Crystal ingot cutting method and cutting system

Abstract

The invention provides a crystal ingot cutting method and cutting system, belongs to the technical field of silicon carbide crystal ingot processing, and solves the problem of high crystal ingot cutting loss in the prior art. The cutting method comprises the following steps that the position of an operation station on a crystal ingot is obtained, the operation station is a crystal ingot surface area facing a laser source, a first light beam is controlled to scan a target depth along a scanning path, and the first light beam is focused at the target depth to form a first light spot; information of a crack formed after the first light beam acts on the crystal ingot is obtained, the crack width is determined to be A level, the time interval of phase modulation between the second light beam and the first light beam and the time interval of phase modulation between the third light beam and the first light beam are controlled to be 20 ns to 50 ns, and / or the minimum space interval between the inhibition area and the action area of the first light spot in the direction parallel to the scanning direction of the first light beam is controlled to be 50 microns to 100 microns. The second light beam and the third light beam are additionally arranged to synchronously scan along with the two sides of the first light beam in a phase modulation mode, and crack propagation is restrained.

Description

Technical Field

[0001] The present application belongs to the technical field of silicon carbide ingot processing, and specifically relates to a method and system for cutting an ingot. Background Art

[0002] At present, laser is generally used to scan and cut the inside of the silicon carbide ingot to form a modified layer, and then the wafer is peeled off from the silicon carbide ingot through ultrasonic vibration or mechanical means.

[0003] However, when existing lasers are used to process silicon carbide ingots, due to the uneven thermal stress inside the ingots, wider cracks are easily generated on the scanning path. In addition, in order to ensure that the wafers can be effectively peeled off, the laser may need to scan repeatedly, causing the cracks to continue to expand, thereby increasing cutting losses and wafer scrap rates.

[0004] Based on the above content, the technical problem to be solved by this application is: the laser cutting loss of silicon carbide ingots is relatively high. Summary of the Invention

[0005] The purpose of this application is to address the above-mentioned problems existing in the prior art and propose a crystal ingot cutting method and cutting system to solve the problem of high laser cutting loss of silicon carbide crystal ingots in the prior art and reduce the laser cutting loss of silicon carbide crystal ingots.

[0006] The purpose of the present application can be achieved through the following technical solutions: A method for cutting a crystal ingot, comprising the following steps: obtaining the position of an operating station on the crystal ingot, wherein the operating station is an area on the surface of the crystal ingot facing a laser source; setting a scanning path and a target depth below the operating station, projecting a first light beam, controlling the first light beam to scan the target depth along the scanning path, and focusing the first light beam at the target depth to form a first light spot; obtaining crack information formed after the first light beam acts on the crystal ingot, wherein the crack information includes crack width, and classifying the crack width; based on the crack width level, executing at least the following strategies: determining that the actual crack width is level A, executing a first crack control strategy: projecting a second light beam to a first side of the first light spot, and projecting a third light beam to a second side of the first light spot. The first beam, the second beam, and the third beam are parallel to each other, and the second beam and the third beam are controlled to scan synchronously with the first beam respectively. The second beam is focused at the target depth to form a second light spot, and the third beam is focused at the target depth to form a third light spot. An inhibition zone is formed between the active area of ​​the second light spot and the active area of ​​the third light spot, and the inhibition zone moves with the synchronous scanning of the second beam and the third beam to phase cover the active area of ​​the first light spot; wherein, the time interval for controlling the phase modulation of the second beam and the third beam with the first beam is 20ns to 50ns, and / or, the minimum spatial spacing between the inhibition zone and the active area of ​​the first light spot in the direction parallel to the scanning direction of the first beam is controlled to be 50μm to 100μm. The first light spot is preferably a Gaussian spot. Of course, in some embodiments, an annular spot or a light spot of other shapes can also be selected. The shapes of the second and third spots can also be selected from Gaussian spots, annular spots, or other conventional shapes.

[0007] In the above-mentioned ingot cutting method, the cross section of the first light spot at the target depth is S1, the cross section of the inhibition zone at the target depth is Q, and the inner edge of Q is controlled to move with the synchronous scanning of the second and third beams to phase cover S1.

