Buffer layer structure for stripping silicon carbide and preparation method thereof
By forming a multi-layer silicon carbide buffer layer structure that gradually increases and grows step by step between the substrate and the silicon carbide epitaxial functional layer, the problem of difficult film thickness and complex process in heterogeneous integration is solved, and the difficulty of substrate peeling is reduced and the quality of the epitaxial functional layer is maintained.
Patent Information
- Application Number
- CN202411772109.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-03-18
AI Technical Summary
The prior art has problems in heterogeneous integration that film thickness is difficult to accurately control, complex process, long time, high equipment requirements and possible lattice damage.
A multi-layer silicon carbide buffer layer structure that is gradually heated and grown in step by step, including a graphene layer and a multi-layer silicon carbide buffer layer. Through this structure, a buffer layer is formed between the substrate and the silicon carbide epitaxial functional layer, reducing the difficulty of substrate peeling and maintaining the crystal quality of the epitaxial functional layer.
It effectively reduces the difficulty of substrate peeling, ensures the overall quality of the epitaxial functional layer, is not affected by the peeling process, and the process is relatively simple and the film thickness is controllable.
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Figure CN119650410A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of semiconductor preparation, and in particular relates to a buffer layer structure for silicon carbide stripping and a preparation method thereof. Background Art
[0002] Silicon carbide is a wide bandgap semiconductor material. Its excellent physical properties have broad application prospects in many fields such as power electronic systems and new energy vehicles. In order to meet the needs of device miniaturization, it is usually necessary to heterogeneously integrate the silicon carbide epitaxial functional layer with other substrates. As demand continues to grow, the performance requirements for materials and devices are getting higher and higher, and costs are constantly being required to be reduced.
[0003] There are two main types of traditional heterogeneous integration methods. One is to grow a silicon carbide epitaxial functional layer on a substrate such as silicon or gallium nitride and then bond it to other substrates that need to be integrated, and then remove the silicon or gallium nitride substrate by thinning to achieve heterogeneous integration. The other is to use high-energy ion beams to form defects within a specific depth range on the surface of the silicon carbide epitaxial functional layer and transfer the film to the substrate that needs to be integrated through heat treatment or laser lift-off to achieve heterogeneous integration.
[0004] However, both of the above methods have defects. For the method of bonding silicon or other substrates with silicon carbide epitaxial functional layers to the substrate to be integrated, and then thinning and removing the silicon or gallium nitride substrate to achieve heterogeneous integration, there are many defects such as difficulty in accurately controlling the film thickness, complex process, and long time consumption. For heterogeneous integration by ion implantation of silicon carbide epitaxial functional layers and transferring the film to the substrate to be integrated through heat treatment or laser stripping, there are high requirements for equipment and the introduction of lattice damage inside the film, resulting in a decrease in material quality.
[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention
[0006] The object of the present invention is to provide a buffer layer structure for silicon carbide stripping and a preparation method thereof. Through the setting of the buffer layer, the difficulty of stripping a substrate with a silicon carbide epitaxial functional layer grown thereon after bonding to other substrates can be significantly reduced, and the stripping process has no effect on the crystal quality of the epitaxial functional layer.
[0007] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:
[0008] A method for preparing a buffer layer for silicon carbide stripping, comprising:
[0009] forming a graphene layer on a surface of a substrate;
[0010] Under a first temperature condition, forming a first silicon carbide buffer layer on the surface of the graphene layer;
[0011] Under a second temperature condition, forming a second silicon carbide buffer layer on the first silicon carbide buffer layer;
[0012] forming a third silicon carbide buffer layer on the second silicon carbide buffer layer under a third temperature condition;
[0013] The first temperature is lower than the second temperature, the second temperature is lower than the third temperature, and the graphene layer, the first silicon carbide buffer layer, the second silicon carbide buffer layer and the third silicon carbide buffer layer together constitute the buffer layer.
[0014] In one or more embodiments of the present invention, the first temperature is 1100°C-1400°C;
[0015] The second temperature is 1300° C.-1500° C.;
[0016] The third temperature is 1500°C-1700°C.
[0017] In one or more embodiments of the present invention, forming a first silicon carbide buffer layer on the surface of the graphene layer includes:
[0018] Under the condition of a temperature of 1100° C. to 1300° C., an inert gas and a gas containing silicon atoms are introduced and maintained for a first preset time to form a first silicon-enriched layer;
[0019] Under the condition of linearly increasing the temperature to 1200° C.-1400° C. at a rate of 60° C. / min-120° C. / min, a gas containing carbon atoms is introduced to form a first silicon carbide buffer layer at a first growth rate.
