A method for transferring a compound semiconductor device layer on a sapphire substrate
Patent Information
- Application Number
- CN202610948159.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-29
- Publication Date
- 2026-11-03
AI Technical Summary
In existing sapphire substrate compound semiconductor device layer transfer technologies, insufficient device protection, difficulty in substrate separation, and difficulty in device transfer lead to limitations in yield and device performance.
By optimizing the temporary bonding process and using specific bonding media and structures, stress buffer and chemical protection layers are constructed on the surface of GaN devices. Combined with high-precision sapphire thinning technology, the remaining thickness of sapphire is precisely controlled, ensuring the controllability and flexibility of the transfer process.
It achieves comprehensive device protection, improves transfer yield, reduces the difficulty of main stripping, expands the process window, and obtains GaN devices with high crystal quality and low residual stress, which are suitable for mass production.
Smart Images
Figure CN123035781A_ABST
Abstract
Description
Technical Field
[0001] This application relates to a method for transferring compound semiconductor device layers on a sapphire substrate, belonging to the field of semiconductor device manufacturing technology. Background Technology
[0002] Sapphire substrates are the mainstream substrates for the epitaxial growth of gallium nitride (GaN)-based devices due to their excellent lattice matching and high-temperature stability. However, the low thermal conductivity of sapphire limits the heat dissipation performance of devices under high power, and its insulating properties also hinder the fabrication of vertical structure devices. Therefore, removing the sapphire substrate and transferring the GaN device onto a new substrate using layer transfer technology has become a key technical means to improve device performance and expand its application range.
[0003] Currently, mainstream layer transfer processes typically include device fabrication, temporary bonding, sapphire substrate thinning, and substrate separation (laser lift-off or dry etching). However, existing technologies still have many shortcomings in these key stages. For example, the support and protection of temporary bonding are insufficient. The main purpose of temporary bonding is to fix the wafer with the device onto a rigid carrier to provide mechanical support for subsequent processing. However, existing temporary bonding processes often only focus on the bonding strength, neglecting the protective function of the bonding medium on the device surface. During subsequent thinning, etching, or laser lift-off, mechanical stress, thermal shock, and chemical environments can easily penetrate the bonding layer and be transmitted to the device surface, causing damage to the device structure and even inducing microcracks in the GaN epitaxial layer, seriously affecting the yield and reliability of the final device. Another example is the trade-off between precision and efficiency in sapphire thinning. Sapphire substrates are typically quite thick (hundreds of micrometers). Direct laser lift-off or dry etching is not only inefficient, but the high-energy laser or prolonged plasma bombardment can easily damage the GaN device layer. While existing technologies attempt to thin sapphire through mechanical grinding, the extremely high hardness of sapphire makes it difficult to precisely control the thickness uniformity (TTV) after thinning using traditional grinding processes. Uneven thickness not only affects the focusing accuracy during subsequent laser lift-off, leading to unstable lift-off energy and severe interface residue, but can also damage the device due to localized over-etching during dry etching.
[0004] In summary, how to achieve efficient substrate separation while providing comprehensive protection for the fragile GaN device layers and ensuring the controllability and flexibility of the transfer process is a pressing problem to be solved in the current layer transfer technology field. Summary of the Invention
[0005] To address the limitations in layer transfer yield and device performance caused by insufficient device protection, difficult substrate separation, and challenging device transfer in existing technologies for sapphire substrate compound semiconductor device layer transfer, this application provides a technical solution for sapphire substrate compound semiconductor device layer transfer. By optimizing the temporary bonding process and employing specific bonding media and structures, an effective stress buffer and chemical protection layer is constructed on the GaN device surface while firmly supporting the wafer. Combined with high-precision sapphire thinning technology, the remaining thickness of the sapphire is precisely controlled, creating favorable conditions for subsequent separation processes.