[0008] In the above-mentioned ingot cutting method, the diameter range of the first light spot is configured to be 15 μm to 25 μm, and the distance between the second light spot and the third light spot in a direction perpendicular to the first light beam scanning direction is controlled to be 5 μm to 25 μm.

[0009] In the above-mentioned ingot cutting method, the diameter range of the second light spot and the third light spot is configured to be 10 μm to 15 μm.

[0010] The above-mentioned ingot cutting method further includes the following steps:

[0011] Based on the crack width level, the actual crack width is determined to be Class C, and the following strategies are implemented:

[0012] Execute the third crack control strategy: increase the pulse width and energy of the first light beam, and reduce the scanning speed of the first light beam; wherein, the crack width range of the C level is smaller than that of the A level.

[0013] The above-mentioned ingot cutting method further includes the following steps:

[0014] Based on the crack width level, the actual crack width is determined to be level B, and the following strategy is implemented:

[0015] The second crack control strategy is implemented: the scanning speed, pulse width and energy of the first light beam are maintained, and the crack width range of the class B is smaller than that of the class A and larger than that of the class C.

[0016] In the above-mentioned ingot cutting method, the third crack control strategy includes the following steps:

[0017] Increase the pulse width and energy of the first light beam, and reduce the scanning speed of the first light beam.

[0018] The above-mentioned ingot cutting method further includes the following steps:

[0019] The crack information includes crack propagation frequency;

[0020] Based on the crack propagation frequency, a fourth crack control strategy is executed, wherein the fourth crack control strategy includes adjusting the time intervals between scanning of the first light beam, the second light beam, and the third light beam.

[0021] In the above-mentioned ingot cutting method, executing the fourth crack control strategy based on the crack propagation frequency includes the following steps:

[0022] Set a standard crack growth frequency range F0, and judge and compare the actual crack growth frequency F with the standard crack growth frequency range F0:

[0023] If F is greater than the maximum value of F0, the time interval between the scanning of the first beam and the second beam and the third beam is synchronously reduced, and the energy of the first beam is reduced;

[0024] If F is within the range of F0, the time interval between the first beam, the second beam and the third beam is maintained;

[0025] If F is less than the minimum value of F0, the time interval between the scanning of the first light beam, the second light beam and the third light beam is increased synchronously, and the scanning speeds of the first light beam, the second light beam and the third light beam are reduced.

[0026] In the above-mentioned ingot cutting method, the wavelength of the first light beam is configured to be 1064 nm, the wavelengths of the second light beam and the third light beam are both configured to be 635 nm, and the energy ratios of the first light beam, the second light beam, and the third light beam are X:Y:Z, respectively, where X∈[5,8], Y∈[2,5], and Z∈[2,5].

[0027] In the above-mentioned ingot cutting method, the position of the operating station on the ingot is obtained, and the operating station is the area on the surface of the ingot facing the laser source, which includes the following steps: adding a fourth light beam, controlling the fourth light beam to scan the surface of the ingot to obtain the surface roughness of the ingot, and adjusting the pulse width and energy of the fourth light beam based on the surface roughness of the ingot.

[0028] Another object of the present application is to provide a silicon carbide ingot cutting system, which is applied to the above-mentioned ingot cutting method, including: a supporting platform, which is used to support the ingot; a cutting module, which is used to output a first light beam, a second light beam and a third light beam to scan along the target depth inside the ingot; and a detection module, which is used to detect the crack extension frequency and crack width formed by the scanning of the first light beam, and to feed back to the cutting module to control and adjust the first light beam, the second light beam and the third light beam.

[0029] Compared with the prior art, this application has the following beneficial effects:

[0030] The present application adds a second light beam and a third light beam, and uses phase modulation to make the second light beam and the third light beam follow the distribution on both sides of the first light beam for synchronous scanning. The second light beam forms a second light spot at the target depth, and the third light beam forms a third light spot at the target depth. The second light spot and the third light spot are distributed on both sides of the first light spot following the phase, thereby forming an inhibition zone. The thermal stress generated in the action area of ​​the first light spot can be offset by the thermal stress outside the inhibition zone, thereby inhibiting crack propagation and reducing silicon carbide material loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the overall process of the ingot cutting method of the present application;

