Gallium oxide substrate and preparation method thereof

Abstract

A gallium oxide substrate and a method for preparing the same are provided. The method comprises the following steps: forming a first groove on the surface of an initial gallium oxide substrate using laser ablation according to a laser ablation pattern; repairing the first groove by wet chemical etching to form a second groove; and filling the second groove with a thermally conductive layer to form a gallium oxide substrate with a thermally conductive layer. Filling the second groove with a highly thermally conductive material using laser etching results in a gallium oxide substrate with a thermally conductive layer having a simple structure and excellent heat dissipation performance.

Description

Technical Field

[0001] The present disclosure relates to the technical field of wide bandgap semiconductor power electronic devices, and in particular to a gallium oxide substrate and a preparation method thereof. Background Art

[0002] Gallium oxide, one of the fourth-generation ultra-wide bandgap semiconductor materials that has rapidly developed in recent years, boasts a wider bandgap than first-, second-, and third-generation semiconductors such as silicon, germanium, gallium arsenide, indium phosphide, silicon carbide, and gallium nitride. Furthermore, its Baliga figure of merit reaches 3444, resulting in a higher breakdown field strength. This material offers significant advantages and enormous potential for the fabrication of power semiconductor electronic devices that are resistant to high voltage, high temperature, and radiation. However, gallium oxide has low carrier mobility and extremely low thermal conductivity, making heat dissipation management a critical issue when used in high-power devices.

[0003] Additionally, gallium oxide is a relatively hard material with excellent mechanical properties and chemical stability. However, when processing it during device fabrication, the etching rates are unsatisfactory, whether using plasma dry etching or strong acid wet etching. Deep processing of gallium oxide is particularly difficult with traditional etching methods. Current solutions to heat dissipation in gallium oxide power devices are mostly based on heterogeneous integration, transferring the gallium oxide material to a substrate with better thermal conductivity. This method is relatively complex, while homoepitaxial devices use mechanical thinning to address heat dissipation, significantly reducing yield and reliability. Summary of the Invention

[0004] (1) Technical issues to be solved

[0005] To address at least one of the aforementioned technical issues with gallium oxide substrates in the prior art, embodiments of the present disclosure provide a gallium oxide substrate and a method for preparing the same. Laser-induced processing is used to etch grooves on the surface of the gallium oxide substrate material and fill it with thermally conductive material to improve the heat dissipation characteristics of the gallium oxide material and the device.

[0006] (2) Technical solution

[0007] In response to the above technical problems, embodiments of the present disclosure provide a method for preparing a gallium oxide substrate and a gallium oxide substrate.

[0008] According to one aspect of the present disclosure, a method for preparing a gallium oxide substrate includes the following steps: machining a first trench on the surface of an initial gallium oxide substrate using laser ablation according to a laser ablation pattern; repairing the first trench by wet chemical etching to obtain a second trench; and filling the second trench with a thermally conductive layer to form a gallium oxide substrate having a thermally conductive layer.

[0009] In some exemplary embodiments, the first groove planing structure is "V"-shaped or "trapezoidal"-shaped, and the second groove planing structure is "concave"-shaped.

[0010] In some exemplary embodiments, the surface of the initial gallium oxide substrate is treated before processing to obtain an initial gallium oxide substrate material with a clean surface.

[0011] In some exemplary embodiments, after performing wet chemical etching to repair the first trench to obtain the second trench, and before filling the second trench with a thermal conductive layer, cleaning is required to remove residual solution from the wet chemical etching repair process.

[0012] In some exemplary embodiments, the initial gallium oxide substrate includes single crystal gallium oxide.

[0013] In some exemplary embodiments, the doping type of the initial gallium oxide substrate includes unintentional doping or n-type doping.

[0014] In some exemplary embodiments, the doping element of the initial gallium oxide substrate includes one or more of silicon, tin, germanium, iron, carbon, and cobalt.

[0015] In some exemplary embodiments, the carrier concentration of the initial gallium oxide substrate is 1×10 13 cm -3 -1×10 20 cm -3 .

[0016] In some exemplary embodiments, the resistivity of the initial gallium oxide substrate is 1×10 -5 Ω.cm-1×10 9 Ω.cm.

[0017] In some exemplary embodiments, the surface roughness of the initial gallium oxide substrate is less than 100 nm.

[0018] In some exemplary embodiments, the thickness of the initial gallium oxide substrate is 100 μm-1500 μm.