[0006] The technical solution adopted in this application is as follows: According to a first aspect of this application, a method for transferring a compound semiconductor device layer on a sapphire substrate is provided, comprising: A GaN-based device with a sapphire substrate and a carrier are provided. The surface of the device on the sapphire substrate is aligned and bonded to the carrier, with bonding adhesive between them. Under vacuum conditions, pressure is applied to the bonded GaN-based device and the carrier to remove air bubbles from the bonding adhesive and make the two tightly bonded. The bonding adhesive is then cured to complete the temporary bonding and form a bonding sheet. The sapphire substrate is thinned; Remove the thinned sapphire substrate; Transfer GaN-based devices onto the target substrate.
[0007] Optionally, the bonding is a permanent bonding or a temporary bonding; when the bonding is a permanent bonding, the bonding adhesive is a permanent bonding adhesive. When the bonding is temporary bonding, the bonding adhesive is temporary bonding adhesive; Optionally, the bonding adhesive pack is selected from at least one of photocurable adhesives, thermocurable adhesives, photoresists, room temperature curing adhesives, anti-tack adhesives, photo-anti-tack adhesives, thermo-anti-tack adhesives, or thermo-photocurable anti-tack adhesives.
[0008] Optionally, curing the bonding adhesive to complete the temporary bonding includes curing by ultraviolet light irradiation, heating, or standing at room temperature.
[0009] Optionally, the conditions for curing by ultraviolet light irradiation include: the wavelength of the ultraviolet light is 200-400 nm, the intensity is 100-10000 mW / cm², and the irradiation time is 10-1000 s.
[0010] Optionally, the conditions for curing by heating include: a heating temperature of 10-500℃ and a heating time of 10-1000 s.
[0011] Optionally, the pressurization conditions include: a pressurization pressure of 10-1000 g / cm², and a pressurization time of 10-600 s.
[0012] Optionally, the vacuum conditions for removing air bubbles from the bonding adhesive include a vacuum level in the range of 1-1000 Pa.
[0013] Optionally, the thickness of the cured bonding adhesive is 1-50 μm.
[0014] Optionally, the material of the carrier is selected from at least one of silicon, glass, quartz, silicate, borosilicate, sapphire, plastic, lithium niobate, lithium tantalate, silicon carbide, gallium nitride, gallium oxide, gallium arsenide, indium phosphide, and gallium antimonide.
[0015] Optionally, the dimensions of the sapphire substrate and the wafer are independently selected from one of 2 inches, 4 inches, 6 inches, 8 inches, and 12 inches.
[0016] Optionally, the removal of the thinned sapphire substrate includes: removing the thinned sapphire substrate by laser lift-off (LLO) or dry back etching process.
[0017] Optionally, the conditions for laser ablation include: a laser energy density of 300-900 mJ / cm². 2 The laser irradiates the sapphire substrate from the side away from the carrier. The laser decomposes GaN at the interface between GaN and the sapphire substrate, generating N2 bubbles, which causes the entire sapphire sheet to fall off.
[0018] Optionally, the conditions for dry back etching include: the etching gas can be a mixture of SF6 / CF4 and Ar, a mixture of BCl3 and Ar / Cl2, or a mixture of CHF3 and Ar; the etching rate is 10-300 nm / min; and etching is stopped when the GaN device layer is reached.
[0019] Optionally, the thinning of the sapphire substrate includes: The sapphire substrate is coarsely thinned to a predetermined thickness; The coarsely thinned sapphire substrate is then finely thinned to the target thickness.
[0020] Optionally, the target thickness is 5-300 μm, and the difference between the preset thickness and the target thickness is 1-100 μm.
[0021] Optionally, the conditions for coarse thinning include: using a 200-1000 mesh grinding wheel and a thinning rate of 30-300 μm / min.
[0022] Optionally, the conditions for fine thinning include: using a 1000-30000 mesh grinding wheel and a thinning rate of 1-60 μm / min.
[0023] The beneficial effects of this application include: (1) Comprehensive device protection and improved transfer yield: This application constructs a bonding structure with both support and buffer functions through bonding process. The bonding layer and the substrate not only provide support for the fragile GaN device layer to prevent it from fragmenting or warping in subsequent processes, but also effectively absorb and buffer the mechanical stress during the thinning process and the thermal shock stress during the laser lift-off process, avoiding microcracks or lattice damage to the GaN device layer.
