A method and system for slicing a single crystal silicon ingot

Abstract

This invention discloses a method and system for cutting monocrystalline silicon ingots. The method includes: drawing a target steel wire from the cutting area of ​​the main wire mesh, corresponding to the region directly below the end face of the monocrystalline silicon ingot, passing through an auxiliary guide wheel, and returning to the main wire mesh to form an auxiliary wire mesh; wherein the auxiliary wire mesh is located below the horizontal plane of the main wire mesh, and the vertical projection of the auxiliary wire mesh at least covers the region directly below the end face of the monocrystalline silicon ingot, and a blank area is formed above the auxiliary wire mesh; when the end face sheet of the monocrystalline silicon ingot falls, the end face sheet falls vertically, passes through the blank area and the auxiliary wire mesh, and falls to the waste collection area, and the fall path of the end face sheet is spatially offset from that of the main wire mesh. Thus, this invention improves the output efficiency and product quality of the final product formed after cutting the monocrystalline silicon ingot.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method and system for cutting single-crystal silicon ingots. Background Technology

[0002] In semiconductor silicon wafer manufacturing, slurry wire cutting is a process used to cut single-crystal silicon ingots into wafers. Its principle involves using a steel wire to drive silicon carbide slurry to grind and cut the ingot. As silicon wafers become larger, the size and weight of the ingots increase, placing higher demands on the stability of the cutting process. Currently, in slurry wire cutting, when the cutting reaches the end face of the ingot, indicating that the cutting is nearing completion, the remaining uncut portion may not be able to support its own weight, causing the end face to suddenly collapse or fall off. The falling end face pieces will fall irregularly into and impact the dense, high-speed wire mesh system below, which can easily lead to the following serious consequences: direct wire breakage, where the falling end face pieces directly break or jam the steel wires, causing the entire batch of crystal ingots to be scrapped, resulting in huge material and time losses; abnormal slotting, where the end face pieces hit the wire mesh, causing the steel wires to come out of the guide wheel slots, disrupting the cutting path and making subsequent cutting impossible, also resulting in product scrapping; sudden changes in wire mesh tension, even if the wires are not directly broken, the impact will cause violent fluctuations in wire mesh tension, resulting in quality defects such as wire marks and excessive total thickness deviation in the silicon wafers in that area.

[0003] In some scenarios, traditional methods typically attempt to mitigate impact by optimizing overall cutting parameters, such as reducing linear speed and slurry flow rate. However, this approach results in low overall cutting efficiency, thus affecting the final product yield. Another approach is to enhance the response speed of the wire mesh tension control system, but this is a passive defense and cannot fundamentally eliminate the impact source of end-face sheet drop. Therefore, the above methods are insufficient to avoid the risk of ingot end-face drop, leading to lower final product yield and quality, which is a technical problem that those skilled in the art need to solve. Summary of the Invention

[0004] This invention discloses a method and system for cutting monocrystalline silicon ingots to solve the problems of low output efficiency and low product quality of the final products formed after cutting monocrystalline silicon ingots.

[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0006] In a first aspect, this application discloses a method for cutting monocrystalline silicon ingots, applied to a slurry wire cutting device, comprising: drawing a target steel wire corresponding to the area directly below the end face of the monocrystalline silicon ingot from the cutting area of ​​the main wire mesh, passing around an auxiliary guide wheel and returning to the main wire mesh to form an auxiliary wire mesh; wherein, the auxiliary wire mesh is located below the horizontal plane where the main wire mesh is located, the vertical projection of the auxiliary wire mesh covers at least the area directly below the end face of the monocrystalline silicon ingot, and the area directly above the auxiliary wire mesh forms a blank area; when the end face sheet of the monocrystalline silicon ingot falls, the end face sheet falls vertically, passes through the blank area and the auxiliary wire mesh and falls to the waste collection area, and the falling path of the end face sheet is spatially offset from the main wire mesh.

