A laser-induced modified ingot wafer peeling device

Abstract

The utility model relates to the technical field of semiconductor material discloses a wafer stripping device of laser-induced modified ingot, the device includes sealed cavity, sealed cavity is connected with a booster pump, is provided with vacuum displacement stage and the vacuum chuck of directly facing the vacuum displacement stage for positioning adsorbing crystal ingot in sealed cavity, vacuum chuck is driven and is connected with a lifting mechanism, is provided with a plurality of adsorption holes on vacuum displacement stage, vacuum chuck includes a plurality of concentric arrangement and is physically separated sub -suction disc, a plurality of air holes are equipped on the adsorption surface of each sub -suction disc, and the air hole of each sub -suction disc is connected with a sub -area adsorption force adjusting device through independent suction pipe, and sub -area adsorption force adjusting device is connected with vacuum pump, and sub -area adsorption force adjusting device is used for controlling the adsorption force of each sub -suction disc. Stripping wafer utilizes the device, and lattice structure damage is small, and material fracture and loss are few, and there is no environmental pollution, and the efficiency is high.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor materials technology, and more specifically, to a wafer stripping device for laser-induced modified ingots. Background Technology

[0002] Silicon carbide (SiC) holds a crucial position in the semiconductor and optics fields due to its exceptional hardness, excellent thermal stability, and superior electrical properties. In the semiconductor industry, SiC is frequently used as a substrate material for manufacturing various electronic devices (such as chips and transistors). However, the extremely high hardness of SiC semiconductors makes the fabrication of device substrates very difficult. Traditional processing methods involve using diamond wire cutting to slice SiC ingots into thin wafers, but this method results in a material loss of over 50%. Laser slicing, which uses laser processing to slice SiC ingots, has attracted widespread attention because it not only reduces material loss during processing but also significantly improves the efficiency of slicing SiC ingots into thin wafers.

[0003] Laser slicing typically involves using a laser with a wavelength that allows light to pass through the ingot to strike the ingot from the ingot's end face and then focus it into the ingot's interior. The crystal material at the focal point is modified by the laser energy. By scanning the entire ingot's end face with the laser, a continuous modified layer can be formed. Then, by applying external force, the ingot is separated from the modified layer to form an independent wafer.

[0004] The existing laser slicing process generally adopts the following technical solution: First, a uniform modified layer is formed inside a silicon carbide ingot using a laser; then, the ingot with the modified layer is transferred to a separation device, where two adhesive pull targets are used to firmly bond and fix the ingot to both ends using adhesive; next, the two pull targets are controlled to move synchronously in opposite directions to apply a peeling force to the ingot, causing the ingot to separate at the modified layer position, thereby obtaining a silicon carbide wafer; finally, through a debinding process, the separated silicon carbide wafer is removed and then subjected to subsequent grinding, polishing and other finishing processes to obtain a silicon carbide wafer that meets the specifications.

[0005] However, existing technologies have significant drawbacks in practical applications. Their peeling process relies on applying a large peeling force to the ingot in a single step to separate the wafers. This method is prone to the following technical problems: 1. Risk of lattice structure damage: Excessive peeling force may cause irreversible damage to the silicon carbide lattice structure, forming microscopic defects such as lattice dislocations. These defects significantly reduce the material's electrical conductivity and optical properties, thus affecting the stability and reliability of the device; 2. Material fracture and loss: Although silicon carbide has high hardness, its brittleness results in poor impact resistance. During peeling, excessive peeling force can easily cause wafer fracture, not only wasting material but also significantly increasing production costs and reducing production yield; 3. Environmental pollution and efficiency issues: Current adhesive methods require a large amount of organic materials, which have negative impacts on the environment and human health. Furthermore, the adhesive's onset and failure times are relatively long, resulting in low efficiency in industrial production.

[0006] The invention patent with authorization announcement number CN118553675B uses concentrically arranged adhesive rings of different sizes to sequentially peel off the silicon carbide release layer from the outside to the inside in different regions, reducing the peeling force required to separate the release layer from the ingot. However, while this technology solves the problem of high single-step peeling force and reduces the damage to the silicon carbide lattice structure caused by high peeling force, thus ensuring the material's photoelectric properties, it still uses an adhesive method to bond both sides of the internally modified silicon carbide ingot to the adhesive rings of the peeling device, and then uses a mechanical pull target to achieve wafer peeling. This method does not overcome the disadvantages of adhesive methods, such as long bonding and debonding times, cumbersome steps, low production efficiency, and the harmful effects of organic matter used in the peeling process on the environment and workers.

[0007] The invention patent application with publication number CN115831825A is based on the suction cup method. It involves placing a suction cup in a sealed container with an applied positive voltage to increase the suction force, and then pulling the suction cup upwards to achieve wafer peeling. However, this peeling technology is still a one-time wafer peeling method. On the one hand, it easily damages the internal lattice structure of the silicon carbide wafer; on the other hand, the force applied during a one-time vertical peeling is relatively large, easily causing fragmentation. Finally, the ingot is still fixed in the sealed container using adhesive methods, which still suffers from the disadvantages of adhesive methods. Utility Model Content

[0008] The technical problem to be solved by this utility model is that existing laser slicing and stripping devices for crystal ingots have the risk of lattice structure damage, material breakage and high loss during wafer stripping, and the use of adhesives causes environmental pollution and low efficiency. In order to overcome the above defects of the prior art, this utility model provides a wafer stripping device for laser-induced modified crystal ingots.

