Method for generating semiconductor wafer

Abstract

The present invention relates to a method for generating a semiconductor wafer, comprising the following steps: first, setting a number of times to perform laser scanning, then setting a scanning path and a point spacing for each instance of laser scanning; based on a preset calculation rule for each instance of laser scanning, determining a laser scanning speed and a laser pulse repetition frequency, and determining a corresponding modified spot diameter, a laser pulse energy and an offset distance of the laser focal point relative to a preset stripping surface; focusing a pulse laser on the preset stripping surface or below the preset stripping surface in a crystal ingot, and performing a number n of instances of laser scanning, so as to sequentially form a modified spot and a crack on the preset stripping surface; and stripping the crystal ingot along the preset stripping surface, to obtain a wafer and a remaining crystal ingot. The present invention can not only eliminate burrs on the edge of a wafer, but can also reduce material loss during laser stripping. The method has the advantages of simple process requirements, good modification layer morphology and low wafer stripping difficulty, and is suitable for large-scale industrial application.

Description

A method for producing a semiconductor wafer Technical Field

[0001] The present invention relates to the technical field of wafer processing, and in particular to a method for producing a semiconductor wafer. Background Art

[0002] In recent years, with the rapid development of the optoelectronics and microelectronics industries, various industries, including aerospace, aviation, machinery, light industry, and chemical engineering, have also been moving towards integration and miniaturization. These trends have correspondingly demanded that semiconductor devices become increasingly integrated, functionally complex, and physically smaller. Silicon carbide substrates are the core material for the recently developed wide-bandgap semiconductors. Devices made from them exhibit high-temperature and high-voltage resistance, high frequency, high power, and radiation resistance. They also offer the advantages of fast switching speeds and high efficiency, significantly reducing product power consumption, improving energy conversion efficiency, and reducing product size. Wafer processing is a key step in silicon carbide substrate manufacturing, and the quality of the slicing process directly impacts the performance of the silicon carbide substrate.

[0003] Laser slicing is a laser technology that separates silicon carbide ingots into individual wafers. This process uses a precision laser beam to form a modified layer inside the ingot, allowing the wafers 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 is focused 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, the stress field will produce a concentrated effect around the microcracks. When the peeling force is mechanically applied, the stress will induce the expansion of cracks at the specified location due to the presence of the modified layer, thereby completing the peeling of the wafer. The above method can significantly reduce material loss during the slicing process and improve wafer production efficiency.

[0004] A Chinese patent with authorization publication number CN107790898B discloses a method for producing a SiC wafer, comprising the following steps: a peeling surface production step, in which a separation layer forming process is performed as follows: a focal point of a pulsed laser beam having a wavelength that is transmissive to SiC is positioned at a depth from the first surface that is equivalent to the thickness of the wafer to be produced, and while the single crystal SiC ingot and the focal point are relatively fed in a first direction perpendicular to a second direction forming the deviation angle, the single crystal SiC ingot is irradiated with a pulsed laser beam, thereby forming a separation layer consisting of a modified layer and cracks; and a wafer production step, in which a portion of the single crystal SiC ingot is peeled off using the peeling surface as an interface to produce a SiC wafer, wherein the processing feed in the peeling surface production step includes forward movement and return movement, and the forward movement causes the focal point to move from one end of the single crystal SiC ingot to the other end relative to the other end. The return movement causes the focal point to move relatively from the other end to the one end while the depth of the focal point is maintained at the same depth as that of the focal point during the forward movement, thereby tracing back the already formed separation layer. During the forward movement, the modified layer initially formed is formed by the focal point, and the modified layer formed subsequent to the initial modified layer is formed at a position slightly shallower than the focal point. A rise of the modified layer occurs at the one end of the single crystal SiC ingot where the irradiation of the pulsed laser beam is started. When the modified layer reaches a depth inside the single crystal SiC ingot at which the power density of the pulsed laser beam becomes a prescribed value, a modified layer is formed near the front of the focal point and at a depth at which the power density is the prescribed value. During the return movement, a modified layer is formed from the other end to the one end of the single crystal SiC ingot, near the front of the focal point and at a depth at which the power density is the prescribed value.

[0005] The above-mentioned existing technical solutions have the following defects: in the peeling surface generation process, the above-mentioned 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; wherein, the burr at the laser scanning end face is mainly caused by the self-organization change of the modified layer during the formation process, that is, after the laser enters the single crystal SiC ingot, the modified point generated by the first laser pulse is located near the geometric focus of the focusing lens, and as the laser moves along the scanning direction, the modified point gradually rises until the overlap rate of adjacent modified points and the laser power density reach a balance. , and forms a stable modified layer at a predetermined depth; referring to Figure 1, this also results in the modification layer climbing in an area about tens of μm away from the end of one side of the single crystal SiC ingot during the forward movement. After actual testing, the lifting amplitude is about 40 to 100 μm. The above method only reduces the burrs left on the wafer to a certain extent, but leads to the problem that the modified point at the laser scanning end face gradually rises toward the peeling surface. Therefore, after the wafer is peeled off, it is still necessary to grind or thin a considerable thickness of material to completely remove the traces left by the laser scanning at the end face, and the material loss is as high as 30%.

[0006] Chinese patent publication number CN115635183A discloses a method for laser stripping a workpiece, comprising: using a pulsed laser with a short pulse width to focus on a preset stripping surface within the workpiece to form a modified point on the preset stripping surface within the workpiece; using a pulsed laser with a long pulse width to focus on the modified point to form a modified zone at the modified point and a crack extending radially along the preset stripping surface; and dividing the workpiece into a first workpiece unit and a second workpiece unit along the preset stripping surface.

