Semiconductor wafer laser internal modification processing method

Abstract

The invention discloses a laser internal modification processing method for a semiconductor wafer. By drawing a three-dimensional light field distribution diagram, calculating a light spot distribution phase diagram and loading the light spot distribution phase diagram to the light spot modulation component, precise modulation of laser beam intensity and phase is realized, and nail-shaped or water-drop-shaped focusing light spots are formed. By means of directional energy distribution of the two light spots, a modified layer and cracks in the wafer extend in the preset direction, laser energy is prevented from being sputtered to the surface of a chip in the multi-layer machining process, and it can be guaranteed that the section of the chip is flat without transverse dislocation scanning. The problems of chip failure, cutting channel size limitation and strength reduction in the prior art are solved, the method is suitable for the field of laser industrial processing and semiconductor wafer processing, and the technical scheme is high in practicability and high in stability.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor wafer manufacturing technology, and specifically relates to a method for laser internal modification of semiconductor wafers. Background Technology

[0002] In precision semiconductor wafer fabrication, laser internal modification cutting technology is widely used due to its advantages such as non-contact operation, high precision, and low damage. Its working principle is as follows: a laser is focused onto the interior of the wafer, causing the material in the focused area to be modified, forming a modified layer and generating microcracks. Through multi-layer bottom-up scanning, the modified layers and cracks are connected, ultimately achieving wafer separation.

[0003] In existing technologies, some processing methods employ laser illumination from the back of the wafer. However, this method has significant drawbacks: when processing the second or higher modification layers, upward-extending cracks in the first layer can interfere with laser propagation, causing laser energy to sputter onto the chip surface at the bottom of the wafer. If the sputtering exceeds the dicing kerf, it can lead to chip failure. Patent CN202311543600.8 discloses a laser cutting method and system for controlling sputtering, along with its semiconductor die, proposing to shift the laser focus position to reduce sputtering. However, this solution still has shortcomings: on the one hand, the sputtering risk cannot be completely eliminated, limiting further reduction in dicing kerf size; on the other hand, lateral misalignment of the laser spot results in a stepped chip cross-section, significantly reducing the chip's mechanical strength.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for laser internal modification of semiconductor wafers, thereby overcoming the defects in the prior art.

[0006] To achieve the above objectives, the present invention provides a method for internal modification processing of semiconductor wafers using lasers, the steps of which are: (1) determining the preset spot shape according to the processing requirements, wherein the preset spot shape is a nail-shaped spot or a teardrop-shaped spot, and drawing a three-dimensional light field distribution map of the corresponding spot; (2) Input the three-dimensional light field distribution map obtained in step (1) into the phase map calculation module to calculate the corresponding light spot distribution phase map. The calculation process of the light spot distribution phase map includes initializing the phase, iterative constraint optimization and convergence verification. (3) Load the light spot distribution phase map obtained in step (2) into the light spot modulation component. The phase map loading control module of the light spot modulation component completes file parsing, pixel matching, phase calibration and loading verification, so that the pixel points of the light spot modulation component correspond precisely with the pixel points of the light spot distribution phase map. (4) Control the laser to output laser light, adjust it to the preset energy range by the energy adjustment component, and then incident it to the spot modulation component to obtain the spot distribution phase information. Then, the laser light is focused by the focusing component to form the preset spot shape. (5) The modulated laser is incident from the back of the wafer and focused at a preset depth inside the wafer to perform the first layer of internal modification processing, forming a modified layer and cracks extending along the preset direction. (6) Adjust the laser focusing depth upward along the wafer thickness direction and perform the second and above internal modification processing in sequence. During the processing, you can choose to maintain the preset spot shape or not apply spot shaping to connect the modification layers and cracks to achieve wafer cutting.

