CN117038803A - Sapphire substrate epitaxial wafer, preparation method thereof and LED - Google Patents

Abstract

The invention relates to the field of semiconductor technology, and specifically discloses a sapphire substrate epitaxial wafer and a preparation method thereof, as well as an LED. The preparation method includes: providing a sapphire substrate; depositing a composite buffer layer on the sapphire substrate; An epitaxial layer is deposited on the buffer layer; the composite buffer layer includes a SiO ₂ pattern layer, a SiON interface layer, a Si ₃ N ₄ layer, a Si-doped AlN interface layer, and an Al pre-deposition layer that are sequentially deposited on the sapphire substrate. AlN transition interface layer and AlN layer. By arranging a composite buffer layer formed by multiple material layers, the present invention effectively improves the crystal quality of epitaxial materials, reduces dislocation defects, and improves luminous efficiency.

Description

Sapphire substrate epitaxial wafer and preparation method thereof, LED

Technical field

The invention relates to the field of semiconductor technology, and in particular to a sapphire substrate epitaxial wafer and a preparation method thereof, and an LED.

Background technique

Existing epitaxial wafers of gallium nitride-based light-emitting diodes are usually prepared by epitaxy on heterogeneous substrates. Among them, sapphire substrates are widely used due to their mature production technology and good stability. However, there is a large lattice mismatch and thermal mismatch between the sapphire substrate and the gallium nitride-based epitaxial material, which causes the epitaxial material to be subject to greater stress during the growth process and is prone to dislocations and defects. The light efficiency of the light-emitting diode is reduced.

Contents of the invention

The object of the present invention is to provide a sapphire substrate epitaxial wafer and its preparation method and LED in view of the existing technical status. The present invention effectively improves the crystal quality of the epitaxial material by providing a composite buffer layer formed by the cooperation of multiple material layers. quality, reduce dislocation defects, and improve luminous efficiency.

In order to achieve the above objects, the present invention adopts the following technical solutions:

First, the present invention provides a method for preparing a sapphire substrate epitaxial wafer, including:

Provide sapphire substrate;

depositing a composite buffer layer on the sapphire substrate;

deposit an epitaxial layer on the composite buffer layer;

The composite buffer layer includes a SiO ₂ pattern layer, a SiON interface layer, a Si ₃ N ₄ layer, a Si-doped AlN interface layer, an Al pre-deposition layer, an AlN transition interface layer and an AlN layer that are sequentially deposited on the sapphire substrate. .

In some embodiments, the SiON interface layer is formed by nitriding the surface of the SiO ₂ pattern layer.

In some embodiments, the preparation steps of the SiON interface layer are as follows:

After depositing the SiO ₂ pattern layer, ammonia gas is introduced to perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1050°C to 1250°C and the pressure is 50torr to 300torr.

In some embodiments, the preparation steps of the Si-doped AlN interface layer are as follows:

Aluminum is pre-paved on the Si ₃ N ₄ layer, and then nitrided.

In some embodiments, the preparation steps of the Si-doped AlN interface layer are as follows:

After the Si ₃ N ₄ layer is deposited, in the MOCVD chamber, N ₂ and H ₂ are used as carrier gases, TMAl gas is introduced into the reaction chamber, and low-temperature aluminum is pre-layed at a temperature of 750°C to 1000°C. , the growth pressure is 50torr~200torr;

After the pre-laying of aluminum is completed, use N ₂ and H ₂ as carrier gases, introduce ammonia and silane into the reaction chamber, and perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1050°C ~ 1250°C and the pressure is 100torr ~ 300torr.

In some embodiments, the AlN transition interface layer is formed by nitriding the surface of the Al pre-deposition layer.

In some embodiments, the preparation steps of the AlN transition interface layer are as follows:

After the Al pre-deposition layer is deposited, in the MOCVD chamber, _N2 and _H2 are used as carrier gases, and ammonia gas is introduced into the reaction chamber to perform low-temperature nitriding treatment. The temperature of the low-temperature nitriding treatment is 850 ℃ ~ 1000 ℃, pressure 100torr ~ 300torr.

