Protection Structure for High-Temperature Annealing of Gallium Nitride and Its Application

Abstract

The present invention discloses a protective structure for high-temperature annealing of gallium nitride and its application. The protective structure for high-temperature annealing of gallium nitride includes: a first protective layer, a second protective layer, and a third protective layer that are sequentially stacked on the surface of the gallium nitride material, and the materials of the first protective layer, the second protective layer, and the third protective layer include AlN. A method for activating high-temperature annealing of gallium nitride provided by an embodiment of the present invention can avoid stress problems caused by growing a protective layer on the surface of GaN.

Description

Technical Field

[0001] The invention relates to a method for activating gallium nitride by high temperature annealing, and in particular to a protection structure for gallium nitride high temperature annealing and application thereof, belonging to the field of semiconductor technology. Background Art

[0002] In recent years, the third-generation semiconductors represented by GaN have become the material of choice for the next generation of semiconductor power devices. GaN has a large bandgap of 3.39eV, which means it can withstand high temperatures and high voltages. Its high electron mobility of 2000 (2DEG)μ(cm2 / V·s) indicates that its devices can be used at higher frequencies. Its good thermal conductivity means that it is easy to dissipate heat when the device is working. Its smaller dielectric constant εr=9 indicates that it has smaller parasitic capacitance. At the same time, the third-generation semiconductor materials have more stable chemical properties and radiation resistance than the first- and second-generation materials, and can theoretically operate in high-temperature environments of up to 700-800°C.

[0003] GaN devices are mainly divided into planar devices and vertical devices. At present, high-voltage vertical devices have become the mainstream of research and development. In the manufacture of vertical devices based on GaN semiconductors, ion implantation is a very attractive and convenient technology, such as electrical and optical selective area doping, dry etching, electrical isolation, quantum well mixing and ion cutting. As a commonly used semiconductor device processing technology, ion implantation initially promoted the development of Si-based CMOS processes in the industry. This method can introduce almost all elements in the periodic table and accurately control the concentration and depth of dopants. It can achieve the effect required by the epitaxial GaN doping process to a certain extent, and it is more flexible than epitaxial doping. Therefore, ion implantation has a greater impact on the optical and electrical properties of GaN materials. Therefore, studying the impact of ion implantation on various aspects of GaN materials is also essential for the rapidly developing GaN industry.

[0004] However, ion implantation can cause damage to GaN materials, which is unavoidable. At the same time, there are certain activation problems with the ions injected into the material. Therefore, high-temperature annealing is usually used to solve these unavoidable side effects after ion implantation. Especially in today's Mg ion implantation to achieve P-type GaN experiments, due to the large activation energy of Mg in GaN, high-temperature and high-pressure annealing is required internationally (mainly the United States and Japan). Before annealing, a very harsh protective layer needs to be added to the GaN to prevent the decomposition of GaN materials or devices under high-temperature annealing.

[0005] Existing solutions for high-temperature annealing of GaN include: 1) epitaxially grow a layer of AlN on GaN by MOCVD, and then perform pulsed annealing with rapid heating and cooling (30 s) from 900 °C to 1400 °C under an atmospheric pressure of 2.0 MPa, which can protect GaN from decomposition during the annealing activation process. This method can protect GaN from decomposition under such harsh conditions and simultaneously anneal and activate the implanted P-type impurities in GaN. However, only the Naval Research Laboratory in the United States and Nagoya University in Japan in the world have such difficult and dangerous conditions, which are difficult to replicate; 2) epitaxially grow or sputter AlN under a high pressure of 3 MPa to 1 GPa, and perform high-temperature annealing at a constant temperature of about 1300 °C to 1500 °C for about half an hour, which can protect GaN from decomposition during the annealing activation process. Although AlN is a semiconductor material that can withstand high temperatures, growing AlN on GaN inevitably causes stress problems due to lattice mismatch. At the same time, annealing is also a process of stress release. Multiple conditions must be parallel to protect GaN from decomposition and prevent the film from rupturing due to stress problems during the annealing process, while protecting GaN.

