A method for generating a semiconductor wafer

Abstract

The present invention relates to a method for generating a semiconductor wafer, which comprises the following steps: first, setting the number of laser scans, and then respectively setting the scan path and the point spacing for each laser scan; based on a preset calculation rule for each laser scan, determining the laser scan speed and the laser pulse repetition frequency, and determining the corresponding modified point diameter, the laser pulse energy, and the offset distance of the laser focus relative to a preset peeling surface; focusing pulsed laser on the preset peeling surface inside the ingot or below the preset peeling surface, and performing n laser scans to sequentially form modified points and cracks on the preset peeling surface; peeling the ingot along the preset peeling surface to obtain a wafer and a remaining ingot. The present invention can not only eliminate burrs on the edge of the wafer, but also further reduce the material loss of laser peeling, and has the advantages of simple process conditions, good morphology of the modified layer, low difficulty in wafer peeling, and suitability for large-scale industrial applications.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer processing, and more particularly to a method for generating a semiconductor wafer. Background Art

[0002] In recent years, with the rapid development of the optoelectronic industry and the microelectronics industry, the entire aerospace, aviation, machinery, light industry, chemical industry and other industries are also developing towards the direction of integration and miniaturization. Correspondingly, it is required that the integration degree of semiconductor devices is getting higher and higher, the functions are getting more and more complex, and the volume is getting smaller and smaller. Silicon carbide substrate is the core material of newly developed wide bandgap semiconductors. Devices made of it have the characteristics of high temperature resistance, high voltage resistance, high frequency, high power, radiation resistance, etc., and have the advantages of fast switching speed and high efficiency. It can greatly reduce product power consumption, improve energy conversion efficiency and reduce product volume. As a key process in the manufacture of silicon carbide substrates, the quality of wafer slicing directly affects the performance of silicon carbide substrates.

[0003] Laser slicing is a laser technology that separates a silicon carbide ingot into individual wafers. In this process, a precise laser beam is used to form a modified layer inside the ingot, enabling the wafer to be precisely separated along the laser scanning path with a slight external force. Laser scanning is the process of forming the modified layer. During this process, the laser will focus at a predetermined depth inside the silicon carbide ingot, inducing the formation of microcracks that extend along the peeling surface. When uniformly distributed microcracks exist in the material, a concentration effect of the stress field will be generated around the microcracks. When a mechanical peeling force is applied, the stress will be induced to a specified position to cause crack propagation due to the existence of the modified layer, thus completing the peeling of the wafer. The above method can greatly reduce the material loss during the slicing process and improve the wafer production efficiency.

[0004] The Chinese patent with the authorization announcement number CN107790898B discloses a method for generating a SiC wafer, which includes the following processes: a peeling surface generation process, which performs the following separation layer formation process: positioning the focus point of a pulsed laser beam with a wavelength that is transmissive to SiC at a depth equivalent to the thickness of the wafer to be generated from the first surface, and while relatively processing and feeding the single-crystal SiC ingot and the focus point in a first direction perpendicular to the second direction in which the deviation angle is formed, irradiating the single-crystal SiC ingot with the pulsed laser beam to form a separation layer composed of a modified layer and cracks; and a wafer generation process, which peels off a part of the single-crystal SiC ingot with the peeling surface as an interface to generate a SiC wafer. In the peeling surface generation process, the processing feed includes a forward movement and a return movement. The forward movement relatively moves the focus point from one end of the single-crystal SiC ingot to the other end. The return movement relatively moves the focus point from the other end to the one end while maintaining the depth of the focus point at the same depth as the depth of the focus point in the forward movement to trace the already formed separation layer. In the forward movement, the initially formed modified layer is formed by the focus point. The modified layer formed subsequent to the initial modified layer is formed at a position slightly shallower than the focus point. The climb of the modified layer occurs from the one end of the single-crystal SiC ingot where the pulsed laser beam irradiation starts. After the modified layer reaches the depth at which the power density of the pulsed laser beam becomes a specified value inside the single-crystal SiC ingot, a modified layer is formed in front of the focus point and at the depth where the power density is the specified value. In the return movement, a modified layer is formed in front of the focus point and at the depth where the power density is the specified value from the other end to the one end of the single-crystal SiC ingot.

[0005] The above prior art solution has the following defects: In the peeling surface generation process, the above method avoids the burr problem at the laser scanning end face of the single-crystal SiC ingot by means of laser back-and-forth scanning to reduce material loss. Among them, the main reason for the generation of burrs at the laser scanning end face is the self-organization change during the formation of the modified layer, that is, after the laser enters the single-crystal SiC ingot, the modified point generated by the first laser pulse is near the geometric focus of the focusing lens. As the laser travels along the scanning direction, the modified point gradually rises until the overlap rate of adjacent modified points and the laser power density reach equilibrium, and a stable modified layer is formed at a predetermined depth; refer to Figure 1, which also causes the climbing of the modified layer in the area about dozens of μm away from one end of the single-crystal SiC ingot during the moving toward the road. After actual testing, the lifting amplitude is about 40-100 μm. The above method only reduces the burrs remaining on the wafer to a certain extent, but causes the problem that the modified points at the laser-scanned end face gradually rise toward the peeling surface. Therefore, after the wafer is peeled off, it is still necessary to grind or thin a quite thick material to completely remove the traces left by laser scanning at the end face, and the material loss is as high as 30%.

[0006] Chinese Patent No. CN115635183A discloses a method for laser peeling a workpiece, including: focusing pulsed laser with a short pulse width on a preset peeling surface inside the workpiece to form modified points on the preset peeling surface inside the workpiece, and focusing pulsed laser with a long pulse width on the modified points to form a modified area and a crack extending along the radial direction of the preset peeling surface; dividing the workpiece into a first workpiece unit and a second workpiece unit along the preset peeling surface.

