A three-step exfoliation method based on gallium oxide exfoliation device

Abstract

The application discloses a three-step peeling method based on a gallium oxide peeling device, and belongs to the technical field of gallium oxide wafer processing. The method comprises the following steps: a control unit controls a moving unit to move a wafer to a pre-cutting unit, and the control unit starts the pre-cutting unit to cut the circumference of the wafer; the control unit controls the moving unit to move the wafer to a laser processing unit, and the control unit starts the laser processing unit to emit laser; and the control unit controls the moving unit to move the wafer to a separation unit, and the separation unit pulls the wafer in the opposite direction to make the wafer peel into two parts along a separation surface. The method has the beneficial effects that a pre-cutting unit is used to pre-segment the circumference of the wafer, then a laser processing unit is used to modify the wafer by low-power laser, and finally a separation unit is used to peel the wafer, so that the loss of gallium oxide is reduced, and the micro-cracks near the modified layer are reduced.

Description

Technical Field

[0001] This application relates to the field of gallium oxide wafer processing technology, and more specifically, to a three-step stripping method based on a gallium oxide stripping device. Background Technology

[0002] Gallium oxide (β-Ga₂O₃), as a next-generation semiconductor material, possesses advantages such as an ultra-wide bandgap, high breakdown electric field strength, high ultraviolet transmittance, and stable physicochemical properties, making it widely applicable in microelectronics, optoelectronics, and power devices. In microelectronics, gallium oxide, due to its rapid response to high-frequency electric fields, is used in the manufacture of devices such as high-frequency field-effect transistors, surface acoustic wave filters, and microwave switches. In optoelectronics, its bandgap matches that of visible light, making it suitable for devices such as LED lamps, thin-film solar panels, and novel photoelectric sensors. In power devices, gallium oxide exhibits a wide bandgap (~4.8 eV), enabling it to operate at higher voltages and power densities, demonstrating greater performance potential compared to silicon carbide.

[0003] Currently, gallium oxide wafers are primarily diced using diamond wire saws, but this method results in significant gallium oxide loss. To address this, patent document 202211507127.3 proposes a method for separating β-Ga₂O₃. This patent suggests using an ultrashort pulse laser with a predetermined wavelength to irradiate the interior of gallium oxide. The laser is focused at a specific thickness from the surface, causing a two-photon absorption process. The resulting high temperature induces thermal modification of the gallium oxide, thereby achieving the purpose of stripping it off. While this method can reduce gallium oxide loss, in practice, directly using laser modification to strip the gallium oxide can lead to several problems. If the laser peak power is too high, excessive microcracks will appear near the modified layer, prolonging the subsequent polishing process and increasing the actual loss. If the laser peak power is too low, adhesion will remain between the wafers above and below the modified layer, making separation difficult. Summary of the Invention

[0004] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0005] To address the technical problems mentioned in the background section, some embodiments of this application provide a three-step stripping method based on a gallium oxide stripping device. The gallium oxide stripping device comprises: a pre-cutting unit for circumferentially cutting a separation surface around the wafer; a laser processing unit emitting a low-power laser beam, which is focused on a focal plane inside the wafer to form a laser spot; a separation unit for pulling the wafer portions on both sides of the separation surface in the opposite direction; a moving unit for clamping the wafer and sequentially moving it to the pre-cutting unit, the laser processing unit, and the separation unit; and a control unit for controlling and coordinating the operation of the pre-cutting unit, the laser processing unit, the separation unit, and the moving unit. The three-step stripping method includes: the control unit controlling the moving unit to move the wafer to the pre-cutting unit, and the control unit initiating the pre-cutting unit to circumferentially cut the wafer; the control unit controlling the moving unit to move the wafer to the laser processing unit, and the control unit initiating the laser processing unit to emit a laser beam; the control unit controlling the moving unit to move the wafer to the separation unit, and the control unit controlling the separation unit to pull the wafer in the opposite direction, causing the wafer to be stripped into two parts along the separation surface.