[0006] Solutions for high-temperature annealing of GaN include that SiN / SiO2 grown by ALD can protect GaN from decomposition under the condition of 1100 °C in an atmospheric nitrogen atmosphere. Growing a layer of GaON on GaN can protect GaN from decomposition within 2 - 3 min under the condition of 1150 °C. SiO2 / SiN grown by PECVD can protect GaN from decomposition under the condition of 1000 °C to 1100 °C. However, the protective layers formed based on the above methods are not only difficult to remove, but also difficult to guarantee reliability. Most importantly, the temperature at which GaN can be protected is relatively low (<1200 °C), and the SiO2 film basically decomposes at a temperature of about 1100 °C, which far fails to meet the requirements for the activation of Mg ion implantation into GaN. Currently, the best-reported epitaxial quality of SiO2 can protect GaN from decomposition under an atmospheric pressure atmosphere at about 1200 °C. Summary of the Invention

[0007] The main objective of the present invention is to provide a protective structure for high-temperature annealing of gallium nitride and its application to overcome the deficiencies in the prior art.

[0008] To achieve the foregoing invention objective, the technical solutions adopted by the present invention include:

[0009] An embodiment of the present invention provides a protective structure for high-temperature annealing of gallium nitride, including a first protective layer, a second protective layer, and a third protective layer sequentially stacked on the surface of a gallium nitride material. The materials of the first protective layer, the second protective layer, and the third protective layer include AlN.

[0010] An embodiment of the present invention also provides a method for activating gallium nitride by high-temperature annealing, including: forming the above-mentioned protective structure on the surface of the gallium nitride material, and then annealing the gallium nitride material under normal pressure at a temperature above 1200°C.

[0011] An embodiment of the present invention also provides a method for preparing a P-type gallium nitride material, including:

[0012] Doping acceptor impurities into the gallium nitride material;

[0013] Growing a first protective layer, a second protective layer, and a third protective layer on the gallium nitride material in sequence by physical and / or chemical vapor deposition to obtain a protective structure, wherein the growth temperature of the second protective layer is lower than that of the first protective layer, and the first protective layer, the second protective layer, and the third protective layer are all AlN layers;

[0014] Annealing the gallium nitride material with the protective structure on its surface under normal pressure at a temperature above 1200°C to activate the acceptor impurities in the gallium nitride material and obtain a P-type gallium nitride material.

[0015] Compared with the prior art, the advantages of the present invention include:

[0016] 1) The method for activating gallium nitride by high-temperature annealing provided by the embodiment of the present invention can protect GaN from decomposing at a temperature below 1250°C without a high-pressure environment;

[0017] 2) The method for activating gallium nitride by high-temperature annealing provided by the embodiment of the present invention can avoid the stress problem caused by growing a protective layer on the surface of GaN;

[0018] 3) The method for activating gallium nitride by high-temperature annealing provided by the embodiment of the present invention overcomes the problem of the rupture of the protective structure during the annealing process. Description of the Drawings

[0019] Figure 1 is a schematic flow chart of a method for activating gallium nitride by high-temperature annealing provided in a typical embodiment of the present invention;

[0020] Figure 2a and Figure 2b are respectively the surface morphology diagrams of the gallium nitride samples before and after annealing in Embodiment 1 of the present invention;

[0021] Figure 3a and Figure 3b are respectively the AFM morphology photos of the surface of the gallium nitride sample before and after removing the protective structure after the annealing in Embodiment 1 of the present invention;

[0022] Figure 4 are respectively the optical microscope photos of the surface of the gallium nitride sample after annealing in Comparative Example 3 of the present invention;

[0023] Figure 5 They are respectively optical microscope photos of the surface of the annealed gallium nitride sample in Comparative Example 4 of the present invention;

[0024] Figure 6 They are respectively optical microscope photos of the surface of the annealed gallium nitride sample in Comparative Example 5 of the present invention. Detailed implementation manners

[0025] In view of the deficiencies in the prior art, through long-term research and a large number of practices by the inventors of this case, the technical solution of the present invention has been proposed. The following will further explain the technical solution, its implementation process, principles, etc.

[0026] The inventors of this case have found that the main defects in the current treatment of high-temperature annealing activation of gallium nitride are as follows: Since GaN decomposes at high temperatures (above 800 °C without protection), and at the same time, AlN with good crystal quality and high density also needs to grow at high temperatures (above 1200 °C), and AlN cannot be grown thick because of stress problems, but if AlN is grown thin, it cannot protect GaN at high temperatures.