[0007] The above existing technical solutions have the following defects: The above method uses pulsed laser with a short pulse width to form modified points on the preset peeling surface inside the silicon carbide, and then uses pulsed laser with a long pulse width to focus on the modified points generated by the short-pulse laser to form a modified area, and further forms a crack extending along the radial direction of the preset peeling surface, so that the workpiece can be easily peeled off. However, this requires that the pulsed lasers with short and long pulse widths not only strictly align the points, but also have a strictly synchronized timing sequence, and the actual operability is poor, which is not conducive to large-scale industrial application. Summary of the Invention

[0008] The problem to be solved by the present invention is to provide a semiconductor wafer generation method in view of the above deficiencies in the prior art, which solves the problem of the climbing of modified points existing in the existing laser round-trip scanning method and the problem of harsh process conditions existing in the sequential scanning of pulsed lasers with short and long pulse widths. It can not only eliminate the burrs on the wafer edge, but also further reduce the material loss of laser peeling, and has the advantages of simple process conditions, good morphology of the modified layer, low difficulty in wafer peeling, and being suitable for large-scale industrial application.

[0009] The above invention object of the present invention is achieved by the following technical solutions:

[0010] A semiconductor wafer generation method includes the following steps,

[0011] S1 First, set the number of laser scans as n times, where n is an integer ≥ 2, and then respectively set the scan path for each laser scan and the point spacing P between two adjacent modified points on the scan path;

[0012] S2 Based on the preset calculation rules for each laser scan, determine the laser scan speed V and the laser pulse repetition frequency F required to achieve the point pitch P, and determine the corresponding modified particle diameter D. Furthermore, determine the laser pulse energy E required to achieve the modified particle diameter D, and the offset distance S of the laser focus relative to the preset peeling surface;

[0013] S3 Focus the pulsed laser on the preset peeling surface inside the ingot or below the preset peeling surface, and perform n laser scans to sequentially form modified particles on the preset peeling surface, and an overlapping area is formed between the modified particles formed by at least two of the laser scans, so as to form a crack extending transversely along the preset peeling surface in the overlapping area;

[0014] S4 Peel the ingot along the preset peeling surface to obtain a wafer and the remaining ingot.

[0015] Specifically, in the present invention, the meaning of the modified particle refers to an independent or continuous laser action point formed on the preset peeling surface. Correspondingly, the point pitch P, the line distance L, and the modified particle diameter D also refer to the point pitch between two adjacent modified particles at the position of the preset peeling surface, the line distance between two scanning sections spaced apart from each other, and the modified particle diameter.

[0016] Furthermore, in the S1, the scanning path of each laser scan is respectively one or a combination of a line-by-line scanning path, a grid interlaced scanning path, a concentric circle scanning, and a spiral scanning path.

[0017] Still further, in the S1, control the line distance L between two scanning sections spaced apart from each other on the scanning path to be 0.05 - 1.00 mm. Among them, the scanning sections on the scanning path are arranged at equal or unequal intervals.

[0018] Furthermore, in the S1, control the point pitch P to be 0.5 - 50 μm.

[0019] Furthermore, in the S2, the calculation rules preset for the 1st to n'th laser scans are that P n′ =V n′ / F n′ , P n′ ≥0.7D n′ , E n′ ≥1 μJ, S n′ is 0 - 5 μm; where P n′ is the point pitch between two adjacent modified particles on the 1st to n'th scanning path, V n′ is the 1st to n'th laser scan speed, F n′ is the 1st to n'th laser pulse repetition frequency, E n′ is the 1st to n'th laser pulse energy, Sn′ is the offset distance of the laser focus relative to the preset peeling surface for the 1st to n'th times, and n' is an integer greater than or equal to 1.

[0020] Further, in the step S2, the calculation rule for the (n'+1)th to n''th laser scans is that P n′+1 =V n′+1 / F n′+1 , where P n′+1 <D n′+1 , E n′+1 ≥5 μJ, S n′+1 is from 0 to 20 μm; where P n′+1 is the point spacing between two adjacent modified points on the (n'+1)th to n''th scan path, V n′+1 is the laser scanning speed for the (n'+1)th to n''th times, F n′+1 is the laser pulse repetition frequency for the (n'+1)th to n''th times, E n′+1 is the laser pulse energy for the (n'+1)th to n''th times, S n′+1 is the offset distance of the laser focus relative to the preset peeling surface for the (n'+1)th to n''th times, and n'' is an integer greater than or equal to 2.

[0021] Even further, in the step S2, control 0.2D n′+1 <P n′+1 <0.6D n′+1 .

[0022] Further, in the step S3, respectively control the laser wavelength range λ of each laser scan to be 780 - 2500 nm and the laser pulse width Δt to be 10 fs - 100 ns.

[0023] Further, in the step S3, the pulsed laser is a pulse train composed of a plurality of sub - pulses; where the time interval between two adjacent sub - pulses does not exceed 100 ns.

[0024] Further, in the step S3, perform aberration correction on the pulsed laser in advance before the 1st to n'th laser scans.

[0025] Even further, in the step S3, control the longitudinal thickness of the modified points in the 1st to n'th laser scans to be 5 - 40 μm.

[0026] Further, in the step S3, a first laser, a first beam combining and beam expanding unit, an aberration correction unit, a first workpiece reflector, a first objective lens, and an ingot are sequentially arranged on the pulsed laser emission path of the first to n'-th laser scans; wherein, at least two first lasers are arranged in parallel, the first beam combining and beam expanding unit includes a first beam combiner arranged on the pulsed laser emission path of one of the first lasers, first laser reflectors respectively arranged between the pulsed laser emission paths of the remaining first lasers and the first beam combiner, and a beam expander arranged on the pulsed laser emission path of the first beam combiner, and the aberration correction unit is set as an adaptive optical element, a diffractive optical element, or a deformable lens.

[0027] Further, in the step S3, the process of aberration correction includes wavefront shaping of the incident beam of the pulsed laser by an adaptive optical element, compensating for the aberration of the focusing lens of the pulsed laser at a specific depth by a diffractive optical element, or presetting the aberration by adjusting a deformable lens and compensating for the aberration of the focusing lens of the pulsed laser at a specific depth. Among them, the adaptive optical element can be, for example but not limited to, a spatial light modulator and a digital micromirror array, the diffractive optical element can be, for example but not limited to, a beam shaper, a beam splitter, a diffractive axicon, a spiral phase plate, a light homogenizer, and a multi-focus long depth of field, and the deformable lens can be, for example but not limited to, a lens with movable lenses or lens groups inside and / or outside.