[0007] Preferably, in the technical solution, in step (1), the process of drawing the three-dimensional light field distribution map of the nail-shaped spot is as follows: First, draw a circular "nail cap" structure at the top along the XY direction (perpendicular to the laser propagation direction). The diameter of the "nail cap" is 1~8μm to ensure that the lateral energy covers the cutting channel range. Then, draw a slender "nail rod" structure downward in the Z direction (parallel to the laser propagation direction). The diameter of the "nail rod" is 1μm and the length is 1~40μm to match the processing requirements of wafers of different thicknesses. When the nail-shaped spot acts on the wafer, the modified layer and cracks extend laterally and downward. The lateral cracks form a physical barrier, effectively blocking the energy sputtering of the subsequent processing laser.

[0008] Preferably, in the technical solution, in step (1), the process of drawing the three-dimensional light field distribution map of the teardrop-shaped spot is as follows: by adjusting the gray value or Zernike phase of the light field distribution map, the intensity of the spot is distributed in a gradient - the intensity at the top is the weakest and the intensity at the bottom is the strongest, forming a "teardrop" structure with laser intensity along the Z direction. The length of the "teardrop" in the Z direction is 1-40μm. When the teardrop-shaped spot acts on the wafer, the modified layer and cracks only extend downward, avoiding the interference of upward cracks on the upper layer processing laser, and eliminating the sputtering risk from the root.

[0009] Preferably, in the technical solution, the calculation process of the light spot distribution phase diagram in step (2) is as follows: (a1) Initialize the phase. Based on the laser wavelength, the focal length of the focusing component, and the pixel resolution of the light spot modulation component, generate a random initial phase map. The initial phase value range is 0~2π to ensure that the phase distribution covers the complete phase period. (a2) Spatial constraints: Perform Fourier transform on the initial phase map to obtain the spatial light field distribution. Compare it with the three-dimensional light field distribution map (spatial light field constraint conditions) drawn in step 1. Based on the comparison results, adjust the intensity of the spatial light field distribution and replace the intensity values ​​in the spatial light field distribution that deviate from the three-dimensional light field distribution map by more than 5%. (a3) Frequency domain constraint: Perform inverse Fourier transform on the spatial optical field distribution after spatial domain constraint adjustment to obtain the phase distribution of the frequency optical field, retain the phase information of the phase distribution, and constrain the amplitude range of the frequency optical field to be within the amplitude threshold of the laser output laser. (a4) Repeat steps (a2)-(a3) for iteration, with the number of iterations being 10-200. After each iteration, calculate the similarity between the current light field distribution and the three-dimensional light field distribution map. (a5) When the similarity between the light field distribution of two consecutive iterations and the three-dimensional light field distribution map is ≥98%, stop the iteration and output the final frequency domain light field phase distribution as a light spot distribution phase map file; if the number of iterations reaches the upper limit and the convergence condition is still not met, adjust the initial phase map or constraint parameters and iterate again; The above steps enable precise mapping between the three-dimensional light field distribution map and the light spot distribution phase map, ensuring the consistency of the light spot morphology.

