Gallium nitride epitaxial diamond structure and method of making same

Abstract

The application provides a gallium nitride epitaxial diamond structure, which comprises a silicon nitride layer on a gallium nitride surface and a diamond layer on a silicon nitride surface. The application optimizes the method, process conditions and environment of the combination growth of gallium nitride and diamond, so that the diamond film grown on the gallium nitride is uniform and dense, has good adhesion and is not easy to fall off; 0 damage of the gallium nitride is realized in the preparation process, the intermediate layer damage is less than 10 nm; high-quality combination of the diamond and the gallium nitride is realized, the quality of the epitaxial layer is high, the electrical characteristics are good, the heat dissipation efficiency is high, the application has good prospects and applicability, and the effect of semiconductor device production and application is improved.

Description

Technical Field

[0001] This application relates to the field of power device technology, and in particular to a gallium nitride epitaxial diamond structure and its preparation method. Background Technology

[0002] Existing silicon power devices have reached their theoretical limits, while gallium nitride (GaN) materials, as third-generation semiconductor materials, have superior fundamental parameters and greater potential for development. GaN power devices are suitable for high-frequency, high-temperature, and high-efficiency applications, effectively reducing system size, increasing power density, and ultimately lowering system costs.

[0003] However, with continuous improvements in the design and fabrication of GaN power devices, their theoretical output power is increasing, their frequency is rising, and their size is shrinking. Yet, under these conditions of miniaturization and power increase, the reliability and stability of GaN-based microwave power devices face serious challenges. The combination of GaN and diamond presents numerous problems. First, the significant difference in thermal expansion coefficients between GaN and diamond leads to stress and strain caused by substantial thermal mismatch, hindering the realization of GaN / diamond structures. Second, lattice mismatch between GaN and diamond also impedes further development. Third, achieving the transfer of thin GaN epitaxial layers onto diamond substrates while ensuring no damage to the epitaxial layer's quality and electrical properties is a major technical challenge. Furthermore, the interfacial thermal resistance between GaN and diamond hinders the heat dissipation efficiency of the high thermal conductivity diamond. Therefore, achieving the combination of the two presents many technical difficulties. Finally, the diamond growth environment can damage gallium nitride, making it difficult to achieve a high-quality bonding interface, directly affecting product quality. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a diamond epitaxial gallium nitride structure and its preparation method that achieves a high-quality bond between diamond and gallium nitride, ensures the quality and electrical properties of the epitaxial layer, and improves heat dissipation efficiency.

[0005] To achieve the above objectives, the first aspect of this application provides a gallium nitride epitaxial diamond structure, including a silicon nitride layer on the surface of gallium nitride and a diamond layer on the surface of silicon nitride.

[0006] In any embodiment, the silicon nitride thickness is 5-500 nm. Too thick a silicon nitride will affect thermal conductivity, while too thin a silicon nitride will not be able to fully protect the gallium nitride.

[0007] The second aspect of this application provides a method for preparing a gallium nitride epitaxial diamond structure, the steps of which are as follows:

[0008] 1) A 5-500 nm thick silicon nitride layer is grown on the surface of gallium nitride using LPCVD as an intermediate layer;

[0009] 2) Clean the gallium nitride / silicon nitride sample;

[0010] 3) After cleaning, use inert gas for drying using a gas spray gun;

[0011] 4) Pretreatment using electrostatic self-assembly method;

[0012] 5) Place the pretreated sample into MPCVD for diamond growth;

[0013] 6) A mixture of hydrogen, methane, and nitrogen was used to grow the material at 600–960 °C, resulting in high-quality gallium nitride-based diamond composites.

[0014] In step 2), the sample is cleaned by ultrasonic cleaning with acetone, alcohol and deionized water for 10 minutes each to clean the sample surface and prevent stains from affecting subsequent epitaxial growth.

[0015] The pretreatment in step 4) includes heat treatment or immersion treatment.