[0009] This invention provides a wafer stripping device for laser-induced modified ingots. The wafer stripping device includes a sealed cavity connected to a booster pump. The sealed cavity contains a vacuum displacement stage for positioning and adsorbing the ingot and a vacuum suction cup facing the vacuum displacement stage. The vacuum suction cup is driven and connected to a lifting mechanism. The vacuum displacement stage has multiple adsorption holes. The vacuum suction cup includes multiple concentrically arranged and physically separated sub-suction cups. Each sub-suction cup has multiple vent holes on its adsorption surface. The vent holes of each sub-suction cup are connected to a regional adsorption force adjustment device via an independent suction pipe. The regional adsorption force adjustment device is connected to a vacuum pump and is used to control the adsorption force of each sub-suction cup.

[0010] Compared with existing technologies, this invention has the following advantages: This invention, through a regional adsorption force adjustment device, can obtain a vacuum chuck with regional adsorption force, breaking through the single adsorption force mode of traditional adsorption devices. It can form a dynamic adsorption force gradient from the edge to the center, significantly reducing overall process energy consumption while ensuring peeling stability. Because it does not use a single uniform peeling force to peel the wafer, certain areas of the wafer are less likely to suffer lattice structure damage or even material fracture due to excessive peeling force. This invention uses chuck physical peeling technology to replace traditional chemical bonding processes, fundamentally eliminating the environmental pollution hazards of adhesive volatiles and avoiding the potential impact of organic solvent residues on wafer performance. Furthermore, through a dynamic peeling force control mechanism, it effectively solves the wafer damage problem caused by instantaneous overload of peeling force in traditional processes, and also solves the low efficiency problem caused by adhesive-debonding.

[0011] In one possible implementation, the vacuum suction cup includes three sub-suction cups separated by a partition wall, namely an annular first sub-suction cup, an annular second sub-suction cup, and a circular third sub-suction cup, wherein the first sub-suction cup is located outside the second sub-suction cup, and the third sub-suction cup is located inside the second sub-suction cup.

[0012] In one possible implementation, each of the sub-suction cups has multiple suction cup adsorption grooves on its adsorption surface, and each suction cup adsorption groove is separated from the others by a partition edge, with the vent located inside the suction cup adsorption groove.

[0013] In one possible implementation, the suction cup adsorption grooves are arranged in a grid pattern, and the vent holes are located at the intersections of the dividing edges.

[0014] In one possible implementation, the regional adsorption force adjustment device includes multiple air inlets, the number of which is the same as the number of sub-suction cups. Each air inlet is connected to a suction pipe, and each air inlet is equipped with an adjustment valve.

[0015] In one possible implementation, the regional adsorption force adjustment device is a four-way air pipe with one air outlet and three air inlets. The three air inlets are respectively connected to a first air extraction pipe, a second air extraction pipe, and a third air extraction pipe, and a first regulating valve, a second regulating valve, and a third regulating valve are respectively provided on the three air inlets.

[0016] In one possible implementation, the booster pump is a gas booster pump or a liquid booster pump.

[0017] In one possible implementation, the lifting mechanism is a screw jack or a hydraulic jack.

[0018] In one possible implementation, the lifting mechanism is a screw jack, which is mounted on a device support frame outside the sealed cavity. The main shaft motor of the screw jack is fixed on a second support base plate at the top of the device support frame. The trapezoidal screw of the screw jack passes through the second support base plate and is fixed to the suction cup connecting column at the top of the vacuum suction cup by a bearing. The screw nut of the screw jack is fixed in conjunction with the main shaft of the main shaft motor.

[0019] In one possible implementation, the bottom of the vacuum displacement stage is fixed to a movable substrate, the bottom of the movable substrate is fixed to the top of the free end of the piston rod of a cylinder, the piston rod of the cylinder is supported on the bottom of the movable substrate by a floating module, and substrate guide rail one and substrate guide rail two are slidably inserted on both sides of the movable substrate outside the sealed cavity.

[0020] The beneficial effects of this utility model are as follows: 1. By precisely controlling the adsorption force in each area and using a sealed chamber structure, a positive pressure environment is created through an external air pressure or hydraulic loading system, ensuring that the suction cup adsorption force reaches the critical threshold required for the peeling process. This avoids the impact of excessive peeling force on the photoelectric properties (crystal structure) of the wafer, reduces the fragmentation rate, ensures peeling stability, and significantly reduces overall process energy consumption, thereby improving production efficiency.

[0021] 2. This utility model fundamentally eliminates the environmental pollution hazards posed by adhesive volatiles, avoids the potential impact of organic solvent residues on wafer performance, and effectively solves the problem of wafer damage caused by instantaneous overload of peel force in traditional processes through a dynamic peel force control mechanism.