In some embodiments, the thickness of the SiO ₂ pattern layer is 1 nm to 10 nm, the thickness of the Si ₃ N ₄ layer is 1 nm to 10 nm, the thickness of the Al pre-deposition layer is 0.5 nm to 5 nm, and the AlN The thickness of the layer is 5 nm to 50 nm, and the thicknesses of the SiON interface layer, the Si-doped AlN interface layer and the AlN transition interface layer are all less than 1 nm.

Secondly, the present invention provides a sapphire substrate epitaxial wafer, including a sapphire substrate, characterized in that a composite buffer layer and an epitaxial layer are sequentially provided on the sapphire substrate along the epitaxial direction, and the composite buffer layer includes a composite buffer layer deposited in sequence on SiO ₂ graphic layer, SiON interface layer, Si ₃ N ₄ layer, Si-doped AlN interface layer, Al pre-deposition layer, AlN transition interface layer and AlN layer on the sapphire substrate.

Furthermore, the present invention provides an LED, including an epitaxial wafer prepared by the above-mentioned method for preparing an epitaxial wafer on a sapphire substrate.

The beneficial effects of the present invention are:

In the present invention, a composite buffer layer is provided between the sapphire substrate and the epitaxial layer, where the lattice constant of the sapphire substrate is The lattice constant of SiO ₂ is/> The lattice constant of Si ₃ N ₄ is/> The lattice constant of AlN is A buffer layer structure with gradient lattice constants and thermal expansion coefficients is formed from the SiO ₂ pattern layer to the AlN layer, thereby reducing the lattice mismatch and thermal mismatch between the material layers, and improving the subsequent growth of the epitaxial layer on the buffer layer. The crystal quality improves the luminous efficiency. In addition, during the high-temperature heat treatment process, the SiO ₂ pattern layer, Si ₃ N ₄ layer and AlN layer will form tensile stress on the sapphire substrate, causing the epitaxial wafer without the epitaxial layer to form a micro-surface As a result of warping, during the subsequent epitaxial layer growth process, this micro-warping structure will reduce the tensile stress of the epitaxial material, making the sapphire substrate more fully in contact with the graphite carrier in the MOCVD reaction chamber, thus making the temperature distribution more precise. Uniform, improving the yield, luminous efficiency and wavelength uniformity of the epitaxial wafer.

Description of the drawings

Figure 1 is a flow chart of a method for preparing a sapphire substrate epitaxial wafer of the present invention.

Figure 2 is a schematic structural diagram of the sapphire substrate epitaxial wafer of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below.

First, referring to Figures 1 and 2, the present invention discloses a method for preparing a sapphire substrate epitaxial wafer, which includes:

S10. Provide sapphire substrate 1;

S20. Deposit composite buffer layer 2 on the sapphire substrate 1;

S30. Deposit epitaxial layer 3 on the composite buffer layer 2;

The composite buffer layer 2 includes a SiO ₂ pattern layer 21, a SiON interface layer 22, a Si ₃ N ₄ layer 23, a Si-doped AlN interface layer 24, and an Al pre-deposition layer 25, which are sequentially deposited on the sapphire substrate 1. AlN transition interface layer 26 and AlN layer 27.

In the present invention, a composite buffer layer 2 is provided between the sapphire substrate 1 and the epitaxial layer 3, where the lattice constant of the sapphire substrate 1 is The lattice constant of SiO ₂ is/> The lattice constant of Si ₃ N ₄ is/> The lattice constant of AlN is/> A buffer layer structure with gradient lattice constants and thermal expansion coefficients is formed from the SiO ₂ pattern layer 21 to the AlN layer 27, thereby reducing the lattice mismatch and thermal mismatch between the material layers, and improving the subsequent growth on the buffer layer. The crystal quality of the epitaxial layer 3 improves the luminous efficiency. In addition, during the high-temperature heat treatment process, the SiO ₂ pattern layer 21, the Si ₃ N ₄ layer 23 and the AlN layer 27 will form tensile stress on the sapphire substrate 1, causing ungrown epitaxial The epitaxial wafer of layer 3 forms a micro-warping result. During the subsequent growth process of epitaxial layer 3, this micro-warping structure will reduce the tensile stress of the epitaxial material, causing the sapphire substrate 1 to contact the graphite carrier in the MOCVD reaction chamber. The wafer contact is more complete, which makes the temperature distribution more uniform and improves the yield, luminous efficiency and wavelength uniformity of the epitaxial wafer.