[0016] The heat treatment is as follows: the dried gallium nitride / silicon nitride sample is heated to 250-650°C and then kept at that temperature for 1-100 minutes in an oxygen-rich atmosphere or a hydrogen-rich atmosphere, followed by natural cooling, so that the gallium nitride / silicon nitride sample is charged with a negative or positive charge in an oxygen-rich atmosphere.

[0017] The impregnation process is as follows: the dried gallium nitride / silicon nitride sample is impregnated with an aqueous solution of a strong anionic polyelectrolyte or a strong cationic polyelectrolyte for 1 to 60 minutes. The strong anionic polyelectrolyte includes PSS solution or CMCNa solution. Impregnation in the strong anionic polyelectrolyte causes the gallium nitride / silicon nitride sample to acquire a negative charge. The strong cationic polyelectrolyte includes PDDA solution. Impregnation in the strong cationic polyelectrolyte causes the gallium nitride / silicon nitride sample to acquire a positive charge. After impregnation, the gallium nitride / silicon nitride sample is removed, cleaned with deionized water, and dried under a nitrogen atmosphere.

[0018] The pretreated gallium nitride / silicon nitride sample carries a negative charge, with a zeta potential of -60 to -35 mV.

[0019] The pretreated gallium nitride / silicon nitride sample carries a positive charge, with a zeta potential of +35 to +60 mV.

[0020] In step 6), the mixed gas contains 90%–100% hydrogen, 0%–10% methane, and 0%–5% nitrogen.

[0021] The beneficial effects of this invention are:

[0022] This invention optimizes the method, process conditions, and environment for the growth of gallium nitride (GaN) and diamond, resulting in a uniform and dense diamond film grown on GaN with excellent adhesion and resistance to detachment. The fabrication process achieves zero damage to GaN, with intermediate layer damage less than 10 nm. It realizes a high-quality bond between diamond and GaN, forming a high-quality epitaxial layer with excellent electrical properties, low interfacial thermal resistance, and high heat dissipation efficiency. This demonstrates promising prospects and applicability, improving the effectiveness of semiconductor device production and applications. Attached Figure Description

[0023] Figure 1 This is a structural diagram of a gallium nitride epitaxial diamond structure product.

[0024] Figure 2 This is a product rendering of Example 1 of a gallium nitride epitaxial diamond structure;

[0025] Figure 3 SEM and optical microscope images of Example 1 of a gallium nitride epitaxial diamond structure;

[0026] Figure 4 SEM and optical microscope images of Example 2, which is a gallium nitride epitaxial diamond structure;

[0027] Figure 5 SEM and optical microscope images of Example 3, a gallium nitride epitaxial diamond structure;

[0028] Figure 6 A product rendering of a gallium nitride epitaxial diamond structure, as shown in Comparative Example 1.

[0029] Figure 7 A product rendering of Comparative Example 2, which shows a gallium nitride epitaxial diamond structure;

[0030] Figure 8 The image shows a product rendering of a gallium nitride epitaxial diamond structure, as shown in Comparative Example 3. Detailed Implementation

[0031] The following detailed description, with appropriate reference to the accompanying drawings, discloses in detail the preparation method and application embodiments of the positive electrode host material of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0034] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0035] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0036] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0037] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0038] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0039] Example 1

[0040] A method for preparing gallium nitride epitaxial diamond structures, comprising the following steps:

[0041] 1) A 200nm thick silicon nitride layer was grown on the surface of gallium nitride using LPCVD as an intermediate layer;

[0042] 2) Clean the gallium nitride / silicon nitride sample by ultrasonic cleaning with acetone, alcohol and deionized water for 10 minutes in sequence to clean the sample surface and prevent stains from affecting subsequent epitaxial growth.