[0022] 3. This utility model is suitable for wafer stripping of various ingots such as 4H-SiC ingots, semi-insulating silicon carbide ingots, or GaN ingots. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the wafer stripping device in an embodiment of the present invention; Figure 2This is a top view of the vacuum suction cup in an embodiment of the present utility model; Figure 3 This is a cross-sectional view of the vacuum suction cup in an embodiment of the present utility model; Figure 4 This is a schematic diagram of the regional adsorption force adjustment device in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the suction cup connecting column and the air tube in an embodiment of this utility model; Figure 6 This is a schematic diagram of the cylinder structure in an embodiment of the present utility model; Figure 7 This is a schematic diagram of the floating module in an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures: 1. Regional adsorption force adjustment device; 1-1. Four-way air pipe; 1-2. First regulating valve; 1-3. Second regulating valve; 1-4. Third regulating valve; 2. First suction pipe; 3. Second suction pipe; 4. Third suction pipe; 5. Support base plate one; 6. Suction cup connecting column; 6-1. Air pipe channel one; 6-2. Air pipe channel two; 6-3. Air pipe channel three; 7. Vacuum suction cup; 7-1. First sub-suction cup; 7-2. Second sub-suction cup; 7-3, Third sub-suction cup; 7-4, Separating edge; 7-5, Vent hole; 7-6, Suction cup adsorption groove; 7-7, Separating wall; 7-8, Threaded hole; 7-9, First air extraction hole; 7-10, Second air extraction hole; 7-11, Third air extraction hole; 8, Base plate guide rail one; 9, Base plate guide rail two; 10, Spindle motor; 11, Force sensor; 12, Trapezoidal lead screw; 13, Lead screw nut; 14, Support 15. Supporting substrate 2; 16. Supporting substrate 3; 17. Sealing cavity; 18. Device support frame; 19. Support frame 1; 10. Support frame 2; 11. Support frame 3; 12. Support frame 4; 13. Support frame 5; 14. Support frame 6; 15. Movable substrate; 16. Evacuation pipe 1; 27. Booster pump; 28. Evacuation pipe 2; 29. ​​Vacuum pump; 20. Cylinder evacuation pipe; 21. Air pump 25. Cylinder; 25-1. Cylinder barrel; 25-2. Front end cover; 25-3. Seal; 25-4. Piston; 25-5. Rear end cover; 25-6. Inlet / outlet port one; 25-7. Inlet / outlet port two; 26. Piston rod; 27. Floating module; 28. Sealing ring; 29. ​​Sealing groove; 30. Ingot; 31. Modified layer; 31-1. Modified line; 31-2. Crack area; 32. Vacuum displacement stage. Detailed Implementation

[0025] To make the above-mentioned objectives, features, and advantages of this utility model more apparent and understandable, specific embodiments of this utility model are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of this utility model, and are not intended to limit the parameter range described in this utility model. Reasonable variations derived therefrom are still within the protection scope of the claims of this utility model.

[0026] See Figures 1-6 As shown, this embodiment discloses a wafer stripping device for laser-induced modified ingots. The device specifically includes three main parts: a device support frame 17, a stripping component, and an external pressure application component. Figure 1 As shown, the entire stripping component and external pressurizing component are mounted on the device support frame 17. The device support frame 17 is divided into three layers. The upper layer consists of support frame one 17-1, support frame two 17-2, and support substrate two 14. Support frame one 17-1 and support frame two 17-2 support support substrate two 14. The middle layer consists of support frame three 17-3, support frame four 17-4, and support substrate one 5. Support frame three 17-3 and support frame four 17-4 support support substrate two 14, while the bottoms of support frame one 17-1 and support frame two 17-2 are fixed to support substrate one 5. The lower layer consists of support frame five 17-5, support frame six 17-6, and support substrate three 15. Support frame five 17-5 and support frame six 17-6 support support substrate three 15, while the bottoms of support frame three 17-3 and support frame four 17-4 are fixed to support substrate three 15. The device support frame 17 is used to support other core components of the device.

[0027] The peeling component mainly consists of the following parts: a concentrically arranged vacuum suction cup 7 with adjustable regional adsorption force, a vacuum displacement stage 32, a lifting mechanism, a regional adsorption force adjustment device 1, an air extraction pipe, and a vacuum pump 22. The vacuum suction cup 7 and the vacuum displacement stage 32 are located in the middle layer of the device support frame 17, and the lifting mechanism is located on the upper layer of the device support frame 17. The air extraction pipe of the regional adsorption force adjustment device 1 is connected to the suction cup connecting column 6 and is located on the outside of the device support frame 17 and connected to the vacuum pump 22 on the outside, making the entire device structure more compact.