[0007] The above-mentioned prior art solution has the following defects: the above method uses a short-pulse-width pulse laser to form a modified point on a preset peeling surface inside the silicon carbide, and then uses a long-pulse-width pulse laser to focus on the modified point generated by the short-pulse laser to form a modified zone, thereby forming a crack extending in the radial direction of the preset peeling surface, so that the workpiece can be easily peeled. However, this requires that the short- and long-pulse-width pulse lasers must not only be strictly aligned with the point, but also strictly synchronized in timing, which has poor practical operability and is not conducive to large-scale industrial application.

[0008] Summary of the Invention

[0009] The problem to be solved by the present invention is to provide a semiconductor chip production method in response to the above-mentioned deficiencies in the prior art. The method solves the problem of modified point climbing in the existing laser reciprocating scanning method and the problem of harsh process conditions in the pulse laser connection scanning with short pulse width and long pulse width. It can not only eliminate the burrs on the edge of the chip, but also further reduce the material loss of laser stripping. It has the advantages of simple process conditions, good morphology of the modified layer, low difficulty in chip stripping, and suitability for large-scale industrial applications.

[0010] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0011] A method for producing a semiconductor wafer comprises the following steps:

[0012] S1: First, set the number of laser scans to n, where n is an integer ≥ 2, and then set the scanning path of each laser scan and the point spacing P between two adjacent modified points on the scanning path;

[0013] S2 determines the laser scanning speed V and laser pulse repetition frequency F required to achieve the point spacing P based on the preset calculation rules for each laser scan, and determines the corresponding modified point diameter D, and further determines the laser pulse energy E required to achieve the modified point diameter D, and the offset distance S of the laser focus relative to the preset peeling surface;

[0014] S3: focusing a pulsed laser on a predetermined peeling surface or below the predetermined peeling surface inside the ingot, and performing n laser scans to sequentially form modified points on the predetermined peeling surface, with an overlapping region formed between the modified points formed by at least two laser scans, so as to form a crack extending laterally along the predetermined peeling surface in the overlapping region;

[0015] S4: peeling the crystal ingot along the preset peeling surface to obtain wafers and remaining crystal ingots.

[0016] Specifically, in the present invention, the meaning of the modified point refers to the independent or continuous laser action point formed on the preset peeling surface. Correspondingly, the point spacing P, line distance L and modified point diameter D also refer to the point spacing between two adjacent modified points at the preset peeling surface position, the line distance between two scanning segments spaced from each other, and the modified point diameter.

[0017] Furthermore, in S1, the scanning path of each laser scanning is one or a combination of the following: a line-by-line scanning path, a grid-interlaced scanning path, a concentric circle scanning path, and a spiral line scanning path.

[0018] Furthermore, in S1, the linear distance L between two scanning segments spaced apart from each other on the scanning path is controlled to be 0.05-1.00 mm, wherein the scanning segments on the scanning path are arranged with equal or unequal spacing.

[0019] Furthermore, in the step S1, the control point spacing P is 0.5 to 50 μm.

[0020] Furthermore, in said S2, the preset calculation rule for the 1st to n′th laser scans is: n′ =V n′ / F n′ , P n′ ≥0.7D n′ , E n′ ≥1μJ, S n′ 0~5μm; among them, P n′ V is the distance between two adjacent modified points on the 1st to nth scanning path, n′ is the laser scanning speed from the 1st to nth time, F n′ is the repetition frequency of the 1st to n′th laser pulses, E n′ is the energy of the 1st to nth laser pulses, S n′ It is the offset distance of the laser focus from the 1st to the nth time relative to the preset peeling surface, where n' is an integer ≥1.

[0021] Furthermore, in said S2, the preset calculation rule for the n′+1 to n″th laser scan is: n′+1 =V n′+1 / F n′+1 , P n′+1 <D n′+1 , E n′+1 ≥5μJ, S n′+1 0~20μm; among them, P n′+1 V is the distance between two adjacent modified points on the n′+1~n″th scanning path, n′+1 is the laser scanning speed of the n′+1~n″th time, F n′+1 is the repetition frequency of the laser pulse from n′+1 to n″, E n′+1 is the laser pulse energy from n′+1 to n″, S n′+1 It is the offset distance of the laser focus from the n′+1th to the n″th time relative to the preset peeling surface, where n″ is an integer ≥2.

[0022] Furthermore, in said S2, 0.2D is controlled n′+1 <P n′+1 <0.6D n′+1 .

[0023] Furthermore, in S3, the laser wavelength range λ of each laser scan is controlled to be 780 to 2500 nm, and the laser pulse width Δt is controlled to be 10 fs to 100 ns.

[0024] Furthermore, in S3, the pulse 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.

[0025] Furthermore, in the step S3, aberration correction is performed on the pulse laser before the 1st to n'th laser scans.

[0026] Furthermore, in said S3, the longitudinal thickness of the modified point of the 1st to n'th laser scans is controlled to be 5 to 40 μm.

[0027] Furthermore, in the S3, a first laser, a first beam combining and expanding unit, an aberration correction unit, a first workpiece reflector, a first objective lens, and a crystal ingot are sequentially arranged on the pulse laser emission path of the 1st to n′th laser scans; wherein, at least two first lasers are arranged in parallel, the first beam combining and expanding unit includes a first beam combining mirror arranged on the pulse laser emission path of one of the first lasers, first laser reflectors respectively arranged between the pulse laser emission paths of the remaining first lasers and the first beam combining mirror, and a beam expanding mirror arranged on the pulse laser emission path of the first beam combining mirror, and the aberration correction unit is configured as an adaptive optical element, a diffraction optical element, or a deformable lens.