[0028] Further, in the step S3, beam shaping of the pulsed laser is pre-performed before the (n'+1)-th to n''-th laser scans.

[0029] Further, in the step S3, the modified spot diameter D of the (n'+1)-th to n''-th laser scans is controlled n′+1 to be 15 to 100 μm.

[0030] Further, in the step S3, a second laser, a second beam combining unit, a beam shaping unit, a second workpiece reflector, a second objective lens, and an ingot are sequentially arranged on the pulsed laser emission path of the (n'+1)-th to n''-th laser scans; wherein, at least two second lasers are arranged in parallel, the second beam combining unit includes a second beam combiner arranged on the pulsed laser emission path of one of the second lasers, and second laser reflectors respectively arranged between the pulsed laser emission paths of the remaining second lasers and the second beam combiner, and the beam shaping unit is set as an adaptive optical element or a diffractive optical element.

[0031] Furthermore, in the step S3, the process of beam shaping includes shaping the incident beam of the pulsed laser through an adaptive optical element, shaping the incident beam of the pulsed laser through a diffractive optical element, or increasing the beam quality factor of the incident beam of the pulsed laser. Among them, the adaptive optical element can be, for example but not limited to, a spatial light modulator and a digital micromirror array, and the diffractive optical element can be, for example but not limited to, a beam shaper, a beam splitter, a diffractive cone lens, a spiral phase plate, a light homogenizer, and a multi-focus long depth of field.

[0032] Specifically, first set the number of laser scans to 2 times, and then set the scan paths of the two laser scans to be line-by-line scan paths respectively. And the scan paths of these two laser scans are completely parallel and overlapping, spaced parallel and overlapping, or cross-orthogonally overlapping. The specific implementation methods are as follows.

[0033] First, during the first laser scan, since the pulsed laser needs to be focused on a preset peeling surface inside the ingot, that is, at a specific depth where the wafer is to be formed inside the ingot, and the driving module is used to drive the relative lateral movement between the ingot and the laser focus, so that the laser scan can form modified points covering the entire wafer. Among them, the modified points formed by the first laser scan are independent of each other, that is, there is no interaction between adjacent two modified points. At this time, the phenomenon that the depth of the modified points gradually rises to self-organize into a modified layer will not occur, and the modified points are uniformly located near the laser focus. To achieve this goal, the processing parameters of the pulsed laser need to meet the following conditions: the point spacing P1 between adjacent two modified points on the same scan section is not less than 0.7 times the diameter D1 of the modified point, that is, P1≥0.7D1. It should be noted that this condition is obtained based on a profound understanding of the self-organization formation principle of the modified layer. That is, when P1<0.7D1, the next laser pulse will be affected by the modified point generated by the previous laser pulse, so that it will no longer propagate to the laser focus, and its modified point position will gradually move up until the overlap rate between adjacent two modified points and the laser power density reach equilibrium, and a stable and very thin modified layer is formed at a specific depth.

[0034] Based on the preset calculation rules for the first laser scan, denote the laser pulse repetition frequency of the laser as F1, and the laser scanning speed (the relative moving speed between the ingot and the laser focus) as V1. Based on P1 = V1 / F1, it is thus possible to set the point spacing P1 by adjusting the laser pulse repetition frequency F1 and the laser scanning speed V1. At the same time, denote the diameter of the modified particle generated by the action of a single laser pulse as D1. Then D1 can be obtained by measuring the diameter of the modified particle with a microscope under the condition that P1 is set to be much larger than D1. D1 is related to the laser pulse energy E1 of the modified particle. The larger E1 is, D1 increases within a certain range, but the extension length of the modified particle in the longitudinal direction also increases accordingly. The smaller E1 is, D1 decreases within a certain range, but if E1 is too small, the laser pulse cannot form a stable modified particle. After selecting appropriate E1 and P1, perform a laser scan on the entire surface of the ingot, and denote the linear distance between two adjacent scan sections on the scan path as L1.

[0035] Preferably, in order to obtain as small a material flaking loss as possible, the focusing lens in this first step needs to be aberration-corrected to eliminate the spherical aberration effect caused by the refraction of the laser at the air-ingot interface, so that the light field inside the ingot is as concentrated as possible in the transmission direction, thereby reducing the longitudinal thickness of the modified particles in the first laser scan.

[0036] Preferably, the laser wavelength λ1 of the first laser scan is selected as pulsed laser in the range of 780 - 2500 nm, the laser pulse width Δt1 is 10 fs - 5 ns, and the laser pulse energy E1 ≥ 1 μJ.

[0037] Preferably, the first laser scan should be carried out under the condition that self-organization to form a modified layer with a gradually increasing depth of the modified particles does not occur, making adjacent modified particles as close as possible, that is, P1 as small as possible; or, for the same processing trace, set the relative movement times m1 of the laser and the ingot to be m1 ≥ 1, such as processing the same processing trace line back and forth (the relative movement times m1 is 2); or, set each laser pulse generating the modified particle as a pulse train with several sub-pulses, where the time interval between adjacent sub-pulses does not exceed 100 ns to obtain as dense a processing effect as possible.

