High-thermal-conductivity gallium oxide composite substrate and preparation method thereof

Abstract

The invention relates to the technical field of semiconductors, in particular to a high-thermal-conductivity gallium oxide composite substrate and a preparation method thereof. The high-thermal-conductivity gallium oxide composite substrate comprises a high-thermal-conductivity substrate and a gallium oxide single crystal, the high-thermal-conductivity substrate is connected with the gallium oxide single crystal in a bonding manner; and the high-thermal-conductivity substrate is made of an alloy ceramic material of Cu and diamond. The high-thermal-conductivity gallium oxide composite substrate with the alloy ceramic material of Cu and diamond as the high-thermal-conductivity substrate is obtained through research, a gallium oxide device prepared from the high-thermal-conductivity gallium oxide composite substrate has remarkably higher heat dissipation performance, and the pressure resistance, the reliability and the working stability are remarkably improved. The high-thermal-conductivity gallium oxide composite substrate provided by the invention can be prepared into various gallium oxide-based power devices, and has important application value.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a high thermal conductivity gallium oxide composite substrate and a preparation method thereof. Background Art

[0002] Gallium oxide (GAO) is a rapidly developing ultra-wide bandgap semiconductor material. Compared to previous generations of semiconductor materials, such as silicon, germanium, gallium arsenide, and gallium nitride, it boasts a wider bandgap and higher breakdown field strength, offering significant advantages in the fabrication of high-temperature, high-voltage, and radiation-resistant power electronic devices. However, GaO's extremely low thermal conductivity has become a major bottleneck restricting its use in high-power electronic devices.

[0003] Currently, some solutions have been proposed to address the heat dissipation problem of gallium oxide power devices. For example, for devices prepared by homoepitaxial growth, substrate thinning or external heat dissipation systems can be used to reduce thermal resistance, but the yield and reliability will be significantly reduced. In contrast, heterogeneous integration methods are more widely used. Transferring gallium oxide materials to some substrates with high thermal conductivity can effectively improve heat dissipation efficiency, but the process is relatively complex. How to obtain more heat-resistant and reliable gallium oxide power devices still needs further exploration. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a high thermal conductivity gallium oxide composite substrate and a preparation method thereof.

[0005] In a first aspect, the present invention provides a gallium oxide composite substrate, comprising: A high thermal conductivity substrate and a gallium oxide single crystal; the high thermal conductivity substrate and the gallium oxide single crystal are bonded together; The high thermal conductivity substrate is an alloy ceramic material of Cu and diamond, and the mass ratio of Cu to diamond is (1-99): (1-99).

[0006] Gallium oxide materials suffer from low thermal conductivity. In currently manufactured gallium oxide electronic devices, heat is primarily concentrated near the gallium oxide material and electrodes. Under high voltage, this heat accumulation severely impacts device stability and reliability. The present invention utilizes a highly thermally conductive material as a transfer substrate and heterogeneously integrates gallium oxide single crystals onto it using wafer bonding technology. The highly thermally conductive material acts as a heat sink substrate that can be connected to an external circuit, enhancing the device's heat dissipation capabilities and reducing the impact of temperature on electron drift. This allows heat generated by the gallium oxide device to be promptly dissipated, reducing the device's temperature and improving its voltage resistance, reliability, and operational stability.

[0007] The advantage of using Cu:diamond alloy ceramic material as the transfer substrate in the present invention is that the high thermal conductivity of diamond is combined with the excellent thermal conductivity of copper, making the composite material have more excellent heat dissipation performance. By adjusting the ratio of diamond and copper and the preparation process, the thermal expansion coefficient of the composite material can be controlled to match it with materials such as chips, reducing stress problems caused by thermal expansion and contraction.

[0008] Furthermore, the thickness of the high thermal conductivity substrate is 10 μm to 1 cm.

[0009] Furthermore, the Cu and diamond alloy ceramic material is prepared by any of the following methods: powder metallurgy, melt infiltration, high temperature and high pressure sintering or vacuum hot pressing sintering.

[0010] Furthermore, the doping type of the gallium oxide single crystal is one of unintentional doping, p-type doping, n-type low doping, high doping or alternating doping.

[0011] Furthermore, the gallium oxide single crystal has a thickness of 10 nm to 1000 μm and a surface roughness of less than 50 nm.

