A method for preparing a patterned h-BN film and a MIS semiconductor device

Abstract

The present invention provides a method for preparing a patterned h-BN film and a MIS semiconductor device. The method for preparing the h-BN film of the present invention comprises the following steps: preparing patterned GaN on a substrate; preparing Cu on the patterned GaN to form patterned Cu; using a boron nitride precursor to grow an h-BN film on the patterned Cu, thereby obtaining a patterned h-BN film; the method for preparing the h-BN film of the present invention utilizes the difference in catalytic properties of Cu and GaN substrates to enable h-BN to grow on the Cu substrate but not on the GaN substrate, thereby achieving the purpose of in-situ growth of micro-patterned h-BN, thereby avoiding edge defects caused by traditional two-dimensional material pattern etching processes, leading to problems such as carrier recombination and leakage; and using the h-BN film prepared by the present invention as a dielectric layer to prepare an MIS semiconductor device, which can improve the performance and operating stability of the semiconductor device.

Description

Technical Field

[0001] The present invention relates to the technical field of two-dimensional material growth and semiconductor devices, and in particular to a method for preparing a patterned h-BN film and a MIS semiconductor device. Background Art

[0002] h-BN (hexagonal boron nitride) thin films exhibit exceptionally high transparency, thermal conductivity, and mechanical strength, as well as high oxidation resistance and excellent stability at high temperatures. Furthermore, due to their ultra-smooth surface, lack of dangling bonds and charge traps, and similar molecular structure to graphene, h-BN films are suitable for a variety of applications, including dielectric layers, transparent and flexible electronic devices, deep ultraviolet emitters, capacitive energy storage devices, protective layers, and multifunctional nanopores. For these applications, the h-BN films used must be large, uniform, and defect-free. However, even when high-quality, large-area, and uniform single-crystalline h-BN films are grown, etching processes are still required to etch the resulting high-quality, large-area, and uniform single-crystalline h-BN films into the desired shape and size. These processes can disrupt the h-BN film structure, particularly at the edges, introducing unavoidable grain boundaries, defects, and contaminants, leading to carrier recombination and leakage problems. This restricts the application of h-BN films and reduces their usability.

[0003] There are many methods for preparing h-BN thin films, including mechanical exfoliation, liquid-phase exfoliation, unfolding BN nanotubes, substitution reactions, radio frequency magnetron sputtering, electron beam irradiation, and chemical vapor deposition (CVD). CVD has been established as a common route for synthesizing large nanosheets. Recently, atmospheric pressure CVD and low-pressure CVD systems have been developed to grow large-area h-BN films.

[0004] Furthermore, h-BN films possess properties such as an ultra-smooth surface, the absence of dangling bonds and charge traps, and a bandgap of ~6 eV, making them a significant advantage as insulating layers in semiconductor devices and applicable to high-performance MIS electronic devices. In CVD systems, Cu foil is often used as a catalytic metal substrate for growing h-BN films. The ease of etching of Cu catalytic metal substrates facilitates the fabrication of micropatterned Cu substrates, upon which micropatterned h-BN films can be grown. Furthermore, since the h-BN films grown on Cu substrates must be transferred, the transfer process involves numerous steps, including photoresist removal from all four sides of the substrate, solution preparation (rapid etching), slow etching, cleaning, transfer, photoresist stripping, and cleaning, making it difficult to avoid damage to the h-BN films.

[0005] Based on the defects of the current preparation method of h-BN thin films, it is necessary to improve it. Summary of the Invention

[0006] In view of this, the present invention proposes a method for preparing a patterned h-BN film and a MIS semiconductor device to solve or at least partially solve the problems existing in the prior art.

[0007] In a first aspect, the present invention provides a method for preparing a patterned h-BN film, comprising the following steps:

[0008] providing a substrate;

[0009] preparing patterned GaN on the substrate;

[0010] Preparing Cu on the patterned GaN to form patterned Cu;

[0011] A h-BN film is grown on the patterned Cu using a boron nitride precursor, thereby obtaining a patterned h-BN film.