[0038] Secondly, during the second laser scanning process, the pulsed laser needs to be focused below the preset peeling plane inside the ingot, and the pulsed laser is made to act on a partial or entire area of the modified points generated by the first laser scanning with a larger spot area. The ingot and the laser focus are driven to move horizontally relative to each other along the scanning path by the driving module, so that a modified layer composed of modified points covering the entire wafer can be formed by laser scanning, and cracks extending along the dissociation plane of the ingot are formed at the modified positions. During this process, when the laser spot overlaps with the modified points generated by the first laser scanning, the modified points generated by the first laser scanning (including amorphous carbon and silicon) will strongly absorb the laser energy, thereby forming a relatively high local internal pressure at the overlapping part, causing the generation and lateral expansion of cracks along the dissociation plane of the ingot. By performing the second laser scanning on the entire area of the ingot, a crack layer covering the entire ingot is generated to form the preset peeling plane. Therefore, the key to the second laser scanning lies in the generation and expansion of cracks, which mainly rely on the modified points generated by the first laser scanning, that is, the cracks are mainly generated in the overlapping area of the two laser scans. If the processing parameters generated by the second laser scanning are used for independent processing, a good modified layer and cracks cannot be formed, thus avoiding the problem that the modified points at the end face of the laser scanning gradually move upward during the process of generating cracks by independent processing.

[0039] In the preset calculation rule of the second laser scanning, let the pulse repetition frequency of the laser be F2, and the scanning speed (the relative moving speed of the ingot and the laser focus) be V2. Then the interval between adjacent modified points on the same scanning line in this second step is P2 = V2 / F2. Let the spot diameter at the depth of the modified points generated in the first step during the processing of this second step be D2. In order to form a good crack layer, P2 and D2 should satisfy: P2 < D2. More specifically, it is preferably 0.2D2 < P2 < 0.6D2.

[0040] Preferably, in order to make the laser have a larger spot area at the depth of the wafer thickness to be generated after being focused by the focusing lens, it is preferred to move the laser focus of the second laser scanning downward by a certain amount. The offset distance S2 is preferably 5 - 20 μm. In order to make the laser not form a good modified layer and cracks when processed independently with the second laser scanning, it is necessary to make the focused beam of this second laser scanning also have a larger spot area at its laser focus.

[0041] Preferably, the laser wavelength λ2 of the second laser scanning is selected as a pulsed laser in the range of 780 - 2500 nm, the laser pulse width Δt2 is 10 ps - 100 ns, and the laser pulse energy E2 ≥ 5 μJ.

[0042] Preferably, for the same processing trace, the relative movement times m2 of the laser with respect to the ingot are set to be m2≥1, such as processing the same processing trace line back and forth (the relative movement times m2 is 2); alternatively, each laser pulse generating the modified points is set as a pulse train having a plurality of sub-pulses, wherein the time interval between adjacent sub-pulses does not exceed 100 ns, so as to obtain a processing effect as dense as possible.

[0043] Finally, during the peeling process, the upper and lower end faces of the ingot that have been scanned by the laser twice can be fixed to two rigid jigs with an adhesive, and external forces in opposite directions are applied to the two jigs to separate the wafer along the peeling surface. Subsequently, the wafer and the remaining ingot are removed from the jigs, and the peeling surface is ground or thinned, and the remaining ingot is used for the next cycle of wafer generation process.

[0044] In summary, the beneficial technical effects of the present invention are as follows: It solves the problem of the climbing phenomenon of the modified points existing in the existing laser back-and-forth scanning method, and the problem of harsh process conditions existing in the pulsed laser stitching scanning with short pulse widths and long pulse widths. It can not only eliminate the burrs on the wafer edge, but also further reduce the material loss of laser peeling. It has the advantages of simple process conditions, good morphology of the modified layer, low difficulty in wafer peeling, and being suitable for large-scale industrial applications. Description of the Drawings

[0045] Figure 1 It is a front view structural schematic diagram of an ingot in the prior art of the present invention during laser scanning.

[0046] Figure 2 It is a connection relationship schematic diagram between a first laser, a first beam combining and expanding unit, an aberration correction unit, a first workpiece mirror, a first objective lens and an ingot in Embodiment 2 of the present invention.

[0047] Figure 3 It is a connection relationship schematic diagram between a second laser, a second beam combining unit, a beam shaping unit, a second workpiece mirror, a second objective lens and an ingot in Embodiment 2 of the present invention.

[0048] Figure 4 It is a front view structural schematic diagram of an ingot in the first laser scanning process in Embodiment 3 of the present invention.

[0049] Figure 5 It is a top view structural schematic diagram of an ingot in the first laser scanning process in Embodiment 3 of the present invention.

[0050] Figure 6 It is a partial enlarged structural schematic diagram of an ingot in the first laser scanning process in Embodiment 3 of the present invention.

[0051] Figure 7It is a front view structural schematic diagram of the ingot in Embodiment 3 of the present invention during the second laser scanning process.

[0052] Figure 8 It is a top view structural schematic diagram of the ingot in Embodiment 3 of the present invention during the second laser scanning process.

[0053] Figure 9 It is a partial enlarged structural schematic diagram of the ingot in Embodiment 3 of the present invention during the second laser scanning process.

[0054] Figure 10 It is a side view characterization diagram of the wafer obtained in Embodiment 3 of the present invention.

[0055] Figure 11 It is a top view structural schematic diagram of the ingot in Embodiment 4 of the present invention during the second laser scanning process.

[0056] Figure 12 It is a partial enlarged structural schematic diagram of the ingot in Embodiment 4 of the present invention during the second laser scanning process.

[0057] In the figure, 1, wafer; 2, ingot; 3, preset peeling surface; 4, modified particle point; 5, crack; 61, first laser; 62, first beam combining and expanding unit; 621, first beam combining mirror; 622, first laser reflecting mirror; 623, beam expander; 63, aberration correction unit; 64, first workpiece reflecting mirror; 65, first objective lens; 71, second laser; 72, second beam combining unit; 721, second beam combining mirror; 722, second laser reflecting mirror; 73, beam shaping unit; 74, second workpiece reflecting mirror; 75, second objective lens. Detailed implementation manners

[0058] In order to make the technical means, creative features, achieved purposes and functions of the present invention clearer and easier to understand, the present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0059] Embodiment 1: A semiconductor wafer generation method disclosed in the present invention includes the following steps.

[0060] S1 First, set the number of laser scans as n times, where n is an integer ≥ 2, and then set the scan path for each laser scan and the point spacing P between two adjacent modified particle points 4 on the scan path respectively.

