A GaN device based on a novel SiC / diamond composite substrate and a method of manufacturing the same

Abstract

The application relates to a GaN device based on a novel SiC / diamond composite substrate and a manufacturing method thereof, and belongs to the technical field of semiconductor materials and devices, and solves at least one of the following problems: how to realize high-quality integration of GaN devices and diamond while avoiding significant changes of 2DEG caused by complete removal of SiC, giving consideration to self-blocking preparation requirements in a substrate etching process, large warping of a diamond substrate, and difficulty in high-quality bonding, etc. The manufacturing method comprises the following steps: S1, providing a SiC / Si composite substrate; S2, epitaxially growing a GaN heterojunction on a SiC surface and preparing a GaN device; S3, bonding a temporary carrier on the front surface of the GaN device; S4, removing the Si substrate; S5, bonding the surface of the SiC layer with diamond; and S6, removing the temporary carrier. High-quality thin-layer SiC of the SiC / Si composite substrate is used for epitaxial growth of GaN material, and the process characteristic that the Si substrate can be selectively etched and removed provides a feasible way for retaining the SiC self-supporting layer and further constructing a GaN device of the SiC / diamond composite substrate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials and devices, and in particular to a GaN device based on a novel SiC / diamond composite substrate and its manufacturing method. Background Technology

[0002] AlGaN / GaN HEMT devices have seen rapid development over the past few decades and are widely used in various electronic systems. Due to the excellent properties of GaN materials, such as wide bandgap, high breakdown electric field, and high carrier velocity, they exhibit significant advantages in high-power microwave applications, with device output power densities exceeding 40 W / mm². However, limited by the internal thermal conductivity of the device, the practical power density that can be used to limit the peak junction temperature and maintain reliability is typically only 5–7 W / mm². Therefore, there is an urgent need to introduce high thermal conductivity materials near the hot spots of the device to improve heat dissipation.

[0003] Diamond, with its high thermal conductivity of up to 2000 W / mK, is an ideal heat dissipation substrate material, and bonding is typically used to integrate diamond with GaN devices. However, in existing technologies, completely removing the SiC substrate after front-side device fabrication can easily lead to significant changes in the two-dimensional electron gas (2DEG) in the AlGaN / GaN heterojunction, thus degrading device performance. Conversely, retaining a small amount of SiC self-supporting layer to maintain device electrical properties makes achieving self-stopping in the SiC substrate etching process difficult. Therefore, how to achieve high-quality integration of GaN devices with diamond while avoiding significant 2DEG changes caused by complete SiC removal, and simultaneously meeting the self-stopping requirements of the substrate etching process, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a GaN device based on a novel SiC / diamond composite substrate and its manufacturing method, in order to solve at least one of the following problems: how to achieve high-quality integration of GaN devices and diamond while avoiding significant 2DEG changes caused by complete removal of SiC, taking into account the self-stop preparation requirements in the substrate etching process, large warpage of diamond substrate, and difficulty in high-quality bonding.

[0005] Embodiments of the present invention provide a method for manufacturing a GaN device based on a novel SiC / diamond composite substrate, comprising: S1 provides a SiC / Si composite substrate; S2, GaN heterojunction is epitaxially grown on the SiC surface of a SiC / Si composite substrate and GaN device is fabricated; S3, a temporary carrier is bonded to the front side of the GaN device; S4, Remove the Si substrate from the SiC / Si composite substrate; S5, bonding the exposed SiC layer surface after removing the Si substrate to the diamond substrate; S6, remove the temporary support to obtain a GaN device based on a SiC / diamond composite substrate.

[0006] Furthermore, in step S1, the warpage of the SiC / Si composite substrate is ≤20μm, and the TTV is ≤10μm.

[0007] Furthermore, in step S1, the thickness of the Si substrate in the SiC / Si composite substrate is ≥100μm, and the thickness of the SiC layer is ≤10μm.

[0008] Further, step S3 includes: S31, Prepare a device protective layer on the front side of the GaN device; S32, Prepare a bonding and adhesive layer on the device protective layer; S33, align the temporary carrier with the bonding adhesive layer and perform hot-press bonding.

