Apparatus and method for uniform exfoliation of semiconductor material

Abstract

The application discloses a device and method for uniformly peeling semiconductor material, which is characterized in that a high-speed camera is arranged behind a focusing system, a CCD camera is arranged in front of the focusing system, the high-speed camera is used to shoot the crack length L1 of the first position of the first machining path when the semiconductor material is induced to be modified by the laser, the incident laser intensity is adjusted according to the crack length L1, and the crack expansion length induced by the laser at the subsequent machining position is kept uniform; meanwhile, the CCD camera is used to shoot the crack expansion length L2 of the first position at the current shooting time when the laser moves to the second position of the second machining path along the set machining path, the incident laser intensity is adjusted according to the crack expansion length L2, and the crack length L3 induced by the laser at the position when the laser moves to the third position of the second machining path satisfies the relationship L2+L3=L, the uniformity of the laser modification is improved, and the machining precision of the laser modification and peeling is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material processing, and more particularly to an apparatus and method for uniformly peeling off semiconductor materials. Background Technology

[0002] With the rapid development of the semiconductor industry, third-generation semiconductor materials, represented by diamond, silicon carbide, and gallium nitride, have begun to be widely used in various fields. Third-generation semiconductors possess superior properties such as wider bandgap, higher breakdown threshold, and higher thermal conductivity, making them highly promising for applications in aerospace, new energy vehicles, and high-field devices. However, due to their high hardness and brittleness, third-generation semiconductors are extremely difficult to process. Traditional contact cutting methods, such as multi-wire cutting, suffer from low efficiency and high losses.

[0003] Patent "CN110010519A" describes a method for laser-induced material modification combined with exfoliation technology to achieve non-contact cutting and thinning of silicon carbide materials. However, existing semiconductor laser modification and exfoliation technologies all face material problems such as uneven resistivity distribution and random impurity distribution. This introduces many uncertainties into the crack propagation process during laser-induced modification, making the precision of crack propagation uncontrollable. These core issues have a significant impact on processing quality.

[0004] Traditional contact processing methods suffer from high losses and low efficiency, while existing laser-modified stripping methods cannot avoid the processing accuracy problems caused by material inhomogeneity. Therefore, there is an urgent need to invent a more precise device and method for uniformly stripping semiconductor materials using lasers. This is of great significance for improving the processing accuracy of third-generation semiconductors and expanding their application range. Summary of the Invention

[0005] In view of this, the present invention provides an apparatus and method for uniformly stripping semiconductor materials. The present invention uses a high-speed camera positioned behind a focusing system and a CCD camera positioned in front of the focusing system. The high-speed camera captures the crack length L1 at a first position on a first processing path when the laser induces semiconductor material modification at that position at the current capture time. The crack propagation velocity V1 is calculated based on the crack length L1. The propagation velocity V1 is then used to estimate the crack propagation length L2′ at the first position when the laser moves to a third position on a second processing path at the current moment. The incident laser intensity is adjusted in real time by combining the crack propagation length L2′ and the crack propagation velocity V1 to ensure that the laser propagates at subsequent processing positions. The crack propagation length induced by the laser is maintained at L / 2. Simultaneously, a CCD camera is used to capture the crack propagation length L2 at the first position when the laser moves along the set processing path to the second position of the second processing path. Based on the crack propagation length L2, the intensity of the incident laser is adjusted so that when the laser moves to the third position of the second processing path, the crack length L3 induced by the laser at that position satisfies the relationship L2+L3=L. This connects the cracks at the first position on two adjacent processing paths with the cracks at the third position, thereby improving the uniformity of laser refining and the processing accuracy of laser refining ablation, providing reliable assistance for improving the success rate of laser refining semiconductor materials.

[0006] A method for uniformly peeling off semiconductor material specifically includes the following steps:

[0007] S1, the laser focus of the laser processing device is focused on the position inside the semiconductor material that needs to be thinned and peeled off, and the semiconductor material is laser processed;

[0008] S2, when the laser induces the semiconductor material to change and generate cracks at the first position of the first processing path, the crack length L1 at that position at the current shooting moment is recorded by a high-speed camera;

[0009] The intensity of the incident laser is adjusted according to the crack length L1 to ensure that the crack propagation length induced by the laser in subsequent processing positions remains uniform.