[0061] S2 Based on the preset calculation rules for each laser scan, determine the laser scan speed V and laser pulse repetition frequency F required to reach the point spacing P, and determine the corresponding diameter D of the modified particle point 4, and further determine the laser pulse energy E required to reach the diameter D of the modified particle point 4 and the offset distance S of the laser focus relative to the preset peeling surface 3.

[0062] S3 focuses the pulsed laser on the preset peeling plane 3 inside the ingot 2 or below the preset peeling plane 3, and performs n laser scans to sequentially form modified particles 4 on the preset peeling plane 3, and an overlapping area is formed between the modified particles 4 formed by at least two laser scans to form a crack 5 extending transversely along the preset peeling plane 3 in the overlapping area;

[0063] S4 peels the ingot 2 along the preset peeling plane 3 to obtain the wafer 1 and the remaining ingot 2.

[0064] Embodiment 2: A method for generating a semiconductor wafer disclosed in the present invention is different from Embodiment 1 in that in S3, aberration correction is pre - performed on the pulsed laser before the first laser scan, and beam shaping is pre - performed on the pulsed laser before the second laser scan.

[0065] Referring to Figure 2 , first, a first laser 61, a first beam combining and expanding unit 62, an aberration correction unit 63, a first workpiece mirror 64, a first objective lens 65, and the ingot 2 are sequentially arranged on the pulsed laser emission path of the first laser scan; among them, two first lasers 61 are arranged in parallel, the first beam combining and expanding unit 62 includes a first beam combining mirror 621 arranged on the pulsed laser emission path of one of the first lasers 61, first laser reflectors 622 respectively arranged between the pulsed laser emission paths of the remaining first lasers 61 and the first beam combining mirror 621, and a beam expander 623 arranged on the pulsed laser emission path of the first beam combining mirror 621. The aberration correction unit 63 is set as an adaptive optical element, a diffractive optical element, or a deformable lens. This embodiment is preferably an SLM beam shaper.

[0066] Specifically, the process of aberration correction includes wavefront shaping of the incident beam of the pulsed laser by an adaptive optical element, compensating for the aberration of the focusing lens of the pulsed laser at a specific depth by a diffractive optical element, or presetting the aberration and compensating for the aberration of the focusing lens of the pulsed laser at a specific depth by adjusting a deformable lens. Among them, the adaptive optical element can be, for example, a spatial light modulator and a digital micromirror array without limitation, the diffractive optical element can be, for example, a beam shaper, a beam splitter, a diffractive cone lens, a spiral phase plate, a light homogenizer, and a multi - focus long - depth - of - field without limitation, and the deformable lens can be, for example, a lens with movable lenses or lens groups inside and / or outside without limitation.

[0067] Referring to Figure 3, secondly, on the pulsed laser emission path of the second laser scanning, a second laser 71, a second beam combining unit 72, a beam shaping unit 73, a second workpiece mirror 74, a second objective lens 75, and an ingot 2 are sequentially arranged; among them, two second lasers 71 are arranged in parallel, the second beam combining unit 72 includes a second beam combining mirror 721 arranged on the pulsed laser emission path of one of the second lasers 71, and second laser reflectors 722 respectively arranged between the pulsed laser emission paths of the remaining second lasers 71 and the second beam combining mirror 721, and the beam shaping unit 73 is set as an adaptive optical element or a diffractive optical element. This embodiment is preferably an SLM beam shaper.

[0068] Specifically, the process of beam shaping includes shaping the incident beam of the pulsed laser through an adaptive optical element, shaping the incident beam of the pulsed laser through a diffractive optical element, or increasing the beam quality factor of the incident beam of the pulsed laser. Among them, the adaptive optical element can be, for example, a spatial light modulator and a digital micromirror array without limitation, and the diffractive optical element can be, for example, a beam shaper, a beam splitter, a diffractive cone lens, a spiral phase plate, a light homogenizer, and a multi-focus long depth of focus without limitation.

[0069] Embodiment 3: Refer to Figures 4 - 9 , a semiconductor wafer generation method disclosed by the present invention, which is different from Embodiment 2 in that it includes the following steps

[0070] S1 First, set the number of laser scans to 2 times, then set the scan paths of each laser scan to be row-by-row scan paths respectively, and the scan paths of these two laser scans are completely parallel and overlapping. Among them, the point spacing P1 between two adjacent modified points 4 on the first scan path = 6 μm, and the line distance L1 between two spaced scan sections = 0.15 mm. The point spacing P2 between two adjacent modified points 4 on the second scan path = 6 μm, and the line distance L2 between two spaced scan sections = L1;

[0071] S2 Based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ, select pulsed laser with a laser wavelength range λ1 of 1030 nm and a laser pulse width Δt1 of 300 fs; determine the laser scan speed V1 = 300 mm / s required to reach the point spacing P1, the laser pulse repetition frequency F1 = 50 kHz, and determine the corresponding modified point 4 diameter D1 = 7 μm, and further determine the laser pulse energy E1 = 8 μJ required to reach the modified point 4 diameter D1, and the offset distance S1 of the laser focus relative to the preset peeling surface 3 = 0 μm;

[0072] S3 focuses the pulsed laser on the preset stripping surface 3 inside the ingot 2 and performs the first laser scanning to sequentially form modified points 4 on the preset stripping surface 3. At this time, the modified points 4 do not exhibit the phenomenon of self-organizing to form a modified layer with a gradually increasing depth, and the modified points 4 are uniformly located near the laser focus of the focusing lens. The longitudinal thickness of the modified points 4 is in the range of 25 - 30 μm.

[0073] S4 is based on the calculation rule preset for the second laser scanning: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. Select a pulsed laser with a laser wavelength range λ2 of 1030 nm and a laser pulse width Δt2 of 50 ps; determine the laser scanning speed V2 = 300 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to reach the point spacing P2, and determine the corresponding diameter D2 of the modified point 4 = 25 μm. Furthermore, determine the laser pulse energy E2 = 20 μJ required to reach the diameter D2 of the modified point 4 and the offset distance S2 of the laser focus relative to the preset stripping surface 3 = 10 μm.