[0012] Preferably, the method for preparing the patterned h-BN thin film, wherein the patterned GaN is prepared on the substrate, specifically comprises:

[0013] growing a GaN thin film on the substrate;

[0014] growing a SiO2 thin film on the GaN thin film;

[0015] Coating a first photoresist on the SiO2 film, exposing a pattern compatible with the patterned GaN, developing, etching the SiO2 film, removing the first photoresist, and forming a patterned SiO2;

[0016] After etching the GaN film, the patterned SiO2 is etched away to obtain patterned GaN.

[0017] Preferably, the method for preparing the patterned h-BN film, wherein Cu is prepared on the patterned GaN to form patterned Cu, specifically comprises:

[0018] A second photoresist is coated on the patterned GaN to expose a pattern matching the patterned Cu, a Cu film is grown on the second photoresist, and the second photoresist and the Cu film on the second photoresist are removed to obtain the patterned Cu.

[0019] Preferably, the method for preparing the patterned h-BN film, using a boron nitride precursor to grow the h-BN film on patterned Cu, specifically comprises:

[0020] The substrate with patterned Cu is annealed at 950-1070°C for 0.5-3h under H2 flow;

[0021] The annealed substrate is placed in a chemical vapor deposition device, the growth chamber is heated to 1030-1070°C, a boron nitride precursor is introduced, the temperature of the precursor heating zone is set to 70-90°C, and the decomposition product of the boron nitride precursor grows on the patterned Cu to obtain an h-BN film.

[0022] Preferably, in the method for preparing the patterned h-BN film, the boron nitride precursor includes at least one of BH3NH3, (HBNH)3, BF3NH3, and BCl3NH3.

[0023] Preferably, the method for preparing the patterned h-BN thin film, wherein the patterned GaN is prepared on the substrate, specifically comprises:

[0024] NH3 and TMGa are used as N source and Ga source for GaN growth respectively, and GaN is grown on the substrate.

[0025] Preferably, in the method for preparing the patterned h-BN film, the substrate comprises one of a sapphire substrate, a silicon carbide substrate, a gallium nitride substrate, a silicon substrate, a sapphire / gallium nitride substrate, and a silicon carbide / gallium nitride substrate;

[0026] In the step of preparing Cu on the patterned GaN, the thickness of Cu is 40-60 nm.

[0027] In a second aspect, the present invention further provides a method for preparing a MIS semiconductor device, comprising the following steps:

[0028] A patterned h-BN film was prepared by the method described above;

[0029] The copper underneath the h-BN film is corroded using a Cu metal etching solution, so that the h-BN film is deposited on the patterned GaN.

[0030] A third photoresist is coated on the h-BN film to expose a pattern matching the patterned h-BN film, and then a metal film is grown on the third photoresist. The third photoresist and the metal film on the third photoresist are removed to obtain a patterned MIS semiconductor device.

[0031] Preferably, in the method for preparing the MIS type semiconductor device, the Cu metal etching solution comprises a mixture of water, HCl and H2O2, wherein the volume ratio of the water, HCl and H2O2 is (140-160):(20-30):(20-30).

[0032] Preferably, in the method for preparing the MIS semiconductor device, the metal film includes one of a Ni film, a Ti film, an Al film, a V film, an Au film, and a Cu film.

[0033] The method for preparing a patterned h-BN film and an MIS semiconductor device of the present invention has the following technical effects compared with the prior art:

[0034] The method for preparing a patterned h-BN film of the present invention deposits a Cu film within a pattern on a patterned GaN substrate, utilizing the difference in catalytic properties between the Cu and GaN substrates to achieve h-BN growth on the Cu substrate while preventing it from growing on GaN, thereby achieving the purpose of in-situ growth of micro-patterned h-BN, thereby avoiding edge defects caused by traditional two-dimensional material pattern etching processes, which lead to problems such as carrier recombination and leakage. The h-BN film prepared by the present invention is used as a dielectric layer to prepare an MIS semiconductor device, which can improve the performance and operating stability of the semiconductor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 Schematic diagram of the process for preparing the patterned h-BN film of the present invention;