[0012] Furthermore, the bonding method includes one or more of metal bonding, dielectric layer bonding, hydrophilic direct bonding or surface active bonding.

[0013] Furthermore, the material system of the metal bonding includes: Au-Au, Au-Sn, Au-In, Au-W, Au-Mo or a combination thereof, and also includes Ti-Au, Ti-Sn, Ti-In, Ti-W, Ti-Mo, Ti-Al, Ti-Ag or a combination thereof.

[0014] The dielectric layer bonded to the dielectric layer includes one or more of SiO2, SiNx, TiOx, SOG, Al2O3, SU-8, ultraviolet glue, PMMA or resin.

[0015] In a second aspect, the present invention provides a diode prepared from the aforementioned gallium oxide composite substrate.

[0016] Furthermore, it also includes a Schottky contact layer and an ohmic contact layer; The Schottky contact layer and the low-doped layer of the gallium oxide single crystal in the gallium oxide composite substrate form a Schottky contact; The ohmic contact layer forms an ohmic contact with the high thermal conductivity substrate in the gallium oxide composite substrate.

[0017] Furthermore, the Schottky contact layer and the ohmic contact layer are prepared by one or more methods such as metal thermal evaporation, magnetron sputtering or electron beam evaporation.

[0018] Furthermore, the Schottky contact layer is formed with the low-doped layer of the gallium oxide single crystal in the gallium oxide composite substrate by rapid thermal annealing at a temperature of 400-500° C. Rapid thermal annealing is used to achieve ohmic contact between the ohmic contact layer and the high thermal conductivity substrate in the gallium oxide composite substrate, and the temperature is 400-500°C.

[0019] In a third aspect, the present invention provides a method for preparing the aforementioned gallium oxide composite substrate, comprising: Epitaxial growth of gallium oxide single crystals on MgO substrates; bonding the gallium oxide single crystal to a high thermal conductivity substrate; peeling off the MgO substrate; The outer surface of the gallium oxide single crystal is subjected to grinding and polishing treatment.

[0020] The present invention uses MgO substrate to epitaxially grow gallium oxide single crystals, which can be peeled off by wet etching, which is highly efficient and does not affect the subsequent processing flow of the outer surface of the gallium oxide single crystal. In addition, high-quality gallium oxide single crystals (such as Figure 3 shown).

[0021] Furthermore, the method of epitaxially growing gallium oxide single crystals includes: one or more of hydride vapor phase epitaxy, metal organic compound vapor deposition, molecular beam epitaxy, pulsed laser deposition, magnetron sputtering or mist chemical vapor deposition; and / or, the method of stripping the MgO substrate includes: one or more of wet etching, ion implantation or laser stripping.

[0022] In a fourth aspect, the present invention provides use of the aforementioned gallium oxide composite substrate in the preparation of gallium oxide-based electronic devices.

[0023] Furthermore, the gallium oxide-based electronic device includes one or more of a power electronic device, a radio frequency electronic device, an optoelectronic device, a sensor or an integrated circuit.

[0024] Furthermore, the power electronic device includes one or more of a Schottky diode, a field-effect transistor, or an insulated gate bipolar transistor. The radio frequency electronic device includes one or more of a radio frequency power amplifier or a radio frequency switch. The optoelectronic device includes one or more of a solar-blind ultraviolet detector and sensor or a deep ultraviolet light-emitting diode. The sensor includes one or more of a gas sensor or a temperature sensor. The integrated circuit includes one or more of a high-density integrated circuit or a radio frequency integrated circuit.

[0025] The present invention has the following beneficial effects: The present invention provides a gallium oxide high thermal conductivity composite substrate based on Cu:diamond alloy ceramic material, which can significantly improve the heat dissipation capacity of the device, reduce the influence of temperature on electron drift, and timely dissipate the heat generated by the gallium oxide device, thereby reducing the temperature of the device itself and improving the pressure resistance, reliability and operating stability of the gallium oxide device.

[0026] The high thermal conductivity gallium oxide composite substrate provided by the present invention can be used to prepare high-performance gallium oxide-based power electronic devices, such as vertical structure SBD devices, effectively improving the heat dissipation problem of gallium oxide power devices and making the device performance more reliable and stable, which is of great significance in the field of gallium oxide material technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are 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.

[0028] Figure 1 This is a flow chart of the composite substrate preparation method provided in Example 1 of the present invention.