[0019] In some exemplary embodiments, the laser ablation pattern includes various regular or irregular geometric shapes that can be obtained by laser processing, such as various regular shapes such as bars, rings, square rings, squares, circles, triangles, ellipses, polygons, etc., as well as various special shapes that may be obtained by laser processing.

[0020] In some exemplary embodiments, a single width of the geometric figure is 0.01 mm to 100 mm, and a ratio of the area of ​​the geometric figure to the surface area of ​​the gallium oxide substrate on which the geometric figure is located is 1% to 99%.

[0021] In some exemplary embodiments, a first groove is machined on the surface of the gallium oxide substrate by laser ablation according to a laser ablation pattern, wherein the machining process parameters include at least one of the following items: a wavelength range of the laser of 100 nm to 2000 nm; an output power of the laser of 0.1 W to 10 W; a repetition frequency of the laser pulse of 10 Hz to 1 MHz; a number of laser machining scanning repetition ablation times of 1 to 1000 times; and a sample stage scanning movement speed of 0.001 mm / s to 100 mm / s.

[0022] In some exemplary embodiments, the first trench is repaired by wet chemical etching to obtain the second trench, and the wet chemical etching solution includes various acidic solutions such as H2SO4, H2O2, H3PO4, HCl, HNO3, HF, and alkaline solutions such as KOH and NaOH.

[0023] In some exemplary embodiments, the temperature of the wet chemical etching solution is 20° C.-500° C.; and the wet chemical etching time is 0.01 h-10 h.

[0024] In some exemplary embodiments, filling the second groove with a thermal conductive layer specifically includes: filling the second groove with a thermal conductive layer by a sintering method, wherein the sintering method for filling the groove with a thermal conductive layer includes the following steps: placing the thermal conductive layer material and the sintering solution in a homogenizer in proportion, so that the thermal conductive layer material is evenly dispersed in the sintering solution to form a homogeneous mixed solution; using a spin coater to spin-coat the homogeneous mixed solution into the second groove to obtain a preform; and placing the preform in a furnace for sintering, wherein the thermal conductive layer material includes one or more of a metal material, a sintered ceramic material and a composite material; and the sintering solution includes a mixed solution formed by one or more solutions of ethylene glycol, polyethylene glycol, nano silver paste and epoxy resin.

[0025] In some exemplary embodiments, a thermal conductive layer is filled in the second groove, wherein the processing parameters include at least one of the following items: a mass ratio of the thermal conductive layer material to the sintering solution is 1:0.01-1:100; a rotation speed of the homogenizer is 1rpm-5000rpm; a spin coating speed of the spin coater is 1rpm-1000rpm; the sintering temperature is 100°C-1800°C; the number of sintering times is 1-100 times; and the sintering time is 0.01h-10h.

[0026] In some exemplary embodiments, a thermal conductive layer is filled in the second groove, wherein the filling material is as follows: the metal material includes a single substance formed by one of copper, nickel, gold, silver and aluminum, or an alloy formed by several of them; the ceramic material includes one or more of aluminum nitride, boron nitride, silicon carbide, diamond, graphene and graphene oxide; and the thermal conductive layer material is in the form of micron / nano-granular material with a particle size range of 1nm-1000μm.

[0027] In some exemplary embodiments, in filling the heat-conducting layer in the second groove, a method of filling the heat-conducting layer includes one or more of thermal evaporation, melt sintering, electron beam evaporation, electroplating and magnetron sputtering, and the material of the heat-conducting layer includes a metal material.

[0028] According to another aspect of the present disclosure, a gallium oxide substrate is provided. The gallium oxide substrate is prepared by any of the methods described above, wherein the thermal conductive layer is parallel to the bottom of the initial gallium oxide substrate but not higher than the initial gallium oxide substrate, and is wrapped by the initial gallium oxide substrate or overflows to cover the bottom of the initial gallium oxide substrate.

[0029] (3) Beneficial effects

[0030] It can be seen from the above technical solutions that the method for improving the heat dissipation performance of a gallium oxide substrate provided by the present disclosure has at least one of the following beneficial effects:

[0031] (1) Using high-power pulsed laser ablation technology, the laser beam is adjusted to a small enough spot and focused on the surface of the semiconductor material. The semiconductor material at the focus generates transient high temperature after absorbing the laser energy, directly ablating and evaporating the semiconductor material, thereby achieving the purpose of precise processing.

[0032] (2) Laser ablation technology is used to process gallium oxide substrate materials to a depth of 100μm or more in a shorter time, thereby improving processing efficiency.