[0028] Among them, such as Figure 2 and Figure 3As shown, the vacuum suction cup 7, as the core component, includes multiple concentrically arranged sub-suction cups. Preferably, there are three sub-suction cups, with the innermost third sub-suction cup 7-3 being circular, the middle second sub-suction cup 7-2, and the outermost first sub-suction cup 7-1 both being annular. The first sub-suction cup 7-1 and the second sub-suction cup 7-2, as well as the second sub-suction cup 7-2 and the third sub-suction cup 7-3, are connected by partition walls 7-7. The adsorption surfaces of the first sub-suction cup 7-1, the second sub-suction cup 7-2, and the third sub-suction cup 7-3 each include multiple suction cup adsorption grooves 7-6. These suction cup adsorption grooves 7-6 are connected to each other by partition edges 7-4. The reason for the presence of suction cup adsorption grooves 7-6 is that the adsorption surface of the sub-suction cup is set slightly lower than the outer wall surface of the entire suction cup; therefore, the adsorption surface is described as a suction cup adsorption groove 7-6. Each sub-suction cup, composed of suction cup adsorption grooves 7-6, has multiple ventilation holes 7-5 on its adsorption surface, located within the suction cup adsorption grooves 7-6. Preferably, the suction cup adsorption grooves 7-6 are arranged in a grid pattern, and the bottom surface of the intersection point where the dividing edges 7-4 of each suction cup adsorption groove 7-6 connect is recessed inward to form the ventilation holes 7-5, which are used to introduce gas during desorption. Alternatively, the adsorption surface of each sub-suction cup, i.e., the suction cup adsorption groove 7-6, can be directly flush with the outer wall surface, thus directly serving as the suction cup adsorption surface without the need for separate suction cup adsorption grooves 7-6. In this case, the ventilation holes 7-5 are directly located on the adsorption surface of each sub-suction cup. The ventilation holes 7-5 within the suction cup adsorption grooves 7-6 replace the traditional porous vacuum suction cup 7, increasing the effective adsorption area of ​​the vacuum suction cup 7.

[0029] The vacuum suction cup 7 creates negative pressure by expelling internal air. External air pressure then presses the vacuum suction cup 7 firmly against the surface of the wafer being suctioned, generating a force called the suction force. The calculation formula is: F = ΔP * A, where F is the suction force (unit: Newtons, N), ΔP is the difference between the external air pressure and the internal air pressure of the suction cup (unit: Pascals, Pa), and A is the effective suction area of ​​the vacuum suction cup 7 (unit: square meters, m²). 2 Furthermore, ΔP = (P1 - P2), where P1 is the external pressure value and P2 is the internal pressure value. The adsorption force ratio of the three sub-suction cups from the inside out—the third sub-suction cup 7-3, the second sub-suction cup 7-2, and the first sub-suction cup 7-1—is 1–9: 27–3: 45–5. This makes the device suitable for wafer peeling from various types of ingots 30, such as silicon carbide or GaN ingots. The required peeling force, i.e., adsorption force, varies slightly depending on the type of ingot 30. The outer ring has the strongest adsorption force, used to open the wafer edge. Once the edge is opened, the required peeling force for the ingot 30 decreases instantly. The internal adsorption force, while ensuring wafer peeling, also provides a flexible force, ensuring that the wafer does not break during the peeling process.

[0030] like Figure 1 and Figure 6 As shown, the vacuum displacement stage 32 is disposed in the middle layer of the device support frame 17. The bottom of the vacuum displacement stage 32 is fixed to a movable substrate 18. The bottom of the movable substrate 18 is fixed to the top of the free end of the piston rod 26 of a cylinder 25. A floating module 27 is fixed to the free end of the piston rod 26 of the cylinder 25. The floating module 27 directly abuts against the bottom of the movable substrate 18. The movable substrate 18 is slidably inserted with substrate guide rail 1 8 and substrate guide rail 2 9 on both sides outside the sealed cavity 16. The substrate guide rail 1 8 and substrate guide rail 2 9 serve to guide the movable substrate 18 to move up and down under the action of the cylinder 25.

[0031] like Figure 7 As shown, the floating module 27 specifically comprises three parts: a support column 27-1, a support plate 27-2, and a retaining ring 27-3. The support plate 27-2 is fixed below the movable base plate 18 by the support column 27-1, and simultaneously, the support plate 27-2 is movably engaged in the middle of the retaining ring 27-3, retaining a certain amount of tilting space. This design ensures that even if the upper suction cup has poor assembly precision and slight tilting, the movable base plate 18 combined with the tilt of the support plate 27-2 on the retaining ring 27-3 can ensure that the vacuum suction cup 7 can adsorb the crystal ingot 30 without damaging it. If the support plate 27-2 is completely immovable, and the upper vacuum suction cup 7 tilts when descending to adsorb the crystal ingot 30, it may fail to adsorb, or even damage the crystal ingot 30.

