Preparation method of SiC composite substrate and SiC composite substrate

Abstract

The invention provides a preparation method of a SiC composite substrate and the SiC composite substrate. The preparation method comprises the following steps: performing H ion implantation on a single crystal SiC substrate to form a hydrogen-injected single crystal SiC substrate; the hydrogen injection single crystal SiC substrate is connected on the supporting substrate in a cementing mode, so that connection between the hydrogen injection single crystal SiC substrate and the supporting substrate is flexible connection; at the H ion injection position, stripping the part, above the H ion injection position, in the hydrogen injection single crystal SiC substrate through annealing, and forming a single crystal SiC layer on the part, which is not stripped, in the hydrogen injection single crystal SiC substrate; forming a polycrystalline SiC layer on the monocrystalline SiC layer by deposition; and removing the glue joint at the glue joint position so as to remove the supporting substrate, and forming the SiC composite substrate comprising the single crystal SiC layer and the polycrystal SiC layer. The technical problem that the SiC composite substrate prepared by a traditional SiC composite substrate preparation process is poor in performance is solved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically, to a method for preparing a SiC composite substrate and the SiC composite substrate itself. Background Technology

[0002] Current SiC composite substrate fabrication techniques involve growing a 3C polycrystalline SiC substrate on a support substrate, followed by bonding the 3C polycrystalline SiC substrate and a 4H single-crystal SiC substrate together to form the SiC composite substrate. However, existing SiC composite substrate fabrication processes require bonding and peeling steps, thus exhibiting the following drawbacks: 1. After bonding, gaps or voids may form at the interface, leading to fluctuations in device performance; 2. Bonding is achieved by bombarding the bonding surface with high-energy ions or atoms to break chemical bonds. This process can cause damage to both single-crystal and polycrystalline surfaces. 3. The bonding process requires high surface quality of the bonding surface, which increases the difficulty of processing polycrystalline SiC substrates; 4. Stress will be generated at the interface during bonding, which will deteriorate the substrate surface profile; 5. The process following bonding is the peeling process. The stress generated during the peeling process can lead to surface deterioration and fragmentation of the thin monocrystalline layer.

[0003] In order to achieve bonding, the surfaces to be bonded need to be polished with high quality, which is a difficult process and also increases the cost.

[0004] Figure 1 This is a schematic diagram of the test sites of a SiC composite substrate formed by bonding in the background art; Figure 2 for Figure 1 The image shown is a SEM cross-section with a resolution of 100 nm at the center test point. Figure 3 for Figure 1 The image shown is a SEM cross-sectional view of the test point with a resolution of 100nm. Figure 4 for Figure 1 The image shown is a SEM cross-section of the test point on the left with a resolution of 100 nm. Figure 5 for Figure 1 The SEM cross-sectional view of the right test point is shown. Figure 6 for Figure 1 The image shown is a SEM cross-sectional view of the test point with a resolution of 100 nm.

[0005] like Figure 1 As shown, samples were prepared at five test sites using FIB (Film Injection Biofilm Analysis). A 100nm resolution SEM cross-sectional image was captured at each test site to form... Figures 2 to 6 SEM cross-sectional image. (e.g.) Figures 2 to 6 As shown, the results indicate that voids or gaps exist at the vast majority of interfaces.

[0006] Figure 7 for Figure 1 The TEM cross-sectional image shown is a TEM image with a resolution of 500 nm at the center test point. Figure 8 for Figure 7 The rectangular frame portion is a magnified image with a resolution of 100nm; Figure 9 for Figure 8 An EDS diagram showing the proportion of the empty elements at the vertical line positions in the middle of the rectangular frame. (See attached diagram.) Figure 9 As shown, the element ratio Si:C at the voids is significantly different from the Si:C=1:1 in the normal region. The Si content at the voids is significantly reduced, and the element ratio Si:C at the voids is no longer the normal 1:1, which seriously affects the device performance.

[0007] The following section uses FIB slices to perform SEM and TEM cross-sectional observations.

[0008] Figure 10 This is a schematic diagram of the observation points of a SiC composite substrate formed by bonding in the background art; Figure 11 for Figure 10 The SEM cross-sectional image shown is taken at the observation point with a resolution of 500 nm. Figure 12 for Figure 10 The SEM cross-sectional image shown is at the observation point on the right with a resolution of 500 nm. Figure 13 for Figure 10 The image shows a cross-sectional view of the central observation point with a resolution of 500 nm.