[0006] Furthermore, the pre-cutting unit includes: a cutting line and a power module; the cutting line forms line contact with the circumference of the wafer, and the power module is connected to the cutting line, causing the cutting line to rub the circumference of the wafer around the axis of the wafer.

[0007] Furthermore, the power module includes a power component and a traction line; the two ends of the traction line are fixed to the two ends of the cutting line respectively, the middle part of the traction line is fixed to the output end of the power component, and the power component causes the traction line to pull the cutting line.

[0008] Furthermore, two dicing lines are provided. Each dicing line forms line contact with half a circumference of the wafer.

[0009] Furthermore, the laser processing unit includes: a laser, an optical scanning module, and a focusing module; the laser emits a laser beam toward the wafer; the optical scanning module is electrically connected to the laser and scans the focusing plane of the wafer; the focusing module is placed on the opposite side of the laser and is used to focus the laser beam into a laser spot on the focusing plane.

[0010] Furthermore, the separation unit includes a coating module and a pulling module; the coating module covers a set of thin films on each of the wafer portions on both sides of the separation surface, and the pulling module clamps the two sets of thin films and pulls the two sets of thin films in opposite directions.

[0011] Furthermore, the moving unit includes a conveying module and a mechanical gripper; the mechanical gripper fixes the wafer, the mechanical gripper is connected to the conveying module, and the conveying module causes the conveying mechanical gripper to move sequentially to the pre-cutting unit, the laser processing unit, and the separation unit.

[0012] Furthermore, the effective length L of the cutting line is related to the diameter D of the wafer as L = 1 / 2π × D, and the radial cutting depth d ranges from 2%D to 5%D.

[0013] Furthermore, the laser beam emitted by the laser has a wavelength of 310nm to 380nm, a pulse width of less than 50ps, a peak power of the pulse between 50kW and 500kW, and a repetition frequency greater than 100kHz.

[0014] The beneficial effects of this application are as follows:

[0015] The pre-cutting unit pre-divides the circumference of the wafer, and then the laser processing unit performs low-power laser refining. Finally, the separation unit peels off the wafer, thereby reducing gallium oxide loss and microcracks near the refining layer. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application.

[0017] Furthermore, throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the elements are not necessarily drawn to scale.

[0018] In the attached diagram:

[0019] Figure 1 This is a flowchart of the three-step stripping method according to this application.

[0020] Figure 2 This is an overall schematic diagram of the gallium oxide stripping apparatus according to this application;

[0021] Figure 3 The bonding relationship between the wafer and the thin film is shown;

[0022] Figure 4 The distribution of the separation surfaces on the circumference of the wafer is shown.

[0023] Figure label:

[0024] 1. Pre-cutting unit; 11. Power unit; 12. Traction line; 13. Cutting line; 2. Laser processing unit; 21. Laser; 22. Optical scanning module; 23. Focusing module; 31. Coating module; 311. Coating controller; 312. Clamping fixture; 313. Coating device; 32. Pulling module; 321. Pulling controller; 322. Pulling claw; 4. Moving unit; 41. Conveying module; 42. Mechanical claw; 5. Control unit. Detailed Implementation

[0025] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0026] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0027] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0028] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0029] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Reference Figure 1-4 ,