[0033] (3) Nanoparticles (particle size <100 nm) are homogenized with the sintering solvent, and high-pressure sintering allows the solution to fully immerse into the grooves after laser ablation, significantly increasing the contact area between the solution and the gallium oxide substrate material, which is beneficial to reducing the interface thermal resistance.

[0034] (4) The bottom surface is vertically structured, and nanoparticles form a high thermal conductivity layer. On this basis, the preparation of high-power devices will not cause unstable device performance due to heat dissipation problems, thereby ensuring the normal operation of high-power devices.

[0035] (5) The homoepitaxial film has higher quality. Since the band gap of gallium oxide reaches 4.8eV, the prepared device has higher voltage resistance.

[0036] (6) Simple structure, excellent heat dissipation performance, easy to promote and apply in large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure schematically shows a flow chart of a method for preparing a gallium oxide substrate according to an embodiment of the present disclosure.

[0038] Figure 2 Schematic diagrams of the three-dimensional structure of the gallium oxide substrate of an embodiment of the present disclosure are schematically shown, wherein (a) schematically shows that the shape of the thermal conductive layer at the bottom of the gallium oxide substrate is a circle distributed in an array, (b) schematically shows that the shape of the thermal conductive layer at the bottom of the gallium oxide substrate is a square ring distributed at intervals, (c) schematically shows that the shape of the thermal conductive layer at the bottom of the gallium oxide substrate is a square, and (d) schematically shows that the shape of the thermal conductive layer at the bottom of the gallium oxide substrate is a circular ring distributed at intervals.

[0039] Figure 3 The laser ablation patterns of the embodiments of the present disclosure are schematically shown, wherein (a) schematically shows that the laser ablation pattern is a circle distributed in an array, (b) schematically shows that the laser ablation pattern is a square ring distributed at intervals, (c) schematically shows that the laser ablation pattern is a square, and (d) schematically shows that the laser ablation pattern is a circular ring distributed at intervals.

[0040] Figure 4 Schematic diagrams of the cross-sectional structure of the initial gallium oxide substrate after laser ablation in an embodiment of the present disclosure are schematically shown, wherein (a) schematically shows the cross-sectional structure of the initial gallium oxide substrate after laser ablation when the laser ablation pattern is a circular array distribution, (b) schematically shows the cross-sectional structure of the initial gallium oxide substrate after laser ablation when the laser ablation pattern is a square ring distribution at intervals, (c) schematically shows the cross-sectional structure of the initial gallium oxide substrate after laser ablation when the laser ablation pattern is a square, and (d) schematically shows the cross-sectional structure of the initial gallium oxide substrate after laser ablation when the laser ablation pattern is a circular ring distribution at intervals.

[0041] Figure 5 Schematic diagrams of the cross-sectional structure of the initial gallium oxide substrate after wet chemical etching repair according to an embodiment of the present disclosure are schematically shown, wherein (a) schematically shows the cross-sectional structure of the initial gallium oxide substrate after wet chemical etching repair when the laser ablation pattern is a circular array distribution, (b) schematically shows the cross-sectional structure of the initial gallium oxide substrate after wet chemical etching repair when the laser ablation pattern is a square ring distribution at intervals, (c) schematically shows the cross-sectional structure of the initial gallium oxide substrate after wet chemical etching repair when the laser ablation pattern is a square, and (d) schematically shows the cross-sectional structure of the initial gallium oxide substrate after wet chemical etching repair when the laser ablation pattern is a circular ring distribution at intervals.

[0042] Figure 6Schematic diagrams of the cross-sectional structure of the gallium oxide substrate after filling with a thermal conductive layer according to an embodiment of the present disclosure are schematically shown, wherein (a) schematically shows the cross-sectional structure of the gallium oxide substrate after filling with a thermal conductive layer when the laser ablation pattern is a circular array distribution, (b) schematically shows the cross-sectional structure of the gallium oxide substrate after filling with a thermal conductive layer when the laser ablation pattern is a square ring distribution, (c) schematically shows the cross-sectional structure of the gallium oxide substrate after filling with a thermal conductive layer when the laser ablation pattern is a square, and (d) schematically shows the cross-sectional structure of the gallium oxide substrate after filling with a thermal conductive layer when the laser ablation pattern is a circular ring distribution distribution.

[0043] Figure 7 Schematic diagrams of the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer in an embodiment of the present disclosure are schematically shown, wherein (a) schematically shows the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer when the laser ablation pattern is a circular array distribution, (b) schematically shows the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer when the laser ablation pattern is a square ring distribution with intervals, (c) schematically shows the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer when the laser ablation pattern is a square, and (d) schematically shows the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer when the laser ablation pattern is a circular ring distribution with intervals.

