphire substrate shown;

[0133] d) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0134] Example 8

[0135] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0136] a) selecting a sapphire substrate with a bevel angle, wherein there is a bevel angle of 10° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0137] b) Etching the sapphire substrate with SF6 plasma at a power of 1500W for 1 minute;

[0138] c) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a vacuum furnace, and the pressure in the vacuum furnace is adjusted to 1×10 -5 -1×10 -2 Pa, and at the same time, the furnace temperature is gradually raised to above 1000℃ and kept at this temperature for 1-3h. After the annealing is completed, the sapphire substrate is taken out. The surface morphology of the patterned sapphire substrate is similar to that of Figure 3 The basic consistency shown is

[0139] d) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0140] Example 9

[0141] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0142] a) selecting a sapphire substrate with a bevel angle, wherein there is a bevel angle of 10° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0143] b) etching the sapphire substrate with CHF3 plasma at a power of 900W for 10min;

[0144] c) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a tube furnace, high-purity nitrogen is introduced as a protective gas at a flow rate of 1-20L / min. At the same time, the furnace temperature is gradually raised to above 1000°C and kept warm for 1-3h. After annealing is completed, the sapphire substrate is taken out. The surface morphology of the patterned sapphire substrate is similar to that of the Figure 3 The basic consistency shown is

[0145] d) epitaxial growth of an AlN film is performed on the patterned sapphire substrate, and the high-resolution XRD rocking curve of the epitaxially grown AlN film is substantially consistent with the result obtained in Example 1.

[0146] Example 10

[0147] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0148] a) selecting a sapphire substrate with a bevel angle, wherein a bevel angle of 6° exists between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0149] b) growing a 5 nm AlN buffer layer on a sapphire substrate using MOCVD (vapor phase epitaxial growth);

[0150] c) immersing and etching the sapphire substrate having the AlN buffer layer formed thereon in a 3 mol / L KOH / NaOH mixed solution (the molar ratio of KOH to NaOH is 0.1-10:1) at 90° C. until the AlN buffer layer is completely removed and the defects on the surface of the sapphire substrate are exposed;

[0151] d) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a high-temperature annealing furnace, heated to 1000° C. in an air atmosphere, and kept at this temperature for 3 hours. After annealing is completed, the sapphire substrate is taken out;

[0152] d) The sapphire substrate was cleaned and placed in a MOCVD chamber for epitaxial growth of an AlN film. The high-resolution XRD rocking curve of the epitaxially grown AlN film was substantially consistent with the result obtained in Example 1.

[0153] Embodiment 11

[0154] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0155] a) selecting a sapphire substrate with a bevel angle, wherein a bevel angle of 6° exists between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0156] b) growing a 100nm GaN buffer layer on a sapphire substrate using MOCVD (vapor phase epitaxial growth);

[0157] c) placing the sapphire substrate having the GaN buffer layer formed thereon in a 75° C., 10 mol / L KOH solution for immersion and etching until the GaN buffer layer is completely removed and the defects on the surface of the sapphire substrate are exposed;

[0158] d) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a high-temperature annealing furnace, high-purity nitrogen is introduced as a protective gas at a flow rate of 1-20L / min, and the furnace temperature is raised to above 1000°C in stages, and kept at this temperature for 1-3 hours. After annealing is completed, the sapphire substrate is taken out;

[0159] d) The sapphire substrate was cleaned and placed in a MOCVD chamber for epitaxial growth of an AlN film. The high-resolution XRD rocking curve of the epitaxially grown AlN film was substantially consistent with the result obtained in Example 1.