[0009] Furthermore, the device protective layer is a high-melting-point wax with a melting point of 150~200℃; and / or, the bonding adhesive layer is a low-melting-point high-temperature adhesive or a low-melting-point wax with a melting point more than 10℃ lower than that of the device protective layer.

[0010] Furthermore, the temporary carrier includes one of sapphire, glass, and silicon substrates.

[0011] Furthermore, in step S5, the SiC layer surface is bonded to the diamond substrate using a room temperature surface activation bonding method.

[0012] Furthermore, in step S5, before bonding the diamond layer, a bonding auxiliary layer is deposited in situ on the surface of the SiC layer and the diamond substrate.

[0013] Further, in step S5, the bonding auxiliary layer includes one of silicon, aluminum nitride, and aluminum oxide; and / or, the thickness of the bonding auxiliary layer is ≤100nm.

[0014] On the other hand, the present invention also provides a GaN device based on a novel SiC / diamond composite substrate, which is prepared by the above-described manufacturing method and includes: a SiC / diamond composite substrate and a GaN device disposed on the composite substrate.

[0015] This invention can achieve at least one of the following beneficial effects: 1. This invention uses a SiC / Si substrate as the basis for GaN epitaxy and device fabrication. GaN epitaxial growth and device fabrication are completed on a high-quality SiC thin film surface. Subsequently, temporary bonding and removal of the Si substrate are performed on the device side, retaining a small amount of SiC self-supporting layer. The SiC surface is then bonded to a diamond substrate, ultimately forming a SiC / diamond composite substrate GaN device. Compared with existing technologies, this invention avoids the problems of significant changes in the two-dimensional electron gas (2DEG) of the AlGaN / GaN heterojunction and device performance degradation caused by the complete removal of SiC after the traditional front-side device fabrication. By retaining a small amount of SiC self-supporting layer, the electrical characteristics of the device are effectively maintained. At the same time, by utilizing the process characteristics of selective etching removal of the Si substrate in the SiC / Si structure, the problem of difficulty in achieving self-stopping of the SiC substrate etching process under the condition of retaining the SiC self-supporting layer is solved.

[0016] 2. In this invention, GaN devices are first fabricated on SiC / Si and then bonded to a diamond substrate. Compared with the fabrication process of first bonding to a diamond substrate and then fabricating GaN devices, the epitaxial growth of GaN on SiC / Si is less difficult than that on SiC / diamond, and the GaN quality is better. Furthermore, the difference in thermal expansion coefficients between SiC and Si is smaller than that between SiC and diamond, making stress control easier and thermal stress lower, thus making it suitable for fabricating larger-sized GaN epitaxial materials.

[0017] 3. This invention achieves integration with a diamond substrate while retaining a high-quality SiC epitaxial interface. It fully leverages the high thermal conductivity of diamond, significantly improving the device's heat dissipation capacity, reducing thermal resistance and junction temperature, while also ensuring high-quality epitaxial growth of GaN material and high device reliability. This provides an effective technical approach for the industrial fabrication of high-performance GaN microwave power devices.

[0018] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0019] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0020] Figure 1 This is a schematic flowchart of a manufacturing method according to some embodiments of the present invention.

[0021] Figure 2This is a schematic diagram of the structure of a GaN device according to some embodiments of the present invention.

[0022] Explanation of reference numerals in the attached figures: 10. SiC / Si composite substrate; 11. Si substrate; 12. SiC layer; 20. GaN heterojunction; 30. GaN device; 40. Temporary carrier; 50. Diamond substrate; 1. Source; 2. Drain; 3. Gate. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, exemplary embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. For clarity and brevity, not all features of actual embodiments are described in the specification.

[0024] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0025] Embodiments of the present invention provide a method for fabricating GaN devices based on a novel SiC / diamond composite substrate, such as... Figure 1 As shown, the manufacturing method includes the following steps: S1 provides a SiC / Si composite substrate 10; S2, GaN heterojunction 20 is epitaxially grown on the SiC surface of SiC / Si composite substrate 10 and GaN device 30 is fabricated; S3, Temporary carrier 40 is bonded to the front side of the GaN device; S4, Remove the Si substrate 11 from the SiC / Si composite substrate 10; S5, the surface of the SiC layer 12 exposed after removing the Si substrate 11 is bonded to the diamond substrate 50; S6, remove the temporary support 40 to obtain a GaN device based on a SiC / diamond composite substrate.