[0007] Secondly, this application discloses a single-crystal silicon ingot cutting system. Based on the single-crystal silicon ingot cutting method mentioned in the first aspect, the disclosed single-crystal silicon ingot cutting system includes: a cutting main frame; an ingot clamping and feeding mechanism, disposed on the cutting main frame, for fixing the single-crystal silicon ingot and controlling the feeding movement of the single-crystal silicon ingot; a main wire mesh section, disposed on the cutting main frame, the main wire mesh section including a pair of main cutting guide wheels, steel wire being reciprocatedly wound on the pair of main cutting guide wheels to form a main wire mesh, the main wire mesh being located directly below the single-crystal silicon ingot for cutting the single-crystal silicon ingot; and an auxiliary wire mesh section, disposed on the cutting main frame, including at least one auxiliary guide wheel, the auxiliary guide wheel being configured to be... The device moves between a retracted position and an extended position. When the auxiliary guide wheel is in the extended position, the target steel wire in the main wire mesh corresponding to the area directly below the end face of the monocrystalline silicon ingot is lifted by the auxiliary guide wheel, forming an auxiliary wire mesh located below the main wire mesh. The auxiliary wire mesh is located below the horizontal plane where the main wire mesh is located, and the vertical projection of the auxiliary wire mesh covers at least the area directly below the end face of the monocrystalline silicon ingot, while the area directly above the auxiliary wire mesh forms a blank area. When the end face of the monocrystalline silicon ingot falls, the end face falls vertically, passes through the blank area and the auxiliary wire mesh, and falls to the waste collection area. The falling path of the end face is spatially offset from that of the main wire mesh.

[0008] Thirdly, this application also discloses a method for cutting monocrystalline silicon ingots, based on the monocrystalline silicon ingot cutting system mentioned in the second aspect, comprising: feeding and centering the ingot, determining the spatial coordinates of the two end faces of the monocrystalline silicon ingot; starting the main wire mesh to cut the monocrystalline silicon ingot; when the cutting position is close to the end face of the monocrystalline silicon ingot, controlling the auxiliary guide wheel to move to the extended position, drawing the target steel wire corresponding to the area directly below the end face of the monocrystalline silicon ingot from the main wire mesh and passing it around the auxiliary guide wheel to form an overhead auxiliary wire mesh directly below the end face; continuing the cutting process, when the end face piece of the monocrystalline silicon ingot falls under the action of gravity, the end face piece falls into the waste collection area after passing through the auxiliary wire mesh, and the falling path of the end face piece is spatially offset from the main wire mesh.

[0009] The technical solution adopted in this invention achieves the following technical effects: By setting an auxiliary wire mesh below the main wire mesh and forming a blank area directly above it, a non-destructive falling channel is pre-set in physical space for the falling end face piece. When the end face piece falls, its falling path is completely offset from the high-speed running main wire mesh that bears the cutting task, avoiding direct contact between the end face piece and the main wire mesh. This eliminates the risk of the end face piece breaking the steel wire or knocking it out of the guide wheel groove, thereby minimizing the wire breakage rate during the cutting process, improving the continuity and reliability of the cutting operation, and thus increasing the output efficiency of the final product. Furthermore, the introduction of the auxiliary wire mesh and the setting of the blank area do not change the normal cutting parameters of the main wire mesh. Throughout the entire cutting process, the main wire mesh can always maintain its original, optimized, high-efficiency cutting state. Therefore, this invention improves the safety of the cutting process without affecting normal cutting efficiency, thereby increasing the output efficiency of the final product. Furthermore, because this invention completely spatially separates the drop path of the end face sheet from the main mesh, the main mesh is not subjected to any physical impact, and its tension remains stable. This avoids sudden tension changes caused by impact, ensuring that the silicon wafers cut from the entire ingot have highly consistent geometric parameters and surface quality, thereby improving the quality of the final product. Attached Figure Description

[0010] Figure 1 This is a schematic flowchart of a method for cutting a single-crystal silicon ingot according to an embodiment of the present invention.

[0011] Figure 2 This is a schematic diagram of the cutting process of a single-crystal silicon ingot disclosed in an embodiment of the present invention.

