Recycling method of silicon-based gallium nitride wafer

Abstract

The invention provides a recovery method of a silicon-based gallium nitride wafer, and relates to the technical field of semiconductor manufacturing, the recovery method aims at the silicon-based gallium nitride wafer comprising a silicon substrate and a gallium nitride-based epitaxial layer arranged on the silicon substrate, and the recovery method comprises the following steps: using an infrared laser beam to scan the silicon-based gallium nitride wafer through a preset laser scanning path strategy; incident light enters the silicon-based gallium nitride wafer from one side of the gallium nitride-based epitaxial layer, so that the gallium nitride-based epitaxial layer is separated from the silicon substrate; and stripping the gallium nitride-based epitaxial layer. And by utilizing the characteristic difference that the gallium nitride-based epitaxial layer is transparent to infrared laser and the silicon substrate strongly absorbs the infrared laser, laser energy accurately acts on the interface of the gallium nitride-based epitaxial layer and the silicon substrate, so that high-efficiency and low-damage separation is realized. The defects that a traditional etching technology is high in cost and heavy in pollution and the substrate is prone to being damaged are overcome, and a brand-new and effective technical path is provided for low-cost and green recovery of the silicon substrate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for recycling silicon-based gallium nitride wafers. Background Technology

[0002] Gallium nitride (GaN), as a core material of third-generation wide-bandgap semiconductors, exhibits unparalleled advantages over traditional silicon (Si) materials in high-frequency, high-voltage, and high-power electronic devices due to its superior physical properties. Among these advancements, the epitaxial growth of gallium nitride on low-cost, large-size silicon substrates—GaN-on-Si technology—has become a key pathway for promoting industrialization in fields such as radio frequency communication and power electronics.

[0003] During the large-scale production of GaN epitaxial layers, a certain proportion of scrap wafers is inevitably generated due to factors such as process fluctuations, equipment conditions, and operational errors. These wafers cannot enter the subsequent device manufacturing process due to surface morphology defects or substandard electrical parameters. Considering that silicon substrates account for a significant proportion of the overall cost of epitaxial wafers, effectively recycling the silicon substrates from these scrap wafers will significantly reduce production costs and have significant economic value for the entire industry.

[0004] Currently, the mainstream technical solutions for recycling silicon substrates are mainly divided into two categories: dry etching and wet etching.

[0005] Dry etching typically employs plasma-enhanced etching (ICP), using reactive gases such as chlorine to remove the epitaxial layer. While this method offers controllable etching rates, it suffers from significant equipment investment, high energy consumption, and extremely high process costs, making it uneconomical for recycling processes aimed at cost reduction. Furthermore, the consumption of toxic gases and the complex exhaust gas treatment systems pose serious environmental and safety challenges.

[0006] Wet etching typically uses hot, strong acid or alkali solutions to etch the GaN epitaxial layer. This method is relatively low-cost, but its fatal flaw lies in its extremely slow etching rate and poor selectivity. While removing GaN, it easily causes irreversible corrosion damage and surface quality deterioration to the silicon substrate itself, making it difficult for the separated substrate to meet the stringent standards for re-epitaxy growth through simple processing.

[0007] In recent years, laser lift-off (LLO) technology, as a highly efficient material separation method, has been applied in the semiconductor field, especially in the manufacture of GaN-based LEDs on sapphire substrates, where it has become very mature. Its core principle is based on the transparency of the sapphire substrate to specific wavelengths of ultraviolet (UV) laser light, while the GaN epitaxial layer strongly absorbs this laser energy. Therefore, by incident from the back of the transparent sapphire substrate, the laser energy is precisely released at the interface between GaN and sapphire, causing the GaN layer at the interface to decompose, thereby achieving the separation of the epitaxial layer from the substrate.

[0008] However, the aforementioned mature LLO technology solutions rely on a key premise—the substrate must be transparent to the laser used. For gallium nitride silicon wafers, the silicon substrate itself is opaque to lasers covering the ultraviolet to visible light bands, which makes the traditional LLO technology route, which involves laser light incident from the back of the substrate, theoretically unsuitable for the recycling of silicon substrates.