[0032] Figure 2 It is a flow chart of the first crack control strategy of this application;

[0033] Figure 3 It is a simple schematic diagram of various distribution positions of the light spots and crack areas of this application;

[0034] Figure 4 It is a flow chart of the second crack control strategy of this application;

[0035] Figure 5 It is a flow chart of the third crack control strategy of this application;

[0036] Figure 6 It is a flow chart of the fourth crack control strategy of the present application;

[0037] In the figure, S1 is the first light spot; S2 is the second light spot; S3 is the third light spot; Q is the inhibition zone. DETAILED DESCRIPTION

[0038] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0039] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0041] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0042] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0043] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0044] Please refer to the attached drawings in the manual Figure 1 and Figure 2 The ingot cutting method of the present application comprises the following steps:

[0045] S100, obtaining a position of an operating station on the ingot, where the operating station is a region on the surface of the ingot facing the laser source;

[0046] S200, setting a scanning path and a target depth below the operating station, projecting a first light beam, controlling the first light beam to scan the target depth along the scanning path, and focusing the first light beam at the target depth to form a first light spot;

[0047] S300, obtaining information about cracks formed after the first light beam acts on the ingot, the crack information including crack width, and classifying the crack widths;

[0048] S400a, based on the crack width level, execute the following strategies:

[0049] S410a. If the actual crack width is determined to be level A, the first crack control strategy is executed: a second light beam is projected onto the first side of the first light spot, and a third light beam is projected onto the second side of the first light spot. The first light beam, the second light beam and the third light beam are parallel to each other, and the second light beam, the third light beam and the first light beam are controlled to scan synchronously with the phases thereof. The second light beam is focused at the target depth to form a second light spot, and the third light beam is focused at the target depth to form a third light spot. An inhibition zone is formed between the active area of ​​the second light spot and the active area of ​​the third light spot, and the inhibition zone moves with the synchronous scanning of the second light beam and the third light beam to cover the active area of ​​the first light spot in phase; wherein the time interval for phase modulation of the second light beam and the third light beam with the first light beam is controlled to be 20ns to 50ns, and / or the minimum spatial interval between the inhibition zone and the active area of ​​the first light spot in the scanning direction parallel to the first light beam is controlled to be 50μm to 100μm.

[0050] S420a, if the actual crack width is determined to be Class B, then execute the second crack control strategy: maintain the scanning speed, pulse width, and energy of the first light beam, and the crack width range of Class B is smaller than that of Class A;

[0051] S430a: If the actual crack width is determined to be Class C, execute the third crack control strategy: increase the pulse width and energy of the first light beam, and reduce the scanning speed of the first light beam. The crack width range of Class C is smaller than that of Class B.