[0024] (2) Reduce the difficulty of main stripping and expand the process window: This application adopts precision thinning / planing technology to significantly reduce the thickness of the sapphire substrate to the tens of micrometers level while ensuring excellent thickness uniformity. On the one hand, it significantly reduces the energy density threshold required for subsequent laser stripping, enabling separation under gentler laser parameters and effectively avoiding thermal damage to the GaN device layer caused by high-energy lasers; on the other hand, if a dry back etching process is used, the etching time is shortened to a fraction of the original process, greatly improving equipment utilization, reducing production costs, and reducing the potential damage to the device caused by long-term plasma bombardment.
[0025] (3) Excellent overall performance, suitable for mass production: Through the above synergistic effect, this application realizes efficient and non-destructive transfer of GaN device layers on sapphire substrates. The GaN devices obtained have the characteristics of high crystal quality and low residual stress. Based on this, the vertical structure devices have better heat dissipation performance, lower leakage current, and higher reliability. At the same time, this method has strong process compatibility, especially suitable for large-size (6 inches and above) wafer-level transfer, and has good industrialization promotion value. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the process flow for transferring the compound semiconductor device layer on the sapphire substrate in this application. Detailed Implementation
[0027] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0028] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0029] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0030] Existing techniques for transferring GaN device layers from a sapphire substrate to a new substrate after removing the sapphire substrate suffer from insufficient device protection, difficulty in substrate separation, and significant challenges in device transfer. This application provides an improved method for transferring compound semiconductor device layers from a sapphire substrate. This method optimizes the bonding process, employs specific bonding media and structures, and while firmly supporting the wafer, constructs an effective stress buffer and chemical protection layer on the GaN device surface. Combined with high-precision sapphire thinning technology, the remaining sapphire thickness is precisely controlled, creating optimal conditions for subsequent separation processes and significantly improving layer transfer yield and device performance. The technical improvements of this application compared to existing technologies, addressing some typical technical problems, are as follows: (1) Insufficient support and protection of bonding: Existing bonding processes often only focus on the strength of the bond, ignoring the protective function of the bonding medium on the device surface. In subsequent thinning, etching or laser lift-off processes, mechanical stress, thermal shock and chemical environment can easily be transmitted to the device surface through the bonding layer, causing damage to the device structure and even causing microcracks in the GaN epitaxial layer, which seriously affects the yield and reliability of the final device.
[0031] To address this issue, this application employs bonding technology, using bonding adhesive to bond silicon wafers to carrier wafers, resulting in bonded wafers with high flatness and good bonding stability. The bonding adhesive layer not only provides high bonding strength but also protects the device.
[0032] (2) Sapphire Thinning Challenges and Industry Technical Bias: In the field of substrate transfer for Micro-LEDs and third-generation semiconductors, the industry has long been constrained by a path-dependent mindset regarding high-hardness sapphire substrates. Existing technical routes are generally trapped in a binary inertia of "either / or": either directly use laser lift-off (LLO) technology to "hard-lift" sapphire hundreds of micrometers thick, or directly switch to dry back etching for full-thickness removal. Behind this technical inertia lies a profound technical bias: the industry generally believes that sapphire is extremely hard, and performing "bonding + ultra-precision thinning" before lift-off or etching is redundant or even a high-risk step that is prone to breakage. The mainstream view is that precision thinning is difficult to achieve while maintaining extremely low total thickness deviation (TTV), and the mechanical stress generated during the thinning process is very likely to cause damage to the GaN device layer; in contrast, although high-energy laser lift-off or simple long-term plasma etching is inefficient and has a high risk of damage, it is regarded as the "standard process" and is widely accepted. In addition, although a few attempts have been made to introduce a grinding step before dry etching, these have only reached the rough grinding stage. The precise control technology to thin sapphire to the tens of micrometer level has not been mastered, so the process window cannot be fundamentally changed.