[0031] A three-step stripping method based on a gallium oxide stripping device includes: a pre-cutting unit 1, a laser processing unit 2, a separation unit, a moving unit 4, and a control unit 5. The control unit 5 is an existing PLC control system used to control and coordinate the operation of the pre-cutting unit 1, laser processing unit 2, separation unit, and moving unit 4. The control unit 5 controls the moving unit 4 to sequentially move the wafer to the pre-cutting unit 1, laser processing unit 2, and separation unit for processing. First, the pre-cutting unit 1 circumferentially cuts the wafer; then, the laser processing unit 2 modifies the interior of the wafer; finally, the separation unit strips the wafer into two parts along the separation surface. The pre-cutting unit 1 is a wire dicing machine used to cut a shallow annular separation surface on the circumference of the wafer, with a depth of 2% to 5% of the wafer diameter, to reduce the overall strength of the circumferential portion of the wafer, thereby reducing the power required for the laser emitted by the subsequent laser processing unit 2. The laser processing unit 2 emits a low-power laser beam. In this embodiment, the laser beam is a pulsed beam with a wavelength of 310nm to 380nm, a pulse width of less than 50ps, a peak power between 50kW and 500kW, and a repetition frequency greater than 100kHz. The laser beam is focused on the focusing plane inside the wafer, causing gallium oxide near the focusing plane to be modified. The separation unit pulls the wafer portions on both sides of the separation surface in the opposite direction. Because the circumference of the wafer is cut by the pre-cutting unit 1 and the interior is modified by the laser processing unit 2, the overall strength of the wafer near the separation surface and the focusing plane decreases, so the separation unit can easily peel the wafer into two parts along the separation surface.

[0032] The three-step separation method includes: First, control unit 5 controls moving unit 4 to move the wafer to pre-cutting unit 1, where control unit 5 activates pre-cutting unit 1 to cut a separation surface around the wafer's circumference. Second, control unit 5 controls moving unit 4 to move the wafer to laser processing unit 2, where control unit 5 activates laser processing unit 2 to emit a low-power laser focused on a focal plane inside the wafer, causing thermal modification of the wafer's interior. Third, control unit 5 controls moving unit 4 to move the wafer to separation unit, where control unit 5 controls separation unit to pull the upper and lower end faces of the wafer in the opposite direction, separating the wafer into two parts along the separation surface and the focal plane.

[0033] Specifically, the pre-cutting unit 1 includes a cutting wire 13 and a power module. The cutting wire 13 is a diamond wire that forms a line contact around the circumference of the wafer. The power module is connected to the cutting wire 13 and causes the cutting wire 13 to rub the circumference of the wafer at high speed around the wafer's axis, thereby cutting an annular separation surface on the circumference of the wafer.

[0034] Specifically, the power module includes a power component 11 and a traction line 12. The two ends of the traction line 12 are wound and fixed to the two ends of the cutting line 13. The power component 11 is a motor, and the middle part of the traction line 12 is wound and fixed to the output end of the power component 11. The high-speed rotation of the output end of the power component causes the traction line 12 to pull the cutting line 13 to perform cutting.

[0035] Specifically, two dicing lines 13 are provided. Each dicing line 13 forms line contact with half of the circumference of the wafer, that is, the effective length L of each dicing line is related to the diameter D of the wafer as L = 1 / 2π × D. The two dicing lines 13 are arranged opposite each other on both sides of the wafer, and the two dicing lines 13 cut the wafer simultaneously to improve the pre-dicing efficiency.

[0036] Specifically, the laser processing unit 2 includes a laser 21, an optical scanning module 22, and a focusing module 23. The laser 21 emits a laser beam towards the wafer. The optical scanning module 22 is an existing line laser scanner, electrically connected to the laser 21. The optical scanning module 22 scans the focusing plane inside the wafer to form a scanning trajectory. The control system then controls the laser 21 to emit a laser beam, which follows the scanning trajectory to irradiate the focusing plane. The focusing module 23 is an existing lens assembly, positioned opposite the laser 21. It focuses the laser beam into a laser spot on the focusing plane. The gallium oxide at the laser spot's irradiation location heats up and undergoes remodeling, thereby generating microcracks inside the wafer.

[0037] Specifically, the separation unit includes a coating module 31 and a pulling module 32. The coating module 31 is an existing wafer coating machine integrating a coating controller 311, a clamping fixture 312, and a coating applicator 313. The coating controller 311 controls the clamping fixture 312 to fix the wafer transported by the moving unit 4, and the coating controller 311 then controls the coating applicator 313 to cover each of the wafer portions on both sides of the separation surface with a set of thin films. The pulling module 32 is an existing technology product integrating a pulling controller 321 and a pulling claw 322. The pulling claw 322 clamps two sets of thin films, and the pulling controller 321 controls the pulling claw 322 to pull the two sets of thin films in the opposite direction. Since the wafer is relatively fragile near the separation surface and the focusing plane, the two sets of thin films can easily drive the two parts of the wafer to be separated into two parts along the separation surface and the focusing plane.