[0012] Figure 3 This is a schematic flowchart of another method for cutting a single-crystal silicon ingot disclosed in an embodiment of the present invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0014] Please refer to Figures 1 to 3 , Figure 1 This is a schematic flowchart of a method for cutting a single-crystal silicon ingot according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the cutting process of a single-crystal silicon ingot disclosed in an embodiment of the present invention. Figure 3This is a schematic flowchart of another method for cutting a single-crystal silicon ingot disclosed in an embodiment of the present invention.

[0015] Step S101: The target steel wire corresponding to the area directly below the end face of the monocrystalline silicon ingot is led out from the cutting area of ​​the main wire mesh, goes around the auxiliary guide wheel and returns to the main wire mesh to form an auxiliary wire mesh.

[0016] The auxiliary mesh is located below the horizontal plane where the main mesh is located. The vertical projection of the auxiliary mesh covers at least the area directly below the end face of the single crystal silicon ingot, and the area directly above the auxiliary mesh forms a blank area.

[0017] When the end face of a single-crystal silicon ingot falls, it falls vertically, passes through the blank area and the auxiliary wire mesh, and then falls into the waste collection area. The falling path of the end face is spatially offset from that of the main wire mesh.

[0018] Specifically, in this embodiment of the invention, the slurry wire cutting equipment is a slurry wire cutting machine as known in the art. It has a main wire mesh, which is formed by reciprocating winding of steel wire around the main cutting guide wheel of the slurry wire cutting machine. When the slurry wire cutting machine cuts a monocrystalline silicon ingot, it cuts the ingot into multiple silicon wafers of uniform size using multiple parallel steel wires. Since the monocrystalline silicon ingot has an end face, this end face may fall prematurely during the cutting process due to gravity, thus impacting the main wire mesh. Therefore, this embodiment of the invention provides an auxiliary wire mesh, forming an overhead auxiliary wire mesh in the area directly below the end face. This auxiliary wire mesh does not participate in the cutting process of the monocrystalline silicon ingot, and the area directly opposite the end face is offset from the steel wires of the main wire mesh.

[0019] Furthermore, in practice, the operator imports the three-dimensional model data of the monocrystalline silicon ingot to be cut into the CNC system of the slurry wire EDM machine, which is equipped with multi-axis precision control capabilities. This data includes at least the length, diameter, and crystal orientation deviation angle (bottom axis rotation angle) of the monocrystalline silicon ingot. Based on this information, the precise position of the monocrystalline silicon ingot in the cutting coordinate system is automatically calculated, especially the spatial coordinates of the two end faces of the monocrystalline silicon ingot.

[0020] Furthermore, based on the calculated coordinates of the end face of the monocrystalline silicon ingot, steel wires corresponding to the area directly below the end face in the main wire mesh are identified and marked as target steel wires. One or more retractable / movable auxiliary guide wheels are controlled to move from the initial position to the working position, for example, extending from below or to the side of the plane where the main wire mesh is located. Then, the target steel wires are led out from the grooves of the original main cutting guide wheels, bypass the auxiliary guide wheels, and then return to another position of the main wire mesh or another groove of the same main cutting guide wheel. Through the above winding method, an independent, continuous auxiliary wire mesh is formed directly below the end face of the monocrystalline silicon ingot by the target steel wires, but it does not participate in the effective cutting of the monocrystalline silicon ingot. This auxiliary wire mesh is spatially located below the horizontal plane where the main wire mesh is located, that is, on the side further away from the feed direction of the monocrystalline silicon ingot. From a vertical projection, the projection area of ​​this auxiliary wire mesh at least completely covers the area directly below the end face of the monocrystalline silicon ingot. Since the auxiliary mesh is lower than the main mesh, and there are no other meshes directly above it and between it and the end face of the monocrystalline silicon ingot, this area forms a physical blank area.

[0021] For example, such as Figure 2 As shown, Figure 2 In the process, the monocrystalline silicon ingot is cut by the main wire mesh. The area where the main wire mesh is located includes a steel wire area 201 and a blank area 202. The blank area 202 is located within the projection area of ​​the end face sheet 203. The steel wires of the main wire mesh do not participate in the cutting of the end face sheet 203, but fall to the auxiliary wire mesh through the blank area 202.