[0074] S5 focuses the pulsed laser below the preset stripping surface 3 inside the ingot 2 and performs the second laser scanning to sequentially form modified points 4 on the preset stripping surface 3, and an overlapping area is formed between the modified points 4 formed by the two laser scans to form a crack 5 extending transversely along the preset stripping surface 3; Refer to Figure 10 , the wafer 1 processed according to the above parameters is characterized. The total thickness of the laser action area is about 50 μm, and there is no problem of the gradually rising modified points 4 at the laser scanning end face, which can effectively reduce the material loss of laser scribing.

[0075] Example 4: Refer to Figures 11 - 12 , a semiconductor wafer generation method disclosed by the present invention. The difference from Example 3 is that in S1, the scanning paths of the two laser scans cross and vertically overlap. Among them, there is no proportional relationship between the line distance L1 and the line distance L2, and they are independently selected from 0.10 - 1.00 mm. In this embodiment, preferably, the line distance L1 between two scanning sections spaced apart from each other on the first scanning path = 0.10 mm, and the line distance L2 between two scanning sections spaced apart from each other on the second scanning path = 0.10 mm.

[0076] Example 5: A semiconductor wafer generation method disclosed by the present invention. The difference from Example 3 is that in S3, the pulsed laser is a pulse train composed of three sub-pulses; among them, the time interval between two adjacent sub-pulses is 50 ns.

[0077] Example 6: A method for generating a semiconductor wafer disclosed in the present invention is different from Example 3 in that in S5, the pulsed laser is a pulse train composed of three sub-pulses; wherein, the time interval between two adjacent sub-pulses is 50 ns.

[0078] Example 7: A method for generating a semiconductor wafer disclosed in the present invention is different from Example 3 in that in S3, for the same processing trace, the relative movement times m1 of the laser with respect to the ingot are set to 2 times, that is, the same processing trace line is processed back and forth along the scanning path of the first laser scan.

[0079] Example 8: A method for generating a semiconductor wafer disclosed in the present invention is different from Example 2 and includes the following steps

[0080] S1 First, set the number of laser scans to 2 times, and then set the scanning path of each laser scan to be a line-by-line scanning path, and the scanning paths of these two laser scans are completely parallel and overlapping. Among them, the point spacing P1 between two adjacent modification points 4 on the first scanning path is 5 μm, and the line distance L1 between two adjacent scanning sections is 0.10 mm. The point spacing P2 between two adjacent modification points 4 on the second scanning path is 15 μm, and the line distance L2 between two adjacent scanning sections is 2L1;

[0081] S2 Based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ, select a pulsed laser with a laser wavelength range λ1 of 800 nm and a laser pulse width Δt1 of 10 fs; determine the laser scanning speed V1 = 250 mm / s required to reach the point spacing P1, the laser pulse repetition frequency F1 = 50 kHz, and determine the corresponding modification point 4 diameter D1 = 7 μm, and further determine the laser pulse energy E1 = 8 μJ required to reach the modification point 4 diameter D1, and the offset distance S1 of the laser focus relative to the preset peeling surface 3 is 0 μm;

[0082] S3 Focus the pulsed laser on the preset peeling surface 3 inside the ingot 2 and perform the first laser scan to sequentially form modification points 4 on the preset peeling surface 3. At this time, the modification points 4 do not show the phenomenon of self-organizing to form a modified layer with a gradually increasing depth, and the modification points 4 are all located near the laser focus of the focusing lens. The longitudinal thickness of the modification points 4 is in the range of 25 - 30 μm;

[0083] S4 Based on the calculation rules preset for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ, select pulsed laser with a laser wavelength range λ2 of 800 nm and a laser pulse width Δt2 of 100 ps; determine the laser scan speed V2 = 750 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2, and determine the corresponding modified particle 4 diameter D2 = 50 μm. Furthermore, determine the laser pulse energy E2 = 40 μJ required to achieve the modified particle 4 diameter D2, and the offset distance S2 = 20 μm of the laser focus relative to the preset peeling surface 3;

[0084] S5 Focus the pulsed laser below the preset peeling surface 3 inside the ingot 2 and perform the second laser scan to sequentially form modified particles 4 on the preset peeling surface 3, and an overlapping area is formed between the modified particles 4 formed by the two laser scans, so as to form a crack 5 extending transversely along the preset peeling surface 3 in the overlapping area.

[0085] Embodiment 9: A semiconductor wafer generation method disclosed by the present invention, which is different from Embodiment 2 in that it includes the following steps.

[0086] S1 First, set the number of laser scans to 2 times, and then set the scan path of each laser scan to be a line-by-line scan path, and the scan paths of these two laser scans are completely parallel and overlapping. Among them, the point spacing P1 between two adjacent modified particles 4 on the first scan path is 8 μm, and the line distance L1 between two spaced scan sections is 0.80 mm. The point spacing P2 between two adjacent modified particles 4 on the second scan path is 30 μm, and the line distance L2 between two spaced scan sections is L1;

[0087] S2 Based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ, select pulsed laser with a laser wavelength range λ1 of 1030 nm and a laser pulse width Δt1 of 200 ps; determine the laser scan speed V1 = 400 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point spacing P1, and determine the corresponding modified particle 4 diameter D1 = 10 μm. Furthermore, determine the laser pulse energy E1 = 12 μJ required to achieve the modified particle 4 diameter D1, and the offset distance S1 = 0 μm of the laser focus relative to the preset peeling surface 3;

[0088] S3 Focus the pulsed laser on the preset peeling surface 3 inside the ingot 2 and perform the first laser scan to sequentially form modified particles 4 on the preset peeling surface 3. At this time, the modified particles 4 do not exhibit the phenomenon of self-organizing to form a modified layer with a gradually increasing depth, and the modified particles 4 are uniformly located near the laser focus of the focusing lens. The longitudinal thickness of the modified particles 4 is in the range of 30 - 35 μm;