[0038] Specifically, the moving unit 4 includes a conveying module 41 and a mechanical gripper 42. The mechanical gripper 42 is used to hold the wafer. The mechanical gripper 42 is connected to the conveying module 41, which uses an electromagnetic track. The mechanical gripper 42 is fixed to the moving part on the electromagnetic track. The conveying module 41 moves the conveying mechanical gripper 42 sequentially to the pre-cutting unit 1, the laser processing unit 2, and the separation unit.

[0039] The above description is merely a selection of preferred embodiments of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A three-step stripping method based on a gallium oxide stripping device, characterized in that, The gallium oxide stripping device includes: A pre-cutting unit is used to cut a separation surface around the circumference of the wafer; The laser processing unit emits a low-power laser beam, which is focused on a focal plane inside the wafer to form a laser spot. Separation unit, used to pull the wafer portions on both sides of the separation surface in the opposite direction; A moving unit is used to clamp the wafer and move the wafer sequentially to the pre-cutting unit, the laser processing unit, and the separation unit; A control unit is used to control and coordinate the operation of the pre-cutting unit, the laser processing unit, the separation unit, and the moving unit; The three-step stripping method includes: The control unit controls the moving unit to move the wafer to the pre-cutting unit, and the control unit starts the pre-cutting unit to perform circumferential cutting on the wafer; The control unit controls the moving unit to move the wafer to the laser processing unit, and the control unit activates the laser processing unit to emit laser light. The control unit controls the moving unit to move the wafer to the separating unit, and the control unit controls the separating unit to pull the wafer in the opposite direction so that the wafer is peeled into two parts along the separating surface; The pre-cutting unit includes: a cutting line and a power module; the cutting line forms line contact with the circumference of the wafer, and the power module is connected to the cutting line and causes the cutting line to rub the circumference of the wafer around the axis of the wafer; The laser processing unit includes a laser, an optical scanning module, and a focusing module; the laser emits a laser beam toward the wafer; the optical scanning module is electrically connected to the laser and scans the focusing plane of the wafer; the focusing module is located on the opposite side of the laser and is used to focus the laser beam into a laser spot on the focusing plane. The separation unit includes a coating module and a pulling module; the coating module covers a set of thin films on each of the wafer portions on both sides of the separation surface, and the pulling module clamps the two sets of thin films and pulls the two sets of thin films in opposite directions; The effective length L of the cutting line is related to the diameter D of the wafer as L = 1 / 2π × D, and the radial cutting depth d ranges from 2%D to 5%D. The laser emits a laser beam with a wavelength of 310nm to 380nm, a pulse width of less than 50ps, a peak power between 50kW and 500kW, and a repetition frequency greater than 100kHz.

2. The three-step stripping method based on a gallium oxide stripping device according to claim 1, characterized in that: The power module includes a power component and a traction line; the two ends of the traction line are fixed to the two ends of the cutting line, the middle part of the traction line is fixed to the output end of the power component, and the power component causes the traction line to pull the cutting line.

3. The three-step stripping method based on a gallium oxide stripping device according to claim 2, characterized in that: Two cutting lines are provided, and each cutting line forms a line contact with half of the circumference of the wafer.

4. The three-step stripping method based on a gallium oxide stripping device according to claim 3, characterized in that: The moving unit includes a conveying module and a mechanical gripper; the mechanical gripper fixes the wafer, and the mechanical gripper is connected to the conveying module, which causes the conveying mechanical gripper to move sequentially to the pre-cutting unit, the laser processing unit, and the separation unit.

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