[0032] like Figure 6 As shown, the cylinder 25 includes a cylinder barrel 25-1, a front end cover 25-2, and a rear end cover 25-5. The rear end cover 25-5 has an air inlet / outlet port 25-6, and the front end cover 25-2 has an air inlet / outlet port 25-7. The piston 25-4 of the cylinder 25 is sealed to the cylinder barrel 25-1 by a sealing element 25-3. When the piston 25-4 drives the piston rod 26 to move downward, the piston rod 26 is connected to the floating module 27, which drives the movable base plate 18 to move downward along the base plate guide rail 8 and the base plate guide rail 9. The design of lifting and lowering the piston rod 26 of the cylinder 25 on the vacuum displacement stage 32 actually provides another lifting control for this device. In addition, in order to control the amount of gas in the cylinder 25, a cylinder suction pipe 23 is connected to the cylinder 25. The outer end of the cylinder suction pipe 23 is connected to an air pump 24, which can be used to evacuate or inject gas into the cylinder 25.

[0033] The lifting mechanism is located on the upper layer of the device support frame 17. The lifting mechanism can be a screw jack or a hydraulic jack. When the lifting mechanism is a screw jack, it is located on the upper layer of the device support frame 17 outside the sealed cavity 16. The main shaft motor 10 of the screw jack is fixed to the second support base plate 14 at the top of the device support frame 17. The trapezoidal screw 12 of the screw jack passes through the second support base plate 14 and is fixed to the suction cup connecting column 6 at the top of the vacuum suction cup 7 via bearings. The screw nut 13 of the screw jack is fixedly connected to the main shaft of the main shaft motor 10. In other embodiments, a hydraulic jack or similar mechanism can also be used to control the rise and fall of the vacuum suction cup 7.

[0034] like Figure 4 and Figure 5 As shown, the regional adsorption force adjustment device 1 includes a four-way air pipe 1-1. The three air inlets of the four-way air pipe 1-1 are respectively connected to the first suction pipe 2, the second suction pipe 3, and the third suction pipe 4. The three air inlets of the four-way air pipe 1-1 are also equipped with a first regulating valve 1-2, a second regulating valve 1-3, and a third regulating valve 1-4, respectively, for adjusting the air volume at the air inlets. The first suction pipe 2, the second suction pipe 3, and the third suction pipe 4 extend into the suction cup connecting post 6 and pass through the internal air pipe channel 1 6-1, air pipe channel 2 6-2, and air pipe channel 3 6-3, respectively, acting on the vacuum suction cup 7. Its unique design allows the adsorption force of each region to be adjusted independently to meet different peeling force requirements.

[0035] like Figure 1 and Figure 5 As shown, the first sub-suction cup 7-1, the second sub-suction cup 7-2, and the third sub-suction cup 7-3 have a first air extraction hole 7-9, a second air extraction hole 7-10, and a third air extraction hole 7-11 respectively on their top surfaces away from the adsorption surface. These holes are connected to the corresponding first air extraction pipe 2, second air extraction pipe 3, and third air extraction pipe 4. The first air extraction pipe 2, second air extraction pipe 3, and third air extraction pipe 4 are connected together to the three air inlets of a four-way air pipe 1-1 located outside the sealed cavity 16. The air outlet of the four-way air pipe 1-1 is connected to a vacuum pump 22 via an external air extraction pipe 21 to adjust the adsorption force of the sub-suction cups in different areas. The outermost ring of the vacuum suction cup 7 also has a threaded hole 7-8 for installation and use.

[0036] like Figure 1As shown, the external pressurization component includes a sealed cavity 16, an external booster pump 20, and a vacuum extraction pipe 19. The sealed cavity 16 is located in the middle layer of the device support frame 17, and contains three components: a vacuum suction cup 7, a suction cup connecting column 6, and a vacuum displacement stage 32, providing an absolute vacuum environment for wafer stripping. The vacuum extraction pipe 19 is connected to the sealed cavity 16, and then to the booster pump 20 located outside the device support frame 17. The external pressurization component delivers gas or liquid into the sealed cavity 16 through the vacuum extraction pipe 19 of the external booster pump 20 to increase pressure, thereby generating a pressure on the vacuum suction cup 7 that far exceeds conventional levels (far greater than 1 kg / cm²). 2 This provides the necessary mechanical conditions for the peeling of the modified ingot. The external booster pump 20 is a gas booster pump 20 or a liquid booster pump 20. The gas in the gas booster pump 20 is air or nitrogen, and the liquid in the liquid booster pump 20 is water or hydraulic oil. The maximum pressure of the external booster pump 20 is 4 MPa, which is sufficient for the wafer peeling of all types of ingots 30.

[0037] In this embodiment, the vacuum suction cup 7 is made of quartz material. Quartz material is preferred because the surface of a suction cup made of quartz material is easier to level, thus achieving a better adsorption effect. In other embodiments, the vacuum suction cup 7 can also be a hard plastic suction cup, a porous ceramic suction cup, or a metal suction cup.

[0038] The working principle of the laser-induced modified ingot wafer peeling device in this embodiment is as follows: First, a pulsed laser is focused inside the silicon carbide ingot to form a modified layer 31, thereby reducing the difficulty of peeling. Then, the modified ingot 30 and the concentric ring-shaped suction cup device are placed together in a pressurizable sealed cavity 16. By pressurizing the sealed cavity 16, a high-intensity pressure environment is formed on the vacuum suction cup 7. Furthermore, since each concentric ring-shaped suction cup of the vacuum suction cup 7 device is equipped with an independent internal chamber and is connected through an external vacuum pump 22, the suction force of each ring-shaped suction cup can be independently adjusted. By finely adjusting the pressure valve of the air extraction port of each suction cup, the suction force of the ring-shaped suction cup is distributed in a decreasing trend from the outside to the inside. Finally, with the precise control of the suction cup lifting device, the wafer is peeled off layer by layer from the ingot 30, thereby obtaining an independent wafer product.