[0044] Description of reference numerals:

[0045] Reference numerals: 1 - initial gallium oxide substrate; 2 - heat conducting layer. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the present disclosure more clearly understood, the present disclosure is further described below in conjunction with specific embodiments and with reference to the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present disclosure, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present disclosure without inventive effort are intended to fall within the scope of protection of the present disclosure.

[0047] Gallium oxide has low carrier mobility and extremely low thermal conductivity, making heat dissipation management a significant concern for high-power devices. Existing solutions for gallium oxide heat dissipation are overly limited. This invention addresses the heat dissipation issues faced by gallium oxide substrate materials and devices by providing a solution that improves the heat dissipation performance of gallium oxide substrates by filling them with a highly thermally conductive material through laser etching.

[0048] An embodiment of the present disclosure shows a method for preparing a gallium oxide substrate. Figure 1 , the preparation method of the gallium oxide substrate is described in detail.

[0049] In step S1 , an initial gallium oxide substrate is processed to obtain an initial gallium oxide substrate with a clean surface.

[0050] In some exemplary embodiments, the initial gallium oxide substrate includes single crystal gallium oxide.

[0051] In some exemplary embodiments, the doping type of the initial gallium oxide substrate includes unintentional doping or n-type doping.

[0052] In some exemplary embodiments, the doping element of the initial gallium oxide substrate includes one or more of silicon, tin, germanium, iron, carbon, and cobalt.

[0053] In some exemplary embodiments, the carrier concentration of the initial gallium oxide substrate is 1×10 13 cm -3 -1×10 20 cm -3 .

[0054] In some exemplary embodiments, the resistivity of the initial gallium oxide substrate is 1×10 -5 Ω.cm-1×10 9 Ω.cm.

[0055] In some exemplary embodiments, the surface roughness of the initial gallium oxide substrate is less than 100 nm.

[0056] In some exemplary embodiments, the thickness of the initial gallium oxide substrate is 100 μm-1500 μm.

[0057] In step S2, a first groove is machined on the surface of the initial gallium oxide substrate by using a laser ablation method according to a laser ablation pattern.

[0058] In some exemplary embodiments, the first groove planing structure is "V"-shaped or "trapezoidal"-shaped.

[0059] In some exemplary embodiments, the laser ablation pattern includes various regular or irregular geometric shapes that can be obtained by laser processing, such as various regular shapes such as bars, rings, square rings, squares, circles, triangles, ellipses, polygons, etc., as well as various special shapes that may be obtained by laser processing.

[0060] In some exemplary embodiments, a single width of the geometric figure is 0.01 mm to 100 mm, and a ratio of the area of ​​the geometric figure to the surface area of ​​the gallium oxide substrate on which the geometric figure is located is 1% to 99%.

[0061] In some exemplary embodiments, a first groove is machined on the surface of the gallium oxide substrate by laser ablation according to a laser ablation pattern, wherein the machining process parameters include at least one of the following items: a wavelength range of the laser of 100 nm to 2000 nm; an output power of the laser of 0.1 W to 10 W; a repetition frequency of the laser pulse of 10 Hz to 1 MHz; a number of laser machining scanning repetition ablation times of 1 to 1000 times; and a sample stage scanning movement speed of 0.001 mm / s to 100 mm / s.

[0062] In step S3, the first trench is repaired by wet chemical etching to obtain a second trench.

[0063] In some exemplary embodiments, the second groove planing structure is concave.

[0064] In some exemplary embodiments, the wet chemical etching solution includes various acidic solutions such as H2SO4, H2O2, H3PO4, HCl, HNO3, HF, and alkaline solutions such as KOH and NaOH.

[0065] In some exemplary embodiments, the temperature of the wet chemical etching solution is 20° C.-500° C.

[0066] In some exemplary embodiments, the wet chemical etching time is 0.01 h-10 h.

[0067] In step S4, cleaning is performed to remove residual solution from the wet chemical etching process.

[0068] In step S5 , a heat-conducting layer is filled in the second trench to form a gallium oxide substrate with a heat-conducting layer.