[0052] It is understandable that the operating station of the crystal ingot is generally selected as the upper surface of the crystal ingot, and when the roughness of the upper surface is less than or equal to 3μm, it is more suitable for the crystal ingot cutting method of the present application. The upper surface of this area is dominated by mirror reflection, the laser energy absorption is stable, and the absorption rate fluctuation is less than 5%. The scanning path and target depth are set below the operating station, that is, inside the crystal ingot. The scanning path is formed by scanning line by line, and the target depth is preferably 80% to 90% of the required wafer thickness. Exemplarily, the first light beam is a nanosecond pulse laser with a pulse width range of 50ns to 500ns and an energy density of 10J / cm 2 ~50J / cm 2, use the first light beam to ablate the target depth area inside the ingot. Since mirror reflection will cause the laser energy to dissipate and the crack will be more likely to expand, it is necessary to avoid overburning, and use crack detection to obtain crack information. The crack information includes the crack width. When the crack width exceeds the set value, such as 30μm, the second and third light beams can be added, and the second and third light beams can be made to follow the distribution on both sides of the first light beam for synchronous scanning in a phase-modulated manner. Because when the second and third light spots act on their respective areas, there is no continuous energy projection in the original action area of ​​the first light spot. The energy distribution of the action area of ​​the first light spot is configured to 0 or extremely low, thereby preventing thermal stress concentration, and the range of the inhibition zone between the second and third light spots tends to cover the original action range of the first light spot as the scanning paths of the second and third light beams follow. The position distribution relationship of the first light spot action area, the second light spot action area, the third light spot action area and the inhibition zone, as shown in the figure. Figure 3 The various distributions shown in (a) and (b) all have a certain inhibitory effect. Figure 3 In part (a), as a preferred embodiment, the cross-section of the first light spot at the target depth is S1, the cross-section of the second light spot at the target depth is S2, the cross-section of the third light spot at the target depth is S3, and the cross-section of the inhibition zone at the target depth is Q. The inner boundary of Q is controlled to move with the synchronous scanning of the second light beam and the third light beam to cover S1 in phase. It should be noted that the definition of coverage in this application can be understood as including the situation where the two completely overlap, the situation where the two partially overlap, and the situation where one completely contains the other. Since the area within the inhibition zone has no energy to continue to project or extremely low energy is involved in the projection, the temperature is relatively low, and thermal stress can be generated from the outer edge to the inside, thereby limiting the expansion of the thermal stress originally generated by the action of the first light spot, thereby reducing the power of crack expansion, that is, suppressing crack expansion, and ultimately reducing laser cutting losses. Figure 3In the distribution method of type (b), the suppression zone partially overlaps with the first light spot, which can also limit the thermal stress generated by the first light spot, but the effect is worse than that of the distribution method of type (a). Regarding the second and third light beams distributed to the first and second sides of the first light spot in a phase-modulated manner, the interference or focus of the laser can be controlled so that the second and third light beams act in time after the first light beam, thereby adjusting the distribution of residual stress. By controlling the time interval between the second and third light beams and the first light beam within 20ns to 50ns, or controlling the spatial interval in the scanning direction of the first light beam within 50μm to 100μm, it is possible to ensure timely intervention before the crack generated by the first light beam propagates. Among them, the roughness can be obtained by introducing a laser to scan the surface profile of the ingot, and the crack width in the crack information can be obtained by photographing with a CCD camera. It can be understood that by monitoring the crack width, the scanning speed, frequency, and energy of the first light beam can be adjusted in time to prevent the crack from extending too far.

[0053] As an embodiment, the diameter range of the first light spot is configured to be 15μm to 25μm, and the spacing range between the second light spot and the third light spot perpendicular to the scanning direction of the first light beam is controlled to be 5μm to 25μm. It can be understood that by configuring the diameter range of the first light spot to be within the range of 15μm to 25μm, a qualified cutting crack can be formed, which is sufficient to cut and peel off the wafer while not losing a lot of silicon carbide material. By controlling the spacing range between the second light spot and the third light spot perpendicular to the scanning direction of the first light beam to be within the range of 15μm to 25μm, it can be ensured that the thermal stress generated in the active area of ​​the second light spot and the active area of ​​the third light spot can tend to effectively offset the thermal stress generated in the active area of ​​the first light spot. If the diameter is greater than this range, the effect of suppressing cracks generated in the active area of ​​the first light beam is no longer significant. If the diameter is less than this range, the cutting crack may increase, thereby losing more silicon carbide material.

[0054] As an embodiment, the diameter range of the second and third light spots is configured to be 10μm to 15μm. It is understandable that by configuring the diameter range of the second and third light spots to be 10μm to 15μm, a larger range of thermal stress can be generated toward the active area of ​​the first light spot, thereby sufficiently offsetting the thermal stress generated in the direction of the second and third light spots after the first light spot acts, thereby suppressing the extension of the cutting crack to the first and second sides of the first beam active area. If the diameter is larger than this range, the cutting crack will increase, resulting in the loss of silicon carbide material. If the diameter is smaller than this range, the thermal stress generated in the active area will not be significantly reduced, and the crack suppression effect will be reduced.

[0055] As an implementation method, based on the crack width level, at least the following strategies are executed, including: if the actual crack width is determined to be level C, then a third crack control strategy is executed: increasing the pulse width and energy of the first light beam, and reducing the scanning speed of the first light beam; wherein, the crack width range of level C is smaller than that of level A.