[0020] In one or more embodiments of the present invention, the flow rate of the inert gas is 100 sccm-200 sccm;
[0021] The flow rate of the gas containing silicon atoms is 1 sccm-20 sccm;
[0022] The flow ratio of the gas containing carbon atoms to the gas containing silicon atoms is (2-4):5;
[0023] The first preset time is 1s-120s;
[0024] The first growth rate is 0.5 μm / h-2 μm / h;
[0025] The growth thickness of the first silicon carbide buffer layer is 0.5 μm-1 μm.
[0026] In one or more embodiments of the present invention, before the step of forming a second silicon carbide buffer layer on the first silicon carbide buffer layer, the step further includes:
[0027] In-situ etching of the surface of the first silicon carbide buffer layer using hydrogen;
[0028] Among them, the hydrogen flow rate is 1L / min-10L / min, and the etching time is 0.5min-5min.
[0029] In one or more embodiments of the present invention, forming a second silicon carbide buffer layer on the first silicon carbide buffer layer includes:
[0030] Under the condition of a temperature of 1300° C. to 1500° C., introducing an inert gas and a gas containing silicon atoms and maintaining the temperature for a second preset time to form a second silicon-enriched layer;
[0031] A gas containing carbon atoms is introduced, and the flow ratio of the gas containing carbon atoms to the gas containing silicon atoms is controlled to be (3-6):10, so as to form a second silicon carbide buffer layer at a second growth rate.
[0032] In one or more embodiments of the present invention, the flow rate of the inert gas is 200 sccm-500 sccm;
[0033] The flow rate of the gas containing silicon atoms is 1 sccm-20 sccm;
[0034] The second preset time is 1s-60s;
[0035] The second growth rate is 1 μm / h-2 μm / h;
[0036] The second silicon carbide buffer layer has a growth thickness of 0.5 μm-1 μm.
[0037] In one or more embodiments of the present invention, forming a third silicon carbide buffer layer on the second silicon carbide buffer layer includes:
[0038] Under the condition of linearly increasing the temperature to 1500°C-1700°C at a rate of 60°C / min-120°C / min, the flow ratio of the gas containing carbon atoms to the gas containing silicon atoms is controlled to be (1-2):1, and a third silicon carbide buffer layer is formed at a third growth rate.
[0039] In one or more embodiments of the present invention, the third growth rate is 2 μm / h-5 μm / h;
[0040] The third silicon carbide buffer layer has a growth thickness of 1 μm-3 μm.
[0041] In one or more embodiments of the present invention, a graphene layer is formed on the surface of the substrate by epitaxial growth or chemical vapor deposition.
[0042] In one or more embodiments of the present invention, the substrate is a silicon carbide substrate;
[0043] Forming a graphene layer on the surface of the substrate by an epitaxial growth method, comprising:
[0044] Under vacuum conditions, the pressure is controlled at 100 mbar-200 mbar, the temperature is between 1400°C-1600°C, and the reaction gas hydrogen is introduced at a flow rate of 50 L / min-100 L / min for 30 min-90 min to form a multi-layer graphene layer on the surface of the silicon carbide substrate.
[0045] A buffer layer structure for silicon carbide stripping is formed between a substrate and a silicon carbide epitaxial functional layer, characterized in that it includes a graphene layer, a first silicon carbide layer, a second silicon carbide layer and a third silicon carbide layer stacked in sequence in a direction away from the substrate, wherein the first silicon carbide layer, the second silicon carbide layer and the third silicon carbide layer are arranged to be formed under different temperature conditions.
[0046] In one or more embodiments of the present invention, the growth temperature of the first silicon carbide layer is lower than the growth temperature of the second silicon carbide layer, and the growth temperature of the second silicon carbide layer is lower than the growth temperature of the third silicon carbide layer; and / or,
[0047] The growth temperature of the first silicon carbide layer is 1100° C.-1400° C.; the growth temperature of the second silicon carbide layer is 1300° C.-1500° C.; the growth temperature of the first silicon carbide layer is 1500° C.-1700° C.; and / or,
[0048] The number of graphene layers is 4-20; and / or,
[0049] The thickness of the first silicon carbide layer is 0.5 μm-1 μm; and / or,
[0050] The thickness of the second silicon carbide layer is 0.5 μm-1 μm; and / or,
[0051] The thickness of the third silicon carbide layer is 1 μm-3 μm.