Wherein, the SiON interface layer 22 is formed by nitriding the surface of the SiO ₂ graphic layer 21 , and the lattice adaptability between the formed SiON interface layer 22 and the SiO ₂ graphic layer 21 is higher. The interface layer 22 reduces the lattice mismatch and thermal mismatch between the SiO ₂ pattern layer 21 and the Si ₃ N ₄ layer 23.

Wherein, the preparation steps of the SiON interface layer 22 are as follows:

After depositing the SiO ₂ graphic layer 21, ammonia gas is introduced to perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1050°C to 1250°C and the pressure is 50torr to 300torr. For example, the high-temperature nitriding treatment is The temperature is 1050°C, 1100°C, 1150°C, 1200°C or 1250°C, but is not limited thereto. Exemplarily, the pressure is 50torr, 100torr, 150torr, 200torr, 250torr or 300torr, but is not limited thereto.

Wherein, the preparation steps of the Si-doped AlN interface layer 24 are as follows:

Aluminum is pre-paved on the Si ₃ N ₄ layer 23 and then nitrided.

Wherein, the preparation steps of the Si-doped AlN interface layer 24 are as follows:

After the Si ₃ N ₄ layer 23 is deposited, in the MOCVD chamber, N ₂ and H ₂ are used as carrier gases, TMAl gas is introduced into the reaction chamber, and low-temperature aluminum is pre-layed at a temperature of 750°C to 1000 ℃, the growth pressure is 50torr to 200torr, and the exemplary temperature is 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, but is not limited thereto. The exemplary growth pressure is 50torr, 100torr, 150torr. or 200torr, but not limited to this;

After the pre-laying of aluminum is completed, use N ₂ and H ₂ as carrier gases, introduce ammonia and silane into the reaction chamber, and perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1050°C ~ 1250°C and the pressure is 100torr ~ 300torr.

The crystal quality of the Si-doped AlN interface layer 24 grown on the Si ₃ N ₄ layer 23 is improved by the growth method of first pre-laying aluminum and then performing high-temperature nitriding treatment.

In addition, the Si-doped AlN interface layer 24 can also be produced by molecular beam epitaxy, magnetron sputtering, or other methods.

The AlN transition interface layer 26 is formed by nitriding the surface of the Al pre-deposition layer 25 to form an AlN transition interface layer 26 with a smooth and dense surface.

Wherein, the preparation steps of the AlN transition interface layer 26 are as follows:

After the Al pre-deposition layer 25 is deposited, in the MOCVD chamber, N ₂ and H ₂ are used as carrier gases, ammonia gas is introduced into the reaction chamber, and low-temperature nitriding treatment is performed. The temperature of the low-temperature nitriding treatment is 850℃～1000℃, the pressure is 100torr～300torr, for example, the temperature is 850℃, 900℃, 950℃ or 1000℃, but not limited to this, for example, the pressure is 100torr, 150torr, 200torr, 250torr or 300torr , but not limited to this.