[0010] S3, when the laser moves along the set processing path to the second position of the second processing path, the CCD camera records the crack propagation length L2 at the first position at the current shooting moment;

[0011] The incident laser intensity is adjusted based on the crack propagation length L2 at the first position when the laser moves to the second position on the second processing path, so that when the laser moves to the third position on the second processing path, the crack length L3 induced by the laser at that position satisfies the relationship L2 + L3 = L.

[0012] The second processing path is adjacent to the first processing path, the distance between the first processing path and the second processing path is L, the abscissa of the third position on the second processing path is equal to that of the first position on the first processing path, the second position on the second processing path is located before the third position and the abscissas of the two are continuous.

[0013] S4, the laser-modified semiconductor material is removed from the laser processing device and placed in the stripping device for stripping, thereby realizing the laser-modified stripping process of the semiconductor material.

[0014] Preferably, the specific steps in step S2, which involve adjusting the incident laser intensity according to the crack length L1 to ensure that the crack propagation length induced by the laser at the subsequent processing position remains uniform, are as follows:

[0015] Calculate the crack propagation velocity V1 based on the crack length L1 and the delay time Δt of the high-speed camera image.

[0016] The intensity of the incident laser is adjusted according to the relationship between the incident laser intensity and the crack propagation velocity V1, so that the crack propagation length induced by the laser in subsequent processing positions remains uniform.

[0017] Preferably, before adjusting the incident laser intensity according to the relationship between the incident laser intensity and the crack propagation velocity V1, it is also necessary to estimate the crack propagation length L2′ at the current moment when the laser moves to the third position of the second processing path; then, combined with the crack propagation length L2′ at the current moment when the laser moves to the third position of the second processing path, the incident laser intensity is adjusted according to the relationship between the incident laser intensity and the crack propagation velocity V1 so that the crack propagation length induced by the laser at the subsequent processing position is kept at L / 2.

[0018] Preferably, the relationship between the incident laser intensity and the crack propagation velocity V1 is as follows:

[0019] When the crack propagation velocity V1 is between 50 μm / s and 200 μm / s, the incident laser intensity can be adjusted within a range of 0.5 GW / cm². 2 -1GW / cm 2 ;

[0020] When the crack propagation velocity V1 is 200 μm / s-400 μm / s, the incident laser intensity can be adjusted within the range of 1 GW / cm. 2 -2GW / cm 2 ;

[0021] When the crack propagation velocity V1 is 400 μm / s-800 μm / s, the incident laser intensity can be adjusted within a range of 2 GW / cm. 2 -4GW / cm 2;

[0022] When the crack propagation velocity V1 is 800 μm / s-1300 μm / s, the incident laser intensity can be adjusted within a range of 4 GW / cm. 2 -8GW / cm 2 .

[0023] Preferably, the crack propagation rate V1 = L1 / Δt;

[0024] When the laser moves to the third position of the second processing path, the length of the crack at the first position at the current moment is L2′=V1*t, where t is the time required for the laser to move from the first position of the first processing path to the third position of the second processing path.

[0025] Preferably, in step S3, when adjusting the incident laser intensity based on the crack propagation length L2 at the first position when the laser moves to the second position of the second processing path,

[0026] When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 100μm-150μm, the incident laser intensity can be adjusted within the range of 0.5GW / cm². 2 -1 GW / cm 2 ;

[0027] When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 150μm-200μm, the incident laser intensity can be adjusted within the range of 1GW / cm². 2 -2 GW / cm 2 ;

[0028] When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 200μm-250μm, the incident laser intensity can be adjusted within a range of 2GW / cm². 2 -4 GW / cm 2 ;

[0029] When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 250μm-300μm, the incident laser intensity can be adjusted within a range of 4GW / cm². 2 -8GW / cm 2 .

[0030] Preferably, the height camera is positioned behind the focusing system of the laser processing device, and the CCD camera is positioned in front of the focusing system of the laser processing device.

[0031] An apparatus for uniformly peeling off semiconductor material includes a laser for emitting two parallel laser beams, a focusing system disposed in the reflection direction of the laser beam path to focus the reflected light onto the desired thinning and peeling position inside the semiconductor material, and a computer.