[0022] Further, the cutting process is initiated. Driven by the feeding mechanism, the monocrystalline silicon ingot descends at a constant speed, and the main wire mesh, carrying slurry, performs a grinding cut on the main body of the ingot. At this time, the auxiliary wire mesh, being lower than the main wire mesh and not in contact with the ingot, remains idle. When the cutting process reaches the end face of the monocrystalline silicon ingot, as the weight of the remaining uncut portion gradually becomes insufficient to support itself, the end face sheet falls under gravity. Since the pre-set blank area and auxiliary wire mesh are directly below this end face sheet, the end face sheet first passes through the unobstructed blank area and then comes into contact with the auxiliary wire mesh. Because the auxiliary wire mesh is not designed to bear the cutting load, its steel wires can move freely or undergo elastic deformation. Therefore, the end face sheet either passes directly through the auxiliary wire mesh or is buffered by the auxiliary wire mesh before continuing to fall, ultimately landing in the waste collection area at the bottom of the equipment. Throughout the entire descent, the falling path of the end face piece is completely spatially offset from the main wire mesh that is being cut above it. Because the main wire mesh is located above the auxiliary wire mesh and separated by a blank area, the main wire mesh will not be subjected to any direct impact or interference, thus completely avoiding problems such as wire breakage, groove slippage, or severe tension fluctuations caused by the impact of the end face piece.

[0023] This invention provides a non-destructive path for falling end faces by setting an auxiliary wire mesh below the main wire mesh and creating a blank area directly above it. When the end face falls, its path is completely offset from the high-speed, cutting main wire mesh, preventing direct contact. This eliminates the risk of the end face breaking the steel wire or knocking it out of the guide wheel groove, minimizing the wire breakage rate during cutting, improving the continuity and reliability of the cutting operation, and ultimately increasing the output efficiency of the final product. Furthermore, the introduction of the auxiliary wire mesh and the creation of the blank area do not change the normal cutting parameters of the main wire mesh (such as linear velocity, slurry flow rate, feed rate, etc.). Throughout the cutting process, the main wire mesh maintains its original, optimized, high-efficiency cutting state. Therefore, this invention improves the safety of the cutting process without affecting normal cutting efficiency, thereby increasing the output efficiency of the final product. Furthermore, because this invention completely spatially separates the drop path of the end face sheet from the main mesh, the main mesh is not subjected to any physical impact, and its tension remains stable. This avoids sudden tension changes caused by impact, ensuring that the silicon wafers cut from the entire ingot have highly consistent geometric parameters and surface quality, thereby improving the quality of the final product.

[0024] Furthermore, as an optional embodiment of the present invention, the tension value of the steel wire in the auxiliary wire mesh is lower than the tension value of the steel wire in the main wire mesh. The tension value of the steel wire in the auxiliary wire mesh is less than 50% of the tension value of the steel wire in the main wire mesh.

[0025] Specifically, to further enhance the buffering effect of the auxiliary wire mesh and its isolation and protection capabilities for the main wire mesh, this embodiment of the invention optimizes the control of the steel wire tension. During the formation of the auxiliary wire mesh, an independent tension control mechanism, such as installing a separate servo motor or magnetic powder brake on the shaft of the auxiliary guide wheel, sets the operating tension value of the steel wire in the auxiliary wire mesh to be lower than the tension value of the main wire mesh. For example, this embodiment of the invention typically sets the tension of the main wire mesh to 25N to 35N to ensure cutting stability and accuracy. The tension of the auxiliary wire mesh is set to 10N to 15N, which is 50% lower than the tension value of the main wire mesh.

[0026] The lower tension results in greater flexibility for the auxiliary wire mesh. When a falling end face plate impacts the auxiliary wire mesh, the lower tension steel wire is more prone to elastic displacement or bending deformation, thus more effectively absorbing impact energy and allowing the end face plate to pass smoothly without causing overload breakage of the steel wire itself. Simultaneously, this flexible connection minimizes the transmission of impact force through the steel wire to the equipment guide wheels and other parts of the main wire mesh. In another, even better embodiment, the tension value of the auxiliary wire mesh can be dynamically adjusted based on the estimated weight of the end face plate, maintaining it within 30% to 50% of the tension value of the main wire mesh to achieve optimal energy absorption.