[0026] This invention uses a SiC / Si composite substrate as the basis for early epitaxy and device fabrication. A GaN heterojunction is epitaxially grown on a high-quality SiC thin layer to complete device fabrication. The selective removal capability of the Si substrate is used to solve the self-cutoff problem in the substrate etching process. At the same time, by retaining a small amount of SiC layer to maintain the stability of the two-dimensional electron gas characteristics of the heterojunction, and further bonding it with a diamond substrate, a SiC / diamond composite substrate GaN device is finally formed. This realizes the integration of the device with the high thermal conductivity diamond substrate, which significantly improves heat dissipation and device reliability while ensuring the stability of the device's electrical performance.

[0027] The method of this invention not only fully utilizes the high thermal conductivity of diamond to improve the heat dissipation capacity of the device, but also relies on a high-quality SiC thin layer with the same crystal structure and lattice constant as GaN to achieve high-quality epitaxial growth, thereby effectively reducing dislocation density and improving reliability issues such as current collapse, providing technical support for the manufacturing of high-performance, high-reliability GaN microwave power devices.

[0028] According to some embodiments of the present invention, in step S1, the warpage of the SiC / Si composite substrate is ≤20μm and the total transflection volume (TTV) is ≤10μm, which is beneficial for preparing a flatter GaN epitaxial structure and providing a flatter substrate for subsequent bonding to diamond. For example, the warpage can be 0μm, 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, or 20μm; and the TTV can be 0μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm.

[0029] It should be noted that TTV (Total Thickness Variation) is one of the core geometric parameters for measuring substrate quality, referring to the absolute difference between the maximum and minimum thickness on the entire substrate.

[0030] According to some embodiments of the present invention, in step S1, the thickness of the Si substrate 11 in the SiC / Si composite substrate is ≥100μm, and the thickness of the SiC layer 12 is ≤10μm. For example, the thickness of the Si substrate 11 can be 100μm, 120μm, 150μm, 200μm, 250μm, 300μm, etc.; the thickness of the SiC layer 12 can be 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc. Considering the self-supporting capability of the Si substrate, the embodiments of the present invention set the Si substrate thickness to be above 100μm, otherwise it is easy to peel off; and the thinner the Si substrate, the better, while satisfying self-support, which is beneficial to reducing the bonding difficulty. The thinner the SiC layer thickness, the better, while ensuring engineering feasibility, which can reduce interface thermal resistance and stress; if it is too thick, the composite substrate is prone to breakage or debonding at high temperatures above 1000℃.

[0031] According to some embodiments of the present invention, in step S1, the SiC / Si composite substrate may further include an isolation layer disposed between the Si substrate 11 and the SiC layer 12, so that the substrate Si material can be removed by dry etching during the subsequent removal of the Si substrate 11, and the etching stops at the surface of the isolation layer to protect the SiC surface from damage. Then, the isolation layer is etched away to reduce the interfacial thermal resistance, leaving only a thin SiC layer. Specifically, the isolation layer is one of silicon oxide, aluminum oxide, silicon nitride, and aluminum nitride.

[0032] According to some embodiments of the present invention, in step S1, during the preparation of the SiC / Si composite substrate, the SiC layer needs to undergo high-temperature annealing, that is, high-temperature annealing is performed after the Si substrate and the SiC layer are bonded. Specifically, the annealing temperature for high-temperature annealing is 700℃~1300℃. For example, the annealing temperature can be 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, or 1300℃ to avoid excessively high temperatures causing Si to melt easily.

[0033] According to some embodiments of the present invention, in step S2, a high-quality GaN heterojunction (e.g., GaN / AlGaN heterojunction) is first epitaxially grown on the surface of SiC layer 12; then, a GaN device is fabricated (i.e., the source, drain, and gate are fabricated to finally obtain a GaN device). The high-quality GaN heterojunction can be fabricated using existing epitaxial growth methods, and the GaN device can also be fabricated using existing methods, which will not be elaborated here.