[0160] Example 12

[0161] A method for preparing a nano-patterned sapphire substrate comprises the following steps:

[0162] a) selecting a sapphire substrate with a bevel angle, wherein a bevel angle of 6° exists between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal;

[0163] b) growing a 20 nm AlN buffer layer on a sapphire substrate using MOCVD (vapor phase epitaxial growth);

[0164] c) immersing and corroding the sapphire substrate having the AlN buffer layer in a 0.1 mol / L H3PO4 solution at 25° C. until the AlN buffer layer is completely removed and the defects on the surface of the sapphire substrate are exposed;

[0165] d) After etching, the sapphire substrate is thoroughly cleaned with ultrapure water, and then placed in a high-temperature annealing furnace, and high-purity argon is introduced as a protective gas at a flow rate of 1-20L / min. At the same time, the furnace temperature is gradually raised to above 1000°C and kept at this temperature for 1-3 hours. After annealing is completed, the sapphire substrate is taken out;

[0166] d) The sapphire substrate was cleaned and placed in a MOCVD chamber for epitaxial growth of an AlN film. The high-resolution XRD rocking curve of the epitaxially grown AlN film was substantially consistent with the result obtained in Example 1.

[0167] It should be noted that the above embodiment only provides an embodiment of growing AlN thin film on a sapphire substrate, but as those skilled in the art know, those skilled in the art can also grow films such as AlGaN and other nitride films on a sapphire substrate, which will not be repeated here.

[0168] The preparation method of a nano-patterned sapphire substrate provided by an embodiment of the present invention has a simple preparation process and a high yield. The existing ordinary patterned sapphire substrate requires a long merging time when epitaxially growing nitrides, especially high-aluminum component AlGaN and AlN-based semiconductor devices, while the patterned structure proposed in the present invention adopts "small closure area" epitaxial growth, which can accelerate film merging and dislocation annihilation, has a short growth time, low cost, and low film stress, which can effectively reduce the probability of cracking.

[0169] A method for preparing a nano-patterned sapphire substrate provided by an embodiment of the present invention does not require expensive mask lithography and etching equipment, thereby reducing production costs and technical barriers. In addition, the pattern morphology and size of the nano-patterned substrate prepared by the method for preparing a nano-patterned sapphire substrate provided by an embodiment of the present invention are easy to control.

[0170] The method for preparing a nano-patterned sapphire substrate provided by an embodiment of the present invention uses an annealing process during the preparation process, and no amorphous layer is introduced during the crystal recrystallization process, so the damage to the crystal quality is relatively small.

[0171] The preparation method of the nano-patterned sapphire substrate provided by the present invention is simple and easy to operate, has low cost, and causes little damage to the crystal quality. In addition, the pattern morphology and size of the prepared nano-patterned sapphire substrate are easy to control, and have good periodicity, uniformity and repeatability, which is conducive to batch preparation.

[0172] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a nano-patterned sapphire substrate, characterized in that include: Performing a first annealing treatment on the sapphire substrate in the presence of a reducing gas at a temperature of 800-1300° C., so as to partially decompose at least a surface layer of the sapphire substrate to form a plurality of defects; The sapphire substrate after the first annealing treatment is etched by wet etching; The etched sapphire substrate is subjected to a second annealing treatment at a temperature above 1000° C. in a protective atmosphere or vacuum condition, so that a nano pattern is formed on the surface of the sapphire substrate.

2. The preparation method according to claim 1, characterized in that: The first annealing treatment specifically includes: placing the sapphire substrate in a reaction chamber, introducing a reducing gas into the reaction chamber at a flow rate of 1-10 L / min, and heating the sapphire substrate to a temperature of 800-1300° C. and keeping the temperature for 5-20 min.

3. The preparation method according to claim 2, characterized in that: The reducing gas includes hydrogen.

4. The preparation method according to claim 1, characterized in that: The etching treatment specifically includes: immersing the sapphire substrate after the first annealing treatment in a 25-90° C. etching solution for 5 minutes to 10 hours.

5. The preparation method according to claim 4, characterized in that: The etching solution includes any one of KOH solution, NaOH solution and H3PO4 solution or a combination of two or more thereof.