[0009] Figure 14 for Figure 10 The TEM cross-sectional image shown is at a resolution of 100 nm at the central observation point. Figure 15 for Figure 10 The image shown is a TEM cross-section with a resolution of 100 nm at the left observation point. Figure 16 for Figure 10 The image shown is a TEM cross-section with a resolution of 20 nm at the left observation point. Figure 17 for Figure 10 The image shown is a TEM cross-section with a resolution of 10 nm at the left observation point.

[0010] like Figures 10 to 13 As shown, SEM observation revealed similar long crack morphologies. Figures 14 to 17 As shown, TEM magnified the crack and observed a significant height difference, which is an interface defect caused by bonding.

[0011] Among them, FIB stands for Focused Ion Beam (FIB), an advanced micro-nano fabrication technology. A cross-sectional image from SEM (Scanning Electron Microscope) typically refers to a high-resolution image of a cross-section obtained after cutting, polishing, or processing a material or object using SEM technology. Transmission Electron Microscope (TEM) is a high-resolution microscope used to observe the internal ultrastructure of materials. EDS stands for Energy Dispersive X-ray Spectroscopy.

[0012] Therefore, the poor performance of SiC composite substrates prepared by traditional SiC composite substrate fabrication processes is a technical problem that urgently needs to be solved by those skilled in the art.

[0013] The information disclosed in the background section is only intended to enhance the understanding of the background of this application, and therefore may contain information that is not part of the prior art known to those skilled in the art. Summary of the Invention

[0014] This application provides a method for preparing a SiC composite substrate and a SiC composite substrate, in order to solve the technical problem of poor performance of SiC composite substrates prepared by traditional SiC composite substrate preparation processes.

[0015] This application provides a method for preparing a SiC composite substrate, comprising the following steps: H-ion implantation is performed on a single-crystal SiC substrate to form a hydrogen-implanted single-crystal SiC substrate. The hydrogen-injected single-crystal SiC substrate is bonded to the support substrate, making the connection between the hydrogen-injected single-crystal SiC substrate and the support substrate a soft connection. At the H ion implantation site, the portion of the hydrogen-implanted single-crystal SiC substrate above the H ion implantation site is stripped off by annealing, and the portion of the hydrogen-implanted single-crystal SiC substrate that is not stripped off forms a single-crystal SiC layer. A polycrystalline SiC layer is formed on top of the single-crystal SiC layer by deposition; Remove the adhesive at the bonding location to remove the supporting substrate, forming a SiC composite substrate including the single-crystal SiC layer and the polycrystalline SiC layer.

[0016] This application also provides a SiC composite substrate, which is prepared by the above-described method for preparing a SiC composite substrate.

[0017] This application, by adopting the above technical solution, has the following technical effects: The method for preparing the SiC composite substrate in this application involves bonding the hydrogen-implanted single-crystal SiC substrate onto a supporting substrate, making the connection between the hydrogen-implanted single-crystal SiC substrate and the supporting substrate a soft connection. This simplifies the subsequent removal of the bonding agent and reduces the process difficulty. Furthermore, a polycrystalline SiC layer is formed on top of the single-crystal SiC layer through deposition, achieving the connection between the single-crystal SiC layer and the polycrystalline SiC layer. This process is simple, easy to operate, and has low processing difficulty.

[0018] Therefore, the SiC composite substrate preparation method of this application does not require a bonding process throughout the entire process, and thus does not have the disadvantages associated with bonding processes. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the test sites of a SiC composite substrate formed by bonding in the background art; Figure 2 for Figure 1 The image shown is a SEM cross-section with a resolution of 100 nm at the center test point. Figure 3 for Figure 1 The image shown is a SEM cross-sectional view of the test point with a resolution of 100nm. Figure 4 for Figure 1 The image shown is a SEM cross-section of the test point on the left with a resolution of 100 nm. Figure 5 for Figure 1 The SEM cross-sectional view of the right test point is shown. Figure 6 for Figure 1 The image shown is a SEM cross-sectional view of the test point with a resolution of 100nm. Figure 7 for Figure 1 The TEM cross-sectional image shown is a TEM image with a resolution of 500 nm at the center test point. Figure 8 for Figure 7 The rectangular frame portion is a magnified image with a resolution of 100nm; Figure 9 for Figure 8 An EDS diagram showing the proportion of the empty elements at the vertical line position in the middle of the rectangular frame; Figure 10This is a schematic diagram of the observation points of a SiC composite substrate formed by bonding in the background art; Figure 11 for Figure 10 The SEM cross-sectional image shown is taken at the observation point with a resolution of 500 nm. Figure 12 for Figure 10 The SEM cross-sectional image shown is at the observation point on the right with a resolution of 500 nm. Figure 13 for Figure 10 The SEM cross-sectional image with a resolution of 500 nm is shown at the central observation point. Figure 14 for Figure 10 The TEM cross-sectional image shown is at a resolution of 100 nm at the central observation point. Figure 15 for Figure 10 The image shown is a TEM cross-section with a resolution of 100 nm at the left observation point. Figure 16 for Figure 10 The image shown is a TEM cross-section with a resolution of 20 nm at the left observation point. Figure 17 for Figure 10 The image shown is a TEM cross-section with a resolution of 10 nm at the left observation point. Figure 18 This is a flowchart of the method for preparing the SiC composite substrate according to this application; Figure 19 A schematic diagram illustrating step S1 of the method for preparing the SiC composite substrate of this application; Figure 20 A schematic diagram illustrating step S2 of the SiC composite substrate preparation method of this application; Figure 21 A schematic diagram illustrating step S3 of the SiC composite substrate preparation method of this application; Figure 22 A schematic diagram illustrating step S4 of the SiC composite substrate preparation method of this application; Figure 23 This is a schematic diagram illustrating step S5 of the method for preparing the SiC composite substrate according to this application.