[0027] The present invention first grows the first AlN layer on the surface of GaN at a temperature of 1100 - 1200 °C, and the growth time is controlled within 1 - 3 minutes. At the same time, a protective gas atmosphere such as nitrogen is provided for protection, so that GaN can be protected from decomposition during this growth time, and at the same time, the growth of the first AlN layer is completed. The thickness of the first AlN layer is 1 - 10 nm; immediately after the growth of the first AlN layer is completed, the temperature is lowered to below 800 °C, and the second AlN layer is grown under the condition of below 800 °C. The growth time is 4 - 10 minutes, and the thickness of the second AlN layer is 5 - 25 nm. If it exceeds 25 nm, it is prone to cracking; then a low-stress AlN is sputtered as the third AlN layer at a temperature of about 200 - 400 °C, and the thickness is controlled between 120 nm and 270 nm. The protection structure formed in this way can both protect GaN and solve the stress problem during the high-temperature annealing process.

[0028] An embodiment of the present invention provides a protection structure for high-temperature annealing of gallium nitride, including a first protection layer, a second protection layer, and a third protection layer that are sequentially stacked on the surface of the gallium nitride material. The materials of the first protection layer, the second protection layer, and the third protection layer include AlN.

[0029] In a more specific implementation manner, the first protection layer and the second protection layer are grown by physical and / or chemical vapor deposition methods, and the growth temperature of the second protection layer is lower than that of the first protection layer.

[0030] In a more specific embodiment, the growth temperature of the first protective layer is 1100-1200 °C, and the growth time is 1-3 min. The growth temperature of the second protective layer is 600-800 °C, and the growth time is 4-10 min.

[0031] In a more specific embodiment, the thickness of the first protective layer is 1-10 nm, and the thickness of the second protective layer is 5-25 nm.

[0032] In a more specific embodiment, the third protective layer is low-stress AlN.

[0033] In a more specific embodiment, the thickness of the third protective layer is 120-270 nm.

[0034] In a more specific embodiment, the third protective layer is formed by physical and / or chemical vapor deposition.

[0035] In a more specific embodiment, the third protective layer is formed by sputtering.

[0036] In a more specific embodiment, the growth temperature of the third protective layer is 200-400 °C.

[0037] The embodiment of the present invention also provides a method for activating gallium nitride by high-temperature annealing, including: forming the above-mentioned protection structure on the surface of the gallium nitride material, and then annealing the gallium nitride material under normal pressure at a temperature above 1200 °C.

[0038] In a more specific embodiment, the annealing temperature is 1200-1250 °C, and the time is 5-30 min.

[0039] In a more specific embodiment, the annealing is carried out in a nitrogen atmosphere.

[0040] The embodiment of the present invention also provides a method for preparing a p-type gallium nitride material, including:

[0041] Doping acceptor impurities into the gallium nitride material;

[0042] Growing a first protective layer, a second protective layer, and a third protective layer on the gallium nitride material in sequence by physical and / or chemical vapor deposition to obtain a protection structure, wherein the growth temperature of the second protective layer is lower than that of the first protective layer, and the first protective layer, the second protective layer, and the third protective layer are all AlN layers;

[0043] Anneal the gallium nitride material with the protection structure on its surface under normal pressure and at a temperature above 1200 °C to activate the acceptor impurities in the gallium nitride material and obtain a p-type gallium nitride material.

[0044] In a more specific embodiment, the growth temperature of the first protective layer is 1100 - 1200 °C, and the growth time is 1 - 3 min. The growth temperature of the second protective layer is 600 - 800 °C, and the growth time is 4 - 10 min.

[0045] In a more specific embodiment, the thickness of the first protective layer is 1 - 10 nm, and the thickness of the second protective layer is 5 - 25 nm.

[0046] In a more specific embodiment, the third protective layer is low-stress AlN.

[0047] In a more specific embodiment, the thickness of the third protective layer is 120 - 270 nm.

[0048] In a more specific embodiment, the growth temperature of the third protective layer is 200 - 400 °C.

[0049] In a more specific embodiment, the annealing temperature is 1200 - 1250 °C, and the time is 5 - 30 min.