[0052] Compared with the prior art, the buffer layer structure for silicon carbide stripping and the preparation method thereof of the present invention, applied between the substrate and the silicon carbide epitaxial functional layer, can effectively reduce the difficulty of subsequent substrate stripping, and can ensure that the epitaxial functional layer can be conveniently and quickly stripped in the subsequent device process to achieve heterogeneous integration, and can also ensure that the overall quality of the epitaxial functional layer is not affected by the stripping process.
[0053] The buffer layer structure for silicon carbide stripping and the preparation method thereof of the present invention can effectively avoid the occurrence of various defects and improve the growth quality of the subsequent silicon carbide epitaxial functional layer by gradually increasing the temperature and growing the multi-layer silicon carbide buffer layer in steps.
[0054] The buffer layer structure for silicon carbide stripping and the preparation method thereof of the present invention directly grow a multi-layer silicon carbide buffer layer based on graphene on a substrate, and in the stripping process after the epitaxial functional layer is bonded to other substrates, the stripping operation has no effect on the crystal quality of the epitaxial functional layer. The buffer layer structure formed by the preparation method of the buffer layer for silicon carbide stripping of the present invention has a controllable film thickness and a relatively simple process, and because the multi-layer graphene layers have low mechanical strength, the requirements for subsequent stripping equipment and processes are relatively low. BRIEF DESCRIPTION OF THE DRAWINGS
[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0056] Figure 1 The process flow chart of the method for preparing the buffer layer for silicon carbide stripping of the present invention;
[0057] Figure 2 A time chart of the process of the method for preparing a buffer layer for silicon carbide stripping of the present invention;
[0058] Figure 3 This is a microscopic observation of the buffer layer for silicon carbide peeling prepared in Example 1 of the present invention after the cracks are colored;
[0059] Figure 4 This is a microscopic observation of the surface of the buffer layer for silicon carbide stripping prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0060] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.
[0061] As mentioned in the background technology, in the prior art, if the silicon or other substrate with a silicon carbide epitaxial functional layer is bonded to the substrate to be integrated, and then the silicon or gallium nitride substrate is thinned and removed to achieve heterogeneous integration, there are many defects such as difficulty in accurately controlling the film thickness, complex process, and long time consumption. If the heterogeneous integration is achieved by ion implantation of the silicon carbide epitaxial functional layer and heat treatment or laser stripping to transfer the film to the substrate to be integrated, there are high requirements for equipment and the problem of introducing lattice damage inside the film, resulting in a decrease in material quality.
[0062] Based on this, the present invention provides a buffer layer structure for silicon carbide stripping and a preparation method thereof. Through the setting of the buffer layer, the difficulty of stripping a substrate with a silicon carbide epitaxial functional layer grown thereon after bonding to other substrates can be significantly reduced, and the stripping process has no effect on the crystal quality of the epitaxial functional layer.
[0063] like Figure 1 As shown, a method for preparing a buffer layer for silicon carbide stripping in one embodiment of the present invention specifically includes the following steps:
[0064] S1, forming a graphene layer on the surface of the substrate.
[0065] The substrate may be a silicon carbide substrate or a silicon substrate or a gallium nitride substrate. When the substrate is a silicon carbide substrate, a graphene layer may be formed on the substrate surface by an epitaxial growth method. When the substrate is a silicon substrate or a gallium nitride substrate, a graphene layer may be formed on the substrate surface by a chemical vapor deposition method.
[0066] S2, forming a first silicon carbide buffer layer on the surface of the graphene layer under a first temperature condition.
[0067] Wherein, the first temperature range is 1100°C-1400°C. By introducing an inert gas, a gas containing silicon atoms and a gas containing carbon atoms, and controlling the flow rate and / or introduction time of each gas, a first silicon carbide buffer layer is formed at a lower first growth rate. The inert gas may include argon, helium, neon, etc. The gas containing silicon atoms may include silane, dichlorosilane, trichlorosilane, etc. The gas containing carbon atoms may include methane, ethylene, propane, etc.
[0068] S3, etching the surface of the first silicon carbide buffer layer.