[0010] Preferably, in the technical solution, the loading process of the phase map loading control module in step (3) is as follows: (b1) File parsing: The phase map loading control module receives the spot distribution phase map file through USB, Ethernet, VGA, DVI or PCIe interface, parses the file, extracts phase data, resolution information, gray level or phase level information, removes redundant data in the file, and converts the phase data into a digital signal format that can be recognized by the spot modulation component. (b2) Pixel matching: Read the pixel resolution of the light spot modulation component and compare it with the resolution of the light spot distribution phase map. If the resolutions are inconsistent, the light spot distribution phase map is scaled by an interpolation algorithm to ensure that the number of pixels in the light spot distribution phase map is completely consistent with the number of pixels in the light spot modulation component. At the same time, a one-to-one mapping relationship between the pixels in the light spot distribution phase map and the pixels in the light spot modulation component is established to generate a pixel matching lookup table. (b3) Phase calibration: First, zero-point calibration is performed. Zero-phase values ​​are loaded onto all pixels of the light spot modulation component. The phase distribution of the output light field is detected by a laser interferometer, and the phase offset error of each pixel is recorded. Then, according to the pixel matching lookup table, the parsed phase data is superimposed with the corresponding phase offset error for compensation, and the calibrated phase data is obtained to ensure that the actual phase output of each pixel deviates from the theoretical phase value by ≤ ±0.01π. (b4) Loading and execution: The calibrated phase data is written into each pixel of the light spot modulation component through the driving circuit, and the phase state of the pixel is controlled to correspond with the phase data; (b5) Loading verification: After loading is completed, the actual phase distribution and spot shape of the output light field are detected by a laser interferometer or spot analyzer and compared with the three-dimensional light field distribution map. If the similarity between the actual spot shape and the set spot shape is ≥97%, the loading is successful and the subsequent processing steps are entered. If the similarity is <97%, return to step (b2) or step (b3), readjust the matching parameters or phase offset error, and load and verify again until the requirements are met. Through the above steps, the pixel resolution of the spot distribution phase map is strictly matched with the pixel resolution of the spot modulation component, ensuring the complete loading of phase information.

[0011] Preferably, in the technical solution, during step (6) of the modification process, the laser scanning trajectory is distributed along the same vertical plane, without the need for lateral misalignment, thus avoiding the formation of a stepped structure on the chip cross-section, ensuring the flatness of the cross-section, and significantly improving the mechanical strength of the chip.

[0012] A laser processing device for implementing the above processing method includes a laser, an energy adjustment component, a spot modulation component, and a focusing component. The energy adjustment component and the spot modulation component are sequentially arranged in the optical path between the laser and the focusing component. The spot modulation component is equipped with a phase map loading control module, which can realize precise loading of the phase map, pixel matching, and real-time adjustment to ensure the stability of the spot shape.

[0013] Compared with the prior art, the present invention has the following beneficial effects: By plotting a three-dimensional light field distribution map, calculating the phase map of the laser spot distribution, and loading it onto the laser spot modulation component, precise modulation of the laser beam intensity and phase is achieved, forming a nail-shaped or teardrop-shaped focused laser spot. Utilizing the directional energy distribution of these two types of spots, the modified layer and cracks inside the wafer are extended along a predetermined direction, preventing laser energy sputtering onto the chip surface during multilayer processing, and ensuring a flat chip cross-section without the need for lateral misalignment scanning. This invention solves the problems of chip failure, limited dicing track size, and reduced strength in existing technologies. It is applicable to laser industrial processing and semiconductor wafer processing fields, and the technical solution is highly feasible and stable. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the process for the internal modification of semiconductor wafers using laser technology according to the present invention. Figure 2 This is a three-dimensional light field distribution diagram of the nail-shaped light spot of the present invention; Figure 3 This is a three-dimensional light field distribution diagram of the teardrop-shaped light spot of the present invention; Figure 4 This is a schematic diagram illustrating the calculation process of the light spot distribution phase diagram of the present invention; Figure 5This is a schematic diagram of the loading process of the phase map loading control module of the present invention. Detailed Implementation

[0015] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0016] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0017] A laser processing device includes a laser, an energy adjustment component, a beam modulation component, and a focusing component. The energy adjustment component and the beam modulation component are sequentially arranged in the optical path between the laser and the focusing component. The beam modulation component is equipped with a phase map loading control module, which can realize precise loading of the phase map, pixel matching, and real-time adjustment to ensure the stability of the beam shape. The beam modulation component is selected from any one of a phase plate, a spatial light modulator, a deformable mirror, and a digital micromirror device.