[0050] In a more specific embodiment, the annealing is carried out in a nitrogen atmosphere.

[0051] In a more specific embodiment, the preparation method further includes: removing the protection structure on the p-type gallium nitride material.

[0052] The technical solution, its implementation process and principle, etc. will be further explained below in conjunction with the drawings and specific implementation cases. Unless otherwise specified, the vapor phase epitaxial growth equipment, sputtering system, ion implantation equipment, annealing equipment and related processes, etc. adopted in the embodiments of the present invention can all be those known to those skilled in the art.

[0053] Example 1

[0054] Please refer to Figure 1 , a method for activating gallium nitride by high-temperature annealing may include the following steps:

[0055] 1) An epitaxial layer of about 2-5 μm thick GaN sample is grown on a sapphire substrate, and then inorganic cleaning is carried out. It should be noted that the GaN sample can be realized by the processes known to those skilled in the art, or directly obtained by purchasing a commercially available GaN sample. The cleaning process may include ultrasonic cleaning in acetone for 5 minutes, ultrasonic cleaning in isopropyl alcohol for 5 minutes, and ultrasonic cleaning in deionized water for 5 minutes.

[0056] 2) Transfer the GaN sample to the growth reaction chamber of a MOCVD (metalorganic chemical vapor deposition) device. First, adjust the temperature in the growth reaction chamber to 1200 °C, the pressure to 150-300 mbar, and introduce an Al source and a nitrogen source into the growth reaction chamber. The flow rate of the Al source is 150-300 sccm, and the flow rate of the nitrogen source is 5 L-15 L, and continue for 2 minutes to epitaxially grow a first AlN layer with a thickness of 4 nm on the surface of the GaN sample.

[0057] 3) Cool down the temperature in the growth reaction chamber to 600 °C, keep the pressure at 150-300 mbar, and continue to introduce the Al source and the nitrogen source into the growth reaction chamber. The flow rate of the Al source is 150-300 sccm, and the flow rate of the nitrogen source is 1 L-3 L, and continue for 10 minutes to epitaxially grow a second AlN layer with a thickness of 10 nm on the surface of the first AlN layer.

[0058] It should be noted that the nitrogen source can be ammonia gas, etc., and the Al source can be known to those skilled in the art. In this embodiment, the first AlN layer and the second AlN layer are sequentially grown at least by changing the growth temperature during the metalorganic chemical vapor deposition process.

[0059] 4) Transfer the GaN sample with the first AlN layer and the second AlN layer formed on its surface to a magnetron sputtering device (sputter). Adjust the temperature in the reaction chamber of the magnetron sputtering device to 250 °C, the pressure to -4 to -10 torr, introduce argon gas and nitrogen gas into the reaction chamber, use aluminum with a purity of 90-100% as the target, and sputter a third AlN layer with a thickness of 200 nm on the second AlN layer by radio frequency magnetron sputtering to obtain a protective structure. The surface of the GaN sample with the protective structure is as Figure 2a shown; wherein, the volume ratio of the argon gas and the nitrogen gas is 1:7, and the sputtering power is 10 KW, and the radio frequency power is 200-250 KW.

[0060] 5) Transfer the GaN sample with the protective structure formed on its surface to a MOCVD device, and anneal the GaN sample under normal pressure, in a nitrogen atmosphere, and at a temperature of 1250 °C for 5 minutes to 30 minutes. After the annealing is completed, the surface of the GaN sample is asFigure 2b As shown, from Figure 2b it can be seen that the surface structure of the GaN sample is complete; the AFM surface topography photo of the GaN sample surface observed under a microscope is as Figure 3a shown;

[0061] 6) After the annealing is completed, the annealed GaN sample is subjected to water bath heating at 100 °C for 12 h with AZ400K developer to remove the protection structure. After removing the protection structure, the surface topography of the GaN sample is observed under a microscope, and its optical microscope photo is as Figure 3b shown, from Figure 3b it can be seen that after removing the protection structure, the surface of the GaN sample presents a complete step flow.