[0027] Furthermore, as an optional embodiment of the present invention, the target steel wire of the main wire mesh is led out from the cutting area of ​​the main wire mesh, passes around the auxiliary guide wheel, and returns to the main wire mesh to form an auxiliary wire mesh. This includes: determining the position coordinates of the end face of the monocrystalline silicon ingot based on the three-dimensional model of the monocrystalline silicon ingot; determining the cutting path of the monocrystalline silicon ingot based on the position coordinates, and generating a virtual empty path at a position directly below the end face of the monocrystalline silicon ingot; controlling the auxiliary guide wheel to move to the extended position, lifting the target steel wire located in the area directly below the end face of the monocrystalline silicon ingot from the main cutting guide wheel and guiding it to the auxiliary guide wheel, passing around the auxiliary guide wheel, and then returning to the main wire mesh. The target steel wire forms a continuous but non-cutting overhead wire mesh segment in the area directly below the end face of the monocrystalline silicon ingot, thus obtaining the auxiliary wire mesh.

[0028] Specifically, in this embodiment of the invention, the position coordinates of the two end faces of the silicon ingot to be cut in the cutting coordinate system are calculated based on the imported three-dimensional model of the single-crystal silicon ingot. For example, for a single-crystal silicon ingot with a total length of 400mm and a diameter of 300mm, if its bonding position is fixed and the bottom axis rotation angle is 0°, then the coordinates of its two end faces in the feed direction (e.g., the Y-axis direction) can be determined as Y=20mm (upper end face) and Y=420mm (lower end face), respectively.

[0029] Furthermore, based on the position coordinates and the preset blank area width requirements, for example, a 5mm wide buffer area is needed below each end face, a virtual blank path is automatically generated in the neighborhood of the end face coordinates during the overall cutting path planning process. For example, within the coordinate ranges of Y=15mm to Y=20mm and Y=420mm to Y=425mm, path segments specifically for forming auxiliary meshes will be planned. This path is represented in the software as a virtual mesh parallel to the main mesh but with a slightly lagging Y-axis coordinate (i.e., located further below).

[0030] Furthermore, when the cutting process is about to reach the starting position of the aforementioned virtual blank path, for example, when the main wire mesh is cut to the Y=22mm position, the CNC system issues a command to drive the actuator of the auxiliary guide wheel (such as a cylinder or a telescopic arm driven by a servo motor) to move the auxiliary guide wheel precisely from its original position to a preset extended position. This extended position is located to the side of the main cutting guide wheel and slightly lower than the groove plane of the main cutting guide wheel. Subsequently, during the reciprocating motion of the steel wire, with the cooperation of the wire laying device, the target steel wire, which should have been embedded in the groove of the main cutting guide wheel and corresponds to the Y=15-20mm and Y=420-425mm regions, is lifted from the main cutting guide wheel and guided to the corresponding groove of the extended auxiliary guide wheel. After the steel wire passes around the auxiliary guide wheel, it is guided back to the rear of the main wire mesh. Following the formation of the groove, a continuous, non-cutting overhead wire mesh segment is created in the region directly below the end face of the monocrystalline silicon ingot. In this way, the target steel wire in the regions of Y=15-20mm and Y=420-425mm is no longer attached to the bottom of the main cutting guide wheel, but is instead "suspended" by the auxiliary guide wheel, forming a continuous wire mesh segment higher than the main wire mesh plane—the auxiliary wire mesh. The region directly above this auxiliary wire mesh (between the silicon ingot end face and the auxiliary wire mesh) naturally forms the required blank area due to the absence of the main wire mesh. When cutting reaches these coordinate intervals, the resulting silicon wafer is an incomplete end face wafer; upon falling, it will directly pass through the blank area and strike the auxiliary wire mesh, without affecting the main wire mesh located in other coordinate intervals (Y=20-420mm).