[0069] While maintaining the first temperature condition, the surface of the first silicon carbide buffer layer is etched. The first silicon carbide buffer layer can be etched in situ with hydrogen; the hydrogen flow rate is 1L / min-10L / min, and the etching time is 0.5min-5min. Lightly etching the first silicon carbide buffer layer can improve the surface quality to a certain extent, which is convenient for the subsequent high-quality growth of the second silicon carbide buffer layer and the third silicon carbide buffer layer.
[0070] S4, forming a second silicon carbide buffer layer on the first silicon carbide buffer layer under a second temperature condition.
[0071] The second temperature is higher than the first temperature. Preferably, the temperature can be linearly increased from the first temperature to the second temperature at a rate of 60°C / min-120°C / min. The second temperature range is 1300°C-1500°C. Similarly, by introducing an inert gas, a gas containing silicon atoms, and a gas containing carbon atoms, and controlling the flow rate and / or introduction time of each gas, a second silicon carbide buffer layer is formed at a lower second growth rate.
[0072] The second growth rate may be greater than or equal to the first growth rate.
[0073] S5, forming a third silicon carbide buffer layer on the second silicon carbide buffer layer under a third temperature condition.
[0074] Wherein, the third temperature is higher than the second temperature. Preferably, the temperature can be linearly increased from the second temperature to the third temperature at a rate of 60°C / min-120°C / min. The third temperature range is 1500°C-1700°C. Similarly, by regulating the flow rate of the inert gas, the gas containing silicon atoms, and the gas containing carbon atoms, the third silicon carbide buffer layer is still formed at a lower third growth rate. The third growth rate is greater than the second growth rate.
[0075] The above-mentioned graphene layer, the first silicon carbide buffer layer, the second silicon carbide buffer layer and the third silicon carbide buffer layer together constitute the buffer layer for silicon carbide stripping of the present invention.
[0076] refer to Figure 2 As shown, Figure 2 A time chart showing the specific steps of preparing a buffer layer for silicon carbide stripping in one embodiment of the present invention is shown.
[0077] First, a graphene layer is formed on a silicon carbide substrate.
[0078] Specifically, a reaction chamber of a chemical vapor deposition (CVD) device is evacuated and replaced with nitrogen, and the vacuum degree is maintained at 100 mbar-200 mbar.
[0079] The nitrogen is turned off and hydrogen is introduced, with the hydrogen flow rate controlled at 50L / min-100L / min. The temperature of the reaction chamber is raised, and when the temperature reaches 1400℃-1600℃, the temperature and pressure are kept stable for 30min-90min to form a stable multi-layer graphene layer on the silicon carbide substrate.
[0080] Secondly, a first silicon carbide buffer layer is formed on the surface of the graphene layer.
[0081] Specifically, the hydrogen gas is turned off, and argon gas with a gas flow rate of 100 sccm-200 sccm is introduced. The temperature of the reaction chamber is lowered to a range of 1100° C.-1300° C., and after stabilization, 1 sccm-20 sccm of silane is introduced for 1 second to 120 seconds to form a first silicon-enriched layer of several atomic layers on the surface of the graphene layer.
[0082] While keeping the argon flow rate unchanged and reducing the silane flow rate, the temperature is linearly increased to 1200℃-1400℃ at a rate of 60℃ / min-120℃ / min. After stabilization, the silane flow rate is adjusted and methane is introduced to ensure that the ratio of carbon in methane to silicon in silane is 0.4-0.8. A first silicon carbide buffer layer with a thickness of 0.5μm-1μm is grown at a growth rate of 0.5μm / h-2μm / h.
[0083] Next, the surface of the first silicon carbide buffer layer is etched.
[0084] Specifically, the temperature is maintained at 1200° C.-1400° C., the introduction of argon, silane and methane is turned off, and 1 L / min-10 L / min of hydrogen is introduced to in-situ etch the surface of the first silicon carbide buffer layer for 0.5 min-5 min.
[0085] Furthermore, a second silicon carbide buffer layer is formed on the first silicon carbide buffer layer.
[0086] Specifically, hydrogen is turned off, and argon is introduced at a flow rate of 200 sccm-500 sccm. The temperature is linearly increased to 1300°C-1500°C at a rate of 60°C / min-120°C / min. After the temperature stabilizes, silane is introduced at a flow rate of 1 sccm-20 sccm for 1s-60s to grow a second silicon-enriched layer.