Wherein, the thickness of the SiO ₂ pattern layer 21 is 1 nm to 10 nm, the thickness of the Si ₃ N ₄ layer 23 is 1 nm to 10 nm, the thickness of the Al pre-deposition layer 25 is 0.5 nm to 5 nm, and the AlN layer The thickness of 27 is 5 nm to 50 nm, and the thickness of the SiON interface layer 22, the Si-doped AlN interface layer 24 and the AlN transition interface layer 26 are all less than 1 nm, where the thickness of the Al pre-deposition layer 25 refers to The thickness of the remaining unnitrided portion after the surface of the Al pre-deposition layer 25 is nitrided to form the AlN layer 27. For example, the thickness of the SiO ₂ pattern layer 21 is 1 nm, 3 nm, 6 nm, 9 nm or 10 nm, and the Si ₃ N ₄ layer The thickness of 23 is 1nm, 2nm, 4nm, 7nm or 10nm, the thickness of Al pre-deposition layer 25 is 0.5nm, 1nm, 2.5nm, 3nm, 4nm or 5nm, the thickness of AlN layer 27 is 5nm, 10nm, 20nm, 25nm, 30nm, 35nm, 45nm or 50nm, the thickness of the SiON interface layer 22 is 0.3nm, 0.5nm, 0.7nm, 0.9nm or 0.99nm, the thickness of the Si-doped AlN interface layer 24 is 0.2nm, 0.6nm, 0.8nm, 0.9 nm or 0.99nm, the thickness of the AlN transition interface layer 26 is 0.2nm, 0.6nm, 0.8nm, 0.9nm or 0.99nm, wherein the thickness of the SiON interface layer 22, the Si-doped AlN interface layer 24 and the AlN transition interface layer 26 Keep it smaller than the thickness of its adjacent material layers to form a better transition, which is beneficial to reducing the lattice mismatch and thermal mismatch between adjacent material layers in the interface layer.

Among them, the epitaxial layer 3 includes an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum well light-emitting layer, an electron blocking layer and a P-type semiconductor layer that are grown sequentially along the epitaxial direction.

Secondly, as shown in Figure 2, the present invention also discloses a sapphire substrate epitaxial wafer, which includes a sapphire substrate 1. The sapphire substrate 1 is sequentially provided with a composite buffer layer 2 and an epitaxial layer 3 along the epitaxial direction. The composite buffer layer 2 It includes SiO ₂ pattern layer 21, SiON interface layer 22, Si ₃ N ₄ layer 23, Si-doped AlN interface layer 24, Al pre-deposition layer 25, AlN transition interface layer 26 and AlN layer 27.

Furthermore, the present invention also discloses an LED, including an epitaxial wafer prepared by the above-mentioned method for preparing an epitaxial wafer on a sapphire substrate.

The present invention will be further described below in conjunction with the accompanying drawings and examples:

Example 1

This embodiment discloses a method for preparing a sapphire substrate epitaxial wafer, which includes:

S10. Provide sapphire substrate;

S20. Deposit a composite buffer layer on the sapphire substrate;

S30. Deposit an epitaxial layer on the composite buffer layer;

The composite buffer layer includes a SiO ₂ pattern layer, a SiON interface layer, a Si ₃ N ₄ layer, a Si-doped AlN interface layer, an Al pre-deposition layer, an AlN transition interface layer and an AlN layer that are sequentially deposited on the sapphire substrate. .

Wherein, the SiON interface layer is formed by nitriding the surface of the SiO ₂ graphic layer.

Wherein, the preparation steps of the SiON interface layer are as follows:

After depositing the SiO ₂ pattern layer, ammonia gas is introduced to perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1150°C and the pressure is 200torr.

Wherein, the preparation steps of the Si-doped AlN interface layer are as follows:

Aluminum is pre-paved on the Si ₃ N ₄ layer, and then nitrided.

Wherein, the preparation steps of the Si-doped AlN interface layer are as follows:

After the Si ₃ N ₄ layer is deposited, in the MOCVD chamber, N ₂ and H ₂ are used as carrier gases, TMAl gas is introduced into the reaction chamber, and low-temperature aluminum is pre-layed at a temperature of 850°C and a growth pressure of is 150torr;

After the pre-laying of aluminum is completed, use N ₂ and H ₂ as carrier gases, introduce ammonia and silane into the reaction chamber, and perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1150°C and the pressure is 250torr.

Wherein, the AlN transition interface layer is formed by nitriding the surface of the Al pre-deposition layer.