[0032] The focusing system is mounted on the Z-axis displacement platform, the semiconductor material is placed on the XY-axis displacement platform, a high-speed camera is set behind the focusing system, and a CCD camera is set in front of the focusing system. The high-speed camera is used to capture the crack length L1 at the current shooting moment when the laser induces the semiconductor material to change at the first position of the first processing path, and transmit the captured data to the computer. The computer controls and adjusts the incident laser intensity according to the received data so that the crack propagation length induced by the laser at subsequent processing positions remains uniform.

[0033] The CCD camera is used to capture the length L2 of the crack expansion at the first position when the laser moves along the set processing path to the second position of the second processing path, and transmits the captured data to the computer. The computer controls and adjusts the intensity of the incident laser light according to the received data so that when the laser moves to the third position of the second processing path, the length L3 of the crack induced by the laser at that position satisfies the relationship L2+L3=L, where L is the distance between the first processing path and the second processing path.

[0034] Preferably, the laser optical path is provided with, in sequence along the direction of light propagation, an attenuator for adjusting the intensity of the laser beam, a beam expander for increasing the diameter of the laser beam, and a laser reflector for reflecting the laser beam to the focusing system.

[0035] Preferably, the laser emits a laser wavelength range of 300-1100nm, a laser pulse width range of 100fs to 100ps, and a laser energy adjustment range of 20μJ to 100μJ.

[0036] The beam expander has an expansion ratio of 1:2 to 1:5.

[0037] The beneficial effects of this invention are:

[0038] 1. This invention uses a high-speed camera positioned behind the focusing system and a CCD camera positioned in front of the focusing system. The high-speed camera captures the crack length L1 at the first position of the first processing path when the laser induces semiconductor material modification. Based on the crack length L1, the crack propagation velocity V1 is calculated. Based on the crack propagation velocity V1, the propagation length L2′ of the crack at the first position when the laser moves to the third position of the second processing path is estimated. The incident laser intensity is adjusted in real time by combining the crack propagation length L2′ and the crack propagation velocity V1 to ensure that the crack propagation length induced by the laser at subsequent processing positions remains at L / 2, thus enabling the laser-modified crack to... More uniform, and better results can be achieved during peeling; at the same time, the CCD camera (10) is used to capture the length L2 of the crack at the first position when the laser moves to the second position of the second processing path along the set processing path. The intensity of the incident laser is adjusted according to the crack length L2 so that when the laser moves to the third position of the second processing path, the crack length L3 induced by the laser at that position satisfies the relationship L2+L3=L, so that the crack at the first position on the two adjacent processing paths is connected to the crack at the third position, thereby improving the uniformity of laser modification and improving the processing accuracy of laser modification peeling, providing reliable help to improve the success rate of laser modification of semiconductor materials.

[0039] 2. This invention utilizes the nonlinear effect generated during the interaction between laser and semiconductor materials to modify and propagate cracks in semiconductor materials from the inside. Compared with traditional contact processing methods, this reduces losses, improves processing efficiency, and brings better benefits.

[0040] 3. This invention can achieve intelligent adaptive laser thinning and peeling processing for any semiconductor material with different properties, materials, sizes, and functions, and has high applicability. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart of a method for uniformly stripping semiconductor materials according to the present invention.

[0043] Figure 2 This is a schematic diagram of a structure for uniformly peeling semiconductor material according to the present invention.

[0044] Figure 3 It is a block diagram of the computer's control principle.

[0045] Figure 4 This is a schematic diagram of the process for uniformly peeling off semiconductor materials according to the present invention.

[0046] Figure 5 This is a processing effect diagram of a uniformly peeled semiconductor material according to the present invention.