[0062] Example 2

[0063] A method for activating gallium nitride by high-temperature annealing may include the following steps:

[0064] 1) A GaN sample with a thickness of about 2 μm is epitaxially grown on a sapphire substrate, and then inorganic cleaning is carried out; it should be noted that the GaN sample can be realized by the processes known to those skilled in the art, or, a commercially available GaN sample can be directly used. The cleaning process may include ultrasonic treatment in acetone for 5 min, ultrasonic treatment in isopropanol for 5 min, and ultrasonic treatment in deionized water for 5 min;

[0065] 2) Transfer the GaN sample to the growth reaction chamber of a MOCVD (metalorganic chemical vapor deposition) device. First, adjust the temperature in the growth reaction chamber to 1150 °C, the pressure to 150 - 300 mbar, and introduce an Al source and a nitrogen source into the growth reaction chamber. The flow rate of the introduced Al source is 150 - 300 sccm, and the flow rate of the introduced nitrogen source is 5 L - 15 L, and continue for 2.5 min to epitaxially grow a first AlN layer with a thickness of 8 nm on the surface of the GaN sample;

[0066] 3) Cool the temperature in the growth reaction chamber to 700 °C, keep the pressure at 150 - 300 mbar, and continue to introduce the Al source and the nitrogen source into the growth reaction chamber. Among them, the flow rate of the introduced Al source is 150 - 300 sccm, and the flow rate of the introduced nitrogen source is 1 L - 3 L, and continue for 4 min to epitaxially grow a second AlN layer with a thickness of 15 nm on the surface of the first AlN layer;

[0067] It should be noted that the nitrogen source can be ammonia, etc., and the Al source can be known to those skilled in the art. In this embodiment, the first AlN layer and the second AlN layer are sequentially grown at least by changing the growth temperature during the metalorganic chemical vapor deposition process;

[0068] 4) Transfer the surface of the GaN sample with the first AlN layer and the second AlN layer formed on it to a magnetron sputtering device (sputter). Adjust the temperature in the reaction chamber of the magnetron sputtering device to 200 °C and the pressure to -4 to -10 torr. Introduce argon and nitrogen into the reaction chamber. Using aluminum with a purity of 90 - 100% as the target, sputter and form a third AlN layer with a thickness of 120 nm on the second AlN layer by means of radio frequency magnetron sputtering, thereby obtaining a protection structure; wherein, the volume ratio of the argon and nitrogen is 1:7, the sputtering power is 10 KW, and the radio frequency power is 200 - 250 KW;

[0069] 5) Transfer the GaN sample with the protection structure formed on its surface to an MOCVD device, and anneal the GaN sample under normal pressure, in a nitrogen atmosphere, and at a temperature of 1250 °C for 5 min to 30 min;

[0070] 6) After the annealing is completed, perform a water bath heating on the annealed GaN sample with AZ400K developer at 100 °C for 1 h to remove the protection structure, and then observe whether the GaN sample has a decomposition condition under a microscope. The result is basically the same as that of Example 1.

[0071] Example 3

[0072] A method for activating gallium nitride by high-temperature annealing may include the following steps:

[0073] 1) Epitaxially grow a GaN sample with a thickness of about 2 μm on a sapphire substrate, and then perform inorganic cleaning; it should be noted that the GaN sample can be realized by a process known to those skilled in the art, or a commercially available GaN sample can be directly used. The cleaning process may include ultrasonic cleaning with acetone for 5 min, ultrasonic cleaning with isopropanol for 5 min, and ultrasonic cleaning with deionized water for 5 min;

[0074] 2) Transfer the GaN sample to the growth reaction chamber of an MOCVD (metalorganic chemical vapor deposition) device. First, adjust the temperature in the growth reaction chamber to 1100 °C, the pressure to 150 - 300 mbar, and introduce an Al source and a nitrogen source into the growth reaction chamber. The introduction flow rate of the Al source is 150 - 300 sccm, and the introduction flow rate of the nitrogen source is 5 L - 15 L, and continue for 1 min to epitaxially grow a first AlN layer with a thickness of 1 nm on the surface of the GaN sample;

[0075] 3) Cool down the temperature in the growth reaction chamber to 800 °C, keep the pressure at 150 - 300 mbar, and continue to introduce the Al source and the nitrogen source into the growth reaction chamber. The flow rate of the introduced Al source is 150 - 300 sccm, and the flow rate of the nitrogen source is 1 L - 3 L, and continue for 8 min to epitaxially grow a second AlN layer with a thickness of 20 nm on the surface of the first AlN layer;