[0069] In some exemplary embodiments, a sintering method is used to fill the second groove with a thermal conductive layer, and the sintering method for filling the groove with a thermal conductive layer includes the following steps: placing the thermal conductive layer material and the sintering solution in a homogenizer in proportion, so that the thermal conductive layer material is evenly dispersed in the sintering solution to form a homogeneous mixed solution; using a spin coater to spin-coat the homogeneous mixed solution into the second groove to obtain a preform; and placing the preform in a furnace for sintering, wherein the thermal conductive layer material includes one or more of a metal material, a sintered ceramic material and a composite material; and the sintering solution includes a mixed solution formed by one or more solutions of ethylene glycol, polyethylene glycol, nano silver paste and epoxy resin.

[0070] In some exemplary embodiments, a thermal conductive layer is filled in the second groove, wherein the processing parameters include at least one of the following items: a mass ratio of the thermal conductive layer material to the sintering solution is 1:0.01-1:100; a rotation speed of the homogenizer is 1rpm-5000rpm; a spin coating speed of the spin coater is 1rpm-1000rpm; the sintering temperature is 100°C-1800°C; the number of sintering times is 1-100 times; and the sintering time is 0.01h-10h.

[0071] In some exemplary embodiments, a thermal conductive layer is filled in the second groove, wherein the filling material is as follows: the metal material includes a single substance formed by one of copper, nickel, gold, silver and aluminum, or an alloy formed by several of them; the ceramic material includes one or more of aluminum nitride, boron nitride, silicon carbide, diamond, graphene and graphene oxide; and the thermal conductive layer material is in the form of micron / nano-granular material with a particle size range of 1nm-1000μm.

[0072] In some exemplary embodiments, in filling the heat-conducting layer in the second groove, a method of filling the heat-conducting layer includes one or more of thermal evaporation, melt sintering, electron beam evaporation, electroplating and magnetron sputtering, and the material of the heat-conducting layer includes a metal material.

[0073] For example, the preparation method may be based on the bottom of the initial gallium oxide substrate being a circular hole array and sintered with a filling metal to improve heat dissipation. The preparation method may include the following steps.

[0074] In step S1 , the surface of the initial gallium oxide substrate is treated to obtain an initial gallium oxide substrate material with a clean surface.

[0075] Single crystal gallium oxide was selected as the initial gallium oxide substrate. The thickness of the single crystal gallium oxide substrate was 500 μm, the surface roughness was less than 1 nm, and the doping concentration was 1×10 18 cm -3 , cleaning the surface of the single crystal gallium oxide substrate to obtain a clean single crystal gallium oxide substrate.

[0076] In step S2, a first trench is formed on the bottom surface of the single crystal gallium oxide substrate by laser ablation.

[0077] The pattern processed on the bottom surface of the single crystal gallium oxide substrate is a circular array with an array size of 12×12. The total area of ​​the pattern accounts for 12.56% of the total area of ​​the single crystal gallium oxide substrate. Figure 3As shown in (a). The bottom surface of the single crystal gallium oxide substrate is processed by laser ablation process. The laser power is 1000KHz, the repetition rate is 100%, the number of ablations is 1000 times, the moving speed is 500mm / s, and the ablation depth is 300μm. The cross-sectional structure after laser ablation is shown in the figure below. Figure 4 As shown in (a).

[0078] In step S3, the first trench is repaired by wet etching to obtain a second trench.

[0079] The initial gallium oxide substrate after laser ablation has a V-shaped surface structure. The V-shaped structure is repaired to a concave shape by wet etching using H2S04:H2O2 (3:1). The cross-sectional structure after wet chemical etching is shown in the figure. Figure 5 As shown in (a).

[0080] In step S4, the gallium oxide substrate is cleaned.

[0081] For example, deionized water may be used for repeated rinsing.

[0082] In step S5 , a high thermal conductivity layer is prepared.

[0083] For example, nano-ceramic particles AlN and sintering solvent ethylene glycol can be added to a beaker at a mass ratio of 1:1, with a ceramic material particle size of 100nm. The mixture is placed in a homogenizer at a speed of 2000r / min to obtain a suspension for preparing a high thermal conductivity layer. A pipette is used to drop the prepared suspension onto the bottom of the initial gallium oxide substrate. The sample is then sent into a high-pressure sintering furnace at a sintering temperature of 1600℃ and a pressure of 2MPa. The sintering is repeated three times to complete the preparation. The cross-sectional structure of the gallium oxide substrate after filling the thermal conductive layer is shown in the figure below. Figure 6 As shown in (a), the schematic diagram of the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 7 As shown in (a), the schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 2 As shown in (a).