[0033] To address this issue, this application innovatively proposes an ultra-precision thinning process based on temporary bonding supports for sapphire thinning. This process allows for precise control of the remaining sapphire thickness, significantly reducing the sapphire substrate thickness to the tens of micrometers level while ensuring excellent thickness uniformity. Obtaining a thinner sapphire layer with good thickness uniformity effectively improves the efficiency of subsequent processes (laser lift-off or dry etching): on the one hand, it significantly reduces the energy density threshold required for subsequent laser lift-off, enabling separation under gentler laser parameters and effectively avoiding thermal damage to the GaN layer from high-energy lasers; on the other hand, if a dry back-etching process is used, the etching time is shortened to a fraction of the original process, significantly improving equipment utilization, reducing production costs, and minimizing potential damage to the device from prolonged plasma bombardment.
[0034] According to one embodiment of this application, a method for transferring a compound semiconductor device layer on a sapphire substrate, the process flow is as follows: Figure 1 As shown, it includes: A GaN-based device with a sapphire substrate and a carrier are provided. The surface of the device on the sapphire substrate is aligned and bonded to the carrier, with bonding adhesive between them. Under vacuum conditions, pressure is applied to the bonded GaN-based device and the carrier to remove air bubbles from the bonding adhesive and make the two tightly bonded. The bonding adhesive is then cured to complete the temporary bonding and form a bonding sheet. The sapphire substrate is thinned; Remove the thinned sapphire substrate; Transfer GaN-based devices onto the target substrate.
[0035] In one embodiment, the bonding adhesive is coated on the device side surface of the sapphire substrate and / or the wafer side surface.
[0036] In one embodiment, the bonding is either a permanent bonding or a temporary bonding; when the bonding is a permanent bonding, the bonding adhesive is a permanent bonding adhesive. When the bonding is temporary, the bonding adhesive is also temporary. After the bonding is completed, the substrate and bonding adhesive can be removed through the debonding process.
[0037] In one embodiment, the bonding adhesive pack is selected from at least one of room temperature curing adhesives, light-curing adhesives, thermosetting adhesives, photoresists, anti-tack adhesives, light-curing anti-tack adhesives, heat-curing anti-tack adhesives, or thermo-light dual-curing anti-tack adhesives. In one embodiment, curing the bonding adhesive to complete the temporary bonding includes curing by ultraviolet light irradiation, heating, or standing at room temperature.
[0038] In one embodiment, the conditions for curing by ultraviolet light irradiation include: the wavelength of the ultraviolet light is 200-400 nm, the intensity is 100-10000 mW / cm², and the irradiation time is 10-1000 s.
[0039] In one embodiment, the conditions for curing by heating include: a heating temperature of 10-500°C and a heating time of 10-1000 s.
[0040] In one embodiment, the step further includes: debonding the bonding sheet to remove the carrier, thereby obtaining a substrate-free GaN-based device; The process of debonding the bonded sheet to remove the carrier includes: debonding by ultraviolet light irradiation or debonding by heating.
[0041] Preferably, the conditions for debonding by ultraviolet light irradiation include: the wavelength of the ultraviolet light is 200-400 nm, the intensity is 100-10000 mW / cm², and the irradiation time is 10-1000 s.
[0042] Preferably, the conditions for debonding by heating at a second temperature include: a heating temperature of 10-500°C and a heating time of 10-1000 s.
[0043] In one embodiment, bonding the device-side surface of the sapphire substrate to the carrier wafer using bonding adhesive includes: A bonding adhesive is uniformly applied to the surface of the carrier and / or the device side surface of the sapphire substrate. The carrier and the sapphire substrate are then bonded together, with the bonding adhesive positioned between them. Pressure is then applied to ensure that the sapphire substrate and the sapphire substrate are tightly bonded together.
[0044] In one embodiment, the pressurization conditions include: a pressurization pressure of 10-1000 g / cm² and a pressurization time of 10-600 s.