[0029] Figure 2 101 is a schematic diagram of a method for preparing a composite substrate provided in Example 1 of the present invention; wherein 101 is an MgO substrate, 102 is a gallium oxide single crystal, 103 is a bonding layer, and 104 is a high thermal conductivity substrate.

[0030] Figure 3 This is an XRC rocking curve diagram of an epitaxial gallium oxide single crystal grown on an MgO substrate provided in Example 1 of the present invention.

[0031] Figure 4 102 is a schematic diagram of the high thermal conductivity gallium oxide substrate structure provided by Example 1 of the present invention; 103 is a bonding layer, 104 is a high thermal conductivity substrate, 105 is a high-doped layer, and 106 is a low-doped layer.

[0032] Figure 5 This is a flow chart for preparing an SBD device based on a gallium oxide composite substrate provided in Example 1 of the present invention.

[0033] Figure 6 Schematic diagram of the method for preparing a high thermal conductivity gallium oxide Schottky device provided in Example 1 of the present invention; wherein 201 is a high thermal conductivity gallium oxide composite substrate, 102 is a gallium oxide single crystal, 103 is a bonding layer, 104 is a high thermal conductivity substrate, 202 is a Schottky contact layer, and 203 is an ohmic contact layer.

[0034] Figure 7Schematic diagram of the structure of a high-performance gallium oxide SBD device provided in Example 1 of the present invention; wherein 201 is a high thermal conductivity gallium oxide composite substrate, 102 is a gallium oxide single crystal, 103 is a bonding layer, 104 is a high thermal conductivity substrate, 202 is a Schottky contact layer, and 203 is an ohmic contact layer. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0036] Unless otherwise specified, the experimental methods involved in the following examples are all conventional methods in the art. For example, reference can be made to experimental manuals in the art, or the conditions recommended by the manufacturer's instructions.

[0037] Unless otherwise specified, the experimental materials and reagents involved in the following examples can be obtained from commercial sources.

[0038] Example 1 1. The present invention provides a high thermal conductivity gallium oxide composite substrate and a preparation method thereof, such as Figure 1 and Figure 2 As shown, the following steps are included: (1) Gallium oxide single crystals are grown epitaxially on MgO substrates (using hydride vapor phase epitaxy) to form gallium oxide wafers. First, a low-doped gallium oxide layer with a thickness of 3 μm is grown epitaxially, followed by a high-doped gallium oxide layer with a thickness of 2 μm, to form an alternatingly doped gallium oxide single crystal layer with a thickness of 5 μm. The doping type of the gallium oxide single crystal is unintentional doping, the thickness is 5 μm, and the surface roughness is 10 nm; Figure 3 shown.

[0039] (2) The gallium oxide wafer is transferred to a high thermal conductivity substrate through wafer bonding technology. The high thermal conductivity substrate is made of a Cu and diamond alloy ceramic material (the mass ratio of Cu to diamond is 1:1, and it is prepared by mixing Cu metal powder and diamond powder and then sintering them at high temperature and high pressure) with a thickness of 1 mm. The wafer bonding technology used is dielectric layer bonding, and the dielectric layer material is SiO2.

[0040] (3) Wet etching of the MgO substrate to peel off the gallium oxide wafer; (4) The surface of the gallium oxide wafer is ground and polished to obtain a high thermal conductivity gallium oxide composite substrate.

[0041] The final high thermal conductivity gallium oxide substrate structure is as follows Figure 4 shown.

[0042] The present invention further provides a process for preparing high-performance electronic devices (such as vertical Schottky barrier diodes SBD) using the above-mentioned high thermal conductivity gallium oxide composite substrate, such as Figure 5 and Figure 6 As shown, including the following: (1) Clean the high thermal conductivity gallium oxide substrate.

[0043] (2) Depositing an Au / Ni metal layer on the gallium oxide single crystal layer and rapidly thermally annealing it to form a Schottky contact between the metal and the gallium oxide low-doped epitaxial layer.

[0044] (3) A Ti / Au metal layer is evaporated on the back of the high thermal conductivity gallium oxide composite substrate and rapidly thermally annealed to form a good ohmic contact.

[0045] The Schottky contact layer and the ohmic contact layer are prepared by a metal thermal evaporation method.

[0046] Rapid thermal annealing is used to achieve ohmic contact between the ohmic contact layer and the high thermal conductivity substrate at a temperature of 450°C.