[0087] The temperature is maintained at 1300°C-1500°C, and methane is introduced. The flow rate of methane is controlled so that the ratio of carbon in methane to silicon in silane is 0.3-0.6. A second silicon carbide buffer layer with a thickness of 0.5μm-1μm is grown at a growth rate of 1μm / h-2μm / h.
[0088] Finally, a third silicon carbide buffer layer is formed on the second silicon carbide buffer layer.
[0089] Specifically, the temperature is linearly increased to 1500°C-1700°C again at a rate of 60°C / min-120°C / min. During the heating process, the introduction of silane and methane is turned off. After the temperature stabilizes, the introduction flow rate of silane is kept consistent with that in the previous step, and the introduction flow rate of methane is controlled to be: the ratio of carbon in methane to silicon in silane is 0.5-1, and a third silicon carbide buffer layer with a thickness of 1μm-3μm is grown at a growth rate of 2μm / h-5μm / h.
[0090] At this point, the entire buffer layer structure for silicon carbide stripping is grown.
[0091] The subsequent growth conditions of the silicon carbide epitaxial functional layer can be referred to, and the corresponding growth temperature, pressure, source gas flow rate and other conditions can be linearly transformed to start the high-speed growth of the silicon carbide epitaxial functional layer. After the growth is completed, the source gas is turned off, the carrier gas is added, the reaction chamber is pressurized, the temperature is lowered to room temperature, the inert gas is replaced, and the sample is taken out.
[0092] The present invention also provides a buffer layer structure for silicon carbide stripping made by the above-mentioned preparation method, which is formed between a substrate and a silicon carbide epitaxial functional layer. The buffer layer structure includes a graphene layer, a first silicon carbide layer, a second silicon carbide layer, and a third silicon carbide layer stacked in sequence in a direction away from the substrate. The first silicon carbide layer, the second silicon carbide layer, and the third silicon carbide layer are configured to be formed under different temperature conditions.
[0093] The growth temperature of the first silicon carbide layer is lower than the growth temperature of the second silicon carbide layer, and the growth temperature of the second silicon carbide layer is lower than the growth temperature of the third silicon carbide layer.
[0094] The growth temperature of the first silicon carbide layer is 1100°C-1400°C; the growth temperature of the second silicon carbide layer is 1300°C-1500°C; the growth temperature of the first silicon carbide layer is 1500°C-1700°C.
[0095] The number of graphene layers is 4-20. The thickness of the first silicon carbide layer is 0.5 μm-1 μm. The thickness of the second silicon carbide layer is 0.5 μm-1 μm. The thickness of the third silicon carbide layer is 1 μm-3 μm.
[0096] Embodiment 1:
[0097] After placing the silicon carbide substrate into the reaction chamber, nitrogen is introduced into the equipment and vacuum is started, dropping from atmospheric pressure to 100 mbar in 1 minute.
[0098] The equipment was switched to hydrogen state with a hydrogen flow rate of 80 L / min, and the temperature was increased to 1500°C at 120°C / min and stabilized for 60 minutes.
[0099] The hydrogen gas was switched to argon gas with a flow rate of 100 sccm, and the reaction chamber was cooled to 1100° C. After stabilization, silane was introduced at a flow rate of 5 sccm for 10 seconds.
[0100] The temperature was raised to 1250°C at a rate of 120°C / min. During the heating process, the flow rate of silane was reduced to 1 sccm. After the temperature stabilized, the flow rate of silane was controlled to 15 sccm, and methane was introduced at a flow rate of 10 sccm to grow the first silicon carbide buffer layer at a low speed with a thickness of 1 μm.
[0101] Turn off the methane, silane, and argon gases, switch to hydrogen, control the hydrogen flow rate at 2 L / min, and continue for 30 seconds for light etching.
[0102] The hydrogen gas was switched to the argon gas state with an argon flow rate of 200 sccm, and the temperature was raised to 1400°C at a rate of 120°C / min. After the temperature stabilized, silane was introduced with a flow rate of 20 sccm and maintained for 2 seconds, and then methane was introduced with a methane flow rate of 10 sccm to grow a second silicon carbide buffer layer with a thickness of 1 μm.