[0039] Taking the stripping of silicon carbide ingots as an example, the specific stripping process is as follows: Step S1: A nanosecond laser with a wavelength of 532 nm is focused inside the silicon carbide ingot to form a crack-ridden modified layer 31. The surface of the ingot 30 closest to the modified layer 31 is defined as the upper end face, and the other surface as the lower end face. In this embodiment, the silicon carbide ingot is a 4H-SiC ingot. This method can also be used for semi-insulating silicon carbide or other types such as GaN ingots.

[0040] Step S2: Place the lower end face of the modified silicon carbide ingot on the vacuum displacement stage 32, and use the adsorption force of the vacuum displacement stage 32 to fix the ingot 30. When placing the ingot 30, extra care must be taken to ensure that the lower end face of the ingot 30 covers all the adsorption holes on the vacuum displacement stage 32 to prevent air leakage that could cause a sharp decrease in adsorption force. Vacuum the contact surface between the vacuum displacement stage 32 and the ingot 30 to reduce the internal pressure of the contact surface, thus connecting the ingot 30 and the vacuum displacement stage 32 into a single unit.

[0041] Step S3: The cylinder 25 pressurizes the piston rod 26 to move upward, which in turn drives the floating module 27 and the movable substrate 18 above the floating module 27 to move upward along the substrate guide rail 1 8 and the substrate guide rail 2 9. The movable substrate 18 has a sealing groove 29 that matches the wall of the sealing cavity 16. The sealing groove 29 has a sealing ring 28. The upward movement of the movable substrate 18 can cause the sealing cavity 16 to be embedded in the sealing groove 29, so that a sealed space is formed inside the sealing cavity 16.

[0042] Step S4: Turn on the spindle motor 10, rotate the trapezoidal lead screw 12 through the lead screw nut 13, and slowly move the suction cup connecting post 6 at the top of the vacuum suction cup 7 downward. Use the force sensor 11 to observe the torque to determine whether the vacuum suction cup 7 is in contact with the crystal ingot 30, and finally connect the vacuum suction cup 7 to the upper end face of the crystal ingot 30. Vacuum the vacuum suction cup 7 through the first suction pipe 2, the second suction pipe 3, the third suction pipe 4 and the vacuum pump 22. Use the regional suction force adjustment device 1 to adjust the internal pressure of the first sub-suction cup 7-1, the second sub-suction cup 7-2 and the third sub-suction cup 7-3, thereby controlling the suction force of each independent suction cup, so that the suction force of the vacuum suction cup 7 decreases in a gradient from the outside to the inside, and connects the crystal ingot 30 and the vacuum suction cup 7 into a whole. In this embodiment, the vacuum suction cup 7 is a quartz suction cup, and in order to further increase the suction force of the vacuum suction cup 7, the traditional vacuum suction cup 7 suction hole is replaced with a suction cup suction groove 7-6. In other embodiments, the vacuum suction cup 7 may also be a porous ceramic suction cup or a metal suction cup.

[0043] In this embodiment, the spindle motor 10, the force sensor 11, the trapezoidal lead screw 12, the lead screw nut 13, the first support base 5, the second support base 14, the suction cup connecting column 6, the first support frame 17-1, and the second support frame 17-2 together constitute the lifting device. The spindle motor 10 and the lead screw nut 13 are fixed on the second support base 14. The force sensor 11 is connected to the trapezoidal lead screw 12. One end of the trapezoidal lead screw 12 is connected to the lead screw nut, and the other end is connected to the concentric ring vacuum suction cup 7 through a bearing. The rise and fall of the vacuum suction cup 7 are controlled by the trapezoidal lead screw 12 and the coaxial motor. In other embodiments, a hydraulic lift or other mechanism can also be used to control the rise and fall of the vacuum suction cup 7.

[0044] In this embodiment, the step of adsorbing and bonding the vacuum chuck 7 with the upper surface of the silicon carbide ingot includes: starting the coaxial motor and rotating it in the forward direction, driving the trapezoidal lead screw 12 to descend, so that the vacuum chuck 7 is connected to the upper surface of the silicon carbide ingot; turning on the vacuum pump 22 to evacuate the vacuum chuck 7 through the first suction pipe 2, the second suction pipe 3, and the third suction pipe 4, so that the vacuum chuck 7 is adsorbed and bonded with the silicon carbide ingot.

[0045] Step S5: Use booster pump 20 to pressurize the sealing cavity 16 to the set pressure value.