[0018] like Figure 1 As shown, a method for internal modification of semiconductor wafers using lasers includes the following steps: (1) Determine the preset spot shape according to the processing requirements. The preset spot shape is either a nail-shaped spot or a teardrop-shaped spot. Draw a three-dimensional light field distribution map of the corresponding spot. (2) Input the three-dimensional light field distribution map obtained in step (1) into the phase map calculation module. The phase map calculation module uses one of the GS algorithm, GSW algorithm or 3DGSW algorithm to calculate the corresponding light spot distribution phase map. The calculation process of the light spot distribution phase map includes initializing the phase, iterative constraint optimization and convergence verification. (3) Load the light spot distribution phase map obtained in step (2) into the light spot modulation component. The phase map loading control module of the light spot modulation component completes file parsing, pixel matching, phase calibration and loading verification, so that the pixel points of the light spot modulation component correspond precisely with the pixel points of the light spot distribution phase map. (4) Control the laser to output laser light, adjust it to the preset energy range by the energy adjustment component, and then incident it to the spot modulation component to obtain the spot distribution phase information. Then, the laser light is focused by the focusing component to form the preset spot shape. (5) The modulated laser is incident from the back of the wafer and focused at a preset depth inside the wafer to perform the first layer of internal modification processing, forming a modified layer and cracks extending along the preset direction. (6) Adjust the laser focusing depth upward along the wafer thickness direction and perform the second and above internal modification processing in sequence. During the processing, you can choose to maintain the preset spot shape or not apply spot shaping to connect the modification layers and cracks to achieve wafer cutting. Example 1