[0103] Turn off silane and methane, and heat up to 1600°C at a rate of 120°C / min. After the temperature stabilizes, the argon flow rate is 200sccm, the silane flow rate is 20sccm, and the methane flow rate is 12sccm. The third silicon carbide buffer layer is grown with a thickness of 2μm, and the growth of the entire buffer layer structure is completed.
[0104] The argon gas was switched to hydrogen with a flow rate of 50 L / min, a silane flow rate of 50 sccm, and a methane flow rate of 60 sccm, and a silicon carbide epitaxial functional layer was grown at a high speed with a thickness of 16 μm.
[0105] After the growth is completed, hydrogen, silane, and methane are turned off, and argon is turned on. The equipment is cooled to 800°C for protection, and then switched to nitrogen. The wafer is taken out after the reaction chamber is cooled to room temperature and pressure.
[0106] The sample in Example 1 was split and the cut was etched with color. Figure 3 As shown, it can be seen through a microscope that the overall thickness of the buffer layer structure and the epitaxial functional layer on the substrate surface is about 20 μm, which is consistent with the designed growth thickness, indicating that the growth method is feasible.
[0107] refer to Figure 4 As shown, the sample in Example 1 was observed under a surface microscope, and many triangular defects and lines were observed on the surface. The lines may be caused by the inconsistency of thermal conductivity and thermal expansion coefficient between graphene and silicon carbide. The growth conditions of the buffer layer can be further optimized to reduce dislocations in the growth process to improve the crystal quality.
[0108] Compared with the prior art, the buffer layer structure for silicon carbide stripping and the preparation method thereof of the present invention, applied between the substrate and the silicon carbide epitaxial functional layer, can effectively reduce the difficulty of subsequent substrate stripping, and can ensure that the epitaxial functional layer can be conveniently and quickly stripped in the subsequent device process to achieve heterogeneous integration, and can also ensure that the overall quality of the epitaxial functional layer is not affected by the stripping process.
[0109] The buffer layer structure for silicon carbide stripping and the preparation method thereof of the present invention can effectively avoid the occurrence of various defects and improve the growth quality of the subsequent silicon carbide epitaxial functional layer by gradually increasing the temperature and growing the multi-layer silicon carbide buffer layer in steps.
[0110] The buffer layer structure for silicon carbide stripping and the preparation method thereof of the present invention directly grow a multi-layer silicon carbide buffer layer based on graphene on a substrate, and in the stripping process after the epitaxial functional layer is bonded to other substrates, the stripping operation has no effect on the crystal quality of the epitaxial functional layer. The buffer layer structure formed by the preparation method of the buffer layer for silicon carbide stripping of the present invention has a controllable film thickness and a relatively simple process, and because the multi-layer graphene layers have low mechanical strength, the requirements for subsequent stripping equipment and processes are relatively low.
[0111] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.
[0112] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.
Claims
1. A method for preparing a buffer layer for silicon carbide peeling, characterized in that: include: forming a graphene layer on a surface of a substrate; Under a first temperature condition, forming a first silicon carbide buffer layer on the surface of the graphene layer; Under a second temperature condition, forming a second silicon carbide buffer layer on the first silicon carbide buffer layer; forming a third silicon carbide buffer layer on the second silicon carbide buffer layer under a third temperature condition; The first temperature is lower than the second temperature, the second temperature is lower than the third temperature, and the graphene layer, the first silicon carbide buffer layer, the second silicon carbide buffer layer and the third silicon carbide buffer layer together constitute the buffer layer.
2. The method for preparing a buffer layer for silicon carbide stripping according to claim 1, characterized in that: The first temperature is 1100° C.-1400° C.; The second temperature is 1300° C.-1500° C.; The third temperature is 1500°C-1700°C.
3. The method for preparing a buffer layer for silicon carbide stripping according to claim 1, characterized in that: Forming a first silicon carbide buffer layer on the surface of the graphene layer, comprising: Under the condition of a temperature of 1100° C. to 1300° C., an inert gas and a gas containing silicon atoms are introduced and maintained for a first preset time to form a first silicon-enriched layer; Under the condition of linearly increasing the temperature to 1200° C.-1400° C. at a rate of 60° C. / min-120° C. / min, a gas containing carbon atoms is introduced to form a first silicon carbide buffer layer at a first growth rate.