[0028] Furthermore, in S3, the aberration correction process includes shaping the wavefront of the incident beam of the pulsed laser using an adaptive optical element, compensating for the aberration of the focusing lens of the pulsed laser at a specific depth using a diffractive optical element, or adjusting a deformable lens to preset the aberration and compensate for the aberration of the focusing lens of the pulsed laser at a specific depth. The adaptive optical element may be, for example, a spatial light modulator and a digital micromirror array, and the diffractive optical element may be, for example, a beam shaper, a beam splitter, a diffractive aconic lens, a spiral phase plate, a light diffuser, and a multi-focal telephoto lens. The deformable lens may be, for example, a lens having internal and / or external movable lenses or lens groups, and may be, for example, a lens having internal and / or external movable lenses or lens groups.

[0029] Furthermore, in S3, the pulse laser is beam-shaped before the n′+1-n″th laser scans.

[0030] Furthermore, in said S3, the diameter D of the modified spot of the n′+1 to n″ laser scans is controlled. n′+1 15~100μm.

[0031] Furthermore, in S3, a second laser, a second beam combining unit, a beam shaping unit, a second workpiece reflector, a second objective lens, and a crystal ingot are sequentially arranged on the pulse laser emission path of the n′+1 to n″th laser scans; wherein, at least two second lasers are arranged in parallel, the second beam combining unit includes a second beam combining mirror arranged on the pulse laser emission path of one of the second lasers, and second laser reflectors respectively arranged between the pulse laser emission paths of the remaining second lasers and the second beam combining mirrors, and the beam shaping unit is configured as an adaptive optical element or a diffraction optical element.

[0032] Furthermore, in S3, the beam shaping process includes shaping the incident pulsed laser beam using an adaptive optical element, shaping the incident pulsed laser beam using a diffractive optical element, or increasing the beam quality factor of the incident pulsed laser beam. The adaptive optical element may be, for example, a spatial light modulator and a digital micromirror array, and the diffractive optical element may be, for example, a beam shaper, a beam splitter, a diffractive axicon, a spiral phase plate, a diffuser, and a multi-focus telephoto lens.

[0033] Specifically, the number of laser scans is first set to 2, and then the scanning paths of the two laser scans are set to be line-by-line scanning paths, and the scanning paths of the two laser scans are completely parallel and overlapped, parallel and overlapped at intervals, or cross-vertically overlapped. The specific implementation method is as follows.

[0034] First, during the first laser scan, the pulsed laser needs to be focused on the preset peeling surface inside the ingot, that is, the specific depth inside the ingot where the wafer is to be generated, and the drive module drives the lateral relative movement between the ingot and the laser focus according to the scanning path, so that the laser scanning 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 two adjacent modified points. At this time, the phenomenon of the modified points gradually increasing in depth and self-organizing to form 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 two adjacent modified points in the same scanning 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 derived based on a deep understanding of the principle of self-organization formation 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, but the position of the modified point will gradually move upward until the overlap rate of the two adjacent modified points and the laser power density reach a balance, and a stable and very thin modified layer is formed at a specific depth.

[0035] Based on the preset calculation rules for the first laser scan, the laser pulse repetition frequency is F1, and the laser scanning speed (the relative movement speed between the ingot and the laser focus) is V1. Based on P1 = V1 / F1, the point spacing P1 can be set by adjusting the laser pulse repetition frequency F1 and the laser scanning speed V1. Furthermore, the diameter of the modified spot produced by a single laser pulse is D1. D1 can be determined by measuring the diameter of the modified spot using a microscope, while setting P1 to be significantly larger than D1. D1 is related to the laser pulse energy E1 used to form the modified spot. A larger E1 increases D1 within a certain range, but the longitudinal extension of the modified spot also increases. A smaller E1 decreases D1 within a certain range, but an excessively small E1 will prevent the laser pulse from forming a stable modified spot. After selecting appropriate E1 and P1, the entire surface of the ingot is laser scanned, and the linear distance between two separated scanning segments along the scanning path is L1.

[0036] Preferably, in order to obtain the smallest possible material peeling loss, 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 point of the first laser scan.

[0037] Preferably, the laser wavelength λ1 of the first laser scan is selected as a pulse laser in the range of 780 to 2500 nm, the laser pulse width Δt1 is 10 fs to 5 ns, and the laser pulse energy E1 is ≥1 μJ.

[0038] Preferably, the first laser scan should make adjacent modified points as close as possible, that is, P1 is as small as possible, under the condition that the depth of the modified points does not gradually increase and self-organize to form a modified layer; or, for the same processing trace, the number of relative movements of the laser and the crystal ingot is set to m1≥1, such as processing the same processing trace line back and forth (the number of relative movements m1 is 2); or, each laser pulse for generating a modified point is set to a pulse train with several sub-pulses, wherein the time interval between adjacent sub-pulses does not exceed 100ns, so as to obtain the densest processing effect possible.