[0037] Figure 2 Schematic diagram of preparing patterned GaN on a substrate according to the present invention;

[0038] Figure 3 Schematic diagram of preparing Cu on patterned GaN to form patterned Cu according to the present invention;

[0039] Figures 4-5 Schematic diagram of the preparation method of the MIS semiconductor device of the present invention. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0043] In the description of the present invention, it should be understood that the directions or positions indicated by “upper” and the like are based on the directions or positions shown in the accompanying drawings, or are the directions or positions in which the product of the invention is usually placed when in use, or are the directions or positions commonly understood by those skilled in the art. These directions or positions are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] The present invention provides a method for preparing a patterned h-BN film. Figure 1 As shown, the following steps are included:

[0046] S1. providing a substrate;

[0047] S2, preparing patterned GaN on a substrate;

[0048] S3, preparing Cu on the patterned GaN to form patterned Cu;

[0049] S4. Using a boron nitride precursor, an h-BN film is grown on the patterned Cu, thereby obtaining a patterned h-BN film.

[0050] The method for preparing a patterned h-BN film of the present application deposits a Cu film within a pattern on a patterned GaN substrate, utilizing the difference in catalytic properties of the two substrates to achieve the growth of h-BN on the Cu substrate but not on the GaN, thereby achieving the purpose of in-situ growth of micro-patterned h-BN, thereby avoiding edge defects caused by traditional two-dimensional material pattern etching processes, which lead to problems such as carrier recombination and leakage, and improving the performance and operating stability of micro-sized semiconductor devices.

[0051] In some embodiments, please refer to Figure 2 As shown, the step S2 of preparing patterned GaN on the substrate specifically includes:

[0052] A GaN thin film 11 is grown on a substrate 10, as shown in FIG. Figure 2 As shown in S20;

[0053] A SiO2 film 12 is grown on the GaN film 11, as shown in FIG. Figure 2 As shown in S21;

[0054] A first photoresist 13 is coated on the SiO2 film 12, such as Figure 2 As shown in S22, a pattern matching the patterned GaN is exposed, developed, and the SiO2 film 12 is etched. Figure 2 As shown in S23-S24, the first photoresist 13 is removed to form a patterned SiO2. Figure 2 As shown in S25;

[0055] After etching the GaN film 11, the patterned SiO2 is etched away, as shown in FIG. Figure 2 As shown in S26-27, patterned GaN is obtained.

[0056] Specifically, in the above embodiment, MOCVD is used to grow a GaN film of a certain thickness (for example, a thickness of 350 to 450 nm) on a substrate; thereafter, a SiO2 film of a certain thickness (for example, a thickness of 150 to 250 nm) is grown on the substrate / GaN by PECVD; then, a first photoresist is coated on the substrate / GaN / SiO2, and a mask is used to expose a pattern that matches the patterned GaN, and the pattern is developed, and the SiO2 film is etched away using RIE equipment using Ar and fluorocarbons (CHF3 or CF4); the first photoresist is removed using acetone and ethanol to form a patterned substrate / GaN / SiO2 template; ICP etching is used to etch GaN of a certain thickness using a Cl2 / BCl3 mixed gas; finally, the same RIE process as above is used to remove the remaining portion of the patterned SiO2 film using Ar and fluorocarbons (CHF3 or CF4), and finally, patterned GaN is obtained.

[0057] In some embodiments, please refer to Figure 3 As shown, in step S3, preparing Cu on the patterned GaN to form patterned Cu specifically includes:

[0058] A second photoresist 14 is coated on the patterned GaN. Figure 3 As shown in S30, a pattern matching the patterned Cu is exposed, and then a Cu film 15 is grown on the second photoresist 14. Figure 3 As shown in S31 in FIG. 3 , the second photoresist 14 and the Cu film 15 on the second photoresist are removed, as shown in S32 in FIG. 3 , thereby obtaining patterned Cu.