[0031] Furthermore, embodiments of the present invention provide a single-crystal silicon ingot cutting system for performing the above... Figure 1 The method for cutting monocrystalline silicon ingots mentioned herein includes: a main cutting frame; an ingot clamping and feeding mechanism, disposed on the main cutting frame, for fixing the monocrystalline silicon ingot and controlling its feeding movement; a main wire mesh section, disposed on the main cutting frame, comprising a pair of main cutting guide wheels, wherein steel wire is reciprocally wound on the pair of main cutting guide wheels to form a main wire mesh, the main wire mesh being located directly below the monocrystalline silicon ingot for cutting the monocrystalline silicon ingot; and an auxiliary wire mesh section, disposed on the main cutting frame, comprising at least one auxiliary guide wheel, the auxiliary guide wheel being configured to move between a retracted position and an extended position.

[0032] When the auxiliary guide wheel is in the extended position, the target steel wire in the main wire mesh corresponding to the area directly below the end face of the monocrystalline silicon ingot is lifted by the auxiliary guide wheel, forming an auxiliary wire mesh located below the main wire mesh. The auxiliary wire mesh is located below the horizontal plane where the main wire mesh is located, and the vertical projection of the auxiliary wire mesh covers at least the area directly below the end face of the monocrystalline silicon ingot, while the area directly above the auxiliary wire mesh forms a blank area. When the end face sheet of the monocrystalline silicon ingot falls, the end face sheet falls vertically, passes through the blank area and the auxiliary wire mesh, and falls to the waste collection area. The falling path of the end face sheet is spatially offset from that of the main wire mesh.

[0033] Specifically, the cutting main frame in this embodiment of the invention adopts a high-strength cast iron or steel plate welded structure, which can be the main frame of the existing slurry wire cutting equipment. The main frame is provided with multiple precision-machined mounting surfaces and positioning holes for mounting and supporting other functional units.

[0034] Furthermore, the ingot clamping and feeding mechanism is located on the upper part of the cutting main frame, including an ingot support platform, an adhesive plate, a clamping device, and a vertical feed drive unit, such as a servo motor coupled with a ball screw. The monocrystalline silicon ingot is bonded to the support platform with resin, and the clamping device provides auxiliary fixation for the ingot from both sides or the top. The vertical feed drive unit controls the ingot support platform to descend uniformly along the vertical direction (Z-axis), causing the monocrystalline silicon ingot to press against the main wire mesh below at a set feed speed, thus realizing the cutting feed motion.

[0035] Furthermore, the main wire mesh section is located in the middle of the cutting main frame, directly below the ingot clamping and feeding mechanism. This main wire mesh section includes a pair of parallel main cutting guide wheels, a left guide wheel and a right guide wheel. Each main cutting guide wheel is driven by an independent servo motor, enabling synchronous forward and reverse rotation. Steel wire is repeatedly wound between the two main cutting guide wheels, forming a parallel main wire mesh with uniform spacing. This main wire mesh is located directly below the monocrystalline silicon ingot and is used to carry slurry to perform abrasive cutting of the ingot during its descent. Multiple parallel annular grooves are formed on the circumferential surface of the main cutting guide wheels; the groove spacing determines the thickness of the cut silicon wafer. The main wire mesh section is also equipped with an independent slurry supply unit for spraying silicon carbide slurry onto the cutting area.

[0036] Furthermore, the auxiliary wire mesh section is also located on the main cutting frame, specifically to the side of the main wire mesh section, for example, below the main cutting guide roller. This auxiliary wire mesh section includes at least one auxiliary guide roller, preferably two, corresponding to the two end faces of the ingot respectively. The auxiliary guide rollers are configured to move between a retracted position and an extended position, and their movement can be linear, oscillating, or rotating.