[0039] Secondly, during the second laser scanning process, the pulsed laser needs to be focused below the preset peeling surface inside the ingot, and the pulsed laser needs to act on a part or all of the modified points generated by the first laser scan with a larger spot area, and the drive module drives the ingot and the laser focus to move relative to each other laterally according to the scanning path, so that the laser scanning can form a modified layer composed of modified points covering the entire wafer, and form cracks extending along the dissociation surface of the ingot at the modified location. In this process, when the laser spot overlaps with the modified points generated by the first laser scan, the modified points generated by the first laser scan (including amorphous carbon and silicon) will strongly absorb the laser energy, thereby forming a higher local internal pressure at the overlapping portion, causing cracks to be generated along the dissociation surface of the ingot and the cracks to extend laterally. By performing a second laser scan on the entire width of the ingot, a crack layer covering the entire ingot is generated, forming a preset peeling surface. Therefore, the key to the second laser scan is the generation and expansion of cracks, which mainly depends on the modified points generated by the first laser scan, 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 scan are used independently, a good modified layer and cracks cannot be formed. This avoids the problem of the modified points at the laser scanning end face gradually moving upward during the crack generation process of separate processing.

[0040] In the calculation rules preset for the second laser scan, let the laser pulse repetition frequency be F2, and the scanning speed (relative movement speed between 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 point produced in the first step in this second step be D2. In order to form a good crack layer, P2 and D2 should satisfy: P2 < D2. More specifically, 0.2D2 is preferred. <P2<0.6D2。

[0041] Preferably, in order to ensure that the laser beam has a larger spot area at the depth of the desired wafer thickness after being focused by the focusing lens, the laser focus of the second laser scan is preferably shifted downward by a certain amount, with the offset distance S2 preferably being 5 to 20 μm. In order to ensure that the laser beam does not form a well-defined modified layer or cracks during the second laser scan after being focused by the focusing lens, the focused beam of the second laser scan also needs to have a larger spot area at its laser focus.

[0042] Preferably, the laser wavelength λ2 of the second laser scan is selected as a pulse laser in the range of 780 to 2500 nm, the laser pulse width Δt2 is 10 ps to 100 ns, and the laser pulse energy E2 is ≥5 μJ.

[0043] Preferably, for the same processing trace, the relative movement times m2 between the laser and the crystal ingot are set to ≥ 1, such as processing the same processing trace line back and forth (the relative movement times m2 is 2); or, each laser pulse for generating a modified point is set to a pulse train with several sub-pulses, wherein the time interval between adjacent sub-pulses does not exceed 100ns, so as to obtain the densest processing effect possible.

[0044] Finally, during the peeling process, the upper and lower end faces of the ingot, which has undergone two laser scans, are fixed to two rigid fixtures with adhesive. Opposite forces are applied to the fixtures to separate the wafers along the peeling surface. The wafers and the remaining ingot are then removed from the fixtures, and the peeling surface is ground or thinned. The remaining ingot is then used for the next wafer generation cycle.

[0045] In summary, the beneficial technical effects of the present invention are: it solves the problem of modified point climbing in the existing laser reciprocating scanning method, and the problem of harsh process conditions in the pulse laser connection scanning of short pulse width and long pulse width. It can not only eliminate the burrs on the edge of the chip, 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 chip peeling, and suitability for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a schematic diagram of the main structure of a crystal ingot during laser scanning according to the prior art of the present invention.

[0047] 2 is a schematic diagram of the connection relationship between the first laser, the first beam combining and expanding unit, the aberration correction unit, the first workpiece reflecting mirror, the first objective lens and the crystal ingot according to Embodiment 2 of the present invention.

[0048] 3 is a schematic diagram of the connection relationship between the second laser, the second beam combining unit, the beam shaping unit, the second workpiece reflecting mirror, the second objective lens and the crystal ingot according to Example 2 of the present invention.

[0049] FIG4 is a schematic diagram of the main structure of the crystal ingot during the first laser scanning process according to Example 3 of the present invention.

[0050] FIG5 is a schematic diagram of the top view of the crystal ingot during the first laser scanning process according to Example 3 of the present invention.

[0051] FIG6 is a schematic diagram of a partially enlarged structure of the crystal ingot during the first laser scanning process according to Example 3 of the present invention.

[0052] FIG7 is a schematic diagram of the main structure of the crystal ingot during the second laser scanning process according to Example 3 of the present invention.

[0053] FIG8 is a schematic diagram of the top view of the crystal ingot during the second laser scanning process according to Example 3 of the present invention.

[0054] FIG9 is a schematic diagram of a partially enlarged structure of the crystal ingot during the second laser scanning process according to Example 3 of the present invention.

[0055] FIG10 is a side view representation diagram of the wafer produced in Example 3 of the present invention.

[0056] FIG11 is a schematic diagram of the top view of the crystal ingot during the second laser scanning process according to Example 4 of the present invention.

[0057] FIG12 is a schematic diagram of a partially enlarged structure of the crystal ingot during the second laser scanning process according to Example 4 of the present invention.

[0058] In the figure, 1, wafer; 2, ingot; 3, preset peeling surface; 4, modified point; 5, crack; 61, first laser; 62, first beam combining and expanding unit; 621, first beam combining mirror; 622, first laser reflection mirror; 623, beam expanding mirror; 63, aberration correction unit; 64, first workpiece reflection mirror; 65, first objective lens; 71, second laser; 72, second beam combining unit; 721, second beam combining mirror; 722, second laser reflection mirror; 73, beam shaping unit; 74, second workpiece reflection mirror; 75, second objective lens. DETAILED DESCRIPTION

[0059] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further explained below with reference to the accompanying drawings and specific implementation methods.