[0084] For example, the preparation method may improve heat dissipation based on electroplating filling metal on the bottom of the substrate into a square shape, and the preparation method may include the following steps.

[0085] In step S1 , the surface of the gallium oxide substrate is processed to obtain a gallium oxide substrate material with a clean surface.

[0086] A single crystal gallium oxide substrate was selected as the initial gallium oxide substrate with a thickness of 500 μm, a surface roughness of less than 1 nm, and a doping concentration of 1×10 18 cm -3 , the surface of the gallium oxide substrate is cleaned to obtain a clean initial gallium oxide substrate.

[0087] In step S2, a first trench is formed on the bottom surface of the single crystal gallium oxide substrate by laser ablation.

[0088] The side length of the square processed at the bottom of the single crystal gallium oxide substrate is 3 mm, and the total area of ​​the pattern accounts for 36% of the overall area of ​​the single crystal gallium oxide substrate. Figure 3 As shown in (c). The bottom surface of the single crystal gallium oxide substrate is processed by laser ablation process. The laser power is 1000KHz, the repetition rate is 100%, the number of ablation times is 1000 times, the moving speed is 500mm / s, and the ablation depth is 300μm. The cross-sectional structure after laser ablation is shown in the figure below. Figure 4 Middle (c).

[0089] In step S3, the first trench is repaired by wet etching to obtain a second trench.

[0090] The cross-sectional structure of the first groove formed after laser ablation of the single crystal gallium oxide substrate is "trapezoidal". The "trapezoidal" first groove is repaired into a "concave" second groove by wet etching using H2S04:H2O2 (3:1). The cross-sectional structure after wet chemical etching is shown in FIG. Figure 5 As shown in (c).

[0091] In step S4, the single crystal gallium oxide substrate is cleaned.

[0092] Rinse repeatedly with deionized water.

[0093] In step S5 , a high thermal conductivity layer is prepared.

[0094] Using the electroplating process, metal Cu is electroplated into the square second groove, and the second groove is filled to the outer surface of the single crystal gallium oxide substrate to complete the preparation. The cross-sectional structure diagram of the gallium oxide substrate after filling the thermal conductive layer is shown in FIG. Figure 6 As shown in (c), the schematic diagram of the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 7 As shown in (c), the schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 2 As shown in (c).

[0095] For example, the preparation method may improve heat dissipation based on the bottom of the substrate being a square sintered filler metal, and the preparation method may include the following steps.

[0096] In step S1 , the surface of the initial gallium oxide substrate is treated to obtain an initial gallium oxide substrate material with a clean surface.

[0097] A single crystal gallium oxide substrate was selected as the initial gallium oxide substrate with a thickness of 500 μm, a surface roughness of less than 1 nm, and a doping concentration of 1×10 18 cm-3 , cleaning the surface of the single crystal gallium oxide substrate to obtain a clean single crystal gallium oxide substrate.

[0098] In step S2, a first trench is formed on the bottom surface of the single crystal gallium oxide substrate by laser ablation.

[0099] The side length of the square processed at the bottom of the single crystal gallium oxide substrate is 3 mm, and the total area of ​​the pattern accounts for 36% of the overall area of ​​the initial gallium oxide substrate. Figure 3 As shown in (c). The bottom surface of the single crystal gallium oxide substrate is processed by laser ablation process. The laser power is 1000KHz, the repetition rate is 100%, the number of ablation times is 1000 times, the moving speed is 500mm / s, and the ablation depth is 300μm. The cross-sectional structure after laser ablation is shown in the figure below. Figure 4 Middle (c).

[0100] In step S3, the first trench is repaired by wet etching to obtain a second trench.

[0101] The cross-sectional structure of the first trench formed after laser ablation of the single-crystal gallium oxide substrate is "trapezoidal". The "trapezoidal" shape is repaired to a "concave" shape by wet etching using H2S04:H2O2 (3:1). The schematic diagram of the cross-sectional structure after wet chemical etching is shown in the figure. Figure 5 As shown in (c).

[0102] In step S4, the gallium oxide substrate is cleaned.

[0103] For example, rinse repeatedly with deionized water.

[0104] In step S5 , a high thermal conductivity layer is prepared.