[0020] Figure label: Hydrogen-implanted single-crystal SiC substrate 1, H ion implantation site 11, single-crystal SiC layer 12. Support substrate 2, Polycrystalline SiC layer 3. Detailed Implementation

[0021] To make the technical solutions and advantages of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0022] Example 1 like Figure 18 As shown, the method for preparing the SiC composite substrate of this application includes the following steps: like Figure 19 As shown, step S1: H ion implantation is performed on the single crystal SiC substrate to form hydrogen-implanted single crystal SiC substrate 1; like Figure 20 As shown, in step S2: the hydrogen-injected single-crystal SiC substrate 1 is bonded to the support substrate 2, so that the connection between the hydrogen-injected single-crystal SiC substrate 1 and the support substrate 2 is a soft connection. like Figure 21 As shown, in step S3: at the H ion implantation position 11, the portion of the hydrogen-implanted single-crystal SiC substrate 1 above the H ion implantation position is stripped by annealing, and the unstripped portion of the hydrogen-implanted single-crystal SiC substrate forms a single-crystal SiC layer 12. like Figure 22 As shown, step S4: A polycrystalline SiC layer 3 is formed on the single-crystal SiC layer 12 by deposition; like Figure 23 As shown, step S5: Remove the adhesive at the bonding position to remove the supporting substrate 2, forming a SiC composite substrate including the single crystal SiC layer 12 and the polycrystalline SiC layer 3.

[0023] The most significant feature of the SiC composite substrate preparation method in this application is that no bonding process is required throughout the entire process, thus avoiding the drawbacks associated with bonding processes.

[0024] Step S2: The hydrogen-implanted single-crystal SiC substrate 1 is bonded to the support substrate 2, making the connection between the hydrogen-implanted single-crystal SiC substrate 1 and the support substrate 2 a soft connection. That is, a bonding process is not required in step S2 of this application.

[0025] Step S4: A polycrystalline SiC layer 3 is formed on the single-crystal SiC layer 12 by deposition. That is, a polycrystalline SiC layer 3 is formed on the single-crystal SiC layer 12 by deposition, achieving the connection between the single-crystal SiC of the single-crystal SiC layer 12 and the polycrystalline SiC of the polycrystalline SiC layer 3. Step S4 in this application does not require a bonding process. If a bonding process is used to connect the polycrystalline SiC layer to the single-crystal SiC layer, the surface of the polycrystalline SiC layer needs to be polished to a high standard before bonding, which is more difficult and costly.

[0026] Since the hydrogen-implanted single-crystal SiC substrate 1 is bonded to the support substrate 2 in step S2, correspondingly, in step S5: the adhesive is removed at the bonding location to remove the support substrate 2, forming a SiC composite substrate including the single-crystal SiC layer 12 and the polycrystalline SiC layer 3. The adhesive is removed by cleaning, which has minimal impact on the single-crystal SiC layer 12 and avoids the problems of surface deterioration and thin single-crystal layer fragmentation caused by peeling; at the same time, the adhesive removal process is simpler and easier to operate.