[0060] Example 1: A method for producing a semiconductor wafer disclosed in the present invention comprises the following steps:

[0061] S1 first sets the number of laser scans to n, where n is an integer ≥ 2, and then sets the scanning path of each laser scan and the point spacing P between two adjacent modified points 4 on the scanning path;

[0062] S2 determines the laser scanning speed V and laser pulse repetition frequency F required to achieve the point spacing P based on the preset calculation rules for each laser scan, and determines the corresponding diameter D of the modified point 4. It then determines the laser pulse energy E required to achieve the diameter D of the modified point 4 and the offset distance S of the laser focus relative to the preset peeling surface 3;

[0063] S3 focuses a pulsed laser on a predetermined peeling surface 3 inside the ingot 2 or below the predetermined peeling surface 3, and performs n laser scans to sequentially form modified points 4 on the predetermined peeling surface 3, with an overlapping region formed between the modified points 4 formed by at least two laser scans, so as to form a crack 5 extending laterally along the predetermined peeling surface 3 in the overlapping region;

[0064] S4: peeling the crystal ingot 2 along the preset peeling surface 3 to obtain the wafer 1 and the remaining crystal ingot 2.

[0065] Example 2: A semiconductor wafer generation method disclosed in the present invention, which differs from Example 1 in that, in S3, the pulse laser is pre-corrected for aberration before the first laser scan, and the pulse laser is pre-beam shaped before the second laser scan.

[0066] 2 , first, a first laser 61, a first beam combining and expanding unit 62, an aberration correction unit 63, a first workpiece reflector 64, a first objective lens 65, and a crystal ingot 2 are sequentially arranged on the pulse laser emission path of the first laser scan. 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 pulse laser emission path of one of the first lasers 61, first laser reflectors 622 arranged between the pulse laser emission paths of the remaining first lasers 61 and the first beam combining mirror 621, and a beam expander 623 arranged on the pulse laser emission path of the first beam combining mirror 621. The aberration correction unit 63 is configured as an adaptive optical element, a diffractive optical element, or a deformable lens. This embodiment is preferably an SLM beam shaper.

[0067] Specifically, the aberration correction process includes shaping the wavefront of the incident pulsed laser beam using an adaptive optical element, compensating for the aberration of the pulsed laser's focusing lens at a specific depth using a diffractive optical element, or adjusting a deformable lens to preset aberrations and compensate for the aberration of the pulsed laser's focusing lens at a specific depth. The adaptive optical element may be, for example, a spatial light modulator and a digital micromirror array, and the diffractive optical element may be, for example, a beam shaper, a beam splitter, a diffractive axicon, a spiral phase plate, a diffuser, and a multi-focal telephoto lens. The deformable lens may be, for example, a lens with internal and / or external movable lenses or lens groups, and may be, for example, a lens with internal and / or external movable lenses or lens groups.

[0068] Referring to Figure 3 , a second laser 71, a second beam combining unit 72, a beam shaping unit 73, a second workpiece reflector 74, a second objective lens 75, and the ingot 2 are sequentially arranged on the pulse laser emission path of the second laser scan. Two second lasers 71 are arranged in parallel. The second beam combining unit 72 includes a second beam combining mirror 721 arranged on the pulse laser emission path of one of the second lasers 71, and second laser reflectors 722 arranged between the pulse laser emission paths of the remaining second lasers 71 and the second beam combining mirrors 721. The beam shaping unit 73 is configured as an adaptive optical element or a diffractive optical element. In this embodiment, an SLM beam shaper is preferably used.

[0069] Specifically, the beam shaping process includes shaping the incident pulsed laser beam using an adaptive optical element, shaping the incident pulsed laser beam using a diffractive optical element, or increasing the beam quality factor of the incident pulsed laser beam. The adaptive optical element may be, for example, a spatial light modulator and a digital micromirror array, and the diffractive optical element may be, for example, a beam shaper, a beam splitter, a diffractive axicon, a spiral phase plate, a diffuser, and a multi-focus telephoto lens.

[0070] Example 3: Referring to Figures 4 to 9, a semiconductor wafer production method disclosed in the present invention is different from Example 2 in that it includes the following steps:

[0071] S1 first sets the number of laser scans to 2, and then sets the scanning path of each laser scan to a line-by-line scanning path, with the scanning paths of the two laser scans completely parallel and overlapping. In the first scanning path, the point spacing between two adjacent modified points 4 is P1 = 6 μm, and the linear distance between two separated scanning segments is L1 = 0.15 mm. In the second scanning path, the point spacing between two adjacent modified points 4 is P2 = 6 μm, and the linear distance between two separated scanning segments is L2 = L1.

[0072] S2 is based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ, and selects a pulsed laser with a laser wavelength range λ1 of 1030 nm and a laser pulse width Δt1 of 300 fs. The laser scanning speed V1 = 300 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point spacing P1 are determined, and the corresponding modified point 4 diameter D1 = 7 μm is determined. Furthermore, the laser pulse energy E1 = 8 μJ and the offset distance S1 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D1 are determined.

[0073] S3 focuses the pulsed laser on the preset peeling surface 3 inside the ingot 2 and performs the first laser scan to sequentially form modified points 4 on the preset peeling surface 3. At this time, the modified points 4 do not gradually increase in depth to form a modified layer by self-organization. The modified points 4 are uniformly located near the laser focus of the focusing lens, and the longitudinal thickness of the modified points 4 is within the range of 25 to 30 μm.

[0074] S4 is based on the preset calculation rules for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. A pulsed laser with a laser wavelength range λ2 of 1030 nm and a laser pulse width Δt2 of 50 ps is selected. The laser scanning speed V2 = 300 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2 are determined. The corresponding diameter of the modified point 4 D2 = 25 μm is determined. Furthermore, the laser pulse energy E2 = 20 μJ and the offset distance S2 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D2 are determined.