[0089] S4's calculation rule preset based on the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. Select a pulsed laser with a laser wavelength range λ2 of 1064 nm and a laser pulse width Δt2 of 20 ns; determine the laser scan speed V2 = 1500 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point pitch P2, and determine the corresponding modified particle 4 diameter D2 = 100 μm. Furthermore, determine the laser pulse energy E2 = 80 μJ required to achieve the modified particle 4 diameter D2, and the offset distance S2 = 20 μm of the laser focus relative to the preset peeling surface 3;

[0090] S5 Focus the pulsed laser below the preset peeling surface 3 inside the ingot 2 and perform the second laser scan to sequentially form modified particles 4 on the preset peeling surface 3, and an overlapping area is formed between the modified particles 4 formed by the two laser scans to form a crack 5 extending horizontally along the preset peeling surface 3 in the overlapping area. Example 10: A method for generating a semiconductor wafer disclosed in the present invention, which is different from Example 2 in that it includes the following steps.

[0091] S1 First, set the number of laser scans to 2 times, and then set the scan path of each laser scan to be a line-by-line scan path, and the scan paths of these two laser scans are completely parallel and overlapping. Among them, the point pitch P1 between two adjacent modified particles 4 on the first scan path is 10 μm, and the line distance L1 between two spaced scan sections is 0.40 mm. The point pitch P2 between two adjacent modified particles 4 on the second scan path is 8 μm, and the line distance L2 between two spaced scan sections is 2L1;

[0092] S2's calculation rule preset based on the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ. Select a pulsed laser with a laser wavelength range λ1 of 1064 nm and a laser pulse width Δt1 of 100 ps; determine the laser scan speed V1 = 500 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point pitch P1, and determine the corresponding modified particle 4 diameter D1 = 5 μm. Furthermore, determine the laser pulse energy E1 = 6 μJ required to achieve the modified particle 4 diameter D1, and the offset distance S1 = 0 μm of the laser focus relative to the preset peeling surface 3;

[0093] S3 Focus the pulsed laser on the preset peeling surface 3 inside the ingot 2 and perform the first laser scan to sequentially form modified particles 4 on the preset peeling surface 3. At this time, the modified particles 4 do not show the phenomenon of self-organizing to form a modified layer with a gradually increasing depth, and the modified particles 4 are all located near the laser focus of the focusing lens. The longitudinal thickness of the modified particles 4 is in the range of 15 - 20 μm;

[0094] S4's calculation rule preset based on the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. Select a pulsed laser with a laser wavelength range λ2 of 1340 nm and a laser pulse width Δt2 of 5 ns; determine the laser scan speed V2 = 400 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2, and determine the corresponding modified particle 4 diameter D2 = 15 μm. Furthermore, determine the laser pulse energy E2 = 12 μJ required to achieve the modified particle 4 diameter D2, and the offset distance S2 = 10 μm of the laser focus relative to the preset peeling surface 3;

[0095] S5 Focus the pulsed laser below the preset peeling surface 3 inside the ingot 2 and perform the second laser scan to sequentially form modified particles 4 on the preset peeling surface 3, and an overlapping area is formed between the modified particles 4 formed by the two laser scans to form a crack 5 extending horizontally along the preset peeling surface 3 in the overlapping area. Example 11: A semiconductor wafer generation method disclosed in the present invention, which is different from Example 2 in that it includes the following steps,

[0096] S1 First, set the number of laser scans to 2 times, and then set the scan path of each laser scan to be a row-by-row scan path, and the scan paths of these two laser scans are completely parallel and overlapping. Among them, the point spacing P1 between two adjacent modified particles 4 on the first scan path is 13 μm, and the line distance L1 between two spaced scan sections is 1.00 mm. The point spacing P2 between two adjacent modified particles 4 on the second scan path is 40 μm, and the line distance L2 = L1 between two spaced scan sections;

[0097] S2's calculation rule preset based on the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ. Select a pulsed laser with a laser wavelength range λ1 of 2100 nm and a laser pulse width Δt1 of 5 ns; determine the laser scan speed V1 = 650 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point spacing P1, and determine the corresponding modified particle 4 diameter D1 = 15 μm. Furthermore, determine the laser pulse energy E1 = 18 μJ required to achieve the modified particle 4 diameter D1, and the offset distance S1 = 0 μm of the laser focus relative to the preset peeling surface 3;

[0098] S3 Focus the pulsed laser on the preset peeling surface 3 inside the ingot 2 and perform the first laser scan to sequentially form modified particles 4 on the preset peeling surface 3. At this time, the modified particles 4 do not show the phenomenon of self-organizing to form a modified layer with a gradually increasing depth, and the modified particles 4 are uniformly located near the laser focus of the focusing lens. The longitudinal thickness of the modified particles 4 is in the range of 35 - 40 μm;

[0099] S4 Based on the calculation rules preset for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ, select pulsed laser with a laser wavelength range λ2 of 1550 nm and a laser pulse width Δt2 of 100 ns; determine the laser scanning speed V2 = 2000 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2, and determine the corresponding modified particle 4 diameter D2 = 80 μm. Furthermore, determine the laser pulse energy E2 = 60 μJ required to achieve the modified particle 4 diameter D2, and the offset distance S2 = 15 μm of the laser focus relative to the preset peeling surface 3;

[0100] S5 Focus the pulsed laser below the preset peeling surface 3 inside the ingot 2 and perform the second laser scan to sequentially form modified particles 4 on the preset peeling surface 3, and an overlapping area is formed between the modified particles 4 formed by the two laser scans to form a crack 5 extending horizontally along the preset peeling surface 3 in the overlapping area. Example 12: A semiconductor wafer generation method disclosed in the present invention, which is different from Example 2 in that it includes the following steps.