[0047] The labels in the diagram mean:

[0048] 1 - Laser, 2 - Attenuator, 3 - Beam expander, 4 - Mirror, 5 - Focusing system, 6 - Z-axis displacement platform, 7 - Semiconductor material, 8 - XY-axis displacement platform, 9 - High-speed camera, 10 - CCD camera, 11 - Computer, 12 - Laser-modified crack, 13 - Crack propagation rate analysis module, 14 - Empirical relationship analysis module between crack propagation size and incident laser intensity, 15 - First laser processing path in the experimental effect diagram, 16 - Second laser processing path in the experimental effect diagram, 17 - Laser-induced silicon carbide crystal modification propagation crack in the experimental effect diagram. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0050] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0051] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0052] Third-generation semiconductors, represented by diamond, silicon carbide, and gallium nitride, are increasingly widely used in aerospace, high-energy high-field, and new energy vehicle fields due to their excellent physical properties such as large bandgap and high breakdown threshold. However, the persistently high cost of third-generation semiconductor materials severely limits their large-scale application. This is due, on the one hand, to the complex growth processes and harsh growth conditions of third-generation semiconductor materials; and on the other hand, to the extremely difficult processing due to their high hardness and brittleness. Traditional contact processing methods result in significant material loss, with conventional processing losses approaching 1:1, while also being time-consuming and inefficient. The novel laser-induced rebar removal technology for semiconductor materials has attracted increasing attention. However, existing laser rebar removal methods have not solved the processing accuracy problem caused by the uneven distribution of material resistance and defects, thus limiting the success rate of laser rebar removal. Therefore, this paper proposes to analyze the speed of laser-induced crack propagation and the intensity of incident laser light by adding a high-speed camera 9 and a CCD camera 10 before and after the laser processing device. This allows for precise control of the crack propagation length, thereby improving processing accuracy and the success rate of rebar removal.

[0053] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0054] The present invention discloses an apparatus for uniformly stripping semiconductor material, comprising a laser 1 for emitting two parallel laser beams, a focusing system 5 disposed in the reflection direction of the laser beam path to focus the reflected light onto the desired thinning stripping position inside the semiconductor material 7, and a computer 11.

[0055] Along the direction of light propagation, the laser optical path is sequentially provided with an attenuator 2 for adjusting the intensity of the laser beam, a beam expander 3 for increasing the diameter of the laser beam, and a laser reflector 4 for reflecting the laser beam to the focusing system 6.

[0056] The focusing system 5 is mounted on the Z-axis displacement platform 6, which can move the focusing system 5 in the Z direction to focus the laser focus on the desired thinning and stripping position inside the semiconductor material 7. The semiconductor material 7 is disposed on the XY-axis displacement platform 8, which can move the semiconductor material 7 in the X and Y directions.

[0057] A high-speed camera 9 is installed behind the focusing system 5, and a CCD camera 10 is installed in front of the focusing system 5. The high-speed camera 9 is used to capture the crack length L1 at the current shooting moment when the laser induces the semiconductor material to change at the first position of the first processing path, and transmits the captured data to the computer 11. The computer 11 calculates the crack propagation speed V1 based on the crack length L1 and the delay time Δt of the high-speed camera 9 taking the picture, and sends a control signal to the attenuator 2 to adjust the incident laser intensity in real time according to the empirical relationship between the crack propagation speed V1 and the incident laser intensity, so that the crack propagation length induced by the laser at the subsequent processing position remains uniform. Preferably, in order to achieve a more uniform mechanical distribution and better peeling effect of semiconductor material during laser ablation, when the computer 11 receives the crack length L1, the computer 11 calculates the crack propagation speed V1 based on the crack length L1 and the delay time Δt of the high-speed camera 9 taking pictures. Based on the crack propagation speed V1, the computer 11 estimates the propagation length L2′ of the crack at the first position when the laser moves to the third position of the second processing path at the current moment. Combining the crack propagation length L2′ and the crack propagation speed V1, the computer 11 sends a control signal to the attenuator 2 to adjust the incident laser intensity in real time, so as to ensure that the crack propagation length induced by the laser at the subsequent processing position remains at L / 2, where L is the distance between the first processing path and the second processing path.

[0058] The CCD camera 10 is used to capture the expansion length L2 of the crack at the first position when the laser moves along the set processing path to the second position of the second processing path at the current shooting moment, and transmits the captured data to the computer 11. The computer 11 controls and adjusts the incident laser intensity according to the received data so that when the laser moves to the third position of the second processing path, the crack length L3 induced by the laser at that position satisfies the relationship L2+L3=L, so as to greatly improve the success rate of uniform peeling.