[0019] A method for laser internal modification of semiconductor wafers, comprising the following steps: (1) determining the preset spot shape according to the processing requirements, wherein the preset spot shape is a nail-shaped spot, and drawing a three-dimensional light field distribution map of the corresponding spot; The process of drawing the three-dimensional light field distribution map of the nail-shaped spot is as follows: First, at the top, draw a circular "nail cap" structure along the XY direction (perpendicular to the laser propagation direction). The "nail cap" has a diameter of 5μm to ensure that the lateral energy covers the cutting path range; then, draw a slender "nail rod" structure downwards in the Z direction (parallel to the laser propagation direction). The "nail rod" has a diameter of 1μm and a length of 20μm, as shown below. Figure 2 As shown; when the nail-shaped laser spot acts on the wafer, the modified layer and cracks extend laterally and downwards. The lateral cracks form a physical barrier, effectively blocking the energy sputtering of the subsequent processing laser. (2) Input the three-dimensional light field distribution map obtained in step (1) into the phase map calculation module. The phase map calculation module uses the GSW algorithm to calculate the corresponding light spot distribution phase map; such as Figure 4 As shown, the calculation process of the light spot distribution phase map is as follows: (a1) Initialize the phase. Based on the laser wavelength, the focal length of the focusing component, and the pixel resolution of the light spot modulation component, generate a random initial phase map. The initial phase value range is 0~2π to ensure that the phase distribution covers the complete phase period. (a2) Spatial constraints: Perform Fourier transform on the initial phase map to obtain the spatial light field distribution. Compare it with the three-dimensional light field distribution map (spatial light field constraint conditions) drawn in step 1. Based on the comparison results, adjust the intensity of the spatial light field distribution. Replace the intensity values ​​in the spatial light field distribution that deviate from the three-dimensional light field distribution map by more than 5%. Retain the intensity characteristics of the "nail cap" and the slender structure of the "nail rod" in the Z direction. (a3) Frequency domain constraint: Perform inverse Fourier transform on the spatial optical field distribution after spatial domain constraint adjustment to obtain the phase distribution of the frequency optical field, retain the phase information of the phase distribution, and constrain the amplitude range of the frequency optical field to be within the amplitude threshold of the laser output laser. (a4) Repeat steps (a2)-(a3) for iteration. After 120 iterations, the similarity between the light field distribution of two adjacent iterations and the three-dimensional light field distribution map reaches 98.5%. Stop the iteration and output the final frequency domain light field phase distribution as a light spot distribution phase map file with a resolution of 1920×1080. (3) Load the light spot distribution phase map obtained in step (2) into the light spot modulation component. The phase map loading control module of the light spot modulation component completes file parsing, pixel matching, phase calibration and loading verification, so that the pixel points of the light spot modulation component correspond precisely with the pixel points of the light spot distribution phase map. like Figure 5 As shown, the loading process of the phase map loading control module is as follows: (b1) File parsing: The phase map loading control module receives the spot distribution phase map file through the USB interface, parses the file, extracts 16-bit phase data, resolution information, and phase level information, removes redundant data from the file, and converts the phase data into a digital signal format that can be recognized by the spot modulation component. (b2) Pixel matching: Read the pixel resolution of the light spot modulation component and compare it with the resolution of the light spot distribution phase map. If the resolutions are inconsistent, the light spot distribution phase map is scaled by an interpolation algorithm to ensure that the number of pixels in the light spot distribution phase map is completely consistent with the number of pixels in the light spot modulation component. At the same time, a one-to-one mapping relationship between the pixels in the light spot distribution phase map and the pixels in the light spot modulation component is established to generate a pixel matching lookup table. (b3) Phase calibration: First, zero-point calibration is performed. Zero-phase values ​​are loaded onto all pixels of the light spot modulation component. The phase distribution of the output light field is detected by a laser interferometer, and the phase offset error of each pixel is recorded. Then, according to the pixel matching lookup table, the parsed phase data is superimposed with the corresponding phase offset error for compensation, and the calibrated phase data is obtained to ensure that the actual phase output of each pixel deviates from the theoretical phase value by ≤ ±0.01π. (b4) Loading and execution: The calibrated phase data is written into each pixel of the light spot modulation component through the driving circuit, and the phase state of the pixel is controlled to correspond with the phase data; (b5) Loading verification: After loading is completed, the actual phase distribution and spot shape of the output light field are detected by a laser interferometer or spot analyzer and compared with the three-dimensional light field distribution map: the similarity between the actual spot shape and the set spot shape is 97.8%, loading is successful, and the subsequent processing steps are entered. (4) Control the laser to output 1064nm laser light, and adjust it to 30µJ / cm by the energy adjustment component. 2 The light is incident on the light spot modulation component to obtain the phase information of the light spot distribution, and then focused by the focusing component to form a nail-shaped light spot; (5) The modulated laser is incident from the back of the wafer and focused on the wafer interior 150 μm away from the back of the wafer. The first layer of internal modification is performed at a scanning speed of 500 mm / s to form a modification layer and cracks extending laterally and downward. The length of the transverse crack is 6 μm. (6) Keep the nail-shaped spot unchanged, and adjust the laser focusing depth sequentially upward along the wafer thickness direction to a position 100μm and 50μm away from the back of the wafer, respectively, to perform internal modification processing of the second and third layers. The processing parameters are the same as those of the first layer. After the three modified layers and cracks are completely connected, wafer cutting is achieved. During the modification process, the laser scanning trajectory is distributed along the same vertical plane, without the need for lateral misalignment, avoiding the formation of a stepped structure on the chip cross section, ensuring the flatness of the cross section, and significantly improving the mechanical strength of the chip.

[0020] Testing revealed no laser sputtering damage on the chip surface, the dicing width was reduced by 25% compared to existing technologies, the chip cross-section flatness error was 0.3μm, and the bending strength was increased by 35%. Example 2