[0045] In one embodiment, the vacuum conditions for the process of removing air bubbles from the bonding adhesive include a vacuum degree ranging from 1 to 1000 Pa.
[0046] In one embodiment, the thickness of the cured bonding adhesive is 1-50 μm.
[0047] In one embodiment, the material of the carrier is selected from at least one of silicon, glass, quartz, silicate, borosilicate, sapphire, and plastic.
[0048] In one embodiment, the dimensions of the sapphire substrate and the wafer are independently selected from one of 2 inches, 4 inches, 6 inches, 8 inches, and 12 inches.
[0049] In one embodiment, the removal of the thinned sapphire substrate includes: removing the thinned sapphire substrate by laser lift-off or dry back etching process.
[0050] In one embodiment, the conditions for laser ablation include: a laser energy density of 300-900 mJ / cm². 2 The laser irradiates the sapphire substrate from the side away from the carrier. The laser decomposes GaN at the interface between GaN and the sapphire substrate, generating N2 bubbles, which causes the entire sapphire sheet to fall off.
[0051] In one embodiment, the dry back etching conditions include: the etching gas is a mixture of SF6 / CF4 and Ar, a mixture of BCl3 and Ar / Cl2, or a mixture of CHF3 and Ar; the etching rate is 10-300 nm / min; and etching is stopped when the GaN device layer is reached.
[0052] In one embodiment, the thinning of the sapphire substrate includes: The sapphire substrate is coarsely thinned to a predetermined thickness; The coarsely thinned sapphire substrate is then finely thinned to the target thickness.
[0053] In one embodiment, the target thickness is 5-300 μm, and the difference between the preset thickness and the target thickness is 1-100 μm.
[0054] In one embodiment, the conditions for coarse thinning include: using a 200-1000 mesh grinding wheel and a thinning rate of 30-300 μm / min.
[0055] In one embodiment, the conditions for fine thinning include: using a 1000-30000 grit grinding wheel and a thinning rate of 1-60 μm / min.
[0056] In one embodiment, transferring the GaN-based device onto the target substrate includes: after removing the sapphire substrate, the GaN-based device layer rests on a carrier wafer, thereby transferring the GaN-based device layer to the target substrate. Subsequently, the GaN-based device layer can be stored on the target substrate as needed, or it can be released from the target substrate through debonding.
[0057] In one embodiment, the method for transferring a compound semiconductor device layer onto a sapphire substrate includes: Step 1: Temporarily bond the sapphire crystal with GaN-based devices to a carrier to obtain a bonded sheet with good flatness and bonding stability. The specific steps are as follows: uniformly cover the device layer surface of the sapphire crystal with GaN-based devices or one side surface of the carrier with bonding adhesive; adhere the device layer surface of the sapphire crystal to the carrier surface, with the bonding adhesive between them; apply pressure to make the two adhere tightly, and remove air bubbles from the bonding adhesive by vacuuming; use ultraviolet light source irradiation or heating to cure the bonding adhesive and complete the bonding reaction.
[0058] The bonding adhesive is selected from at least one of the following: room temperature curing adhesive, UV curing adhesive, thermosetting adhesive, photoresist, anti-tack adhesive, photosensitive anti-tack adhesive, thermosensitive anti-tack adhesive, or thermo-photosensitive dual-curing anti-tack adhesive. The curing conditions for the bonding adhesive are ultraviolet light irradiation or heating; the pressure range is 10-1000 g / cm³. 2 The pressurization time is 10-600 s; the wavelength range of the ultraviolet light source is 200-400 nm, and the light source intensity is 100-10000 mW / cm². 2 The irradiation time is 10-1000 s; the heating temperature range is 10-500℃, and the heating time is 10-1000 s; the thickness of the bonded adhesive after curing is 1-50 μm.
[0059] Step 2: Perform precision thinning of the sapphire substrate to the target thickness. This precision thinning includes a coarse thinning step and a fine thinning step. Specifically, the silicon wafer is first reduced to a thickness 20 μm thicker than the target thickness using coarse thinning, and then reduced to the target thickness using fine thinning. The target thickness is 5-300 μm. The coarse thinning rate is 30-300 μm / min, and the fine thinning rate is 1-60 μm / min.