[0059] The second processing path is adjacent to the first processing path. The third position on the second processing path has the same x-coordinate as the first position on the first processing path. The second position on the second processing path is located before the third position, and their x-coordinates are continuous.

[0060] Computer 11 controls laser 1 to emit two parallel laser beams. The intensity of the incident laser beams is adjusted by attenuator 2, then the aperture of the incident laser is expanded by beam expander 3, and finally reflected by laser reflector 4 and incident perpendicularly into focusing system 5, and finally focused into semiconductor material 7. By adjusting Z-axis displacement platform 6, the laser focus is moved to the position inside semiconductor material 7 that needs to be peeled off, and by moving XY-axis displacement platform 8, the peeling process of semiconductor material 7 begins.

[0061] When the laser focus moves to the first position on the first processing path, the laser modifies the material at that position to induce cracks inside the material. However, since the crack length propagation is slow, the crack length L1 at the first position captured by the high-speed camera 9 is only the length of the crack extension at the moment of capture, not the final length of the crack at the first position. The sum of the final length L2 of the crack at the first position and the final length L3 of the crack at the third position should be equal to the distance L between the first and second processing paths to ensure that the laser-induced modified crack at a certain position is connected to the crack at the corresponding position on the adjacent path, thereby improving the uniformity of laser modification and the processing accuracy of laser modification and peeling. Therefore, during the laser processing, the intensity of the incident laser light needs to be adjusted according to the crack length captured by the high-speed camera 9 and the CCD camera 10.

[0062] In this embodiment, the laser wavelength emitted by laser 1 is in the range of 300-1100nm, the laser pulse width is in the range of 100fs to 100ps, and the laser energy of the laser emitted by the laser is adjustable in the range of 20μJ to 100μJ.

[0063] In this embodiment, the beam expansion ratio of the beam expander 3 is 1:2 to 1:5.

[0064] In this embodiment, semiconductor material 7 can be any semiconductor material such as diamond, silicon carbide, or gallium nitride.

[0065] This invention also provides a method for uniformly peeling off semiconductor materials, specifically including the following steps:

[0066] S1 focuses the laser focal point of the laser processing device on the location inside the semiconductor material that needs to be thinned and peeled off, and performs laser processing on the semiconductor material.

[0067] The device mentioned above refers to the apparatus for uniformly stripping semiconductor material.

[0068] S2, when the laser induces the semiconductor material to change and generate cracks at the first position of the first processing path, the crack length L1 at the current shooting moment is recorded using a high-speed camera; the intensity of the incident laser light is adjusted according to the crack length L1 so that the crack propagation length induced by the laser at subsequent processing positions remains uniform.

[0069] Specifically, the steps for adjusting the incident laser intensity based on the crack length L1 to ensure uniform crack propagation length induced by the laser at subsequent processing positions are as follows: First, calculate the crack propagation velocity V1 based on the crack length L1 and the delay time Δt of the high-speed camera image, where V1 = L1 / Δt; then, adjust the incident laser intensity according to the empirical relationship between the incident laser intensity and the crack propagation velocity V1 to ensure uniform crack propagation length induced by the laser at subsequent processing positions (i.e., the crack propagation length at each subsequent processing position is approximately equal).

[0070] For example, when the crack propagation velocity V1 is 50 μm / s-200 μm / s, the incident laser intensity can be adjusted within a range of 0.5 GW / cm². 2 -1 GW / cm 2 ;

[0071] When the crack propagation velocity V1 is 200 μm / s-400 μm / s, the incident laser intensity can be adjusted within the range of 1 GW / cm. 2 -2GW / cm 2 ;

[0072] When the crack propagation velocity V1 is 400 μm / s-800 μm / s, the incident laser intensity can be adjusted within a range of 2 GW / cm. 2 -4GW / cm 2 ;

[0073] When the crack propagation velocity V1 is 800 μm / s-1300 μm / s, the incident laser intensity can be adjusted within a range of 4 GW / cm. 2 -8GW / cm 2 .