[0027] In summary, the SiC composite substrate preparation method of this application involves bonding the hydrogen-implanted single-crystal SiC substrate 1 onto the supporting substrate 2, making the connection between the hydrogen-implanted single-crystal SiC substrate 1 and the supporting substrate 2 a soft connection. This simplifies the subsequent removal of the bonding agent and reduces the process difficulty. Furthermore, a polycrystalline SiC layer 3 is formed on the single-crystal SiC layer 12 through deposition, achieving the connection between the single-crystal SiC of the single-crystal SiC layer 12 and the polycrystalline SiC of the polycrystalline SiC layer 3. This process is simple, easy to operate, and has low processing difficulty.

[0028] Therefore, the SiC composite substrate preparation method of this application does not require a bonding process throughout the entire process, and thus does not have the disadvantages associated with bonding processes.

[0029] In practice, in step S2, a high-temperature resistant adhesive is used for bonding, and the temperature range of the high-temperature resistant adhesive is greater than or equal to 1100℃ and less than or equal to 1500℃.

[0030] By using high-temperature resistant adhesive as the bonding material, the high-temperature resistant adhesive has excellent thermal stability and can withstand extreme high-temperature environments with temperatures not lower than 1100℃ and not higher than 1500℃ for a long time, thereby ensuring the structural integrity and connection reliability of the bonding interface during high-temperature processes.

[0031] In practice, the methods for removing adhesive at the adhesive joint in step S5 include: First, clean with an organic solvent; the organic solvent may be acetone, ethanol, or hexafluoroisopropanol. Then clean with a low-concentration strong acid; wherein the low-concentration strong acid is 5% HCl, or 5% H2SO4, or a mixture of 5% HCl and HNO3, or a mixture of sulfuric acid and hydrogen peroxide.

[0032] By employing a step-by-step process to remove adhesive at the bonding site, the bonding site is first cleaned with an organic solvent, which can effectively swell or dissolve the organic polymer components in the adhesive layer, achieving initial softening and partial removal of the adhesive layer. Subsequently, a second cleaning is performed using a low-concentration strong acid, which can further hydrolyze the organic solvent-resistant cross-linked structures or inorganic-organic hybrid components in the adhesive layer, and remove residual carbides or interface byproducts, significantly improving the thoroughness and uniformity of adhesive removal.

[0033] In practice, step S4 specifically involves: A polycrystalline SiC layer 3 is formed on the single-crystal SiC layer 12 by chemical vapor deposition. The process parameters for chemical vapor deposition include: The carbon-silicon atom ratio of the carbon source and the silicon source is a:1; where the value of a ranges from greater than or equal to 1 to less than or equal to 2. The temperature range for chemical vapor deposition is greater than or equal to 1100℃ and less than or equal to 1500℃; The cavity pressure range for chemical vapor deposition is greater than or equal to 20,000 Pa and less than or equal to 30,000 Pa.

[0034] Growing polycrystalline SiC layers on single-crystal SiC layers via chemical vapor deposition (CVD) enables controllable and uniform deposition of polycrystalline SiC layers while maintaining high interface purity and good adhesion. Polycrystalline SiC layers, serving as process buffer layers or conductive / thermal conductive functional layers for subsequent processing, can effectively mitigate the adverse effects of thermal stress, lattice mismatch, or surface defects caused by subsequent processes (such as epitaxial growth, device fabrication, or bonding). Furthermore, polycrystalline SiC layers have similar chemical compositions and coefficients of thermal expansion to single-crystal SiC layers, significantly reducing interfacial thermal mismatch stress and improving structural stability and thermal cycling reliability.

[0035] Growing polycrystalline SiC layers on single-crystal SiC layers via chemical vapor deposition (CVD) achieves the connection between single-crystal and polycrystalline SiC, improving structural reliability and preventing surface deterioration or crack propagation. The reasons are as follows: Single-crystal SiC and other materials (such as Si, When metals are directly connected, large stresses are often generated due to the mismatch of thermal expansion coefficients, leading to warping or cracking.

[0036] Depositing a layer of polycrystalline SiC on a single-crystal SiC substrate can serve as a stress buffer layer, alleviating mechanical stress during thermal cycling.

[0037] In implementation, step S4 is as follows: A polycrystalline SiC layer is formed on the single-crystal SiC layer 12 by physical vapor deposition or electrochemical deposition.

[0038] In practice, the thickness of the single-crystal SiC layer 12 is greater than or equal to 500 nm and less than or equal to 900 nm.

[0039] In practice, the thickness of the polycrystalline SiC layer 3 is greater than or equal to 370 μm and less than or equal to 600 μm.

[0040] In practice, the single-crystal SiC layer 12 is a 4H single-crystal SiC layer; The polycrystalline SiC layer 3 is a 3C polycrystalline SiC layer.