[0021] A method for internal modification of semiconductor wafers using laser technology, comprising the following steps: (1) Pre-setting the spot shape as a teardrop-shaped spot and drawing a three-dimensional light field distribution map of the corresponding spot: By adjusting the gray value or Zernike phase of the light field distribution map, the intensity of the spot is made to have a gradient distribution—the intensity at the top is the weakest and the intensity at the bottom is the strongest, forming a "teardrop" structure. The "teardrop" has a length of 15 μm in the Z direction, such as Figure 3 As shown; when the teardrop-shaped laser spot acts on the wafer, the modified layer and cracks only extend downwards, avoiding the interference of upward cracks on the upper processing laser, thus eliminating the risk of sputtering from the source; (2) Input the three-dimensional light field distribution map obtained in step (1) into the phase map calculation module. The phase map calculation module uses the 3DGSW algorithm to calculate the corresponding light spot distribution phase map. The calculation process of the light spot distribution phase map is as follows: (a1) Initialize the phase. Based on the laser wavelength, the focal length of the focusing component, and the pixel resolution of the light spot modulation component, generate a random initial phase map. The initial phase value range is 0~2π to ensure that the phase distribution covers the complete phase period. (a2) Spatial constraints: Perform Fourier transform on the initial phase map to obtain the spatial light field distribution. Compare it with the three-dimensional light field distribution map (spatial light field constraint conditions) drawn in step 1. Based on the comparison results, adjust the intensity of the spatial light field distribution. Replace the intensity values ​​in the spatial light field distribution that deviate from the three-dimensional light field distribution map by more than 5%, and retain the intensity characteristics of the "water droplet" structure. (a3) Frequency domain constraint: Perform inverse Fourier transform on the spatial optical field distribution after spatial domain constraint adjustment to obtain the phase distribution of the frequency optical field, retain the phase information of the phase distribution, and constrain the amplitude range of the frequency optical field to be within the amplitude threshold of the laser output laser. (a4) Repeat steps (a2)-(a3) for iteration. After 150 iterations, the similarity between the light field distribution of two adjacent iterations and the three-dimensional light field distribution map reaches 98.2%. Stop the iteration and output the final frequency domain light field phase distribution as a light spot distribution phase map file with a resolution of 1280×1024. (3) Load the light spot distribution phase map obtained in step (2) into the light spot modulation component. The phase map loading control module of the light spot modulation component completes file parsing, pixel matching, phase calibration and loading verification, so that the pixel points of the light spot modulation component correspond precisely with the pixel points of the light spot distribution phase map. The loading process of the phase map loading control module is as follows: (b1) File parsing: The phase map loading control module receives the spot distribution phase map file via Ethernet, parses the file, extracts 16-bit phase data, resolution information, and phase level information, removes redundant data from the file, and converts the phase data into a digital signal format that can be recognized by the spot modulation component. (b2) Pixel matching: Read the pixel resolution of the light spot modulation component and compare it with the resolution of the light spot distribution phase map. If the resolutions are inconsistent, the light spot distribution phase map is scaled by an interpolation algorithm to ensure that the number of pixels in the light spot distribution phase map is completely consistent with the number of pixels in the light spot modulation component. At the same time, a one-to-one mapping relationship between the pixels in the light spot distribution phase map and the pixels in the light spot modulation component is established to generate a pixel matching lookup table. (b3) Phase calibration: First, zero-point calibration is performed. Zero-phase values ​​are loaded onto all pixels of the light spot modulation component. The phase distribution of the output light field is detected by a laser interferometer, and the phase offset error of each pixel is recorded. Then, according to the pixel matching lookup table, the parsed phase data is superimposed with the corresponding phase offset error for compensation, and the calibrated phase data is obtained to ensure that the actual phase output of each pixel deviates from the theoretical phase value by ≤ ±0.01π. (b4) Loading and execution: The calibrated phase data is written into each pixel of the light spot modulation component through the driving circuit, and the phase state of the pixel is controlled to correspond with the phase data; (b5) Loading verification: After loading is completed, the actual phase distribution and spot shape of the output light field are detected by a laser interferometer or spot analyzer and compared with the three-dimensional light field distribution map: the similarity between the actual spot shape and the set spot shape is 97.5%, loading is successful, and the subsequent processing steps are entered. (4) Control the laser to output 1064nm laser light, and adjust it to 40µJ / cm by the energy adjustment component. 2 The light is incident on the light spot modulation component to obtain the phase information of the light spot distribution, and then focused by the focusing component to form a teardrop-shaped light spot; (5) The modulated laser is incident from the back of the wafer and focused on the interior of the wafer 80 μm away from the back of the wafer. The first layer of internal modification is performed at a scanning speed of 600 mm / s to form a modification layer and cracks that extend only downwards. The crack length is 30 μm. (6) Turn off the spatial light modulator, do not apply spot shaping, adjust the laser focusing depth upward along the wafer thickness direction to a position 40μm away from the back of the wafer, and perform the second layer of internal modification processing. The processing parameters are the same as the first layer. After the two modification layers and cracks are completely connected, wafer cutting is achieved. During the modification process, the laser scanning trajectory is distributed along the same vertical plane, without the need for lateral misalignment, avoiding the formation of a stepped structure on the chip cross section, ensuring the flatness of the cross section, and significantly improving the mechanical strength of the chip.