[0056] As an implementation method, the crack width levels are divided into Class A, Class B, and Class C from large to small. It can also be divided into Class A and Class B only, or only into Class A and Class C, and the corresponding strategy is executed according to the determined crack width level. In some implementation methods, the crack width range of Class A is >30μm, the crack width range of Class B is ≥20μm and ≤30μm, and the crack width range of Class C is <20μm. Exemplarily, the standard crack width range W0 is set to 20μm to 30μm, that is, Class B is the standard crack width. If the actual crack width W monitored is within W0, it is determined that the actual crack width is Class B, see Figure 4 , then the second crack control strategy is implemented: maintain the scanning speed, pulse width and energy of the first beam. Figure 5 The third crack control strategy includes the following steps: increasing the pulse width and energy of the first beam and reducing the scanning speed of the first beam. If the actual crack width W detected is less than 20μm, it is determined to be Class C, indicating poor cutting quality. The scanning speed of the first beam is reduced to extend the first beam's dwell time at the target depth to improve cutting quality, thus implementing the third crack control strategy. Cutting parameters can be controlled through a PID closed-loop control.

[0057] As an embodiment, the ingot cutting method of the present application further includes the following steps:

[0058] S300, obtaining information about cracks formed after the first light beam acts on the ingot, S310b, the crack information including the crack propagation frequency;

[0059] S400b. Based on the crack propagation frequency, execute the fourth crack control strategy. The fourth crack control strategy includes: adjusting the time intervals between the first light beam and the second light beam and the third light beam. It is understandable that the crack is monitored by the crack propagation frequency, so that the scanning phases of the second light beam, the third light beam and the first light beam are adjusted in time to ensure that the crack propagation is suppressed. Among them, if it is detected that the crack propagation frequency is too fast, it is necessary to reduce the phases of the second light beam, the third light beam and the first light beam, and reduce the energy of the first light beam, so as to suppress the crack propagation. If the crack propagation frequency is too slow or the crack propagation frequency is intermittent and not continuous, it is necessary to increase the phases of the second light beam, the third light beam and the first light beam, and reduce the scanning speeds of the first light beam, the second light beam and the third light beam, so as to ensure the cutting effect and prevent incomplete cutting. The crack propagation frequency is preferably detected by an acoustic emission sensor to obtain the sound waves generated by the crack propagation. In some embodiments, it can be detected by optical detection such as machine vision or infrared thermal imaging, or by X-ray or CT scanning, etc.

[0060] See also Figure 6 As an embodiment, S400b, executing the fourth crack control strategy based on the crack propagation frequency includes the following steps:

[0061] S410b, setting a standard crack growth frequency range F0, judging and comparing the actual crack growth frequency F with the standard crack growth frequency range F0:

[0062] S420b. If F is greater than the maximum value of F0, the time interval between the scanning of the first beam and the second beam and the third beam is simultaneously reduced, and the energy of the first beam is reduced. If F is within the range of F0, the time interval between the scanning of the first beam and the second beam and the third beam is maintained. If F is less than the minimum value of F0, the time interval between the scanning of the first beam and the second beam and the third beam is simultaneously increased, and the scanning speed of the first beam, the second beam and the third beam is reduced. It is understandable that crack propagation can be affected by factors such as beam energy and scanning speed, resulting in intermittent or continuous crack propagation. These conditions can be reflected by the frequency of crack propagation, and the frequency of crack propagation can be obtained by detecting the acoustic wave feedback generated by crack propagation. In this application, an acoustic emission sensor is preferably used to obtain the crack propagation frequency. For example, the standard crack propagation frequency range F0 is set to 400 Hz to 800 Hz. If the actual crack propagation frequency F monitored exceeds 800 Hz, it is characterized as excessive crack propagation. Therefore, the crack propagation is suppressed by reducing the phase of the second beam, the third beam and the first beam and reducing the energy of the first beam. If the actual crack propagation frequency F detected is within F0, it indicates that the current cutting crack is at a normal level and the existing cutting parameters can be maintained. If the actual crack propagation frequency F detected exceeds 800 Hz, it indicates that the crack propagation is too slow or the crack propagation is intermittent and not continuous. Therefore, it is necessary to synchronously increase the phase of the second and third beams with the first beam and reduce the scanning speed of the first, second and third beams to ensure the cutting effect and prevent incomplete cutting. The cutting parameters can be controlled by PID closed loop.