[0009] Therefore, it is necessary to improve the existing technology for removing the epitaxial layer of silicon-based gallium nitride wafers in order to overcome the shortcomings of the existing technology. Summary of the Invention

[0010] To overcome the problems existing in related technologies, the purpose of this invention is to provide a method for recycling silicon-based gallium nitride wafers. This method uses an infrared laser beam to scan, separate, and peel off the gallium nitride-based epitaxial layer from one side. This overcomes the problems of high cost, heavy pollution, and substrate damage in traditional etching methods, which make it difficult to achieve high-quality recycling, as well as the limitations of existing laser peeling technology, which relies on transparent substrates and is not applicable to silicon-based gallium nitride wafers.

[0011] A method for recycling a silicon-based gallium nitride (GaN) wafer, the GaN wafer comprising a silicon substrate and a GaN-based epitaxial layer disposed on the silicon substrate, the method comprising the following steps:

[0012] Using an infrared laser beam, and following a preset laser scanning path strategy, the laser beam is incident from one side of the gallium nitride-based epitaxial layer onto the silicon-based gallium nitride wafer, thereby separating the gallium nitride-based epitaxial layer from the silicon substrate.

[0013] The gallium nitride-based epitaxial layer is stripped away.

[0014] Furthermore, the laser scanning path strategy includes one of the following modes:

[0015] A global scan mode is used to remove the entire gallium nitride-based epitaxial layer on the silicon-based gallium nitride wafer in one go.

[0016] A selective scanning mode is used to remove the gallium nitride-based epitaxial layer in a predetermined defect region on the silicon-based gallium nitride wafer.

[0017] Global scanning mode is suitable for rapid, batch recycling of entire scrapped wafers to maximize cost savings; while selective scanning mode can precisely repair high-value wafers with only local defects, thereby saving wafers and preventing them from being discarded as a whole, significantly improving production yield and economic benefits.

[0018] Furthermore, the global scanning mode includes:

[0019] Define a scan area covering the entire surface of the gallium nitride-based epitaxial layer;

[0020] Within the scanning area, continuous surface scanning is performed in a pattern-filling manner to separate the entire gallium nitride-based epitaxial layer from the silicon substrate.

[0021] The workflow employing a "defined full-coverage area" and "pattern-filling surface scanning" ensures that laser energy uniformly and comprehensively covers the entire epitaxial layer surface when processing the entire wafer. This systematic scanning method guarantees the uniformity and consistency of separation, avoiding the problem of incomplete separation in local areas, and provides an efficient and repeatable implementation plan for large-scale, automated, and highly reliable silicon substrate recycling.

[0022] Furthermore, the selective scanning mode includes:

[0023] Identify the predetermined defect region on the silicon-based gallium nitride wafer;

[0024] A first laser scan is performed along the boundary of the predetermined defect region to cut the gallium nitride-based epitaxial layer and form an isolation trench extending into the silicon substrate;

[0025] A second laser scan is performed within the region defined by the isolation trench to separate the gallium nitride-based epitaxial layer from the silicon substrate within that region.

[0026] By limiting the selective scanning mode to a two-step process of "first cutting the boundary to form an isolation trench, then separating the internal region," both high removal accuracy and effective protection of surrounding defect-free areas are achieved. The formed isolation trench effectively prevents the laser from causing thermal shock or mechanical damage to the healthy epitaxial layer outside the demarcated area, ensuring the precision and safety of the repair process. Local repair of high-value wafers maximizes the preservation of the wafer's usability.

[0027] Furthermore, after stripping the gallium nitride-based epitaxial layer, the process further includes performing a chemical mechanical polishing treatment on the surface of the silicon substrate to restore the silicon substrate to a state where epitaxial growth can be performed again.

[0028] The laser-treated silicon substrate is transformed from an intermediate product into a "regenerated product" with a flat surface, meeting quality standards, and ready for direct use in epitaxial growth, thus truly realizing the closed-loop recycling and value reconstruction of silicon substrates.

[0029] Furthermore, the stripping of the gallium nitride-based epitaxial layer specifically includes:

[0030] The separated gallium nitride-based epitaxial layer is detached from the silicon substrate using an adhesive tool.