[0074] In a preferred embodiment, to achieve a more uniform mechanical distribution and better peeling effect during laser ablation of semiconductor materials, the crack propagation length induced by the laser at each processing position should be kept at L / 2, even if the crack eventually extends to the center position of two adjacent processing paths. Therefore, in this embodiment, the step of adjusting the incident laser intensity according to the crack length L1 to keep the crack propagation length induced by the laser at subsequent processing positions uniform is as follows: First, calculate the crack propagation velocity V1 based on the crack length L1 and the delay time Δt of the high-speed camera, where V1 = L1 / Δt; then, estimate the laser displacement based on the crack propagation velocity V1. When the laser moves to the third position of the second processing path, the crack at the first position has an extension length L2′ at the current moment, where L2′ = V1*t, and t is the time required for the laser to move from the first position of the first processing path to the third position of the second processing path. Then, based on the extension length L2′ of the crack at the first position when the laser moves to the third position of the second processing path, the incident laser intensity is adjusted according to the empirical relationship between the incident laser intensity and the crack propagation velocity V1 (as described above) so that the crack propagation length induced by the laser at the subsequent processing position remains at L / 2.

[0075] S3, when the laser moves along the set processing path to the second position of the second processing path, the CCD camera records the crack propagation length L2 at the first position at the current shooting moment;

[0076] Then, based on the empirical relationship between the crack propagation length L2 at the first position when the laser moves to the second position of the second processing path and the incident laser intensity, the incident laser intensity is adjusted so that when the laser moves to the third position of the second processing path, the crack length L3 induced by the laser at that position satisfies the relationship L2 + L3 = L.

[0077] For example, when the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 100μm-150μm, the incident laser intensity can be adjusted within the range of 0.5GW / cm². 2 -1 GW / cm 2 ;

[0078] When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 150μm-200μm, the incident laser intensity can be adjusted within the range of 1GW / cm². 2 -2 GW / cm 2 ;

[0079] When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 200μm-250μm, the incident laser intensity can be adjusted within a range of 2GW / cm². 2 -4 GW / cm 2 ;

[0080] When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 250μm-300μm, the incident laser intensity can be adjusted within a range of 4GW / cm². 2 -8 GW / cm 2 .

[0081] S4. Following the above steps, continuously adjust the intensity of the incident laser and move the XY axis displacement platform 8 to complete the laser modification of the semiconductor material 7. Then, remove the laser-modified semiconductor material from the XY axis displacement platform 8 and place it on the peeling device for peeling, thereby realizing the laser modification and peeling process of the semiconductor material.

[0082] The specific embodiments of the present invention will be illustrated below with examples.

[0083] Assuming the semiconductor material 7 to be processed is a silicon carbide crystal with a diameter of 150 mm and a thickness of 25 mm, the laser emitted by the laser 1 is a laser beam with a wavelength of 1030 nm, a pulse width of 300 fs, a single pulse energy of 50 μJ, a repetition rate of 300 kHz, and a diameter of 6 mm, and the focusing system 5 is a microscope objective with a magnification of 20 times and a numerical aperture of 0.4.

[0084] The two parallel laser beams emitted by the laser 1 pass through the attenuator 2, the beam expander 3, and the reflector 4, and are reflected downwards through the focusing system 5 placed on the Z-axis displacement platform 6, and finally focused into the silicon carbide crystal 7. By moving the Z-axis displacement platform 6, the laser focus is moved to a depth of 200 μm from the surface inside the silicon carbide bulk crystal.

[0085] Then, the XY axis displacement platform is moved at a speed of 10m / s to begin laser modification of the silicon carbide crystal 7, with a spacing of 400μm between adjacent processing paths.

[0086] During the laser modification process, a high-speed camera 9 is placed 10mm behind the focusing system 5. When the laser moves to the first position of the first processing path, the high-speed camera 9 records the crack length L1 at the first position as 10μm. Then, based on the image delay time Δt of 100ms and the speed of the XY axis displacement platform of 10m / s, the crack propagation velocity can be calculated as 0.1*10^-3m / s. Assuming that the time t required for the laser to move from the first position of the first processing path to the third position of the adjacent second processing path is 1.5s, the time it takes for the laser to move to the third position of the second processing path can be estimated. The crack at the first location has a current propagation length L2′ of 150 μm. The propagation length L2′ has not reached the midpoint (200 μm) between the two adjacent processing paths. At this time, based on the empirical relationship between the incident laser intensity and the crack propagation velocity V1, by adjusting the laser attenuator 2, the incident laser intensity is increased from 0.6 GW / cm2 to 1.2 GW / cm2. This allows the crack to propagate as far as possible to half the distance (400 μm) between the adjacent paths (200 μm) when the laser processing position is moved to the same coordinate as the adjacent path. This improves the uniformity of crack propagation in laser-modified processes and ensures a more uniform mechanical distribution and better peeling effect during the peeling process.