[0105] Nano-metal particles Cu and sintering solvent polyethylene glycol were added to a beaker at a mass ratio of 1:1. The mixture was placed in a homogenizer at a speed of 2000 r / min to obtain a suspension for preparing a high thermal conductivity layer. The prepared suspension was dropped onto the bottom of a single crystal gallium oxide substrate using a pipette gun. The sample was then placed in a high-pressure sintering furnace at a sintering temperature of 300°C and a pressure of 2 MPa. The sintering was repeated twice to complete the preparation. The cross-sectional structure of the gallium oxide substrate after filling the thermal conductive layer is shown in the figure below. Figure 6 As shown in (c), the schematic diagram of the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 7 As shown in (c), the schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 2 As shown in (c).

[0106] For example, the laser ablation pattern is a square ring with spaced distributions, see Figure 3 (b) Schematic diagram of the cross-sectional structure after laser ablation. Figure 4(b) is a schematic diagram of the cross-sectional structure after wet chemical corrosion repair. Figure 5 As shown in (b), the cross-sectional structure of the gallium oxide substrate after filling the thermal conductive layer is shown in Figure 6 As shown in (b), the schematic diagram of the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 7 As shown in (b), the schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 2 As shown in (b).

[0107] For example, the laser ablation pattern is a circular pattern with spaced distributions, see Figure 3 (d) Schematic diagram of the cross-sectional structure after laser ablation. Figure 4 (d) is a schematic diagram of the cross-sectional structure after wet chemical corrosion repair. Figure 5 As shown in (d), the cross-sectional structure of the gallium oxide substrate after filling the thermal conductive layer is shown in Figure 6 As shown in (d), the schematic diagram of the laser ablation surface structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 7 As shown in (d), the schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the thermal conductive layer is as follows Figure 2 As shown in (d).

[0108] An embodiment of the present disclosure provides a gallium oxide substrate, comprising an initial gallium oxide substrate and a heat-conducting layer. The heat-conducting layer is parallel to the bottom of the initial gallium oxide substrate but not higher than the initial gallium oxide substrate, and is wrapped by the initial gallium oxide substrate or overflows to cover the initial gallium oxide substrate.

[0109] In some exemplary embodiments, the initial gallium oxide substrate includes single crystal gallium oxide.

[0110] In some exemplary embodiments, the doping type of the initial gallium oxide substrate includes unintentional doping or n-type doping.

[0111] In some exemplary embodiments, the doping element of the initial gallium oxide substrate includes one or more of silicon, tin, germanium, iron, carbon, and cobalt.

[0112] In some exemplary embodiments, the carrier concentration of the initial gallium oxide substrate is 1×10 13 cm -3 -1×10 20 cm -3 .

[0113] In some exemplary embodiments, the resistivity of the initial gallium oxide substrate is 1×10 -5 Ω.cm-1×10 9 Ω.cm.

[0114] In some exemplary embodiments, the surface roughness of the initial gallium oxide substrate is less than 100 nm.

[0115] In some exemplary embodiments, the thickness of the initial gallium oxide substrate is 100 μm-1500 μm.

[0116] In some exemplary embodiments, the shape of the thermal conductive layer includes various regular or irregular geometric shapes that can be obtained by laser processing, such as various regular shapes such as bars, rings, square rings, squares, circles, triangles, ellipses, polygons, etc., as well as various special shapes that can be obtained by laser processing.

[0117] In some exemplary embodiments, the single width of the heat-conducting layer is 0.01 mm-100 mm, and the area of ​​the heat-conducting layer accounts for 1%-99% of the surface area of ​​the gallium oxide substrate on which the heat-conducting layer is located.

[0118] In some exemplary embodiments, the heat conductive layer material includes one or more of a metal material, a sintered ceramic material, and a composite material.

[0119] For example, the shape of the heat-conducting layer at the bottom of the gallium oxide substrate is a circle distributed in an array. The schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the heat-conducting layer is shown in FIG. Figure 2 Middle (a).

[0120] For example, the shape of the heat-conducting layer at the bottom of the gallium oxide substrate is a square ring with intervals. The schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the heat-conducting layer is shown in FIG. Figure 2 Middle (b).

[0121] For example, the shape of the heat conducting layer at the bottom of the gallium oxide substrate is square. The schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the heat conducting layer is shown in FIG. Figure 2 Middle (c).

[0122] For example, the shape of the heat-conducting layer at the bottom of the gallium oxide substrate is annular with intervals. The schematic diagram of the three-dimensional structure of the gallium oxide substrate after filling the heat-conducting layer is shown in FIG. Figure 2 Middle (d).

[0123] So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings.