[0031] Compared to hard mechanical tools that may cause scratches, adhesive tools can gently and evenly peel off the separated gallium nitride epitaxial layer from the silicon substrate surface, minimizing secondary damage to the valuable regenerated silicon substrate and ensuring the surface integrity of the recycled substrate.

[0032] Furthermore, in the first laser scan, the focal point of the infrared laser beam is set on the surface of the gallium nitride-based epitaxial layer;

[0033] In the second laser scan, the focal point of the infrared laser beam is located inside the silicon substrate and adjacent to the interface between the gallium nitride-based epitaxial layer and the silicon substrate.

[0034] The first scan focuses on the surface to concentrate energy for a clean cut, creating a clear isolation trench. The second scan focuses on the area near the substrate interface to maximize the excitation of the interface separation effect. This precise control of laser parameters, optimized for different purposes, significantly improves the success rate and final quality of local repairs.

[0035] Furthermore, the infrared laser beam is a pulsed laser, and the pulse width of the infrared laser beam is on the order of picoseconds or femtoseconds.

[0036] This method utilizes the unique "cold processing" characteristics of pulsed lasers. The extremely short pulse duration minimizes heat accumulation and thermal diffusion effects, significantly reducing the thermally affected area of ​​the silicon substrate. This results in less surface damage and lower roughness on the separated silicon substrate, improving the final quality of the regenerated substrate.

[0037] Furthermore, the adhesive tool is an adhesive tape or a heat-release adhesive tape.

[0038] The tackiness of heat-release tape can be precisely controlled by heating, making it easy to integrate into automated equipment, thus making the removal process of epitaxial layers more efficient, controllable, and clean.

[0039] Furthermore, the chemical mechanical polishing treatment results in a surface roughness of less than 0.5 nm for the silicon substrate.

[0040] The beneficial effects of this invention are as follows:

[0041] This invention provides a method for recycling gallium nitride (GaN) wafers on silicon. The method employs an infrared laser beam, incident from the GaN epitaxial layer side via a pre-defined laser scanning path strategy. Its core lies in utilizing the physical difference between the GaN epitaxial layer's near-transparency to the infrared laser and the silicon substrate's strong absorption of the laser energy. This allows the laser energy to penetrate the epitaxial layer and be precisely deposited at the interface, inducing a physical separation effect. This fundamentally overcomes the drawbacks of traditional dry / wet etching techniques, such as high cost, high pollution, low efficiency, and easy substrate damage. It also solves the fundamental problem that existing laser lift-off techniques, dependent on transparent substrates, are unsuitable for opaque silicon substrates. This provides a new and effective technical path for achieving rapid, low-damage, and green recycling of silicon substrates. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the silicon-based gallium nitride wafer involved in this application;

[0043] Figure 2 This is a schematic diagram illustrating the principle of how an infrared laser beam interacts with a silicon-based gallium nitride wafer to achieve interface separation in this application.

[0044] Figure 3 This is a schematic diagram of the laser scanning path strategy in this application;

[0045] Figure 4 This is a schematic diagram of the silicon substrate recycling method based on global scanning mode in this application;

[0046] Figure 5 This is a schematic diagram of the gallium nitride-based epitaxial layer local removal method based on selective scanning mode in this application.

[0047] Figure label:

[0048] 11. Undoped gallium nitride epitaxial layer structure; 12. High-power HEMT device epitaxial layer structure; 13. LED device epitaxial layer structure; 21. Infrared laser beam; 22. Gallium nitride-based epitaxial layer; 23. Interface separation effect region; 24. Silicon substrate; 31. Laser scanning path strategy; 41. Wafer cleaning step; 42. Laser separation and lift-off step; 43. Silicon substrate cleaning step; 44. Chemical mechanical polishing step; 45. Silicon substrate inspection step; 46. Epitaxial growth step on regenerated silicon substrate. Detailed Implementation

[0049] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0050] The core technology of the method for recycling silicon-based gallium nitride wafers disclosed in this application lies in utilizing the significant differences in the absorption characteristics of different material layers within the silicon-based gallium nitride wafer for specific wavelengths of laser light. For example... Figure 1 As shown, the silicon-based gallium nitride wafer includes a silicon substrate and a gallium nitride-based epitaxial layer disposed thereon. The present invention uses an infrared laser beam whose photon energy (e.g., ≤1.54 eV when the wavelength is ≥808 nm) is lower than the bandgap of the gallium nitride-based epitaxial layer (>3.4 eV), but higher than the bandgap of the silicon substrate (1.10 eV).