Wherein, the preparation steps of the AlN transition interface layer are as follows:

After the Al pre-deposition layer is deposited, in the MOCVD chamber, use N ₂ and H ₂ as carrier gases, introduce ammonia gas into the reaction chamber, and perform low-temperature nitriding treatment. The temperature of the low-temperature nitriding treatment is 950 ℃, pressure is 300torr.

Wherein, the thickness of the SiO ₂ graphic layer is 10 nm, the thickness of the Si ₃ N ₄ layer is 8 nm, the thickness of the Al pre-deposition layer is 1 nm, the thickness of the AlN layer is 18 nm, and the SiON interface layer , the thickness of the Si-doped AlN interface layer and the AlN transition interface layer are both 0.8nm.

The epitaxial layer includes an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum well light-emitting layer, an electron blocking layer and a P-type semiconductor layer that are grown sequentially along the epitaxial direction.

Secondly, this embodiment also discloses a sapphire substrate epitaxial wafer, which includes a sapphire substrate. A composite buffer layer and an epitaxial layer are sequentially provided on the sapphire substrate along the epitaxial direction. The composite buffer layer includes a composite buffer layer and is sequentially deposited on the sapphire substrate. SiO ₂ graphic layer, SiON interface layer, Si ₃ N ₄ layer, Si-doped AlN interface layer, Al pre-deposition layer, AlN transition interface layer and AlN layer.

Furthermore, this embodiment also discloses an LED, including an epitaxial wafer prepared by the above-mentioned method for preparing an epitaxial wafer on a sapphire substrate.

Example 2

This embodiment discloses a method for preparing a sapphire substrate epitaxial wafer, which includes:

S10. Provide sapphire substrate;

S20. Deposit a composite buffer layer on the sapphire substrate;

S30. Deposit an epitaxial layer on the composite buffer layer;

The composite buffer layer includes a SiO ₂ pattern layer, a SiON interface layer, a Si ₃ N ₄ layer, a Si-doped AlN interface layer, an Al pre-deposition layer, an AlN transition interface layer and an AlN layer that are sequentially deposited on the sapphire substrate. .

Wherein, the SiON interface layer is produced by molecular beam epitaxy.

Wherein, the preparation steps of the Si-doped AlN interface layer are as follows:

Aluminum is pre-paved on the Si ₃ N ₄ layer, and then nitrided.

Wherein, the preparation steps of the Si-doped AlN interface layer are as follows:

After the Si ₃ N ₄ layer is deposited, in the MOCVD chamber, N ₂ and H ₂ are used as carrier gases, TMAl gas is introduced into the reaction chamber, and low-temperature aluminum is pre-layed at a temperature of 850°C and a growth pressure of is 150torr;

After the pre-laying of aluminum is completed, use N ₂ and H ₂ as carrier gases, introduce ammonia and silane into the reaction chamber, and perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1150°C and the pressure is 250torr.

Wherein, the AlN transition interface layer is formed by nitriding the surface of the Al pre-deposition layer.

Wherein, the preparation steps of the AlN transition interface layer are as follows:

After the Al pre-deposition layer is deposited, in the MOCVD chamber, use N ₂ and H ₂ as carrier gases, introduce ammonia gas into the reaction chamber, and perform low-temperature nitriding treatment. The temperature of the low-temperature nitriding treatment is 950 ℃, pressure is 300torr.

Wherein, the thickness of the SiO ₂ graphic layer is 10 nm, the thickness of the Si ₃ N ₄ layer is 8 nm, the thickness of the Al pre-deposition layer is 1 nm, the thickness of the AlN layer is 18 nm, and the SiON interface layer , the thickness of the Si-doped AlN interface layer and the AlN transition interface layer are both 0.8nm.

The epitaxial layer includes an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum well light-emitting layer, an electron blocking layer and a P-type semiconductor layer that are grown sequentially along the epitaxial direction.

Secondly, this embodiment also discloses a sapphire substrate epitaxial wafer, which includes a sapphire substrate. A composite buffer layer and an epitaxial layer are sequentially provided on the sapphire substrate along the epitaxial direction. The composite buffer layer includes a composite buffer layer and is sequentially deposited on the sapphire substrate. SiO ₂ graphic layer, SiON interface layer, Si ₃ N ₄ layer, Si-doped AlN interface layer, Al pre-deposition layer, AlN transition interface layer and AlN layer.