4. The method for preparing a buffer layer for silicon carbide stripping according to claim 3, characterized in that: The flow rate of the inert gas is 100 sccm-200 sccm; The flow rate of the gas containing silicon atoms is 1 sccm-20 sccm; The flow ratio of the gas containing carbon atoms to the gas containing silicon atoms is (2-4):5; The first preset time is 1s-120s; The first growth rate is 0.5 μm / h-2 μm / h; The growth thickness of the first silicon carbide buffer layer is 0.5 μm-1 μm.
5. The method for preparing a buffer layer for silicon carbide stripping according to claim 1, characterized in that: Before the step of forming a second silicon carbide buffer layer on the first silicon carbide buffer layer, the method further includes: In-situ etching of the surface of the first silicon carbide buffer layer using hydrogen; Among them, the hydrogen flow rate is 1L / min-10L / min, and the etching time is 0.5min-5min.
6. The method for preparing a buffer layer for silicon carbide stripping according to claim 1, characterized in that: Forming a second silicon carbide buffer layer on the first silicon carbide buffer layer, comprising: Under the condition of a temperature of 1300° C. to 1500° C., introducing an inert gas and a gas containing silicon atoms and maintaining the temperature for a second preset time to form a second silicon-enriched layer; A gas containing carbon atoms is introduced, and the flow ratio of the gas containing carbon atoms to the gas containing silicon atoms is controlled to be (3-6):10, so as to form a second silicon carbide buffer layer at a second growth rate.
7. The method for preparing a buffer layer for silicon carbide stripping according to claim 6, characterized in that: The flow rate of the inert gas is 200 sccm-500 sccm; The flow rate of the gas containing silicon atoms is 1 sccm-20 sccm; The second preset time is 1s-60s; The second growth rate is 1 μm / h-2 μm / h; The second silicon carbide buffer layer has a growth thickness of 0.5 μm-1 μm.
8. The method for preparing a buffer layer for silicon carbide stripping according to claim 6, characterized in that: Forming a third silicon carbide buffer layer on the second silicon carbide buffer layer, comprising: Under the condition of linearly increasing the temperature to 1500°C-1700°C at a rate of 60°C / min-120°C / min, the flow ratio of the gas containing carbon atoms to the gas containing silicon atoms is controlled to be (1-2):1, and a third silicon carbide buffer layer is formed at a third growth rate.
9. The method for preparing a buffer layer for silicon carbide stripping according to claim 8, characterized in that: The third growth rate is 2 μm / h-5 μm / h; The growth thickness of the third silicon carbide buffer layer is 1 μm-3 μm.
10. The method for preparing a buffer layer for silicon carbide stripping according to claim 1, characterized in that: A graphene layer is formed on the surface of the substrate by epitaxial growth or chemical vapor deposition.
11. The method for preparing a buffer layer for silicon carbide stripping according to claim 10, characterized in that: The substrate is a silicon carbide substrate; Forming a graphene layer on the surface of the substrate by an epitaxial growth method, comprising: Under vacuum conditions, the pressure is controlled at 100 mbar-200 mbar, the temperature is between 1400°C-1600°C, and the reaction gas hydrogen is introduced at a flow rate of 50 L / min-100 L / min for 30 min-90 min to form a multi-layer graphene layer on the surface of the silicon carbide substrate.
12. A buffer layer structure for silicon carbide stripping, formed between a substrate and a silicon carbide epitaxial functional layer, characterized in that: It comprises a graphene layer, a first silicon carbide layer, a second silicon carbide layer and a third silicon carbide layer which are stacked in sequence in a direction away from a substrate, wherein the first silicon carbide layer, the second silicon carbide layer and the third silicon carbide layer are configured to be formed under different temperature conditions.
13. The buffer layer structure for silicon carbide stripping according to claim 12, characterized in that: The growth temperature of the first silicon carbide layer is lower than the growth temperature of the second silicon carbide layer, and the growth temperature of the second silicon carbide layer is lower than the growth temperature of the third silicon carbide layer; and / or, The growth temperature of the first silicon carbide layer is 1100° C.-1400° C.; the growth temperature of the second silicon carbide layer is 1300° C.-1500° C.; the growth temperature of the first silicon carbide layer is 1500° C.-1700° C.; and / or, The number of graphene layers is 4-20; and / or, The thickness of the first silicon carbide layer is 0.5 μm-1 μm; and / or, The thickness of the second silicon carbide layer is 0.5 μm-1 μm; and / or, The thickness of the third silicon carbide layer is 1 μm-3 μm.