[0051] Therefore, as Figure 2 As shown, when the infrared laser beam is incident from one side of the gallium nitride-based epitaxial layer, the gallium nitride-based epitaxial layer is highly transparent to the laser beam, allowing the laser energy to penetrate almost without loss and be precisely projected onto the surface of the underlying silicon substrate. Due to intrinsic absorption, the silicon substrate strongly absorbs the laser energy, instantly generating a complex physical effect of plasma expansion, material melting and remelting in the interface region adjacent to the gallium nitride-based epitaxial layer, forming a localized explosive shock wave, thus creating submicron-sized gaps at the interface. Through a preset laser scanning path strategy, these tiny separation gaps are continuously and extensively connected, ultimately achieving physical separation between the gallium nitride-based epitaxial layer and the silicon substrate. Subsequently, the gallium nitride-based epitaxial layer can be peeled off using simple mechanical methods.

[0052] The infrared laser beam is preferably a pulsed laser with a pulse width on the order of picoseconds or femtoseconds. This ultrashort pulse laser has a "cold processing" characteristic, with an extremely short action time, which can confine the heat-affected zone (HAZ) to a very small area, effectively avoiding excessive thermal damage to the silicon substrate and thus ensuring the high quality of the recycled silicon substrate.

[0053] Example 1: Recycling gallium nitride silicon wafers that are rendered unusable due to physical scratches during transportation.

[0054] This embodiment provides a method for recycling silicon-based gallium nitride wafers, specifically corresponding to... Figure 4 The process is shown below.

[0055] The silicon-based gallium nitride wafer to be processed has the following structure: Figure 1As shown, the wafer consists of a silicon substrate with a (111) crystal orientation, a buffer layer, and an undoped gallium nitride (u-GaN) layer, in sequence. The silicon substrate has a thickness of 1000±25μm, the total thickness of the gallium nitride-based epitaxial layer is 5±0.5μm, and the wafer diameter is 2 inches. The wafer was scrapped due to physical scratches during transportation.

[0056] The specific steps of the recycling method are as follows:

[0057] S1, Wafer Cleaning:

[0058] Place the scrapped wafers in a two-fluid cleaning device and clean for 30 seconds, repeating 3 times to remove surface dust and large particulate contaminants. After cleaning, spin dry at 1000 RPM to avoid water residue.

[0059] S2, Laser separation of epitaxial layer:

[0060] This step uses global scan mode.

[0061] S21. Define a scanning area covering the entire surface of the gallium nitride-based epitaxial layer, specifically set as a circular area with a diameter of 51 mm to ensure complete coverage of the 2-inch wafer.

[0062] S22. Use an infrared picosecond laser (wavelength 1064nm, pulse width 20ps), set the average laser power to 1.2W, the pulse repetition frequency to 100KHz, and set the focus of the infrared laser beam inside the silicon substrate and near the interface between the gallium nitride-based epitaxial layer and the silicon substrate, specifically by setting the defocusing amount to -0.6mm.

[0063] S23, such as Figure 3 As shown, within the scanning area, continuous surface scanning is performed using a pattern-filling method. The scanning speed is set to 1700 mm / s, and the scanning spacing (i.e., the distance between adjacent scanning paths) is set to 0.017 mm. The laser beam performs a full scan of the wafer according to this laser scanning path strategy, thereby separating the entire gallium nitride-based epitaxial layer from the silicon substrate. The entire process takes less than 2 minutes.

[0064] S3. Stripping the gallium nitride-based epitaxial layer:

[0065] After laser processing, the separated gallium nitride-based epitaxial layer forms a thin film covering the silicon substrate. Using tools such as fine antistatic tweezers or adhesive tools (such as low-tack adhesive tape), the separated gallium nitride-based epitaxial layer is gently peeled off from the wafer edge and collected completely from the silicon substrate for subsequent gallium metal recovery.

[0066] S4 silicon substrate cleaning:

[0067] The silicon substrate after the epitaxial layer is stripped is then subjected to two-fluid cleaning to remove any tiny epitaxial layer fragments and sputtering particles that may remain on the surface due to laser action.