[0043] 3) After cleaning, use inert gas for drying using a gas spray gun;

[0044] 4) Pretreatment using electrostatic self-assembly method, the pretreatment being heat treatment: the dried gallium nitride / silicon nitride sample is heated to 200-300℃ and then kept at that temperature for 100 min in an oxygen-rich atmosphere or a hydrogen-rich atmosphere, followed by natural cooling, so that the gallium nitride / silicon nitride sample is charged with negative or positive charge in an oxygen-rich atmosphere.

[0045] 5) Place the pretreated sample into MPCVD for diamond growth;

[0046] 6) Growth is achieved using a mixture of hydrogen, methane, and nitrogen at 600-750℃, with hydrogen comprising 95-100%, methane 0-2%, and nitrogen 0-3%; this yields high-quality gallium nitride-based diamond composite materials. The product structure and effects are as follows... Figure 1 , 2 As shown, the product's SEM and optical microscope images are as follows. Figure 3 The diamond grains are very sparse.

[0047] Example 2

[0048] A method for preparing gallium nitride epitaxial diamond structures, comprising the following steps:

[0049] 1) A 200nm thick silicon nitride layer was grown on the surface of gallium nitride using LPCVD as an intermediate layer;

[0050] 2) Clean the gallium nitride / silicon nitride sample by ultrasonic cleaning with acetone, alcohol and deionized water for 10 minutes in sequence to clean the sample surface and prevent stains from affecting subsequent epitaxial growth.

[0051] 3) After cleaning, use inert gas for drying using a gas spray gun;

[0052] 4) Pretreatment using electrostatic self-assembly method, the pretreatment being an immersion treatment: The dried gallium nitride / silicon nitride sample is immersed in an aqueous solution of a strong anionic polyelectrolyte or a strong cationic polyelectrolyte, wherein the immersion time is 45 min. The strong anionic polyelectrolyte includes PSS solution or CMCNa solution. Immersion in the strong anionic polyelectrolyte causes the gallium nitride / silicon nitride sample to acquire a negative charge. The strong cationic polyelectrolyte includes PDDA solution. Immersion in the strong cationic polyelectrolyte causes the gallium nitride / silicon nitride sample to acquire a positive charge. After immersion, the gallium nitride / silicon nitride sample is removed, cleaned with deionized water, and dried under a nitrogen atmosphere.

[0053] 5) Place the pretreated sample into MPCVD for diamond growth;

[0054] 6) Growth is achieved using a mixture of hydrogen, methane, and nitrogen at 600-800℃, with hydrogen comprising 93-98%, methane 0-1%, and nitrogen 1-6%; this yields high-quality gallium nitride-based diamond composite materials. SEM and optical microscope images of the product are shown below. Figure 4 The diamond grains are more compact.

[0055] Example 3

[0056] A method for preparing gallium nitride epitaxial diamond structures, comprising the following steps:

[0057] 1) A 400nm thick silicon nitride layer was grown on the surface of gallium nitride using LPCVD as an intermediate layer;

[0058] 2) Clean the gallium nitride / silicon nitride sample by ultrasonic cleaning with acetone, alcohol and deionized water for 10 minutes in sequence to clean the sample surface and prevent stains from affecting subsequent epitaxial growth.

[0059] 3) After cleaning, use inert gas for drying using a gas spray gun;

[0060] 4) Pretreatment using electrostatic self-assembly method, the pretreatment being an immersion treatment: the dried gallium nitride / silicon nitride sample is heated to 550-750℃ and then kept at that temperature for 50 min in an oxygen-rich atmosphere or a hydrogen-rich atmosphere, followed by natural cooling, so that the gallium nitride / silicon nitride sample is charged with a negative or positive charge in an oxygen-rich atmosphere.

[0061] 5) Place the pretreated sample into MPCVD for diamond growth;

[0062] 6) Growth is achieved using a mixture of hydrogen, methane, and nitrogen at 600-900℃, with hydrogen comprising 90-98%, methane 1-4%, and nitrogen 1-8%; this yields high-quality gallium nitride-based diamond composite materials. SEM and optical microscope images of the product are shown below. Figure 5 Diamond grains form a dense film.