[0034] According to some embodiments of the present invention, in step S3, a temporary carrier 40 is bonded to the front side of the GaN device. Specifically, bonding the temporary carrier in S3 includes the following steps: S31, Prepare a device protective layer on the front side of the GaN device; S32, Prepare a bonding and adhesive layer on the device protective layer; S33, align the temporary carrier with the bonding adhesive layer and perform hot-press bonding.

[0035] In step S31, the device protective layer can be a high-melting-point wax, such as a high-melting-point wax with a melting point of 150~200℃. The preparation process of the device protective layer specifically includes: coating the front side of the GaN device with high-melting-point wax as a device protective layer, so that it completely covers all GaN device structures on the front side; and then performing gradient baking and curing to solidify the high-melting-point wax on the front side of the GaN device to form a device protective layer.

[0036] The gradient baking and curing process includes: pre-baking at 40~80℃ for 5~10 min, followed by curing at 120~160℃ for 5~10 min to remove solvent and prevent subsequent bubble formation. The curing temperature should be lower than the melting point of the device protective layer. For example, the pre-baking temperatures are 40℃, 50℃, 60℃, 70℃, and 80℃, and the pre-baking times are 5 min, 6 min, 7 min, 8 min, 9 min, and 10 min, respectively; the curing temperatures are 120℃, 130℃, 140℃, 150℃, and 160℃, and the curing times are 5 min, 6 min, 7 min, 8 min, 9 min, and 10 min, respectively.

[0037] Before fabricating the protective layer for the device, the front side of the GaN device can also be cleaned, for example, with organic and standard RCA cleaning, to remove surface particles and organic residues.

[0038] In step S32, the bonding adhesive layer can be a low-melting-point high-temperature adhesive or a low-melting-point wax. The melting point of the bonding adhesive layer is more than 10°C lower than that of the device protective layer to avoid softening and deformation of the device protective layer during baking and curing, which could damage the device. The preparation process of the bonding adhesive layer specifically includes: coating the device protective layer with a low-melting-point high-temperature adhesive or a low-melting-point wax, followed by gradient baking and curing to remove the solvent. The gradient baking and curing process is the same as in step S31, only the curing temperature needs to be controlled below the melting point of the bonding adhesive layer; it will not be elaborated further here. The thickness of the prepared bonding adhesive layer should be at least 5 μm to smooth out any unevenness in the device protective layer and ensure subsequent bonding.

[0039] In step S33, the temporary carrier can be aligned with the surface of the bonding adhesive layer, and then hot-press bonding can be performed. The hot-press bonding process specifically includes: heating the device obtained in step S32 above the melting point of the bonding adhesive layer to soften it; applying a pressure of 0.1~0.3 MPa and holding it for 5~10 minutes; after the pressure holding period, slowly cooling to room temperature to complete the bonding. At this point, the bonded adhesive layer, once cured, provides sufficient bonding strength to support subsequent back-side processes. For example, the bonding pressures are 0.1 MPa, 0.2 MPa, and 0.3 MPa, and the holding times are 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes.

[0040] According to some embodiments of the present invention, the temporary carrier includes one of sapphire, glass, and silicon wafers. Specifically, the warpage of the temporary carrier is ≤20μm, and the total transflection volume (TTV) is ≤10μm. For example, the warpage of the temporary carrier can be 0μm, 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, or 20μm; the TTV can be 0μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm. Preferably, the temporary carrier 40 is an ultra-flat sheet, which facilitates the bonding of the temporary bonding material to the diamond substrate; the flatter the temporary carrier, the better.

[0041] According to some embodiments of the present invention, in step S4, wet etching can be used to selectively remove the Si substrate 11 from the SiC / Si composite substrate 10. Specifically, the etching solution can be KOH or a mixed solution of HF and HNO3, which can selectively remove the Si substrate. The etching stops at the SiC surface, and the use of a mixed solution of HF and HNO3 results in a more uniform surface and no metal ion contamination.