Furthermore, this embodiment also discloses an LED, including an epitaxial wafer prepared by the above-mentioned method for preparing an epitaxial wafer on a sapphire substrate.

Example 3

This embodiment discloses a method for preparing a sapphire substrate epitaxial wafer, which includes:

S10. Provide sapphire substrate;

S20. Deposit a composite buffer layer on the sapphire substrate;

S30. Deposit an epitaxial layer on the composite buffer layer;

The composite buffer layer includes a SiO ₂ pattern layer, a SiON interface layer, a Si ₃ N ₄ layer, a Si-doped AlN interface layer, an Al pre-deposition layer, an AlN transition interface layer and an AlN layer that are sequentially deposited on the sapphire substrate. .

Wherein, the SiON interface layer is formed by nitriding the surface of the SiO ₂ graphic layer.

Wherein, the preparation steps of the SiON interface layer are as follows:

After depositing the SiO ₂ pattern layer, ammonia gas is introduced to perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1150°C and the pressure is 200torr.

Wherein, the Si-doped AlN interface layer is produced by molecular beam epitaxy.

Wherein, the AlN transition interface layer is formed by nitriding the surface of the Al pre-deposition layer.

Wherein, the preparation steps of the AlN transition interface layer are as follows:

After the Al pre-deposition layer is deposited, in the MOCVD chamber, use N ₂ and H ₂ as carrier gases, introduce ammonia gas into the reaction chamber, and perform low-temperature nitriding treatment. The temperature of the low-temperature nitriding treatment is 950 ℃, pressure is 300torr.

Wherein, the thickness of the SiO ₂ graphic layer is 10 nm, the thickness of the Si ₃ N ₄ layer is 8 nm, the thickness of the Al pre-deposition layer is 1 nm, the thickness of the AlN layer is 18 nm, and the SiON interface layer , the thickness of the Si-doped AlN interface layer and the AlN transition interface layer are both 0.8nm.

The epitaxial layer includes an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum well light-emitting layer, an electron blocking layer and a P-type semiconductor layer that are grown sequentially along the epitaxial direction.

Secondly, this embodiment also discloses a sapphire substrate epitaxial wafer, which includes a sapphire substrate. A composite buffer layer and an epitaxial layer are sequentially provided on the sapphire substrate along the epitaxial direction. The composite buffer layer includes a composite buffer layer and is sequentially deposited on the sapphire substrate. SiO ₂ graphic layer, SiON interface layer, Si ₃ N ₄ layer, Si-doped AlN interface layer, Al pre-deposition layer, AlN transition interface layer and AlN layer.

Furthermore, this embodiment also discloses an LED, including an epitaxial wafer prepared by the above-mentioned method for preparing an epitaxial wafer on a sapphire substrate.

Comparative example 1

The difference between this comparative example and Example 1 is that the thickness of the SiO ₂ pattern layer is 10 nm, the thickness of the Si ₃ N ₄ layer is 8 nm, the thickness of the Al pre-deposition layer is 1 nm, and the thickness of the AlN The thickness of the layer is 18 nm, and the thickness of the SiON interface layer, the Si-doped AlN interface layer and the AlN transition interface layer are all 20 nm.

Comparative example 2

The difference between this comparative example and Example 1 is that the composite buffer layer does not have a SiON interface layer, a Si-doped AlN interface layer and an AlN transition interface layer, and accordingly the SiON interface layer, Si-doped AlN interface layer and AlN transition layer are omitted. Interface layer preparation steps.

Comparative example 3

The difference between this comparative example and Example 1 is that the composite buffer layer does not include a SiON interface layer, a Si ₃ N ₄ layer, and a Si-doped AlN interface layer, and accordingly the SiON interface layer, Si-doped AlN interface layer, and AlN interface layer are omitted. Preparation steps for the transition interface layer.

Test method: The epitaxial wafers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were made into 10*24mil chips for photoelectric performance testing.