[0060] Step 3: The substrate is removed by laser lift-off or dry back etching. The laser lift-off step is as follows: the laser irradiates the back of the sapphire, and the laser decomposes GaN at the GaN / sapphire interface to generate N2 bubbles, so that the entire sapphire sheet is removed. The dry back etching process involves selecting a suitable etching gas to selectively etch sapphire without etching GaN, stopping the etching process when the GaN layer is reached. Examples of etching gases include SF6 / CF4+Ar; a mixture of BCl3+Ar / Cl2; or a mixture of CHF3+Ar. The etching rate is 10-300 nm / min.
[0061] In one embodiment, after removing the sapphire substrate, a corresponding debonding method is selected based on the type of bonding adhesive to remove the carrier and release the GaN device. The debonding method includes ultraviolet light irradiation or heating, wherein the wavelength range of the ultraviolet light source is 200-400 nm, and the light source intensity is 100-10000 mW / cm². 2 The irradiation time is 10-1000 s; the heating temperature range is 10-500℃, and the heating time is 10-1000 s.
[0062] Reference Figure 1 The process will be illustrated with specific examples, as follows: Example 1 Step 1: Temporary bonding Uniformly coat the upper surface of the silicon substrate with UV-curable adhesive; bond the surface of the sapphire device layer with GaN-based devices to the substrate surface, with the UV-curable adhesive positioned between them; apply pressure (100 g / cm²). 2 The two materials were pressed together for 60 seconds to ensure a tight bond. A vacuum was then applied to remove air bubbles from the bonding adhesive. The bonding adhesive was then irradiated with a 365 nm wavelength ultraviolet light source to perform a photocuring reaction and complete the bonding process. The thickness of the bonded adhesive after curing was 10 μm. This resulted in a bonded sheet with good flatness and bonding stability.
[0063] Step 2, Precision thinning The sapphire was coarsely reduced to a thickness of 120 μm using a thinning machine (speed 100 μm / min), and then finely reduced to 100 μm using a fine-tuning machine (speed 10 μm / min).
[0064] Step 3: Remove the substrate The substrate was removed using laser lift-off. A laser lift-off machine was used, with a laser wavelength of 248 nm and an energy density of 350 mJ / cm². 2 The laser is directed from the back of the sapphire crystal. The laser decomposes the GaN at the GaN / sapphire interface, generating N2 bubbles, which causes the entire sapphire crystal to detach.
[0065] Step 4: Transfer to the target substrate After the sapphire substrate is removed, the GaN-based device layer is transferred to the target substrate by resting on a new silicon wafer.
[0066] Example 2 Step 1: Temporary bonding The upper surface of the glass substrate is uniformly covered with heat-resistant adhesive; the surface of the sapphire device layer with GaN-based devices is bonded to the substrate surface, with the adhesive positioned between them; pressure is applied (pressure 200 g / cm). 2The two parts are pressed together for 100 seconds to ensure a tight bond. Vacuum is then applied to remove air bubbles from the bonding adhesive. The adhesive is heated to 120°C to cure and complete the bonding reaction. The thickness of the cured adhesive is 15 μm. This process yields a bonded sheet with good flatness and bonding stability.
[0067] Step 2, Precision thinning The silicon wafer is coarsely reduced to 70 μm thickness using a thinning machine (speed 150 μm / min), and then finely reduced to 50 μm thickness using a fine reduction machine (speed 2 μm / min); then the silicon wafer surface is planarized using chemical mechanical polishing.
[0068] Step 3: Remove the substrate The substrate was removed using a dry back etching method. An inductively coupled plasma (ICP) apparatus was used, with a mixture of SF6 / CF4 and Ar as the etching gas, and an etching rate of 100 nm / min.
[0069] Step 4: Transfer to the target substrate After the sapphire substrate is removed, the GaN-based device layer is transferred to the target substrate by resting on a new glass carrier.