[0042] According to some embodiments of the present invention, in step S4, the Si substrate 11 in the SiC / Si composite substrate 10 can be removed by dry etching. Specifically, a deep silicon etching machine can be used to dry etch the Si substrate, and the etching interface can be controlled to stop at the surface of the isolation layer before the isolation layer is etched away.

[0043] According to some embodiments of the present invention, in step S4, the surface roughness of the SiC after etching or etching is ≤1 nm. In embodiments of the present invention, by etching the Si substrate or etching the Si substrate followed by etching the isolation layer, the etchant used does not substantially corrode the SiC layer, thus allowing it to maintain its basic state before processing.

[0044] According to some embodiments of the present invention, in step S4, after removing the Si substrate, the SiC surface can be planarized and smoothed to ensure that the surface roughness of the SiC layer is ≤1nm.

[0045] Specifically, chemical mechanical polishing (CMP) or cluster ion beam treatment can be used to planarize and smooth the SiC surface. When using CMP, a slow polishing process is employed. The polishing slurry includes abrasives, an oxidant, and a pH adjuster. The pH of the slurry is 10-11. The oxidant is H₂O₂, with a concentration controlled at 1-3 wt% (e.g., 1 wt%, 2 wt%, 3 wt%). The abrasive is low-hardness nano-SiO₂ abrasive with a particle size controlled at 50-100 nm. When using cluster ion beam treatment, the voltage is set to 20-60 kV, and the beam current is ≤50 mA; for example, voltages of 20 kV, 30 kV, 40 kV, 50 kV, and 60 kV, and beam currents of 50 mA, 40 mA, 30 mA, and 20 mA, etc.

[0046] According to some embodiments of the present invention, in step S5, the SiC layer surface can be bonded to the diamond substrate using the room temperature surface activated bonding method (SAB).

[0047] Specifically, when using room temperature surface activated bonding (SAB) for bonding, the vacuum level is reduced to 1×10⁻⁶. 5 Below Pa, the surface of the SiC layer and the surface of the diamond substrate are activated by Ar ions; then the activated SiC layer surface and the diamond substrate surface are bonded together under pressure at room temperature. The activation voltage is 1~2kV, the beam current is 20~100mA, and the applied bonding pressure is above 2MPa. For example, the activation voltage is 1kV, 1.2kV, 1.4kV, 1.5kV, 1.6kV, 1.8kV, 2kV, the beam current is 20mA, 30mA, 40mA, 50mA, 60mA, 70mA, 80mA, 90mA, 100mA, and the bonding pressure is 2MPa, 5MPa, 8MPa, 10MPa, 12MPa, 15MPa, etc.

[0048] According to some embodiments of the present invention, in step S5, before bonding the diamond substrate, a bonding auxiliary layer can be deposited in situ on the surface of the SiC layer and the surface of the diamond substrate. This allows the elements of the bonding auxiliary layer to establish a bridge between the SiC and the C element of the diamond substrate, increasing the adhesion of the bonding interface. Specifically, during the in-situ deposition of the bonding auxiliary layer, the sputtering voltage can be controlled to be 1~2kV and the beam current to be 50~80mA; exemplary examples include sputtering voltages of 1kV, 1.2kV, 1.4kV, 1.5kV, 1.6kV, 1.8kV, and 2kV, and beam currents of 50mA, 60mA, 70mA, and 80mA.

[0049] Specifically, the bonding auxiliary layer includes one of silicon, aluminum nitride, and aluminum oxide.

[0050] Specifically, the thickness of the bonding auxiliary layer is ≤100nm, for example, it can be 1nm, 5nm, 10nm, 15nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, or 100nm. Preferably, the thickness of the in-situ deposited bonding auxiliary layer is 5~10nm, for example, 5nm, 6nm, 7nm, 8nm, 9nm, or 10nm.

[0051] According to some embodiments of the present invention, in step S6, the temporary carrier 40 on the surface of the GaN device is removed to obtain... Figure 2 The GaN device shown is an example. Specifically, acid-base etching or a resist-removing solution can be used to remove the protective layer and bonding layer of the device, thereby removing the temporary carrier. Acid-base etching or resist-removing solutions have little effect on GaN materials, with extremely low etching rates, and will not cause damage to the surface of the GaN device.