[0063] As an embodiment, the wavelength of the first light beam is configured to be 1064nm, the wavelength of the second light beam and the third light beam are both configured to be 635nm, and the energy ratio of the first light beam, the second light beam, and the third light beam is X:Y:Z, where X∈[5,8], Y∈[2,5], and Z∈[2,5]. It can be understood that the first light beam uses a 1064nm nanosecond pulse laser with a pulse width of 50ns to 500ns and an energy density of 10J / cm 2 ~50J / cm 2 The second beam and the third beam both use 635nm laser, and the ratio of the two is determined to facilitate processing.

[0064] As an embodiment, obtaining the location of an operating station on an ingot, where the operating station is the area on the ingot surface facing the laser source, includes the following steps: adding a fourth beam, controlling the fourth beam to scan the ingot surface to obtain the ingot surface roughness, and adjusting the pulse width and energy of the fourth beam based on the ingot surface roughness. It is understood that the fourth beam is configured as a 635nm continuous laser with a power of less than 5W and a scanning resolution of 5μm. This can scan the surface topography (TTV) and roughness value in real time and generate three-dimensional coordinates, thereby quickly locating the operating station.

[0065] The silicon carbide ingot cutting system of the present application (not shown) is applied to the ingot cutting method of the present application, and includes: a carrier, a cutting module, and a detection module. The carrier is used to carry the ingot. The cutting module is used to output a first light beam, a second light beam, and a third light beam to scan along the target depth inside the ingot. The detection module is used to detect the crack propagation frequency and crack width formed by the scanning of the first light beam, so as to feed back to the cutting module to control and adjust the first light beam, the second light beam, and the third light beam. Exemplarily, the carrier is a vacuum adsorption carrier that can adsorb and fix the ingot to facilitate processing. The cutting module is mainly an optical path part, including structures such as a laser, a reflector, a beam expander, a piezoelectric ceramic, an acousto-optic modulator or a spatial light modulator. The acousto-optic modulator or the spatial light modulator is used to split the light beam emitted by the laser into a first light beam and a second light beam. The detection module includes an acoustic emission sensor and a high-speed CCD camera. The acoustic emission sensor is used to detect the frequency of crack propagation formed when the first light beam cuts the inside of the ingot, and the high-speed CCD camera is used to visually detect the width of the crack. The information detected by the detection module can be fed back to the cutting module, so that the cutting module can adjust the first light beam, the second light beam and the third light beam, such as the time interval and spatial interval of the scanning path, or the laser parameters such as the scanning speed, pulse width and energy.

[0066] Beneficial effects:

[0067] The present application adds a second light beam and a third light beam, and uses phase modulation to make the second light beam and the third light beam follow the distribution on both sides of the first light beam for synchronous scanning. The second light beam forms a second light spot at the target depth, and the third light beam forms a third light spot at the target depth. The second light spot and the third light spot are phase-followed and distributed on both sides of the first light spot, thereby forming an inhibition zone. The thermal stress generated in the action area of ​​the first light spot can be offset by the thermal stress outside the inhibition zone, thereby inhibiting crack propagation and reducing silicon carbide material loss; by controlling the time interval between the second light beam, the third light beam and the first light beam within 20ns to 50ns, timely intervention can be ensured before the crack propagates; the crack is monitored by obtaining the crack propagation frequency, so as to timely adjust the scanning phase of the second light beam, the third light beam and the first light beam to ensure that the crack propagation is inhibited; by monitoring the crack width, the scanning speed, frequency and energy of the first light beam can be adjusted in time to prevent the crack from propagating too large.