[0087] Meanwhile, the CCD camera placed in front of the focusing system 5 records that when the laser moves to the second position of the second processing path, the crack propagation length L2 at the first position at the current shooting moment is 180μm. Since the second and third positions on the second processing path are adjacent, based on the empirical relationship between the incident laser intensity and the crack propagation distance L2, the incident laser intensity is increased from 1.6GW / cm2 to 2.3GW / cm2 by adjusting the laser attenuator 2. This ensures that when the laser moves to the third position of the second processing path, the crack length L3 induced by the laser at that position can reach 220μm, thereby connecting the cracks of the two adjacent processing paths, i.e., 180μm + 220μm = 400μm, thus improving the accuracy and uniformity of laser-modified crack propagation.

[0088] Finally, the laser-modified silicon carbide crystal is removed from the XY-axis displacement platform 8 and placed on the vacuum adsorption platform. The modified silicon carbide sheet is peeled off from the silicon carbide crystal by a mechanical pulling force of 30 Newtons, thus realizing the thinning and peeling process of the silicon carbide crystal.

[0089] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for uniformly peeling off semiconductor material, characterized in that, Specifically, the following steps are included: S1, the laser focus of the laser processing device is focused on the position inside the semiconductor material that needs to be thinned and peeled off, and the semiconductor material is laser processed; S2, when the laser induces the semiconductor material to change and generate cracks at the first position of the first processing path, the crack length L1 at that position at the current shooting moment is recorded by a high-speed camera; The intensity of the incident laser is adjusted according to the crack length L1 to ensure that the crack propagation length induced by the laser in subsequent processing positions remains uniform. S3, when the laser moves along the set processing path to the second position of the second processing path, the CCD camera records the crack propagation length L2 at the first position at the current shooting moment; The incident laser intensity is adjusted based on the crack propagation length L2 at the first position when the laser moves to the second position on the second processing path, so that when the laser moves to the third position on the second processing path, the crack length L3 induced by the laser at that position satisfies the relationship L2 + L3 = L. The second processing path is adjacent to the first processing path, the distance between the first processing path and the second processing path is L, the abscissa of the third position on the second processing path is equal to that of the first position on the first processing path, the second position on the second processing path is located before the third position and the abscissas of the two are continuous. S4, the laser-modified semiconductor material is removed from the laser processing device and placed in the stripping device for stripping, thereby realizing the laser-modified stripping process of the semiconductor material.

2. The method for uniformly peeling off semiconductor material according to claim 1, characterized in that, The specific steps in step S2, which involve adjusting the incident laser intensity based on the crack length L1 to ensure uniform crack propagation length induced by the laser at subsequent processing positions, are as follows: Calculate the crack propagation velocity V1 based on the crack length L1 and the delay time Δt of the high-speed camera image. The intensity of the incident laser is adjusted according to the relationship between the incident laser intensity and the crack propagation velocity V1, so that the crack propagation length induced by the laser in subsequent processing positions remains uniform.

3. The method for uniformly peeling off semiconductor material according to claim 2, characterized in that, Before adjusting the incident laser intensity based on the relationship between the incident laser intensity and the crack propagation velocity V1, it is necessary to estimate the crack propagation length L2´ at the current moment when the laser moves to the third position of the second processing path. Then, combined with the crack propagation length L2´ at the current moment when the laser moves to the third position of the second processing path, the incident laser intensity is adjusted according to the relationship between the incident laser intensity and the crack propagation velocity V1 so that the crack propagation length induced by the laser at the subsequent processing position remains at L / 2.