The test results are as follows:

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person familiar with the technology in the art Without departing from the scope of the technical solution of the present invention, personnel can make some changes or modify the above-mentioned technical contents into equivalent embodiments with equivalent changes. In essence, any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the present invention.

Claims (10)

1. A method for preparing a sapphire substrate epitaxial wafer, which is characterized by comprising: Provide sapphire substrate; depositing a composite buffer layer on the sapphire substrate; deposit an epitaxial layer on the composite buffer layer; The composite buffer layer includes a SiO ₂ pattern layer, a SiON interface layer, a Si ₃ N ₄ layer, a Si-doped AlN interface layer, an Al pre-deposition layer, an AlN transition interface layer and an AlN layer that are sequentially deposited on the sapphire substrate. . 2. The method for preparing an epitaxial wafer on a sapphire substrate according to claim 1, wherein the SiON interface layer is formed by nitriding the surface of the _SiO2 pattern layer. 3. The preparation method of sapphire substrate epitaxial wafer according to claim 1, characterized in that the preparation steps of the SiON interface layer are as follows: After depositing the SiO ₂ pattern layer, ammonia gas is introduced to perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1050°C to 1250°C and the pressure is 50torr to 300torr. 4. The preparation method of sapphire substrate epitaxial wafer according to claim 1, characterized in that the preparation steps of the Si-doped AlN interface layer are as follows: Aluminum is pre-paved on the Si ₃ N ₄ layer, and then nitrided. 5. The preparation method of sapphire substrate epitaxial wafer according to claim 4, characterized in that the preparation steps of the Si-doped AlN interface layer are as follows: After the Si ₃ N ₄ layer is deposited, in the MOCVD chamber, N ₂ and H ₂ are used as carrier gases, TMAl gas is introduced into the reaction chamber, and low-temperature aluminum is pre-layed at a temperature of 750°C to 1000°C. , the growth pressure is 50torr~200torr; After the pre-laying of aluminum is completed, use N ₂ and H ₂ as carrier gases, introduce ammonia and silane into the reaction chamber, and perform high-temperature nitriding treatment. The temperature of the high-temperature nitriding treatment is 1050°C ~ 1250°C and the pressure is 100torr ~ 300torr. 6. The method for preparing an epitaxial wafer on a sapphire substrate according to claim 1, wherein the AlN transition interface layer is formed by nitriding the surface of the Al pre-deposition layer. 7. The preparation method of sapphire substrate epitaxial wafer according to claim 1, characterized in that the preparation steps of the AlN transition interface layer are as follows: After the Al pre-deposition layer is deposited, in the MOCVD chamber, _N2 and _H2 are used as carrier gases, and ammonia gas is introduced into the reaction chamber to perform low-temperature nitriding treatment. The temperature of the low-temperature nitriding treatment is 850 ℃ ~ 1000 ℃, pressure 100torr ~ 300torr. 8. The preparation method of sapphire substrate epitaxial wafer according to claim 1, characterized in that the thickness of the SiO ₂ pattern layer is 1 nm to 10 nm, and the thickness of the Si ₃ N ₄ layer is 1 nm to 10 nm, so The thickness of the Al pre-deposition layer is 0.5nm~5nm, the thickness of the AlN layer is 5nm~50nm, and the thickness of the SiON interface layer, the Si-doped AlN interface layer and the AlN transition interface layer are all less than 1nm. . 9. A sapphire substrate epitaxial wafer, including a sapphire substrate, characterized in that a composite buffer layer and an epitaxial layer are sequentially provided on the sapphire substrate along the epitaxial direction, and the composite buffer layer includes a composite buffer layer deposited on the sapphire substrate in sequence. SiO ₂ graphic layer, SiON interface layer, Si ₃ N ₄ layer, Si-doped AlN interface layer, Al pre-deposition layer, AlN transition interface layer and AlN layer on the substrate. 10. An LED, characterized by comprising an epitaxial wafer prepared by the method for preparing a sapphire substrate epitaxial wafer according to any one of claims 1 to 8.