[0075] S5 focuses the pulsed laser below the preset peeling surface 3 inside the ingot 2 and performs a second laser scan to sequentially form modified points 4 on the preset peeling surface 3, and an overlapping area is formed between the modified points 4 formed by the two laser scans, so as to form a crack 5 extending laterally along the preset peeling surface 3 in the overlapping area; referring to Figure 10, the chip 1 processed according to the above parameters is characterized, and its total laser active area thickness is about 50μm. There is no problem of gradual rise of the modified points 4 at the laser scanning end face, which can effectively reduce the material loss of laser peeling.

[0076] Example 4: Referring to Figures 11 to 12, a semiconductor wafer generation method disclosed in the present invention is different from Example 3 in that, in S1, the scanning paths of the two laser scans cross and overlap vertically, wherein there is no proportional relationship between the line distance L1 and the line distance L2, and each is independently selected from 0.10 to 1.00 mm. Preferably, in this embodiment, the line distance L1 between the two scanning segments spaced apart from each other on the first scanning path is 0.10 mm, and the line distance L2 between the two scanning segments spaced apart from each other on the second scanning path is 0.10 mm.

[0077] Example 5: A semiconductor wafer production method disclosed in the present invention, which is different from Example 3 in that, in S3, the pulse laser is a pulse train consisting of three sub-pulses; wherein the time interval between two adjacent sub-pulses is 50ns.

[0078] Example 6: A semiconductor wafer production method disclosed in the present invention, which is different from Example 3 in that, in S5, the pulse laser is a pulse train consisting of three sub-pulses; wherein the time interval between two adjacent sub-pulses is 50ns.

[0079] Example 7: A semiconductor chip generation method disclosed in the present invention is different from Example 3 in that, in S3, for the same processing trace, the number of relative movements m1 between the laser and the crystal ingot is set to 2 times, that is, the same processing trace line is processed back and forth according to the scanning path of the first laser scan.

[0080] Example 8: A method for producing a semiconductor wafer disclosed in the present invention, which differs from Example 2 in that it includes the following steps:

[0081] S1 first sets the number of laser scans to 2, and then sets the scanning path of each laser scan to a line-by-line scanning path, with the scanning paths of the two laser scans completely parallel and overlapping. In the first scanning path, the point spacing between two adjacent modified points 4 is P1 = 5 μm, and the linear distance between two separated scanning segments is L1 = 0.10 mm. In the second scanning path, the point spacing between two adjacent modified points 4 is P2 = 15 μm, and the linear distance between two separated scanning segments is L2 = 2L1.

[0082] S2 is based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ, and selects a pulsed laser with a laser wavelength range λ1 of 800 nm and a laser pulse width Δt1 of 10 fs. The laser scanning speed V1 = 250 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point spacing P1 are determined, and the corresponding modified point 4 diameter D1 = 7 μm is determined. Furthermore, the laser pulse energy E1 = 8 μJ and the offset distance S1 = 0 μm of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D1 are determined.

[0083] S3 focuses the pulsed laser on the preset peeling surface 3 inside the ingot 2 and performs the first laser scan to sequentially form modified points 4 on the preset peeling surface 3. At this time, the modified points 4 do not gradually increase in depth to form a modified layer by self-organization. The modified points 4 are uniformly located near the laser focus of the focusing lens, and the longitudinal thickness of the modified points 4 is within the range of 25 to 30 μm.

[0084] S4 is based on the calculation rules preset for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. A pulsed laser with a laser wavelength range λ2 of 800 nm and a laser pulse width Δt2 of 100 ps is selected. The laser scanning speed V2 = 750 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2 are determined. The corresponding diameter of the modified point 4 D2 = 50 μm is determined. Furthermore, the laser pulse energy E2 = 40 μJ and the offset distance S2 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D2 are determined.

[0085] S5 focuses the pulsed laser below the preset peeling surface 3 inside the ingot 2 and performs a second laser scan to sequentially form modified points 4 on the preset peeling 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 laterally along the preset peeling surface 3 in the overlapping area.

[0086] Example 9: A method for producing a semiconductor wafer disclosed in the present invention, which differs from Example 2 in that it includes the following steps:

[0087] S1 first sets the number of laser scans to 2, and then sets the scanning path of each laser scan to a line-by-line scanning path, with the scanning paths of the two laser scans completely parallel and overlapping. In the first scanning path, the point spacing between two adjacent modified points 4 is P1 = 8 μm, and the linear distance between two separated scanning segments is L1 = 0.80 mm. In the second scanning path, the point spacing between two adjacent modified points 4 is P2 = 30 μm, and the linear distance between two separated scanning segments is L2 = L1.

[0088] S2 is based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ. A pulsed laser with a laser wavelength range λ1 of 1030 nm and a laser pulse width Δt1 of 200 ps is selected. The laser scanning speed V1 = 400 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point spacing P1 are determined. The corresponding diameter of the modified point 4 D1 = 10 μm is determined, and the laser pulse energy E1 = 12 μJ and the offset distance S1 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D1 are further determined.

[0089] S3 focuses the pulsed laser on the preset peeling surface 3 inside the ingot 2 and performs the first laser scan to sequentially form modified points 4 on the preset peeling surface 3. At this time, the modified points 4 do not gradually increase in depth to form a modified layer by self-organization. The modified points 4 are uniformly located near the laser focus of the focusing lens, and the longitudinal thickness of the modified points 4 is within the range of 30 to 35 μm.

[0090] S4 is based on the preset calculation rules for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. A pulsed laser with a laser wavelength range λ2 of 1064 nm and a laser pulse width Δt2 of 20 ns is selected. The laser scanning speed V2 = 1500 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2 are determined. The corresponding diameter of the modified point 4 D2 = 100 μm is determined. Furthermore, the laser pulse energy E2 = 80 μJ and the offset distance S2 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D2 are determined.