[0101] S1 First, set the number of laser scans to 2 times, and then set the scan path of each laser scan to be a line-by-line scan path, and the scan paths of these two laser scans are completely parallel and overlapping. Among them, the point spacing P1 between two adjacent modified particles 4 on the first scan path is 6 μm, and the line distance L1 between two spaced-apart scan sections is 0.30 mm. The point spacing P2 between two adjacent modified particles 4 on the second scan path is 7 μm, and the line distance L2 between two spaced-apart scan sections is 2L1;

[0102] S2 Based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ, select pulsed laser with a laser wavelength range λ1 of 1340 nm and a laser pulse width Δt1 of 50 ps; determine the laser scanning speed V1 = 600 mm / s and the laser pulse repetition frequency F1 = 100 kHz required to achieve the point spacing P1, and determine the corresponding modified particle 4 diameter D1 = 7 μm. Furthermore, determine the laser pulse energy E1 = 5 μJ required to achieve the modified particle 4 diameter D1, and the offset distance S1 = 0 μm of the laser focus relative to the preset peeling surface 3;

[0103] S3 Focus the pulsed laser on the preset peeling surface 3 inside the ingot 2 and perform the first laser scan to sequentially form modified particles 4 on the preset peeling surface 3. At this time, the modified particles 4 do not exhibit the phenomenon of self-organizing to form a modified layer with a gradually increasing depth, and the modified particles 4 are uniformly located near the laser focus of the focusing lens. The longitudinal thickness of the modified particles 4 is in the range of 5 - 10 μm;

[0104] S4's calculation rule based on the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. Select pulsed laser with a laser wavelength range λ2 of 2100 nm and a laser pulse width Δt2 of 10 ns; Determine the laser scan speed V2 = 700 mm / s and the laser pulse repetition frequency F2 = 100 kHz required to achieve the point spacing P2, and determine the corresponding modified particle 4 diameter D2 = 25 μm. Furthermore, determine the laser pulse energy E2 = 20 μJ required to achieve the modified particle 4 diameter D2, and the offset distance S2 = 10 μm of the laser focus relative to the preset peeling surface 3;

[0105] S5 Focus the pulsed laser below the preset peeling surface 3 inside the ingot 2, and perform the second laser scan to sequentially form modified particles 4 on the preset peeling surface 3, and form an overlapping area between the modified particles 4 formed by the two laser scans, so as to form a crack 5 extending horizontally along the preset peeling surface 3 in the overlapping area.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for generating a semiconductor wafer, characterized in that: Including the following steps, S1 First, set the number of laser scans to n times, where n is an integer greater than or equal to 2. Then, set the scan path for each laser scan and the point spacing P between two adjacent modified points on the scan path respectively; S2 Based on the preset calculation rules for each laser scan, determine the laser scan speed V and the laser pulse repetition frequency F required to reach the point spacing P, and determine the corresponding modified point diameter D. Furthermore, determine the laser pulse energy E required to reach the modified point diameter D and the offset distance S of the laser focus relative to the preset peeling surface; S3 Focus the pulsed laser on the preset peeling surface inside the ingot or below the preset peeling surface, and perform n laser scans to sequentially form modified points on the preset peeling surface. Moreover, an overlapping region is formed between the modified points formed by at least two of the laser scans, so as to form a crack extending transversely along the preset peeling surface in the overlapping region; S4 Peel the ingot along the preset peeling surface to obtain a wafer and a remaining ingot; In the step S2, the calculation rules for the 1st to n'th laser scans are as follows: P n′ =V n′ / F n′ , P n′ ≥0.7D n′ , E n′ ≥1μJ, S n′ is from 0 to 5μm; where P n′ is the point spacing between two adjacent modified particles on the 1st to n'th scan path, D n′ is the diameter of the modified particle for the 1st to n'th laser scan, V n′ is the 1st to n'th laser scan speed, F n′ is the 1st to n'th laser pulse repetition frequency, E n′ is the 1st to n'th laser pulse energy, S n′ is the offset distance of the 1st to n'th laser focus relative to the preset peeling surface, and n' is an integer greater than or equal to 1; In the step S2, the calculation rule for the (n'+1)-th to n''-th laser scans is that P n′+1 =V n′+1 / F n′+1 , where P n′+1 <D n′+1 , E n′+1 ≥5 μJ, and S n′+1 ranges from 0 to 20 μm; where P n′+1 is the distance between two adjacent modified points on the scan path of the (n'+1)-th to n''-th scans, D n′+1 is the diameter of the modified point of the (n'+1)-th to n''-th laser scans, V n′+1 is the scanning speed of the (n'+1)-th to n''-th laser scans, F n′+1 is the laser pulse repetition frequency of the (n'+1)-th to n''-th laser scans, E n′+1 is the laser pulse energy of the (n'+1)-th to n''-th laser scans, S n′+1 is the offset distance of the (n'+1)-th to n''-th laser focus relative to the preset peeling surface, and n'' is an integer greater than or equal to 2.

2. The semiconductor wafer generation method according to claim 1, wherein: In S1, the scan path for each laser scan is respectively one or a combination of a line-by-line scan path, a grid-interleaved scan path, a concentric circle scan path, and a spiral scan path.

3. A method for generating a semiconductor wafer according to claim 2, wherein: In S1, control the line distance L between two scan sections spaced apart from each other on the scan path to be 0.05 - 1.00 mm.

4. A method for generating a semiconductor wafer according to claim 1, characterized in that: In S2, control 0.2D n′+1 <P n′+1 <0.6D n′+1 .

5. A method for generating a semiconductor wafer according to claim 1, wherein: In S3, control the laser wavelength range λ for each laser scan to be 780 - 2500 nm and the laser pulse width Δt to be 10 fs - 100 ns respectively.

6. A method for generating a semiconductor wafer according to claim 1, characterized in that: In S3, the pulsed laser is a pulse train composed of a plurality of sub-pulses; wherein, the time interval between two adjacent sub-pulses does not exceed 100 ns.

7. A method for generating a semiconductor wafer according to claim 1, wherein: In S3, perform aberration correction on the pulsed laser prior to the 1st to n'th laser scans.

8. A method for generating a semiconductor wafer according to claim 1, wherein: In S3, perform beam shaping on the pulsed laser prior to the (n'+1)th to n''th laser scans.

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