[0052] Embodiments of the present invention also provide a GaN device based on a novel SiC / diamond composite substrate, which can be fabricated using the above-described manufacturing method. Figure 2 As shown, the GaN device includes a SiC / diamond composite substrate and a GaN device 30 disposed on the composite substrate. The GaN device 30 includes a GaN heterojunction 20 and a source 1, a drain 2, and a gate 3 disposed on the GaN heterojunction 20.

[0053] The technical solution of the present invention will be further illustrated below with specific embodiments.

[0054] Example 1 The method for fabricating GaN devices based on novel SiC / diamond composite substrates in this embodiment includes: S1 provides a SiC / Si composite substrate: the Si substrate thickness is 200μm, the SiC thickness is 5μm, the warpage of the SiC / Si composite substrate is less than 20μm, and the TTV is less than 10μm; S2, GaN heterojunction 20 is epitaxially grown on the SiC surface of a SiC / Si composite substrate and GaN device is fabricated; S3, bonding a temporary carrier on the front side of the GaN device: S31. Apply a high melting point wax with a melting point of 180℃ to the front side of the GaN device as a protective layer to completely cover all GaN device structures on the front side; then perform gradient baking and curing, first pre-baking at 60℃ for 5 minutes, and then curing at 140℃ for 8 minutes, so that the high melting point wax is cured on the front side of the GaN device to form a protective layer. S32. Apply a low-melting-point wax with a melting point of 140℃ to the device protective layer, and then perform gradient baking curing. First, pre-bake at 60℃ for 5 minutes, and then cure at 120℃ for 8 minutes. S33. Align the temporary carrier ultraflat sheet with the surface of the bonding layer, heat to 150°C to soften the bonding layer, apply 0.1MPa pressure and hold for 10 minutes; cool to room temperature to complete the bonding. S4, Si substrate removal: The Si substrate is selectively removed by etching with a mixed solution of HF and HNO3; then the exposed SiC layer surface is planarized and smoothed by cluster ion beam treatment technology with a voltage of 20kV and a beam current of 50mA. S5, bonding the SiC layer surface to the diamond substrate: First, an auxiliary silicon layer is deposited in situ on both the SiC layer surface and the diamond substrate surface using a sputtering voltage of 1 kV and a beam current of 50 mA, resulting in a silicon layer thickness of 5 nm; then, room temperature surface activation bonding is used for bonding, reducing the vacuum level to 1 × 10⁻⁶. 5 Below Pa, the SiC layer surface and the diamond substrate surface are activated by Ar ions with an activation voltage of 1kV and a beam current of 100mA; then the activated SiC layer surface and the diamond substrate surface are bonded together by applying pressure at room temperature with a bonding pressure of 5MPa. S6, Remove temporary support: Remove the temporary support by etching with a resist remover solution to obtain GaN device based on SiC / diamond composite substrate.