[0124] The above specific embodiments further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are 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 gallium oxide substrate, wherein: The method comprises the following steps: According to the laser ablation pattern, a first groove is processed on the surface of the initial gallium oxide substrate by laser ablation, wherein the planed structure of the first groove is "V"-shaped or "trapezoidal"; Performing wet chemical etching to repair the first groove to obtain a second groove, wherein the planed surface structure of the second groove is concave; and Filling the second trench with a heat-conducting layer to form a gallium oxide substrate with a heat-conducting layer, Wherein, the laser ablation pattern includes various regular or irregular geometric shapes that can be obtained by laser processing; The single width of the geometric figure is 0.01 mm to 100 mm; Filling the second groove with a heat-conducting layer specifically includes: filling the second groove with a heat-conducting layer by a sintering method, Filling the thermal conductive layer in the groove by the sintering method comprises the following steps: Put the heat conductive layer material and the sintering solution into a homogenizer according to the proportion, so that the heat conductive layer material is evenly dispersed in the sintering solution to form a homogeneous mixed solution; Spin-coating the homogeneous mixed solution into the second groove using a spin coater to obtain a preform; and The preform is placed in a furnace for sintering, Wherein, the heat conducting layer material includes one or more of metal materials, sintered ceramic materials and composite materials; and The sintering solution includes a mixed solution formed by one or more solutions of ethylene glycol, polyethylene glycol, nano silver paste and epoxy resin.

2. The method for preparing a gallium oxide substrate according to claim 1, wherein: The initial gallium oxide substrate comprises single crystal gallium oxide; The doping type of the single crystal gallium oxide is unintentional doping or n-type doping; The doping elements of the single crystal gallium oxide include one or more of silicon, tin, germanium, iron, carbon and cobalt; The carrier concentration of the single crystal gallium oxide is 1×10 13 cm -3 -1×10 20 cm -3 ; The resistivity of the single crystal gallium oxide is 1×10 -5 Ω.cm-1×10 9 Ω.cm; The surface roughness of the single crystal gallium oxide is less than 100 nm; and The thickness of the single crystal gallium oxide is 100 μm-1500 μm.

3. The method for preparing a gallium oxide substrate according to claim 1 or 2, wherein: The area of ​​the geometric figure accounts for 1%-99% of the surface area of ​​the gallium oxide substrate on which the geometric figure is located.

4. The method for preparing a gallium oxide substrate according to claim 1 or 2, wherein: The step of machining the first trench on the surface of the gallium oxide substrate using a laser ablation method according to the laser ablation pattern specifically includes machining the first trench using first process parameters, wherein the first process parameters include at least one of the following: The wavelength range of the laser is 100nm-2000nm; The laser output power is 0.1W-10W; The laser pulse repetition frequency is 10 Hz-1 MHz; Laser processing scanning and ablation repetition times 1-1000 times; and The sample stage scanning movement speed is 0.001mm / s-100mm / s.

5. The method for preparing a gallium oxide substrate according to claim 1 or 2, wherein: Performing wet chemical etching repair on the first trench to obtain a second trench specifically includes: repairing the second trench using second process parameters, where the second process parameters include at least one of the following: The wet chemical etching solution includes one of an acidic solution and an alkaline solution; The temperature of the wet chemical etching solution is 20° C.-500° C.; and The wet chemical etching time is 0.01h-10h.

6. The method for preparing a gallium oxide substrate according to claim 1 or 2, wherein: The mass ratio of the heat-conducting layer material to the sintering solution is 1:0.01-1:100; and / or The speed of the homogenizer is 1 rpm-5000 rpm; and / or The spin coating speed of the spin coater is 1 rpm-1000 rpm; and / or The sintering temperature is 100°C-1800°C; and / or The sintering times are 1 to 100 times; and / or The sintering time is 0.01h-10h.

7. The method for preparing a gallium oxide substrate according to claim 1 or 2, wherein: The metal material includes a single substance or an alloy formed by one of copper, nickel, gold, silver and aluminum; The ceramic material includes one or more of aluminum nitride, boron nitride, silicon carbide, diamond, graphene, and graphene oxide; and The heat-conducting layer material is in the form of micron / nano particle material, and the particle size ranges from 1 nm to 1000 μm.

8. The method for preparing a gallium oxide substrate according to claim 1 or 2, wherein: In filling the second groove with the heat-conducting layer, a method of filling the heat-conducting layer includes one or more of thermal evaporation, melt sintering, electron beam evaporation, electroplating and magnetron sputtering, and a material of the heat-conducting layer includes a metal material.

9. A gallium oxide substrate, wherein: The gallium oxide substrate is prepared by the method according to any one of claims 1 to 8.

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