[0046] In this embodiment, the maximum pressure achievable by pressurization is 3-4 MPa, which is sufficient to meet the requirements for silicon carbide wafer stripping. This device generates a pressure far exceeding conventional levels (greater than 1 kg / cm²) on the vacuum chuck 7 by applying pressure to the sealed cavity 16. 2 This provides the necessary mechanical conditions for the stripping of the crystal ingot 30.

[0047] In this embodiment, the pressure generated by the preset pressure value in the sealed cavity 16 is greater than the pressure required for wafer separation.

[0048] In this embodiment, the external booster pump 20 is a gas booster pump 20, and the gas is air, nitrogen, or other suitable gas. In other embodiments, the external booster pump 20 is a liquid booster pump 20, and the liquid is water or other suitable hydraulic oil.

[0049] In this embodiment, the pressurization step of the sealing cavity 16 includes: first, checking the connection between the movable substrate 18 and the sealing cavity 16 to determine that the sealing cavity 16 is embedded in the sealing groove 29 on the movable substrate 18 where the sealing ring 28 has been installed, so that a sealed space is formed in the sealing cavity 16; then, turning on the booster pump 20; and finally, injecting compressed air into the sealing cavity 16 through the pipeline. When the pressure in the sealing cavity 16 reaches the preset value, the pressurization is stopped.

[0050] Step S6: Use a lifting mechanism to lift the vacuum chuck 7, so that the silicon carbide wafer is separated from the silicon carbide ingot to form an independent wafer.

[0051] In this embodiment, the step of lifting the vacuum suction cup 7 includes: starting the coaxial motor and rotating in the reverse direction, driving the trapezoidal lead screw 12 to rise, the suction cup connecting column 6 connected below the trapezoidal lead screw 12 and the vacuum suction cup 7 rising with the trapezoidal lead screw 12, and stopping the reverse rotation of the coaxial motor when the load force fed back by the force sensor 11 becomes smaller.

[0052] As the vacuum chuck 7 rises, the upper part of the silicon carbide ingot receives an upward pulling force, causing the portion above the modified layer 31 to be pulled apart from the ingot 30 to form an independent wafer.

[0053] Step S7: Depressurize the sealed cavity 16 and lower the movable substrate 18 to remove the silicon carbide wafer.

[0054] In this embodiment, the steps of depressurizing the sealed cavity 16 and removing the wafer include: depressurizing the sealed cavity 16 to atmospheric pressure; venting air from the inlet / outlet 25-6 of the rear end cover 25-5 of the cylinder 25 and venting air from the inlet / outlet 25-7 of the front end cover 25-2, causing the piston 25-4 to move the piston rod 26 downward, while the piston rod 26 connected to the floating module 27 moves the movable substrate 18 downward along the substrate guide rail 8 and the substrate guide rail 9; breaking the vacuum of the vacuum chuck 7 and removing the wafer from the vacuum chuck 7, thus completing the stripping of the wafer from the ingot 30.

[0055] Step S8: Repeat steps S1-S7 to form multiple separate wafers.

[0056] In this embodiment, the removed wafers and the remaining ingots 30 are ground, and a modified layer 31 is formed again inside the ground ingots 30. Steps 1 to 7 are repeated to separate the silicon carbide ingots into multiple independent silicon carbide wafers.

[0057] The sealed cavity 16 of the device can be pressurized externally up to 4MPa. The following calculations are performed for the adsorption force in each area, specifically for the first suction cup (6 inches outer diameter, 4 inches inner diameter), the second suction cup (4 inches outer diameter, 2 inches inner diameter), and the central suction cup (a vacuum suction cup 7 with a diameter of 2 inches). Regarding the calculation of the suction force of the vacuum suction cup 7, the suction cup creates negative pressure by expelling internal air, and the external air pressure presses the suction cup tightly against the surface to be suctioned; the force generated is called the suction force. The calculation formula is: F=ΔP*A Where F is the adsorption force (unit: Newton, N), ΔP is the difference between the external air pressure and the internal air pressure of the suction cup (unit: Pascal, Pa), and A is the effective adsorption area of ​​the suction cup (unit: square meter, m²). 2 ).

[0058] Also, ΔP = (Pex - Pin), where Pex is the external environmental pressure and Pin is the internal environmental pressure.

[0059] Assuming the vacuum level in different regions is adjustable from 10% to 90%, when the external ambient pressure is 4 MPa, Pex = 4 MPa = 4 × 10⁶ Pa When the vacuum degree is 10%, the maximum pin pressure is 4 × (1 - 0.1) = 3.6 MPa. When the vacuum degree is 90%, the minimum pin pressure is 4 × (1 - 0.9) = 0.4 MPa. Therefore, the adjustable range of Pin is 0.4-3.6 MPa; The adjustable range of suction force for each of the three suction cups is calculated below: First suction cup: Suction cup area: A1 = π × (R01 - Ri1) 2 =0.010134m 2 Adsorption force range: Minimum adsorption force Fmin = (4MPa - 3.6MPa) × A1 = 4053.6N The maximum adsorption force Fmax = (4MPa - 0.4MPa) × A1 = 36482.4N Second suction cup: Suction cup area: A2 = π × (R02 - Ri2) 2 =0.006080m 2 Adsorption force range: Minimum adsorption force Fmin = (4MPa - 3.6MPa) × A1 = 2432.0N Maximum adsorption force Fmax = (4MPa - 0.4MPa) × A1 = 21888.0 N Third suction cup: Suction cup area: A3 = π × (R03 - Ri3) 2 =0.002027m 2 Adsorption force range: Minimum adsorption force Fmin = (4MPa - 3.6MPa) × A1 = 810.8N The maximum adsorption force Fmax = (4MPa - 0.4MPa) × A1 = 7297.2N Under these conditions, the adjustable adsorption force ratio of the three different adsorption regions from the outside to the inside is: 45~5:27~3:1~9.