[0068] S5 chemical mechanical polishing:

[0069] The surface of the silicon substrate is subjected to chemical mechanical polishing (CMP). Using conventional silicon wafer polishing slurry and processes, the microscopic oxide layer and molten reconstituted layer left at the interface by laser action are removed. This CMP treatment results in a surface roughness of less than 0.5 nm for the silicon substrate, achieving a mirror-like finish suitable for further epitaxial growth.

[0070] S6 silicon substrate inspection and reuse:

[0071] After testing the roughness, flatness (TTV), thickness, and other key indicators of the polished silicon substrate, once it is confirmed to be qualified, it can be used as a recycled substrate in a new epitaxial growth process.

[0072] This embodiment addresses conventional gallium nitride (GaN) silicon wafers scrapped due to physical damage. Through a global scanning mode, it achieves complete removal of the epitaxial layer and recycling of the silicon substrate with extremely high efficiency (less than 2 minutes per wafer). This directly verifies the feasibility, efficiency, and completeness of the core technical solution of this invention, proving that this method can transform worthless scrap into high-value regenerated substrates that can be directly used for further epitaxial growth. This provides a direct and economical solution for scaling up the cost of GaN silicon wafer manufacturing.

[0073] Example 2: Recycling of silicon-based gallium nitride wafers that fail to meet standards due to mismatch in epitaxial growth process parameters

[0074] This embodiment provides a method for recycling silicon-based gallium nitride (GaN) wafers. The GaN wafer to be processed has a structure consisting of a silicon substrate, a buffer layer, and an N-type doped GaN layer (n-GaN). The silicon substrate thickness is 675±25 μm, the total thickness of the GaN-based epitaxial layer is 5±0.5 μm, and the wafer diameter is 6 inches. This wafer is scrapped due to mismatch in epitaxial growth process parameters and substandard electrical performance.

[0075] Reference Figure 4 The specific steps of the recycling method are as follows:

[0076] S1, Wafer Cleaning:

[0077] The scrapped wafers were subjected to two-fluid cleaning, with each cleaning cycle lasting 60 seconds and repeated three times, to remove large particulate contaminants from the surface. After cleaning, the remaining liquid was spun dry at 800 RPM to avoid watermarks.

[0078] S2, Laser separation of epitaxial layer:

[0079] This step employs a global scanning mode. Since the intrinsic external absorption of 1064nm laser light by the N-type doped gallium nitride layer is slightly increased compared to the undoped layer, the laser process parameters need to be adjusted to ensure effective separation while avoiding excessive energy input.

[0080] S21. Define a scanning area covering the entire surface of the gallium nitride-based epitaxial layer, specifically set as a circular area with a diameter of 152 mm.

[0081] S22. Use an infrared picosecond laser (wavelength 1064nm, pulse width 20ps), set the average laser power to 1.54W, the laser repetition frequency to 100KHz, and the defocusing amount to -0.4mm.

[0082] S23. Within the scanning area, continuous surface scanning is performed in a pattern-filling manner at a scanning speed of 1600 mm / s and a scanning spacing of 0.016 mm. This laser scanning path strategy separates the entire gallium nitride-based epitaxial layer from the silicon substrate. The separation rate is approximately 15 minutes per 6-inch wafer.

[0083] S3. Stripping the gallium nitride-based epitaxial layer:

[0084] After laser processing, an adhesive tool, such as an adhesive tape, is used to completely separate the separated gallium nitride-based epitaxial film from the silicon substrate and collect it.

[0085] S4, Silicon substrate cleaning:

[0086] The silicon substrate after epitaxial layer removal was subjected to two-fluid cleaning, with each cleaning cycle lasting 60 seconds and repeated three times, to remove any spatter particles and epitaxial layer debris that may remain after laser treatment. After cleaning, the remaining liquid was spun dry at 800 RPM.

[0087] S5, Chemical Mechanical Polishing:

[0088] The surface of the silicon substrate is subjected to chemical mechanical polishing (CMP) until it is restored to a mirror finish. This CMP process reduces the surface roughness of the silicon substrate to less than 0.5 nm, meeting the requirements for further epitaxial growth.