[0059] Specifically, in the above embodiment, a second photoresist is coated on the patterned substrate / GaN and a corresponding pattern is exposed; then, an electron beam evaporation device is used, a Cu metal evaporation source is selected, and a Cu film with a thickness of 40 to 60 nm is grown based on monitoring by a film thickness meter; then, acetone is used to remove the photoresist and the Cu film on the photoresist, thereby forming a patterned substrate / GaN / Cu.

[0060] In some embodiments, please refer to Figure 4 As shown, the h-BN film is grown on patterned Cu using a boron nitride precursor, specifically including:

[0061] The substrate with patterned Cu is annealed at 900-1200°C for 0.5-2h under H2 flow;

[0062] The annealed substrate is placed in a chemical vapor deposition device, and a boron nitride precursor is introduced. The temperature of the precursor heating zone is set to 70-90° C. The decomposed product of the boron nitride precursor grows on the patterned Cu to obtain an h-BN film 16.

[0063] Specifically, in the above embodiment, before growth, the patterned substrate / GaN / Cu is annealed at 950-1070°C for 0.5-3h under a flow of H2 at 250-350 standard cubic centimeters (sccm) per minute; the annealed substrate / GaN / Cu is then placed in a chemical vapor deposition device, the growth chamber is heated to 1030-1070°C (preferably, the growth chamber is heated to 1050°C), a boron nitride precursor is introduced, the temperature of the precursor heating zone is set to 70-90°C, and the decomposition product of the boron nitride precursor is introduced into the h-BN growth zone, and the growth is carried out for 25-35 minutes, so that h-BN is grown on the patterned substrate / GaN / Cu, but an h-BN film cannot be grown on GaN; after the h-BN film is grown, the precursor and growth zone heating programs are turned off, and the growth zone of the h-BN film is naturally cooled to room temperature under a flow of H2 at 25-35sccm.

[0064] In some embodiments, the boron nitride precursor includes at least one of BH3NH3, (HBNH)3, BF3NH3, and BCl3NH3.

[0065] In some embodiments, forming patterned GaN on a substrate specifically includes:

[0066] GaN is grown on a substrate using NH3 and TMGa as the N source and Ga source, respectively.

[0067] Specifically, a GaN film is grown on a substrate using MOCVD, with NH3 and TMGa (trimethylgallium) serving as the N source and Ga source, respectively; H2 serving as a carrier gas; the temperature of the reaction chamber substrate tray is fixed at 1000-1100°C and rotated at a rate of 5-15 r / min; the temperature of the reaction chamber top wall is fixed at 300-400°C, and the flow rate of TMGa is fixed at 100-200 μmol / min; and the above conditions are used to grow a GaN film of 350-450 nm.

[0068] In some embodiments, the substrate includes one of a sapphire substrate, a silicon carbide substrate, a gallium nitride substrate, a silicon substrate, a sapphire / gallium nitride substrate, and a silicon carbide / gallium nitride substrate; wherein, if the substrate is sapphire (Sapphire), silicon carbide (SiC), silicon Si and other materials, the Sapphire / GaN, SiC / GaN template substrate material is grown by the metal organic chemical vapor deposition (MOCVD) method, mainly utilizing the properties of the GaN wide bandgap semiconductor; preferably, the Sapphire / GaN template substrate material is used, and a catalytic metal Cu film is deposited on the surface of the Sapphire / GaN template for selective catalytic growth of an h-BN micro-pattern array.