[0060] The outer ring has the strongest adhesion, used to open the wafer edge. Once the edge is opened, the wafer peeling force decreases instantly. The internal adhesion, while ensuring wafer peeling, also provides a flexible force, ensuring that the wafer does not break during the peeling process.

[0061] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wafer stripping device for laser-induced modified crystal ingots, characterized in that, The device includes a sealed cavity (16) connected to a booster pump (20). The sealed cavity (16) is equipped with a vacuum displacement stage (32) for positioning and adsorbing crystal ingots (30) and a vacuum chuck (7) facing the vacuum displacement stage (32). The vacuum chuck (7) is driven and connected to a lifting mechanism. The vacuum displacement stage (32) is provided with multiple adsorption holes. The vacuum chuck (7) includes multiple concentrically arranged and physically separated sub-chucks. Each sub-chuck has multiple ventilation holes (7-5) on its adsorption surface. The ventilation holes (7-5) of each sub-chuck are connected to a regional adsorption force adjustment device (1) through an independent air extraction pipe. The regional adsorption force adjustment device (1) is connected to a vacuum pump (22) and is used to control the adsorption force of each sub-chuck.

2. The wafer stripping device for laser-induced modified ingots according to claim 1, characterized in that, The vacuum suction cup (7) includes three sub-suction cups separated by a partition wall (7-7), namely a first annular sub-suction cup (7-1), a second annular sub-suction cup (7-2), and a third circular sub-suction cup (7-3). The first sub-suction cup (7-1) is located outside the second sub-suction cup (7-2), and the third sub-suction cup (7-3) is located inside the second sub-suction cup (7-2).

3. The wafer stripping device for laser-induced modified ingots according to claim 2, characterized in that, Each of the sub-suction cups has multiple suction cup adsorption grooves (7-6) on its adsorption surface. Each of the suction cup adsorption grooves (7-6) is separated from each other by a partition edge (7-4). The vent hole (7-5) is located in the suction cup adsorption groove (7-6).

4. The wafer stripping device for laser-induced modified ingots according to claim 3, characterized in that, The suction cup adsorption grooves (7-6) are distributed in a grid pattern, and the vent holes (7-5) are located at the intersection of the dividing edges (7-4).

5. The wafer stripping device for laser-induced modified ingots according to claim 1, characterized in that, The regional adsorption force adjustment device (1) includes multiple air inlets, the number of which is the same as the number of sub-suction cups. Each air inlet is connected to a suction pipe, and each air inlet is equipped with an adjustment valve.

6. The wafer stripping device for laser-induced modified ingots according to claim 5, characterized in that, The regional adsorption force adjustment device (1) is a four-way air pipe (1-1) with one air outlet and three air inlets. The three air inlets are respectively connected to the first air extraction pipe (2), the second air extraction pipe (3) and the third air extraction pipe (4), and the three air inlets are respectively equipped with a first regulating valve (1-2), a second regulating valve (1-3) and a third regulating valve (1-4).

7. The wafer stripping device for laser-induced modified ingots according to claim 1, characterized in that, The booster pump (20) is a gas booster pump or a liquid booster pump.

8. The wafer stripping device for laser-induced modified ingots according to claim 1, characterized in that, The lifting mechanism is a screw jack or a hydraulic jack.

9. A wafer stripping device for laser-induced modified ingots according to claim 8, characterized in that, The lifting mechanism is a screw jack. The screw jack is set on the device support frame (17) outside the sealed cavity (16). The main shaft motor (10) of the screw jack is fixed on the second support base plate (14) at the top of the device support frame (17). The trapezoidal screw (12) of the screw jack passes through the second support base plate (14) and is fixed to the suction cup connecting column (6) at the top of the vacuum suction cup (7) by bearing. The screw nut (13) of the screw jack is fixed in conjunction with the main shaft of the main shaft motor (10).

10. The wafer stripping device for laser-induced modified ingots according to claim 1, characterized in that, The bottom of the vacuum displacement stage (32) is fixed on a movable substrate (18). The bottom of the movable substrate (18) is fixed on the top of the free end of the piston rod (26) of a cylinder (25). The piston rod (26) of the cylinder (25) is pushed against the bottom of the movable substrate (18) through a floating module (27). The movable substrate (18) is slidably inserted with substrate guide rail one (8) and substrate guide rail two (9) on both sides outside the sealed cavity (16).

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