4. The method for uniformly peeling off semiconductor material according to claim 2, characterized in that, The relationship between the incident laser intensity and the crack propagation velocity V1 is as follows: When the crack propagation velocity V1 is between 50 μm / s and 200 μm / s, the incident laser intensity can be adjusted within a range of 0.5 GW / cm². 2 -1 GW / cm 2 ; When the crack propagation velocity V1 is between 200 μm / s and 400 μm / s, the incident laser intensity can be adjusted within a range of 1 GW / cm². 2 -2 GW / cm 2 ; When the crack propagation velocity V1 is 400 μm / s-800 μm / s, the incident laser intensity can be adjusted within a range of 2 GW / cm². 2 -4 GW / cm 2 ; When the crack propagation velocity V1 is between 800 μm / s and 1300 μm / s, the incident laser intensity can be adjusted within a range of 4 GW / cm². 2 -8 GW / cm 2 .

5. The method for uniformly peeling off semiconductor material according to claim 2, characterized in that, The crack propagation rate is V1 = L1 / Δt; When the laser moves to the third position on the second processing path, the crack at the first position at the current moment has an expansion length L2´= V1. t, where t is the time required for the laser to move from the first position on the first processing path to the third position on the second processing path.

6. The method for uniformly peeling off semiconductor material according to claim 1, characterized in that, In step S3, when adjusting the incident laser intensity based on the crack propagation length L2 at the first position when the laser moves to the second position of the second processing path, When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 100μm-150μm, the incident laser intensity can be adjusted within the range of 0.5 GW / cm². 2 -1 GW / cm 2 ; When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 150μm-200μm, the incident laser intensity can be adjusted within a range of 1 GW / cm². 2 -2 GW / cm 2 ; When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 200μm-250μm, the incident laser intensity can be adjusted within a range of 2 GW / cm². 2 -4 GW / cm 2 ; When the laser moves to the second position on the second processing path, and the crack propagation length L2 at the first position is 250μm-300μm, the incident laser intensity can be adjusted within a range of 4 GW / cm². 2 -8 GW / cm 2 .

7. The method for uniformly peeling off semiconductor material according to claim 1, characterized in that, The high-speed camera is positioned behind the focusing system of the laser processing device, while the CCD camera is positioned in front of the focusing system of the laser processing device.

8. An apparatus for uniformly stripping semiconductor material, characterized in that, It includes a laser (1) for emitting two parallel laser beams, a focusing system (5) set in the laser beam reflection direction to focus the reflected light onto the desired thinning and stripping position inside the semiconductor material (7), and a computer (11). The focusing system (5) is mounted on the Z-axis displacement platform (6), the semiconductor material (7) is set on the XY-axis displacement platform (8), a high-speed camera (9) is set behind the focusing system (5), and a CCD camera (10) is set in front of the focusing system (5). The high-speed camera (9) is used to capture the crack length L1 at the current shooting moment when the laser induces the semiconductor material to change at the first position of the first processing path, and transmit the captured data to the computer (11). The computer (11) controls and adjusts the incident laser intensity according to the received data so that the crack propagation length induced by the laser at the subsequent processing position remains uniform. The CCD camera (10) is used to capture the expansion length L2 of the crack at the first position when the laser moves along the set processing path to the second position of the second processing path at the current shooting time, and transmit the captured data to the computer (11). The computer (11) controls and adjusts the intensity of the incident laser light according to the received data so that when the laser moves to the third position of the second processing path, the crack length L3 induced by the laser at that position satisfies the relationship L2+L3=L, where L is the distance between the first processing path and the second processing path, the abscissa of the third position on the second processing path is equal to that of the first position on the first processing path, the second position on the second processing path is in front of the third position and the abscissas of the two are continuous.

9. The apparatus for uniformly stripping semiconductor material according to claim 8, characterized in that, Along the direction of light propagation, the laser beam path is provided with an attenuator (2) for adjusting the intensity of the laser beam, a beam expander (3) for increasing the diameter of the laser beam, and a laser reflector (4) for reflecting the laser beam to the focusing system (5).

10. The apparatus for uniformly stripping semiconductor material according to claim 9, characterized in that, The laser (1) emits a laser wavelength range of 300-1100nm, a laser pulse width range of 100fs to 100ps, and a laser energy adjustment range of 20μJ to 100μJ. The beam expansion ratio of the beam expander (3) is 1:2 to 1:5.

Images