[0022] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for laser internal modification processing of semiconductor wafers, characterized in that, The steps are as follows: (1) Determine the preset spot shape according to the processing requirements. The preset spot shape is a nail-shaped spot or a teardrop-shaped spot. Draw the three-dimensional light field distribution map of the corresponding spot. (2) Input the three-dimensional light field distribution map obtained in step (1) into the phase map calculation module to calculate the corresponding light spot distribution phase map. The calculation process of the light spot distribution phase map includes initializing the phase, iterative constraint optimization and convergence verification. (3) Load the light spot distribution phase map obtained in step (2) into the light spot modulation component. The phase map loading control module of the light spot modulation component completes file parsing, pixel matching, phase calibration and loading verification, so that the pixel points of the light spot modulation component correspond precisely with the pixel points of the light spot distribution phase map. (4) Control the laser to output laser light, adjust it to the preset energy range by the energy adjustment component, and then incident it to the spot modulation component to obtain the spot distribution phase information. Then, the laser light is focused by the focusing component to form the preset spot shape. (5) The modulated laser is incident from the back of the wafer and focused at a preset depth inside the wafer to perform the first layer of internal modification processing, forming a modified layer and cracks extending along the preset direction. (6) Adjust the laser focusing depth upward along the wafer thickness direction and perform the second and above internal modification processing in sequence. During the processing, you can choose to maintain the preset spot shape or not apply spot shaping to connect the modification layers and cracks to achieve wafer cutting.

2. The method for laser internal modification of semiconductor wafers according to claim 1, characterized in that: In step (1), the process of drawing the three-dimensional light field distribution map of the nail-shaped spot is as follows: First, draw a circular "nail cap" structure along the XY direction at the top. The diameter of the "nail cap" is 1~8μm to ensure that the lateral energy covers the cutting channel range. Then, draw a slender "nail rod" structure downward in the Z direction. The diameter of the "nail rod" is 1μm and the length is 1~40μm to match the processing requirements of wafers of different thicknesses. When the nail-shaped spot acts on the wafer, the modified layer and cracks extend laterally and downward. The lateral cracks form a physical barrier to effectively block the energy sputtering of the subsequent processing laser.

3. The method for laser internal modification of semiconductor wafers according to claim 1, characterized in that: In step (1), the process of drawing the three-dimensional light field distribution map of the teardrop-shaped spot is as follows: by adjusting the gray value or Zernike phase of the light field distribution map, the intensity of the spot is distributed in a gradient - the intensity at the top is the weakest and the intensity at the bottom is the strongest, forming a "teardrop" structure with laser intensity along the Z direction. The length of the "teardrop" in the Z direction is 1-40μm. When the teardrop-shaped spot acts on the wafer, the modified layer and cracks only extend downward, avoiding the interference of upward cracks on the upper layer processing laser, thus eliminating the risk of sputtering from the root.