[0091] S5 focuses the pulsed laser below the preset peeling surface 3 inside the ingot 2 and performs a second laser scan to sequentially form modified points 4 on the preset peeling surface 3, and an overlapping area is formed between the modified points 4 formed by the two laser scans, so that cracks 5 extending laterally along the preset peeling surface 3 are formed in the overlapping area. Example 10: A semiconductor wafer production method disclosed in the present invention is different from Example 2 in that it includes the following steps:

[0092] S1 first sets the number of laser scans to 2, and then sets the scanning path of each laser scan to a line-by-line scanning path, with the scanning paths of the two laser scans completely parallel and overlapping. In the first scanning path, the point spacing between two adjacent modified points 4 is P1 = 10 μm, and the linear distance between two separated scanning segments is L1 = 0.40 mm. In the second scanning path, the point spacing between two adjacent modified points 4 is P2 = 8 μm, and the linear distance between two separated scanning segments is L2 = 2L1.

[0093] S2 is based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ. A pulsed laser with a laser wavelength range λ1 of 1064 nm and a laser pulse width Δt1 of 100 ps is selected. The laser scanning speed V1 = 500 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point spacing P1 are determined. The corresponding diameter of the modified point 4 D1 = 5 μm is determined, and the laser pulse energy E1 = 6 μJ and the offset distance S1 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D1 are further determined.

[0094] S3 focuses the pulsed laser on the preset peeling surface 3 inside the ingot 2 and performs the first laser scan to sequentially form modified points 4 on the preset peeling surface 3. At this time, the modified points 4 do not gradually increase in depth to form a modified layer by self-organization. The modified points 4 are uniformly located near the laser focus of the focusing lens, and the longitudinal thickness of the modified points 4 is within the range of 15 to 20 μm.

[0095] S4 is based on the calculation rules preset for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. A pulsed laser with a laser wavelength range λ2 of 1340 nm and a laser pulse width Δt2 of 5 ns is selected. The laser scanning speed V2 = 400 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2 are determined. The corresponding diameter of the modified point 4 D2 = 15 μm is determined. Furthermore, the laser pulse energy E2 = 12 μJ and the offset distance S2 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D2 are determined.

[0096] S5 focuses the pulsed laser below the preset peeling surface 3 inside the ingot 2 and performs a second laser scan to sequentially form modified points 4 on the preset peeling surface 3. An overlapping area is formed between the modified points 4 formed by the two laser scans, so that cracks 5 extending laterally along the preset peeling surface 3 are formed in the overlapping area. Example 11: A semiconductor wafer production method disclosed in the present invention is different from Example 2 in that it includes the following steps:

[0097] S1 first sets the number of laser scans to 2, and then sets the scanning path of each laser scan to a line-by-line scanning path, with the scanning paths of the two laser scans completely parallel and overlapping. In the first scanning path, the point spacing between two adjacent modified points 4 is P1 = 13 μm, and the linear distance between two separated scanning segments is L1 = 1.00 mm. In the second scanning path, the point spacing between two adjacent modified points 4 is P2 = 40 μm, and the linear distance between two separated scanning segments is L2 = L1.

[0098] S2 is based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ. A pulsed laser with a laser wavelength range λ1 of 2100 nm and a laser pulse width Δt1 of 5 ns is selected. The laser scanning speed V1 = 650 mm / s and the laser pulse repetition frequency F1 = 50 kHz required to achieve the point spacing P1 are determined. The corresponding diameter of the modified point 4 D1 = 15 μm is determined, and the laser pulse energy E1 = 18 μJ and the offset distance S1 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D1 are further determined.

[0099] S3 focuses the pulsed laser on the preset peeling surface 3 inside the ingot 2 and performs the first laser scan to sequentially form modified points 4 on the preset peeling surface 3. At this time, the modified points 4 do not gradually increase in depth to form a modified layer by self-organization. The modified points 4 are uniformly located near the laser focus of the focusing lens, and the longitudinal thickness of the modified points 4 is within the range of 35 to 40 μm.

[0100] S4 is based on the preset calculation rules for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. A pulsed laser with a laser wavelength range λ2 of 1550 nm and a laser pulse width Δt2 of 100 ns is selected. The laser scanning speed V2 = 2000 mm / s and the laser pulse repetition frequency F2 = 50 kHz required to achieve the point spacing P2 are determined. The corresponding diameter of the modified point 4 D2 = 80 μm is determined. Furthermore, the laser pulse energy E2 = 60 μJ and the offset distance S2 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D2 are determined.

[0101] S5 focuses the pulsed laser below the preset peeling surface 3 inside the ingot 2 and performs a second laser scan to sequentially form modified points 4 on the preset peeling surface 3. An overlapping area is formed between the modified points 4 formed by the two laser scans, so that cracks 5 extending laterally along the preset peeling surface 3 are formed in the overlapping area. Example 12: A semiconductor wafer production method disclosed in the present invention is different from Example 2 in that it includes the following steps:

[0102] S1 first sets the number of laser scans to 2, and then sets the scanning path of each laser scan to a line-by-line scanning path, with the scanning paths of the two laser scans completely parallel and overlapping. In the first scanning path, the point spacing between two adjacent modified points 4 is P1 = 6 μm, and the linear distance between two separated scanning segments is L1 = 0.30 mm. In the second scanning path, the point spacing between two adjacent modified points 4 is P2 = 7 μm, and the linear distance between two separated scanning segments is L2 = 2L1.