[0068] The specific embodiments described herein are merely illustrative of the spirit of the present application. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A method for cutting an ingot, characterized in that: The following steps are involved: Obtaining a position of an operating station on the ingot, wherein the operating station is a region of the ingot surface facing the laser source; A scanning path and a target depth are set below the operating station, a first light beam is projected, and the first light beam is controlled to scan the target depth along the scanning path, where the first light beam is focused to form a first light spot at the target depth; obtaining information about cracks formed after the first light beam acts on the ingot, the crack information including crack width, and classifying the crack widths; Based on the crack width level, the actual crack width is determined to be Class A, and the following strategies are implemented: Execute a first crack control strategy: project a second light beam onto a first side of the first light spot, and project a third light beam onto a second side of the first light spot, the first light beam, the second light beam and the third light beam are parallel to each other, and the second light beam, the third light beam and the first light beam are controlled to scan synchronously with each other in phase, the second light beam is focused at the target depth to form a second light spot, the third light beam is focused at the target depth to form a third light spot, an inhibition zone is formed between the active area of ​​the second light spot and the active area of ​​the third light spot, and the inhibition zone moves with the synchronous scanning of the second light beam and the third light beam to cover the active area of ​​the first light spot in phase; wherein, the time interval for controlling the phase modulation of the second light beam and the third light beam with the first light beam is 20ns to 50ns, and / or the minimum spatial interval between the inhibition zone and the active area of ​​the first light spot in a scanning direction parallel to the first light beam is controlled to be 50μm to 100μm.

2. The ingot cutting method according to claim 1, wherein: The cross section of the first light spot at the target depth is S1, the cross section of the inhibition zone at the target depth is Q, and the inner edge of Q is controlled to move with the synchronous scanning of the second light beam and the third light beam to cover S1 in phase.

3. The ingot cutting method according to claim 1, wherein: The diameter of the first light spot is configured to be in the range of 15 μm to 25 μm, and the distance between the second light spot and the third light spot in a direction perpendicular to the scanning direction of the first light beam is controlled to be in the range of 5 μm to 25 μm.

4. The ingot cutting method according to claim 1, wherein: The diameter range of the second light spot and the third light spot is configured to be 10 μm to 15 μm.

5. The ingot cutting method according to claim 1, wherein: The following steps are also included: Based on the crack width level, the actual crack width is determined to be Class C, and the following strategies are implemented: Execute the third crack control strategy: increase the pulse width and energy of the first light beam, and reduce the scanning speed of the first light beam; wherein, the crack width range of the C level is smaller than that of the A level.

6. The ingot cutting method according to claim 1, wherein: The following steps are also included: The crack information includes crack propagation frequency; Based on the crack propagation frequency, a fourth crack control strategy is executed, wherein the fourth crack control strategy includes adjusting the time intervals between scanning of the first light beam, the second light beam, and the third light beam.

7. The ingot cutting method according to claim 6, wherein: The implementation of the fourth crack control strategy based on the crack propagation frequency includes the following steps: Set a standard crack growth frequency range F0, and judge and compare the actual crack growth frequency F with the standard crack growth frequency range F0: If F is greater than the maximum value of F0, the time interval between the scanning of the first beam and the second beam and the third beam is synchronously reduced, and the energy of the first beam is reduced; If F is within the range of F0, the time interval between the first beam, the second beam and the third beam is maintained; If F is less than the minimum value of F0, the time interval between the scanning of the first light beam, the second light beam and the third light beam is increased synchronously, and the scanning speeds of the first light beam, the second light beam and the third light beam are reduced.

8. The ingot cutting method according to claim 1, wherein: The wavelength of the first light beam is configured to be 1064 nm, the wavelengths of the second light beam and the third light beam are both configured to be 635 nm, and the energy ratios of the first light beam, the second light beam, and the third light beam are X:Y:Z, respectively, where X∈[5,8], Y∈[2,5], and Z∈[2,5].

9. The ingot cutting method according to claim 1, wherein: The method of obtaining the position of the operating station on the crystal ingot, wherein the operating station is the crystal ingot surface area facing the laser source, includes the following steps: adding a fourth light beam, controlling the fourth light beam to scan the crystal ingot surface to obtain the crystal ingot surface roughness, and adjusting the pulse width and energy of the fourth light beam based on the crystal ingot surface roughness.

10. A silicon carbide ingot cutting system, applied to the ingot cutting method according to any one of claims 1 to 9, characterized in that: include: A carrying platform, the carrying platform is used to carry the crystal ingot; a cutting module configured to output a first light beam, a second light beam, and a third light beam to scan along a target depth inside the ingot; as well as The detection module is used to detect the crack extension frequency and crack width formed by the scanning of the first light beam, and feed back to the cutting module to control and adjust the first light beam, the second light beam and the third light beam.

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