[0089] S6. Silicon Substrate Inspection and Reuse:

[0090] After testing the roughness, flatness, thickness, and other indicators of the polished silicon substrate, and confirming that it meets the requirements, the silicon substrate can be recycled and reused and sent back to the epitaxial growth line.

[0091] This embodiment demonstrates the dynamic adaptability and wide applicability of the method by processing 6-inch N-type N-doped gallium nitride (GaN) silicon wafers that are scrapped due to substandard electrical performance. By precisely controlling process parameters such as laser power and defocusing amount, it successfully accommodates the recycling needs of wafers with different doping types and sizes, proving that it is not limited to a specific structure or a single defect type. It can effectively address various performance-deficient scrap wafers caused by process fluctuations in industrial production, providing a reliable technical solution for large-scale, diversified GaN silicon wafer recycling.

[0092] Example 3: Precise removal of localized defects on wafers to recover gallium nitride silicon wafers

[0093] This embodiment provides a method for recycling silicon-based gallium nitride (GaN) wafers, used to precisely remove localized defects on the wafer to salvage high-value wafers. The silicon-based GaN LED wafer to be processed has a complex epitaxial layer structure (including a buffer layer, u-GaN, n-GaN, multiple quantum well layer (MQWS), and p-GaN), with a total thickness of 8±0.5 μm. The silicon substrate thickness is 525±25 μm, and the wafer diameter is 4 inches. Due to improper clamping, predetermined defect areas such as mechanical scratches and holes have appeared on the wafer surface.

[0094] Reference Figure 5 The specific steps of the recycling method are as follows:

[0095] S1, Wafer Cleaning:

[0096] The scrapped wafers were subjected to two-fluid cleaning, with each cleaning cycle lasting 45 seconds and repeated three times to remove large particulate contaminants from the surface. After cleaning, the residual liquid was spun dry at 1000 RPM.

[0097] S2, Laser selective separation of epitaxial layers:

[0098] This step uses a selective scanning mode, which is completed through two laser scans targeting different objects in tandem.

[0099] S21, First laser scan (boundary cutting):

[0100] The predetermined defect region on the gallium nitride (GaN) wafer is identified using a machine vision system, and a square path is planned to precisely surround the defect region. A first laser scan is performed along the boundary of the predetermined defect region. In this scan, the focus of the infrared laser beam is set on the surface of the GaN-based epitaxial layer, specifically by setting the defocusing amount to 0 mm. An infrared picosecond laser is used, with an average laser power of 1.54 W, a laser repetition frequency of 100 kHz, and a scanning speed of 120 mm / s. The purpose of this scan is to cut the GaN-based epitaxial layer and form an isolation trench extending into the silicon substrate. This isolation trench physically separates the defect region from the surrounding intact epitaxial layer, thereby protecting the defect-free region from thermal shock or mechanical stress during subsequent separation steps.

[0101] S22, Second laser scan (internal separation):

[0102] A second laser scan is performed within the area defined by the isolation trench. In this scan, the focus of the infrared laser beam is set inside the silicon substrate and adjacent to the interface between the gallium nitride-based epitaxial layer and the silicon substrate, specifically achieved by setting a defocusing amount of -0.3 mm. The laser power and frequency remain constant, the scanning speed is increased to 1500 mm / s, and a pattern-filling surface scan is performed on the square area within the isolation trench at a scanning interval of 0.015 mm to separate the gallium nitride-based epitaxial layer from the silicon substrate within this area.

[0103] S3. Stripping the gallium nitride-based epitaxial layer:

[0104] Using an adhesive tool, specifically thermally release tape, apply it to the treated defect area. Its initial tack allows the cut and separated defective epitaxial film to be detached from the silicon substrate. Subsequently, if the film needs to be recycled, the thermally release tape can be heated to significantly reduce its tack, allowing the film to be easily and cleanly removed from the tape.

[0105] S4. Wafer Cleaning:

[0106] The wafer with the locally defective epitaxial layer removed was subjected to two-fluid cleaning, with each cleaning cycle lasting 45 seconds and repeated 3 times, to remove spatter particles and epitaxial layer debris from the surface after laser treatment. After cleaning, it was spun dry at 800 RPM.