[0055] Example 2 The method for fabricating GaN devices based on novel SiC / diamond composite substrates in this embodiment includes: S1 provides a SiC / Si composite substrate: the Si substrate thickness is 200μm, the SiC thickness is 5μm, the warpage of the SiC / Si composite substrate is less than 20μm, and the TTV is less than 10μm; the SiC / Si composite substrate includes a silicon oxide isolation layer located between the SiC layer and the Si substrate. S2, GaN heterojunction 20 is epitaxially grown on the SiC surface of a SiC / Si composite substrate and GaN device is fabricated; S3, bonding a temporary carrier on the front side of the GaN device: S31. Apply a high melting point wax with a melting point of 180℃ to the front side of the GaN device as a protective layer to completely cover all GaN device structures on the front side; then perform gradient baking and curing, first pre-baking at 60℃ for 5 minutes, and then curing at 140℃ for 8 minutes, so that the high melting point wax is cured on the front side of the GaN device to form a protective layer. S32. Apply a low-melting-point wax with a melting point of 140℃ to the device protective layer, and then perform gradient baking curing. First, pre-bake at 60℃ for 5 minutes, and then cure at 120℃ for 8 minutes. S33. Align the temporary carrier ultraflat sheet with the surface of the bonding layer, heat to 150°C to soften the bonding layer, apply 0.1MPa pressure and hold for 10 minutes; cool to room temperature to complete the bonding. S4, Removal of Si substrate: The Si substrate is dry-etched using a deep silicon etching machine, which can control the etching interface to stop at the surface of the silicon oxide isolation layer. Then, it is removed by etching with an HF-based solution. Then, the exposed SiC layer surface is planarized and smoothed using chemical mechanical polishing technology. The polishing solution has a pH of 10-11, the oxidant H2O2 concentration is 2wt%, and the low-hardness nano-SiO2 abrasive particles have a particle size of 50-100nm. S5, bonding the SiC layer surface to the diamond substrate: First, an auxiliary silicon layer is deposited in situ on both the SiC layer surface and the diamond substrate surface using a sputtering voltage of 1kV and a beam current of 50mA, resulting in a silicon layer thickness of 10nm; then, room temperature surface activation bonding is used for bonding, reducing the vacuum level to 5×10⁻⁶. 6 Below Pa, the SiC layer surface and the diamond substrate surface are activated by Ar ions with an activation voltage of 1kV and a beam current of 100mA; then the activated SiC layer surface and the diamond substrate surface are bonded together by applying pressure at room temperature with a bonding pressure of 10MPa. S6, Remove temporary support: Remove the temporary support by acid etching to obtain GaN device based on SiC / diamond composite substrate.

[0056] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing GaN devices based on a novel SiC / diamond composite substrate, characterized in that, include: S1 provides a SiC / Si composite substrate; S2, epitaxially growing a GaN heterojunction on the SiC surface of the SiC / Si composite substrate and fabricating a GaN device; S3, a temporary carrier is bonded to the front side of the GaN device; S4, Remove the Si substrate from the SiC / Si composite substrate; S5, the exposed surface of the SiC layer after removing the Si substrate is bonded to the diamond substrate; S6, remove the temporary carrier to obtain a GaN device based on a SiC / diamond composite substrate.

2. The manufacturing method according to claim 1, characterized in that, In step S1, the warpage of the SiC / Si composite substrate is ≤20μm and the TTV is ≤10μm.

3. The manufacturing method according to claim 1, characterized in that, In step S1, the thickness of the Si substrate in the SiC / Si composite substrate is ≥100μm, and the thickness of the SiC layer is ≤10μm.

4. The manufacturing method according to claim 1, characterized in that, Step S3 includes: S31, a device protective layer is prepared on the front side of the GaN device; S32, a bonding layer is prepared on the protective layer of the device; S33, Align the temporary carrier with the bonding adhesive layer and perform hot-press bonding.

5. The manufacturing method according to claim 4, characterized in that, The device protective layer is a high-melting-point wax with a melting point of 150~200℃; and / or, the bonding adhesive layer is a low-melting-point high-temperature adhesive or a low-melting-point wax with a melting point at least 10℃ lower than that of the device protective layer.

6. The manufacturing method according to claim 1 or 4, characterized in that, The temporary carrier includes one of sapphire, glass, and silicon wafers.

7. The manufacturing method according to claim 1, characterized in that, In step S5, the SiC layer surface is bonded to the diamond substrate using a room temperature surface activation bonding method.

8. The manufacturing method according to claim 1, characterized in that, In step S5, before bonding the diamond layer, a bonding auxiliary layer is deposited in situ on the surface of the SiC layer and the diamond substrate.

9. The manufacturing method according to claim 8, characterized in that, In step S5, the bonding auxiliary layer includes one of silicon, aluminum nitride, and aluminum oxide; and / or, the thickness of the bonding auxiliary layer is ≤100nm.

10. A GaN device based on a novel SiC / diamond composite substrate, characterized in that, The device is prepared by the manufacturing method according to any one of claims 1-9, comprising: a SiC / diamond composite substrate and a GaN device disposed on the composite substrate.

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