[0069] In some embodiments, during the step of forming Cu on patterned GaN, the Cu thickness is 40 to 60 nm. Although the electron-beam evaporated Cu film is deposited on the patterned GaN substrate, excess h-BN film may be produced due to the Cu film extending beyond the edge of the patterned GaN. This can cause grain boundaries to form at the edges of the h-BN film when the patterned h-BN film, after etching the patterned Cu substrate, lands on the GaN, thereby affecting the quality of the semiconductor device. The thickness of the patterned Cu substrate must be controlled to prevent excessive h-BN film. This application utilizes the different growth mechanisms of h-BN films grown on GaN and Cu substrates to improve the ability to grow patterned h-BN films. Furthermore, the differences in growth mechanisms and the control of the Cu substrate thickness play a crucial role in controlling the size and shape of the h-BN film, thereby achieving a semiconductor device with patterned h-BN film that can significantly improve device performance and stability. This primarily addresses the problem of the potential for defects that are unavoidable when using h-BN films with specific sizes and shapes in the fabrication of semiconductor devices. The present invention has the advantages of simple process, significant effect, broad application prospect, etc.

[0070] Based on the same inventive concept, an embodiment of the present application further provides a method for preparing a MIS semiconductor device, comprising the following steps:

[0071] The patterned h-BN film was prepared by the above method;

[0072] The copper underneath the h-BN film is corroded using a Cu metal etching solution, so that the h-BN film is deposited on the patterned GaN.

[0073] A third photoresist is coated on the h-BN film to expose a pattern matching the patterned h-BN film, and then a metal film is grown on the third photoresist. The third photoresist and the metal film on the third photoresist are removed to obtain a patterned MIS semiconductor device.

[0074] The MIS semiconductor device of the present application is a semiconductor-insulator-metal (MIS) type semiconductor device, which uses h-BN thin film as a dielectric layer and the micro-patterned h-BN as a dielectric layer to prepare a high-performance MIS type semiconductor device array. Specifically, refer to Figures 4-5 As shown, the copper film 15 below the h-BN film 16 is corroded by using a Cu metal etching solution, as shown in FIG. Figure 4 As shown in S41, the etched h-BN film 16 lands on the patterned GaN, and the interaction between the h-BN film and the patterned GaN surface is utilized to ensure that the h-BN film can be left on the top of the patterned GaN after the Cu etching is completed, as shown in FIG. Figure 4As shown in S42; coating a third photoresist 17 on the h-BN film 16, as shown Figure 5 As shown in S50, a pattern matching the patterned h-BN film is exposed, and then a metal film 18 is grown on the third photoresist 17. Figure 5 As shown in S51, the third photoresist 17 and the metal film 18 on the third photoresist are removed. Figure 5 As shown in S52, a patterned MIS semiconductor device is obtained.

[0075] In some embodiments, the Cu metal etching solution includes a mixture of water, HCl, and H2O2, wherein the volume ratio of water, HCl, and H2O2 is (140-160):(20-30):(20-30).

[0076] Specifically, the corrosion of the Cu substrate in the patterned h-BN film includes rapid corrosion and slow corrosion. The rapid corrosion solution is prepared by mixing 150 ml of deionized water, 25 ml of HCl, and 25 ml of H2O2 (more HCl and H2O2 can be added to ensure a 1:1 volume ratio). The slow corrosion solution is prepared by adding enough Na2(SO4)2 powder to 1000 ml of deionized water to prepare a saturated Na2(SO4)2 solution, which is the slow corrosion solution.

[0077] Rapid etching is sufficient to a thickness similar to that of paper; during slow etching, the fan of the fume hood should be turned off. When Cu is completely etched, the remaining material is very thin and easily damaged by vibration. The height of the rapid etching solution is roughly parallel to the height of the substrate / GaN / Cu / h-BN. The corroded h-BN film floats above the patterned GaN, making it easier to retrieve it later. The height of the slow etching solution here also needs to be roughly parallel to the height of the substrate / GaN / Cu / h-BN. The substrate / GaN and h-BN film after Cu etching are slowly transferred to deionized water and washed. The washed material film is placed in deionized water, and the h-BN film is slowly scooped up with the substrate / GaN and left to dry naturally (heating evaporation drying cannot be used, otherwise special wrinkles will be produced). The h-BN film can be deposited on the patterned substrate / GaN.