[0076] It should be noted that the nitrogen source can be ammonia gas, etc., and the Al source can be known to those skilled in the art. In this embodiment, the first AlN layer and the second AlN layer are sequentially grown at least after changing the growth temperature during the vapor phase epitaxial growth process;

[0077] 4) Transfer the surface of the GaN sample with the first AlN layer and the second AlN layer formed on it to a magnetron sputtering device (sputter). Adjust the temperature in the reaction chamber of the magnetron sputtering device to 400 °C, adjust the pressure to -4 to -10 torr, introduce argon gas and nitrogen gas into the reaction chamber, use aluminum with a purity of 90 - 100% as the target, and sputter a third AlN layer with a thickness of 270 nm on the second AlN layer by radio frequency magnetron sputtering to obtain a protection structure; wherein, the volume ratio of the argon gas and the nitrogen gas is 1:7, the sputtering power is 10 KW, and the radio frequency power is 200 - 250 KW;

[0078] 5) Transfer the GaN sample with the protection structure formed on its surface to a MOCVD device, and anneal the GaN sample under normal pressure, in a nitrogen atmosphere, and at a temperature of 1250 °C for 5 min to 30 min;

[0079] 6) After the annealing is completed, use AZ400K developer to perform water bath heating on the annealed GaN sample at 100 °C for 1 h to remove the protection structure, and then observe whether the GaN sample has a decomposition condition under a microscope. The result is basically the same as that of Example 2.

[0080] Comparative Example 1

[0081] A method for activating gallium nitride by high-temperature annealing provided in Comparative Example 1 is basically the same as that in Example 1. Only the differences are introduced here: Comparative Example 1 completes the growth of the first AlN layer and the second AlN layer at 600 - 800 °C. It can be understood that the first AlN layer and the second AlN layer are integrally grown.

[0082] It was found through testing that since AlN requires high-temperature heterojunction growth, it is very difficult to grow the first and second AlN layers at 600 - 800 °C, and the probability of successful growth is very low. Even if a protective structure is finally formed, the protective effect of this protective structure on the high-temperature annealing of the GaN sample is extremely poor, and there are serious stress problems, resulting in cracks on the surface of the GaN sample.

[0083] Comparative Example 2

[0084] A method for activating high-temperature annealing of gallium nitride provided in Comparative Example 2 is basically the same as that in Example 1. Only the differences are introduced here: In Comparative Example 2, the second AlN layer was first grown on the surface of the GaN sample at 800 °C, and then the temperature was raised to 1200 °C for the growth of the first AlN layer.

[0085] It was found through testing that the crystal quality of the AlN layer grown on the surface of the GaN sample at 800 °C is very poor. Even if a protective structure is finally formed, the protective effect of this protective structure on the high-temperature annealing of the GaN sample is extremely poor, and there are serious stress problems, resulting in cracks on the surface of the GaN sample.

[0086] Comparative Example 3

[0087] A method for activating high-temperature annealing of gallium nitride provided in Comparative Example 3 is basically the same as that in Example 2. Only the differences are introduced here: In Comparative Example 3, a third AlN layer was first sputtered on the surface of the GaN sample, and then the first and second AlN layers were grown on the surface of the third AlN layer; the GaN sample with this protective structure was annealed, and the optical microscope photograph of the surface of the GaN sample after removing the protective structure is as Figure 4 shown, and it can be seen from Figure 4 that a large number of cracks appear on the surface of the annealed GaN sample.

[0088] It was found through testing that the third AlN layer directly sputtered on the surface of the GaN sample by sputtering is not dense enough. During annealing, it causes the decomposition of GaN, and moreover, it is difficult for the first and second AlN layers to achieve epitaxial growth on the third AlN layer.

[0089] Comparative Example 4

[0090] A method for activating high-temperature annealing of gallium nitride provided in Comparative Example 4 is basically the same as that in Example 1. The difference is that: in Comparative Example 4, the third AlN layer formed by the protective structure is less than 120 nm, and the optical microscope photograph of the surface of the finally annealed GaN sample is as Figure 5 shown.