[0107] S5. Wafer Inspection and Reuse:

[0108] The repaired wafer was inspected, confirming that the epitaxial layer in the intact area was unaffected and met subsequent production standards. The wafer could then be directly used in the subsequent chip manufacturing process, thus achieving selective local removal of the epitaxial layer and rapid wafer reuse, significantly mitigating economic losses.

[0109] This embodiment demonstrates the high precision and high value-added application of selective scanning mode by performing localized repair on high-value LED wafers with complex epitaxial layer structures. The two-step strategy of "first cutting to form isolation trenches, then separating the internal regions" achieves surgical-like precision removal of epitaxial layer defects while effectively protecting surrounding intact functional areas from damage. Repairing high-value wafers directly salvages their economic value and provides a solution for improving the production yield of complex devices and avoiding the scrapping of entire wafers.

[0110] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application. Any specific values ​​in all examples shown and discussed herein should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0111] Furthermore, it should be noted that the use of terms such as "first" and "second" is merely for ease of distinction, and unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recycling a silicon-based gallium nitride wafer, the silicon-based gallium nitride wafer comprising a silicon substrate and a gallium nitride-based epitaxial layer disposed on the silicon substrate, characterized in that, The method includes the following steps: Using an infrared laser beam, and following a preset laser scanning path strategy, the laser beam is incident from one side of the gallium nitride-based epitaxial layer onto the silicon-based gallium nitride wafer, thereby separating the gallium nitride-based epitaxial layer from the silicon substrate. The gallium nitride-based epitaxial layer is stripped away.

2. The method for recycling silicon-based gallium nitride wafers according to claim 1, characterized in that: The laser scanning path strategy includes one of the following modes: A global scan mode is used to remove the entire gallium nitride-based epitaxial layer on the silicon-based gallium nitride wafer in one go. A selective scanning mode is used to remove the gallium nitride-based epitaxial layer in a predetermined defect region on the silicon-based gallium nitride wafer.

3. The method for recycling silicon-based gallium nitride wafers according to claim 2, characterized in that: The global scanning modes include: Define a scan area covering the entire surface of the gallium nitride-based epitaxial layer; Within the scanning area, continuous surface scanning is performed in a pattern-filling manner to separate the entire gallium nitride-based epitaxial layer from the silicon substrate.

4. The method for recycling silicon-based gallium nitride wafers according to claim 2, characterized in that: The selective scanning modes include: Identify the predetermined defect region on the silicon-based gallium nitride wafer; A first laser scan is performed along the boundary of the predetermined defect region to cut the gallium nitride-based epitaxial layer and form an isolation trench extending into the silicon substrate; A second laser scan is performed within the region defined by the isolation trench to separate the gallium nitride-based epitaxial layer from the silicon substrate within that region.

5. The method for recycling silicon-based gallium nitride wafers according to claim 3, characterized in that: After stripping the gallium nitride-based epitaxial layer, the process further includes performing a chemical mechanical polishing treatment on the surface of the silicon substrate to restore the silicon substrate to a state where it can be epitaxially grown again.

6. The method for recycling silicon-based gallium nitride wafers according to claim 1, characterized in that: The stripping of the gallium nitride-based epitaxial layer specifically includes: The separated gallium nitride-based epitaxial layer is detached from the silicon substrate using an adhesive tool.

7. The method for recycling silicon-based gallium nitride wafers according to claim 4, characterized in that: In the first laser scan, the focal point of the infrared laser beam is set on the surface of the gallium nitride-based epitaxial layer; In the second laser scan, the focal point of the infrared laser beam is located inside the silicon substrate and adjacent to the interface between the gallium nitride-based epitaxial layer and the silicon substrate.

8. The method for recycling silicon-based gallium nitride wafers according to any one of claims 1 to 4, characterized in that: The infrared laser beam is a pulsed laser, and the pulse width of the infrared laser beam is on the order of picoseconds or femtoseconds.

9. The method for recycling silicon-based gallium nitride wafers according to claim 6, characterized in that: The adhesive tool is an adhesive tape or a heat-release adhesive tape.

10. The method for recycling silicon-based gallium nitride wafers according to claim 5, characterized in that: The chemical mechanical polishing treatment results in a surface roughness of less than 0.5 nm for the silicon substrate.

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