[0063] Comparative Example 1

[0064] Step 4) pretreatment is omitted; all other steps are the same as in Example 1. Experimental results are as follows: Figure 6 No diamonds grow on the surface, and the damage to the intermediate layer is visible to the naked eye.

[0065] Comparative Example 2

[0066] Diamond was grown in an MPCVD at a temperature of 500°C, with other steps identical to those in Example 1. The experimental results are as follows: Figure 7 The surface diamond growth effect is poor, and it causes a certain degree of damage to the intermediate layer.

[0067] Comparative Example 3

[0068] Diamond was grown in an MPCVD at a temperature of 1000℃, with other steps identical to those in Example 1. The experimental results are as follows: Figure 8 The surface diamond growth effect is poor, and it severely damages the intermediate layer.

[0069] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a gallium nitride epitaxial diamond structure, characterized in that, Includes the following steps: 1) A 5-500 nm thick silicon nitride layer is grown on the surface of gallium nitride using LPCVD as an intermediate layer; 2) Clean the gallium nitride / silicon nitride sample; 3) After cleaning, use inert gas to dry; 4) Pretreatment using electrostatic self-assembly method; 5) Place the pretreated sample into MPCVD for diamond growth; 6) High-quality gallium nitride-based diamond composite material was obtained by growing a mixture of hydrogen, methane, and nitrogen at 750~960℃. The pretreatment in step 4) includes heat treatment or immersion treatment; The heat treatment is as follows: the dried gallium nitride / silicon nitride sample is heated to 650~750℃ and then kept at that temperature for 1~100 min in an oxygen-rich atmosphere or a hydrogen-rich atmosphere, followed by natural cooling. In the oxygen-rich atmosphere, the gallium nitride / silicon nitride sample is charged with a negative or positive charge. The impregnation process is as follows: the dried gallium nitride / silicon nitride sample is impregnated with an aqueous solution of a strong anionic polyelectrolyte or a strong cationic polyelectrolyte for 1-60 min. The strong anionic polyelectrolyte includes PSS solution or CMCNa solution. Impregnation in the strong anionic polyelectrolyte causes the gallium nitride / silicon nitride sample to acquire a negative charge. The strong cationic polyelectrolyte includes PDDA solution. Impregnation in the strong cationic polyelectrolyte causes the gallium nitride / silicon nitride sample to acquire a positive charge. After impregnation, the gallium nitride / silicon nitride sample is removed, cleaned with deionized water, and dried under a nitrogen atmosphere. The pretreated gallium nitride / silicon nitride sample carries a negative charge with a negative zeta potential of -60 to -35 mV; the pretreated gallium nitride / silicon nitride sample carries a positive charge with a positive zeta potential of +35 to +60 mV. Among them, the damage to the intermediate layer after diamond growth is less than 10nm.

2. The method for preparing a gallium nitride epitaxial diamond structure according to claim 1, characterized in that, In step 2), the sample is cleaned by ultrasonic cleaning with acetone, alcohol and deionized water for 10 minutes each. The concentration of acetone and alcohol is not required. The purpose of this step is to clean the sample surface to prevent stains from affecting subsequent epitaxial growth.

3. The method for preparing a gallium nitride epitaxial diamond structure according to claim 1, characterized in that, In step 6), the mixed gas has a hydrogen ratio of 90% to 100%, a methane ratio of 0% to 10%, and a nitrogen ratio of 0% to 5%.

4. A gallium nitride epitaxial diamond structure, characterized in that, The preparation method described in any one of claims 1-3 is used to obtain the product, which includes a silicon nitride layer on the surface of gallium nitride and a diamond layer on the surface of silicon nitride.

5. A gallium nitride epitaxial diamond structure according to claim 4, characterized in that, The thickness of the silicon nitride is 5-500 nm.

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