[0091] Comparative Example 5

[0092] A method for activating gallium nitride by high-temperature annealing provided in Comparative Example 5 is basically the same as that in Example 1, except that: in Comparative Example 5, the third AlN layer formed by the protection structure is greater than 270 nm, and an optical microscope photograph of the surface of the GaN sample after final annealing is as shown in Figure 6 shown, from Figure 6 which it can be seen that there are serious cracks on the surface of the GaN sample.

[0093] The inventors of this case have found through research that due to the stress between the materials themselves, and at the same time the need for thermal annealing, high-temperature growth of AlN, and prevention of the decomposition of GaN at high temperatures, the innermost layer of the specific protection structure must be a thin layer of AlN rapidly epitaxially formed under the condition of 1100-1200 °C, and the outermost layer is sputtered low-stress AlN. Otherwise, it is impossible to protect GaN during the high-temperature annealing process and at the same time overcome the stress effect between the materials.

[0094] A method for activating gallium nitride by high-temperature annealing provided in an embodiment of the present invention can protect GaN from decomposing at temperatures below 1250 °C without a high-pressure environment. And through various debugging, the method for activating gallium nitride by high-temperature annealing provided in the embodiment of the present invention can also avoid the stress problem generated by growing a protective layer on the surface of GaN. At the same time, the method for activating gallium nitride by high-temperature annealing provided in the embodiment of the present invention overcomes the problem of the rupture of the protection structure during the annealing process.

[0095] It should be understood that the above embodiments are only used to illustrate the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A protection structure for high-temperature annealing of gallium nitride, characterized in that Comprising: A first protective layer, a second protective layer, and a third protective layer that are sequentially stacked on the surface of a gallium nitride material. The materials of the first protective layer, the second protective layer, and the third protective layer include AlN. Among them, the third protective layer is low-stress AlN; The first protective layer, the second protective layer, and the third protective layer are formed by physical and / or chemical vapor deposition. The first protective layer is formed under an atmosphere of nitrogen as a protective gas. The growth temperature of the first protective layer is 1100 - 1200 °C, the growth time is 1 - 3 min, the thickness of the first protective layer is 1 - 10 nm, the growth temperature of the second protective layer is 600 - 800 °C, the growth time is 4 - 10 min, the thickness of the second protective layer is 5 - 25 nm, the growth temperature of the third protective layer is 200 - 400 °C, and the thickness of the third protective layer is 120 - 270 nm.

2. The protection structure according to claim 1, characterized in that: The third protective layer is formed by sputtering.

3. A method for activating gallium nitride by high-temperature annealing, characterized in that Comprising: Forming the protective structure as described in any one of claims 1 - 2 on the surface of the gallium nitride material, and then annealing the gallium nitride material under normal pressure at 1200 - 1250 °C.

4. The method according to claim 3, wherein: The annealing time is 5 - 30 min.

5. The method according to claim 3, characterized in that: The annealing is carried out in a nitrogen atmosphere.

6. A method for preparing a P-type gallium nitride material, characterized in that Comprising: Doping acceptor impurities into the gallium nitride material; Using physical and / or chemical vapor deposition to sequentially grow a first protective layer, a second protective layer, and a third protective layer on the gallium nitride material to obtain a protective structure. Among them, the first protective layer is formed under an atmosphere of nitrogen as a protective gas. The growth temperature of the first protective layer is 1100 - 1200 °C, the growth time is 1 - 3 min, the growth temperature of the second protective layer is 600 - 800 °C, the growth time is 4 - 10 min, the thickness of the first protective layer is 1 - 10 nm, the thickness of the second protective layer is 5 - 25 nm, the growth temperature of the third protective layer is 200 - 400 °C, the thickness of the third protective layer is 120 - 270 nm. The first protective layer, the second protective layer, and the third protective layer are all AlN layers. Among them, the third protective layer is low-stress AlN; Annealing the gallium nitride material with the protective structure covering its surface under normal pressure at 1200 - 1250 °C to activate the acceptor impurities in the gallium nitride material and obtain a P-type gallium nitride material.

7. The preparation method according to claim 6, characterized in that: The annealing time is 5 - 30 min.

8. The preparation method according to claim 6, characterized in that: The annealing is carried out in a nitrogen atmosphere.

9. The preparation method according to claim 6, wherein Further comprising: Removing the protective structure on the P-type gallium nitride material.

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