[0041] In practice, the support substrate 2 is made of graphite or single-crystal silicon.

[0042] In practice, the high-temperature resistant adhesive is an inorganic high-temperature resistant adhesive, which may be an alumina high-temperature adhesive, an aluminosilicate high-temperature adhesive, or an inorganic ceramic high-temperature adhesive.

[0043] Example 2 This application provides a SiC composite substrate, which is prepared by the SiC composite substrate preparation method described in Example 1.

[0044] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0045] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0046] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0047] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0048] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0049] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for preparing a SiC composite substrate, characterized in that, Includes the following steps: H ion implantation was performed on a single-crystal SiC substrate to form a hydrogen-implanted single-crystal SiC substrate (1). The hydrogen-injected single-crystal SiC substrate (1) is bonded on the support substrate (2) such that the connection between the hydrogen-injected single-crystal SiC substrate (1) and the support substrate (2) is a soft connection. At the H ion implantation site (11), the portion of the hydrogen-implanted single-crystal SiC substrate (1) above the H ion implantation site is stripped by annealing, and the unstripped portion of the hydrogen-implanted single-crystal SiC substrate (1) forms a single-crystal SiC layer (12). A polycrystalline SiC layer (3) is formed on the single-crystal SiC layer (12) by deposition. Remove the adhesive at the bonding location to remove the supporting substrate (2), forming a SiC composite substrate including the single-crystal SiC layer (12) and the polycrystalline SiC layer (3).

2. The method for preparing the SiC composite substrate according to claim 1, characterized in that, In the step of bonding the hydrogen-implanted single-crystal SiC substrate onto the support substrate, a high-temperature resistant adhesive is used, wherein the temperature range of the high-temperature resistant adhesive is greater than or equal to 1100°C and less than or equal to 1500°C.

3. The method for preparing the SiC composite substrate according to claim 1, characterized in that, Methods for removing adhesive at the joint include: First, clean with an organic solvent; the organic solvent may be acetone, ethanol, or hexafluoroisopropanol. Then clean with a low-concentration strong acid; wherein the low-concentration strong acid is 5% HCl, or 5% H2SO4, or a mixture of 5% HCl and HNO3, or a mixture of sulfuric acid and hydrogen peroxide.

4. The method for preparing a SiC composite substrate according to any one of claims 1 to 3, characterized in that, The step of forming a polycrystalline SiC layer by deposition on the single-crystal SiC layer specifically includes: A polycrystalline SiC layer is formed on top of the single-crystal SiC layer by chemical vapor deposition; The process parameters for chemical vapor deposition include: The carbon-silicon atom ratio of the carbon source and the silicon source is a:1; where the value of a ranges from greater than or equal to 1 to less than or equal to 2. The temperature range for chemical vapor deposition is greater than or equal to 1100℃ and less than or equal to 1500℃; The cavity pressure range for chemical vapor deposition is greater than or equal to 20,000 Pa and less than or equal to 30,000 Pa.

5. The method for preparing a SiC composite substrate according to any one of claims 1 to 3, characterized in that, The step of forming a polycrystalline SiC layer by deposition on the single-crystal SiC layer specifically includes: A polycrystalline SiC layer is formed on top of the single-crystal SiC layer by physical vapor deposition or electrochemical deposition.

6. The method for preparing a SiC composite substrate according to any one of claims 1 to 3, characterized in that, The thickness of the single-crystal SiC layer is greater than or equal to 500 nm and less than or equal to 900 nm.

7. The method for preparing a SiC composite substrate according to claim 6, characterized in that, The thickness of the polycrystalline SiC layer is greater than or equal to 370 μm and less than or equal to 600 μm.

8. The method for preparing the SiC composite substrate according to claim 7, characterized in that, The single-crystal SiC layer is a 4H single-crystal SiC layer; The polycrystalline SiC layer is a 3C polycrystalline SiC layer.

9. The method for preparing a SiC composite substrate according to any one of claims 1 to 3, characterized in that, The support substrate is made of graphite or monocrystalline silicon.

10. The method for preparing a SiC composite substrate according to claim 2, characterized in that, The high-temperature resistant adhesive is an inorganic high-temperature resistant adhesive, which may be an alumina high-temperature adhesive, an aluminosilicate high-temperature adhesive, or an inorganic ceramic high-temperature adhesive.

11. A SiC composite substrate, characterized in that, The SiC composite substrate was prepared by the method described in any one of claims 1 to 10.

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