[0078] Specifically, when etching the Cu substrate in the patterned h-BN film, the fast etching time is 30 seconds and the slow etching time is 5 minutes.

[0079] In some embodiments, a photolithography process is used to coat a third photoresist on the h-BN film, and the patterned sapphire substrate / GaN / h-BN and substrate / third photoresist are exposed; thereafter, an electron beam evaporation process is used to deposit a metal film (as a metal electrode) with a thickness of 90 to 110 nm on the patterned sapphire substrate / GaN / h-BN, and the evaporated metal may include: Ni, Ti, Al, V, Au, Cu and other metals; then, acetone is used to wash away the third photoresist and the metal film thereon to form a patterned substrate / GaN / h-BN metal structure, and then a MIS type semiconductor device array is formed.

[0080] In some embodiments, the first photoresist, the second photoresist, and the third photoresist used in the present application can all be conventional photoresists, such as AZ703 photoresist, SU-8 photoresist, etc.

[0081] The following further illustrates the method for preparing the patterned h-BN thin film and the method for preparing the MIS semiconductor device of the present application using specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0082] Example 1

[0083] The present invention provides a method for preparing a patterned h-BN film, comprising the following steps:

[0084] S1. Provide a sapphire substrate;

[0085] S2. GaN thin film was grown on a sapphire substrate using MOCVD, with NH3 and TMGa (trimethylgallium) as the N and Ga sources, respectively; H2 was used as the carrier gas; the temperature of the reaction chamber substrate tray was fixed at 1050°C and rotated at a rate of 10 r / min; the temperature of the reaction chamber top wall was fixed at 350°C, and the flow rate of TMGa was fixed at 150 μmol / min; a 400 nm thick GaN film was grown using the above conditions;

[0086] S3, using PECVD to grow a 200nm thick SiO2 film on the sapphire substrate / GaN; then coating a first photoresist on the sapphire substrate / GaN / SiO2, using a mask to expose a pattern that matches the patterned GaN, developing, and using RIE equipment to etch away the SiO2 film using Ar and fluorocarbons (CHF3 or CF4); using acetone and ethanol to remove the first photoresist to form a patterned substrate / GaN / SiO2 template; using ICP etching with a Cl2 / BCl3 mixed gas to etch a 400nm thick GaN; finally, using the same RIE process as above, using Ar and fluorocarbons (CHF3 or CF4) to remove the remaining portion of the patterned SiO2 film, ultimately obtaining a patterned sapphire substrate / GaN;

[0087] S4. Applying a second photoresist on the patterned sapphire substrate / GaN and exposing a corresponding pattern; then, using an electron beam evaporation device, selecting a Cu metal evaporation source, and growing a 50 nm thick Cu film based on monitoring by a film thickness meter; then, using acetone to remove the photoresist and the Cu film on the photoresist, forming a patterned sapphire substrate / GaN / Cu;

[0088] S5. Anneal the patterned sapphire substrate / GaN / Cu at 1050°C for 1 hour under a flow of H2 at 300 standard cubic centimeters per minute (sccm); then place the annealed substrate / GaN / Cu in a chemical vapor deposition device, heat the growth chamber to 1050°C, introduce an ammonia borane (H3N-BH3) precursor, set the temperature of the precursor heating zone to 80°C, introduce the decomposition product of the boron nitride precursor into the h-BN growth zone, and grow for 30 minutes to grow an h-BN film on the patterned sapphire substrate / GaN / Cu; after the h-BN film is grown, turn off the precursor and growth zone heating programs, and naturally cool the growth zone of the h-BN film to room temperature under a flow of H2 at 30 sccm.