[0047] Rapid thermal annealing is used to achieve Schottky contact between the Schottky contact layer and the gallium oxide epitaxial layer at a temperature of 450°C.

[0048] The obtained Schottky diode structure is as follows Figure 7 As shown, specifically including: High thermal conductivity gallium oxide composite substrate 1, its structure reference Figure 4 , from top to bottom, it includes a gallium oxide single crystal layer 2 (including a low-doped region and a high-doped region), a bonding layer 3 and a high thermal conductivity substrate 4; The Schottky contact layer 5 includes a Ni layer and an Au layer from bottom to top, and forms a Schottky contact with the low-doped gallium oxide epitaxial layer; The ohmic contact layer 6 includes an Au layer and a Ti layer from bottom to top, and forms an ohmic contact with the electrically conductive and highly thermally conductive substrate.

[0049] Example 2 This embodiment provides a high thermal conductivity gallium oxide composite substrate and a preparation method thereof, which is the same as that of embodiment 1, except that: A gallium oxide single crystal is epitaxially grown on a MgO substrate by metal organic compound vapor deposition. The doping type is n-type doping, the thickness is 1 μm, and the surface roughness is 5 nm.

[0050] Example 3 This embodiment provides a high thermal conductivity gallium oxide composite substrate and a preparation method thereof, which is the same as that of embodiment 1, except that: The wafer bonding technology used is dielectric layer bonding, and the dielectric layer material is Al2O3.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A gallium oxide composite substrate, characterized in that include: A high thermal conductivity substrate and a gallium oxide single crystal; the high thermal conductivity substrate and the gallium oxide single crystal are bonded together; The high thermal conductivity substrate is an alloy ceramic material of Cu and diamond, and the mass ratio of Cu to diamond is (1-99): (1-99).

2. The gallium oxide composite substrate according to claim 1, characterized in that The thickness of the high thermal conductivity substrate is 10 μm to 1 cm; and / or, The Cu and diamond alloy ceramic material is prepared by any of the following methods: powder metallurgy, melt infiltration, high temperature and high pressure sintering or vacuum hot pressing sintering.

3. The gallium oxide composite substrate according to claim 1 or 2, characterized in that The doping type of the gallium oxide single crystal is one of unintentional doping, p-type doping, n-type low doping, high doping or alternating doping.

4. The gallium oxide composite substrate according to claim 1 or 2, characterized in that The gallium oxide single crystal has a thickness of 10 nm to 1000 μm and a surface roughness of less than 50 nm.

5. The gallium oxide composite substrate according to claim 1 or 2, characterized in that: The bonding method includes one or more of metal bonding, dielectric layer bonding, hydrophilic direct bonding or surface active bonding.

6. A diode, characterized in that: The gallium oxide composite substrate is prepared from the gallium oxide composite substrate according to any one of claims 1 to 5.

7. The diode according to claim 6, characterized in that Also includes a Schottky contact layer and an ohmic contact layer; The Schottky contact layer and the low-doped layer of the gallium oxide single crystal in the gallium oxide composite substrate form a Schottky contact; The ohmic contact layer forms an ohmic contact with the high thermal conductivity substrate in the gallium oxide composite substrate.

8. The method for preparing the gallium oxide composite substrate according to any one of claims 1 to 5, comprising: Epitaxial growth of gallium oxide single crystals on MgO substrates; bonding the gallium oxide single crystal to a high thermal conductivity substrate; peeling off the MgO substrate; The outer surface of the gallium oxide single crystal is subjected to grinding and polishing treatment.

9. The preparation method according to claim 8, characterized in that The method for epitaxially growing gallium oxide single crystals includes: one or more of hydride vapor phase epitaxy, metal organic compound vapor deposition, molecular beam epitaxy, pulsed laser deposition, magnetron sputtering, or mist chemical vapor deposition; and / or, the method for stripping the MgO substrate includes: one or more of wet etching, ion implantation, or laser stripping.

10. Use of the gallium oxide composite substrate according to any one of claims 1 to 5 in the preparation of gallium oxide-based electronic devices; The gallium oxide-based electronic device comprises: One or more of Schottky diodes, field effect transistors, radio frequency power amplifiers, radio frequency switches, solar-blind ultraviolet detectors and sensors, deep ultraviolet light-emitting diodes, gas sensors, temperature sensors, high-density integrated circuits, or radio frequency integrated circuits.

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