[0070] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for transferring a compound semiconductor device layer onto a sapphire substrate, characterized in that, include: A GaN-based device with a sapphire substrate and a carrier are provided. The surface of the device on the sapphire substrate is aligned and bonded to the surface of the carrier, with bonding adhesive between them. Under vacuum conditions, the bonded GaN-based device and the carrier are pressurized to remove air bubbles in the bonding adhesive and make the two tightly bonded. The bonding adhesive is then cured to complete the bonding and form a bonded sheet. The sapphire substrate is thinned; Remove the thinned sapphire substrate; Transfer GaN-based devices onto the target substrate.
2. The method according to claim 1, characterized in that, The bonding can be a permanent bonding or a temporary bonding; When the bonding is a permanent bonding, the bonding adhesive is a permanent bonding adhesive; When the bonding is temporary bonding, the bonding adhesive is temporary bonding adhesive; Preferably, the bonding adhesive pack is selected from at least one of photocurable adhesive, thermocurable adhesive, photoresist, room temperature curing adhesive, anti-tack adhesive, photo-anti-tack adhesive, thermo-anti-tack adhesive, or thermo-photocurable anti-tack adhesive.
3. The method according to claim 1, characterized in that, The process of curing the bonding adhesive to complete the bonding includes: curing by ultraviolet light irradiation, heating, or standing at room temperature.
4. The method according to claim 3, characterized in that, The conditions for curing by ultraviolet light irradiation include: the wavelength of the ultraviolet light is 200-400 nm, the intensity is 100-10000 mW / cm², and the irradiation time is 10-1000 s.
5. The method according to claim 3, characterized in that, The conditions for curing by heating include: a heating temperature of 10-500℃ and a heating time of 10-1000 s.
6. The method according to claim 5, characterized in that, The pressurization conditions include: a pressurization pressure of 10-1000 g / cm², and a pressurization time of 10-600 s.
7. The method according to claim 1, characterized in that, The vacuum conditions for the process of removing air bubbles from the bonding adhesive include a vacuum degree ranging from 1 to 1000 Pa.
8. The method according to claim 1, characterized in that, The thickness of the cured bonding adhesive is 1-50 μm; Preferably, the material of the carrier is selected from at least one of silicon, glass, quartz, silicate, borosilicate, sapphire, plastic, lithium niobate, lithium tantalate, silicon carbide, gallium nitride, gallium oxide, gallium arsenide, indium phosphide, and gallium antimonide; Preferably, the dimensions of the sapphire substrate and the carrier are independently selected from one of 2 inches, 4 inches, 6 inches, 8 inches, and 12 inches.
9. The method according to claim 1, characterized in that, The removal of the thinned sapphire substrate includes: removing the thinned sapphire substrate by laser lift-off or dry back etching process; Preferably, the conditions for laser ablation include: a laser energy density of 300-900 mJ / cm². 2 The laser irradiates the sapphire substrate from the side away from the carrier, and the laser decomposes GaN at the interface between GaN and sapphire substrate to generate N2 bubbles, causing the entire sapphire sheet to fall off. Preferably, the conditions for dry back etching include: the etching gas is a mixture of SF6 / CF4 and Ar, a mixture of BCl3 and Ar / Cl2, or a mixture of CHF3 and Ar; the etching rate is 10-300 nm / min; and etching is stopped when the GaN device layer is reached.
10. The method according to claim 1, characterized in that, The thinning of the sapphire substrate includes: The sapphire substrate is coarsely thinned to a predetermined thickness; The coarsely thinned sapphire substrate is then finely thinned to the target thickness. Preferably, the target thickness is 5-300 μm, and the difference between the preset thickness and the target thickness is 1-100 μm; Preferably, the conditions for coarse thinning include: using a 200-1000 mesh grinding wheel and a thinning rate of 30-300 μm / min; Preferably, the conditions for fine thinning include: using a 1000-30000 grit grinding wheel and a thinning rate of 1-60 μm / min.