[0103] S2 is based on the calculation rules preset for the first laser scan: P1 = V1 / F1, P1 ≥ 0.7D1, E1 ≥ 1 μJ. A pulsed laser with a laser wavelength range λ1 of 1340 nm and a laser pulse width Δt1 of 50 ps is selected. The laser scanning speed V1 = 600 mm / s and the laser pulse repetition frequency F1 = 100 kHz required to achieve the point spacing P1 are determined. The corresponding diameter of the modified point 4 D1 = 7 μm is determined, and the laser pulse energy E1 = 5 μJ and the offset distance S1 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D1 are further determined.

[0104] S3 focuses the pulsed laser on the preset peeling surface 3 inside the ingot 2 and performs the first laser scan to sequentially form modified points 4 on the preset peeling surface 3. At this time, the modified points 4 do not gradually increase in depth to form a modified layer by self-organization. The modified points 4 are uniformly located near the laser focus of the focusing lens, and the longitudinal thickness of the modified points 4 is within the range of 5 to 10 μm.

[0105] S4 is based on the preset calculation rules for the second laser scan: P2 = V2 / F2, P2 < D2, E2 ≥ 5 μJ. A pulsed laser with a laser wavelength range λ2 of 2100 nm and a laser pulse width Δt2 of 10 ns is selected. The laser scanning speed V2 = 700 mm / s and the laser pulse repetition frequency F2 = 100 kHz required to achieve the point spacing P2 are determined. The corresponding diameter of the modified point 4 D2 = 25 μm is determined. Furthermore, the laser pulse energy E2 = 20 μJ and the offset distance S2 of the laser focus relative to the preset peeling surface 3 required to achieve the modified point 4 diameter D2 are determined.

[0106] S5 focuses the pulsed laser below the preset peeling surface 3 inside the ingot 2 and performs a second laser scan to sequentially form modified points 4 on the preset peeling 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 laterally along the preset peeling surface 3 in the overlapping area.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for producing a semiconductor wafer, characterized in that: The following steps are included: S1 first sets the number of laser scans to n, where n is an integer ≥ 2, and then sets the scanning path of each laser scan and the point spacing P between two adjacent modified points on the scanning path; S2 determines the laser scanning speed V and laser pulse repetition frequency F required to achieve the point spacing P based on the preset calculation rules for each laser scan, and determines the corresponding modified point diameter D, and then determines the laser pulse energy E required to achieve the modified point diameter D, and the offset distance S of the laser focus relative to the preset peeling surface; S3: focusing a pulsed laser on a preset peeling surface inside the ingot or below the preset peeling surface, and performing n laser scans to sequentially form modified points on the preset peeling surface, and forming an overlapping area between the modified points formed by at least two laser scans, so as to form a crack extending laterally along the preset peeling surface in the overlapping area; S4: peeling the crystal ingot along the preset peeling surface to obtain a wafer and a remaining crystal ingot.

2. A semiconductor wafer production method according to claim 1, characterized in that: In S1, the scanning path of each laser scanning is one or a combination of the following: a line-by-line scanning path, a grid-interlaced scanning path, a concentric circle scanning path, and a spiral line scanning path.

3. A semiconductor wafer production method according to claim 2, characterized in that: In S1, the line distance L between two scanning sections spaced apart from each other on the scanning path is controlled to be 0.05-1.00 mm.

4. A semiconductor wafer production method according to claim 1, characterized in that: In S2, the preset calculation rule for the 1st to n'th laser scans is: n′ =V n′ / F n′ , P n′ ≥0.7D n′ , E n′ ≥1μJ, S n′ 0~5μm; among them, P n′ V is the distance between two adjacent modified points on the 1st to nth scanning path, n′ is the laser scanning speed from the 1st to the nth time, F n′ is the repetition frequency of the 1st to nth laser pulses, E n′ is the energy of the 1st to nth laser pulses, S n′ It is the offset distance of the 1st to n'th laser focus relative to the preset peeling surface, and n' is an integer ≥1.

5. A semiconductor wafer production method according to claim 1, characterized in that: In S2, the preset calculation rule for the n′+1 to n″th laser scan is: n′+1 =V n′+1 / F n′+1 , P n′+1 <D n′+1 , E n′+1 ≥5μJ, S n′+1 0~20μm; among them, P n′+1 V is the distance between two adjacent modified points on the n′+1~n″th scanning path, n′+1 is the laser scanning speed of the n′+1~n″th time, F n′+1 is the laser pulse repetition frequency of the n′+1~n″th time, E n′+1 is the laser pulse energy of the n′+1~n″th time, S n′+1 It is the offset distance of the laser focus from the n′+1th to the n″th time relative to the preset peeling surface, where n″ is an integer ≥2.

6. A semiconductor wafer production method according to claim 5, characterized in that: In S2, control 0.2D n′+1 <P n′+1 <0.6D n′+1 .

7. A semiconductor wafer production method according to claim 1, characterized in that: In S3, the laser wavelength range λ of each laser scan is controlled to be 780 to 2500 nm, and the laser pulse width Δt is controlled to be 10 fs to 100 ns.

8. A semiconductor wafer production method according to claim 1, characterized in that: In S3, the pulse 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.

9. A semiconductor wafer production method according to claim 1, characterized in that: In the above-mentioned S3, the aberration correction of the pulse laser is performed in advance before the 1st to n'th laser scans.

10. A semiconductor wafer production method according to claim 1, characterized in that: In the above S3, the pulse laser is beam shaped before the n′+1 to n″th laser scans.

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