[0089] Example 2

[0090] The present invention provides a method for preparing a MIS semiconductor device, comprising the following steps:

[0091] S1. Obtain a patterned h-BN film using the method in Example 1;

[0092] S2. Using a Cu metal etching solution, the copper below the h-BN film is corroded to deposit the h-BN film on the patterned GaN film; the Cu metal etching solution comprises a mixture of 150 mL of water, 25 mL of HCl, and 25 mL of H2O2;

[0093] S3. Coat a third photoresist on the h-BN film to expose a pattern that matches the patterned h-BN film, and use an electron beam evaporation process to deposit a 100nm thick metal film Ni on the patterned sapphire substrate / GaN / h-BN; then, use acetone to wash away the photoresist and the metal film Ni thereon to form a patterned sapphire substrate / GaN / h-BN / metal structure, thereby obtaining an MIS semiconductor device.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a patterned h-BN film, characterized in that: The following steps are involved: providing a substrate; Preparing a patterned GaN film on the substrate, wherein the process of preparing a patterned GaN film on the substrate specifically includes: growing a GaN thin film on the substrate; growing a SiO2 thin film on the GaN thin film; Coating a first photoresist on the SiO2 film, exposing a pattern compatible with the patterned GaN, developing, etching the SiO2 film, removing the first photoresist, and forming a patterned SiO2; After etching the GaN film, the patterned SiO2 is etched away to obtain patterned GaN; Preparing Cu on the patterned GaN film to form a patterned Cu film with a thickness of 40 to 60 nm; A h-BN film is grown on a patterned Cu film using a boron nitride precursor, thereby obtaining a patterned h-BN film.

2. The method for preparing a patterned h-BN thin film according to claim 1, wherein: Preparing Cu on the patterned GaN to form patterned Cu specifically includes: A second photoresist is coated on the patterned GaN to expose a pattern matching the patterned Cu, a Cu film is grown on the second photoresist, and the second photoresist and the Cu film on the second photoresist are removed to obtain the patterned Cu.

3. The method for preparing a patterned h-BN thin film according to claim 1, wherein: The h-BN film is grown on patterned Cu using a boron nitride precursor, specifically including: The substrate with patterned Cu is annealed at 950-1070°C for 0.5-3h under H2 flow; The annealed substrate is placed in a chemical vapor deposition device, the growth chamber is heated to 1030-1070°C, a boron nitride precursor is introduced, the temperature of the precursor heating zone is set to 70-90°C, and the decomposition product of the boron nitride precursor grows on the patterned Cu to obtain an h-BN film.

4. The method for preparing a patterned h-BN thin film according to claim 1, wherein: The boron nitride precursor includes at least one of BH3NH3, (HBNH)3, BF3NH3, and BCl3NH3.

5. The method for preparing a patterned h-BN thin film according to claim 1, wherein: The method of preparing patterned GaN on the substrate specifically includes: NH3 and TMGa are used as N source and Ga source for GaN growth respectively, and GaN is grown on the substrate.

6. The method for preparing a patterned h-BN thin film according to claim 1, wherein: The substrate includes one of a sapphire substrate, a silicon carbide substrate, a gallium nitride substrate, a silicon substrate, a sapphire / gallium nitride substrate, and a silicon carbide / gallium nitride substrate; In the step of preparing Cu on the patterned GaN, the thickness of Cu is 40-60 nm.

7. A method for preparing a MIS semiconductor device, characterized in that: The following steps are involved: A patterned h-BN film is prepared by the method according to any one of claims 1 to 6; The copper underneath the h-BN film is corroded using a Cu metal etching solution, so that the h-BN film is deposited on the patterned GaN. A third photoresist is coated on the h-BN film to expose a pattern matching the patterned h-BN film, and then a metal film is grown on the third photoresist. The third photoresist and the metal film on the third photoresist are removed to obtain a patterned MIS semiconductor device.

8. The method for preparing a MIS semiconductor device according to claim 7, wherein: The Cu metal etching solution includes a mixture of water, HCl and H2O2, wherein the volume ratio of water, HCl and H2O2 is (140-160):(20-30):(20-30).

9. The method for preparing a MIS semiconductor device according to claim 7, wherein: The metal film includes one of a Ni film, a Ti film, an Al film, a V film, an Au film, and a Cu film.

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