4. The method for laser internal modification of semiconductor wafers according to claim 1, characterized in that: In step (2), the calculation process of the light spot distribution phase map is as follows: (a1) Initialize the phase. Based on the laser wavelength, the focal length of the focusing component, and the pixel resolution of the light spot modulation component, generate a random initial phase map. The initial phase value range is 0~2π to ensure that the phase distribution covers the complete phase period. (a2) Spatial constraints: Perform Fourier transform on the initial phase map to obtain the spatial light field distribution. Compare it with the three-dimensional light field distribution map (spatial light field constraint conditions) drawn in step 1. Based on the comparison results, adjust the intensity of the spatial light field distribution and replace the intensity values ​​in the spatial light field distribution that deviate from the three-dimensional light field distribution map by more than 5%. (a3) Frequency domain constraint: Perform inverse Fourier transform on the spatial optical field distribution after spatial domain constraint adjustment to obtain the phase distribution of the frequency optical field, retain the phase information of the phase distribution, and constrain the amplitude range of the frequency optical field to be within the amplitude threshold of the laser output laser. (a4) Repeat steps (a2)-(a3) for iteration, with the number of iterations being 10-200. After each iteration, calculate the similarity between the current light field distribution and the three-dimensional light field distribution map. (a5) When the similarity between the light field distribution of two adjacent iterations and the three-dimensional light field distribution map is ≥98%, stop the iteration and output the final frequency domain light field phase distribution as a light spot distribution phase map file; if the number of iterations reaches the upper limit and the convergence condition is not met, adjust the initial phase map or constraint parameters and iterate again.

5. The method for laser internal modification of semiconductor wafers according to claim 1, characterized in that: In step (3), the loading process of the phase map loading control module is as follows: (b1) File parsing: The phase map loading control module receives the spot distribution phase map file through USB, Ethernet, VGA, DVI or PCIe interface, parses the file, extracts phase data, resolution information, gray level or phase level information, removes redundant data in the file, and converts the phase data into a digital signal format that can be recognized by the spot modulation component. (b2) Pixel matching: Read the pixel resolution of the light spot modulation component and compare it with the resolution of the light spot distribution phase map. If the resolutions are inconsistent, the light spot distribution phase map is scaled by an interpolation algorithm to ensure that the number of pixels in the light spot distribution phase map is completely consistent with the number of pixels in the light spot modulation component. At the same time, a one-to-one mapping relationship between the pixels in the light spot distribution phase map and the pixels in the light spot modulation component is established to generate a pixel matching lookup table. (b3) Phase calibration: First, zero-point calibration is performed. Zero-phase values ​​are loaded onto all pixels of the light spot modulation component. The phase distribution of the output light field is detected by a laser interferometer, and the phase offset error of each pixel is recorded. Then, according to the pixel matching lookup table, the parsed phase data is superimposed with the corresponding phase offset error for compensation, and the calibrated phase data is obtained to ensure that the actual phase output of each pixel deviates from the theoretical phase value by ≤ ±0.01π. (b4) Loading and execution: The calibrated phase data is written into each pixel of the light spot modulation component through the driving circuit, and the phase state of the pixel is controlled to correspond with the phase data; (b5) Loading verification: After loading is completed, the actual phase distribution and spot shape of the output light field are detected by a laser interferometer or spot analyzer and compared with the three-dimensional light field distribution map. If the similarity between the actual spot shape and the set spot shape is ≥97%, the loading is successful and the subsequent processing steps are entered. If the similarity is <97%, return to step (b2) or step (b3), readjust the matching parameters or phase offset error, and load and verify again until the requirements are met.

6. The method for laser internal modification of semiconductor wafers according to claim 1, characterized in that: In step (6), during the modification process, the laser scanning trajectory is distributed along the same vertical plane.

7. A laser processing device, characterized in that: The semiconductor wafer is processed using the laser internal modification processing method as described in any one of claims 1-6. The equipment includes a laser, an energy adjustment component, a spot modulation component, and a focusing component. The energy adjustment component and the spot modulation component are sequentially arranged in the optical path between the laser and the focusing component. The spot modulation component is equipped with a phase map loading control module.

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