6. The preparation method according to claim 4, characterized in that: The etching solution comprises a mixed solution of KOH and NaOH, and the mass ratio or molar ratio of KOH to NaOH in the mixed solution is 0.1-10:

1.

7. The preparation method according to claim 4, characterized in that The concentration of the corrosive solution is 0.1-10 mol / L.

8. The preparation method according to claim 1, characterized in that: The second annealing treatment specifically includes: placing the etched sapphire substrate in a reaction chamber, introducing a protective gas into the reaction chamber at a flow rate of 1-20 L / min, and heating the temperature of the sapphire substrate to above 1000° C. and keeping it at that temperature for more than 1 hour.

9. The preparation method according to claim 8, characterized in that: The protective gas includes any one of nitrogen, ammonia, oxygen, air and inert gas or a mixture of two or more thereof.

10. The preparation method according to claim 9, characterized in that The vacuum degree of the vacuum condition is 1×10 -5 -1×10 -2 Pa.

11. The preparation method according to claim 1, characterized in that Specifically include: First, a group III nitride material layer is formed by epitaxial growth on the surface of a sapphire substrate, and then the group III nitride material layer is completely etched away by wet etching. Thereafter, the sapphire substrate is annealed in air at a temperature above 1000° C. to form a nano-pattern on the surface of the sapphire substrate.

12. The preparation method according to claim 11, characterized in that: The thickness of the group III nitride material layer is 5-100 nm.

13. The preparation method according to claim 11, characterized in that: The material of the group III nitride material layer includes AlN or GaN.

14. The preparation method according to claim 11, characterized in that: The preparation method specifically comprises: immersing a sapphire substrate with a group III nitride material layer grown on the surface in a 25-90° C. etching solution until the nitride buffer layer is completely removed.

15. The preparation method according to claim 14, characterized in that: The etching solution includes any one of KOH solution, NaOH solution and H3PO4 solution or a combination of two or more thereof.

16. The preparation method according to claim 14, characterized in that: The etching solution comprises a mixed solution of KOH and NaOH, and the mass ratio or molar ratio of KOH to NaOH in the mixed solution is 0.1-10:

1.

17. The preparation method according to claim 14, characterized in that: The concentration of the corrosive solution is 0.1-10 mol / L.

18. The preparation method according to claim 11, characterized in that: The preparation method specifically includes: placing the etched sapphire substrate in a reaction chamber, introducing a protective gas into the reaction chamber at a flow rate of 1-20L / min, and heating the temperature of the sapphire substrate to above 1000°C and keeping it warm for more than 1h.

19. The preparation method according to claim 11, characterized in that: The annealing treatment time is 1-3h.

20. The preparation method according to claim 18, characterized in that: The protective gas includes any one of nitrogen, ammonia, oxygen, air and inert gas or a mixture of two or more thereof.

21. The preparation method according to claim 1, characterized in that: The nano-pattern includes a plurality of sub-micrometer or nanometer-scale pattern structures distributed periodically.

22. The preparation method according to claim 21, characterized in that: The submicron or nanometer-scale graphic structure includes a plurality of submicron or nanometer-scale protrusions and / or a plurality of submicron or nanometer-scale recesses distributed on the surface of the sapphire substrate.

23. The preparation method according to claim 1, characterized in that: There is an off-cut angle of 0.5-10° between the surface of the sapphire substrate and the (002) crystal plane of the wurtzite structure crystal.

24. The preparation method according to claim 22, characterized in that: The submicron or nanometer-scale protrusions are triangular or fish-scale structures.

25. The preparation method according to claim 22, characterized in that: The submicron or nanometer-scale protrusion has a plurality of atomic layer steps arranged along the longitudinal direction, and the length of each atomic layer step in the lateral direction is 50-500 nm.

26. A nano-patterned sapphire substrate prepared by the preparation method according to any one of claims 1 to 25.

27. Use of the nano-patterned sapphire substrate according to claim 26 in the preparation of semiconductor devices.

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