[0037] Furthermore, when the system is normally cutting the main body of the monocrystalline silicon ingot, the auxiliary guide wheel is in the retracted position and does not interfere with the normal operation of the main wire mesh. When the cutting process approaches the end face of the ingot, the control system issues a command to drive the auxiliary guide wheel to move to the extended position. In this position, the target steel wire in the main wire mesh corresponding to the area directly below the end face of the monocrystalline silicon ingot is lifted or suspended from the groove of the main cutting guide wheel by the auxiliary guide wheel, thereby forming an independent and continuous auxiliary wire mesh below the horizontal plane of the main wire mesh.

[0038] The auxiliary mesh, projected vertically, completely covers the area directly beneath the end face of the monocrystalline silicon ingot. Since the auxiliary mesh is located below the main mesh, and there are no other meshes directly above it and between it and the ingot end face, this area naturally forms a physical blank space. When the end face sheet falls, it descends vertically, first passing through the unobstructed blank space, then contacting and passing through the auxiliary mesh. The low-tension or flexible structure of the auxiliary mesh allows the end face sheet to pass through, eventually falling into the waste collection area. Throughout the entire descent, the end face sheet never contacts the main mesh that is being cut above it, thus effectively protecting the main mesh.

[0039] Furthermore, as an optional embodiment of the present invention, the auxiliary wire mesh section further includes: a guide rail fixed to the main cutting frame; a slider bracket slidably engaged with the guide rail, and an auxiliary guide wheel mounted on the slider bracket; a first positioning block and a second positioning block sequentially arranged on the guide rail along the sliding direction; when the slider bracket abuts against the first positioning block, the auxiliary guide wheel is in the extended position, and its wheel surface is higher than the bottom surface of the groove of the main cutting guide wheel to lift the target steel wire; when the slider bracket abuts against the second positioning block, the auxiliary guide wheel is in the retracted position, and its wheel surface is lower than the bottom surface of the groove of the main cutting guide wheel to disengage from the target steel wire.

[0040] Specifically, the guide rail is a linear guide rail, fixed to the side wall of the cutting main frame by bolts. Its extension direction intersects the axis of the main cutting guide wheel, preferably perpendicular or oblique. The two ends of the guide rail correspond to the two extreme working positions of the auxiliary guide wheel. The slider bracket slides with the guide rail and can move freely along the extension direction of the guide rail. The auxiliary guide wheel is mounted on the end of the slider bracket via bearings, allowing it to rotate freely. The slider bracket also has a drive interface for connecting a drive device, such as a cylinder, hydraulic cylinder, or a lead screw mechanism driven by a servo motor. The first and second positioning blocks are sequentially arranged on the guide rail along the sliding direction; their specific positions can be calibrated according to the required extension and retraction positions of the auxiliary guide wheel. The positioning blocks can be mechanical limit blocks with buffer pads, or a combination of high-precision proximity switches and hard limits.

[0041] Furthermore, when the drive device pushes the slider bracket along the guide rail until it abuts against the first positioning block, the auxiliary guide wheel is in its extended position. In this position, the highest point of the auxiliary guide wheel's surface is higher than the bottom surface of the annular groove of the main cutting guide wheel, i.e., the lowest point of the groove. Therefore, when the steel wire passes through this area, it is lifted upwards by the surface of the auxiliary guide wheel, thus detaching from the bottom of the groove of the main cutting guide wheel, forming an overhead auxiliary wire mesh. When the drive device pulls the slider bracket in the opposite direction until it abuts against the second positioning block, the auxiliary guide wheel is in its retracted position. In this position, the highest point of the auxiliary guide wheel's surface is lower than the bottom surface of the annular groove of the main cutting guide wheel. At this time, the steel wire is no longer lifted by the auxiliary guide wheel, but instead is normally embedded in the bottom of the groove of the main cutting guide wheel, the auxiliary wire mesh disappears naturally, and the main wire mesh returns to its complete cutting shape.

[0042] Thus, through the aforementioned mechanical positioning structure, each extension and retraction of the auxiliary guide wheel can be accurately reproduced, ensuring the consistency and reliability of the auxiliary wire mesh position.

[0043] Furthermore, as an optional embodiment of the present invention, the main cutting guide wheel is provided with multiple parallel annular grooves, and the steel wires form a uniformly spaced main wire network in each parallel annular groove; the number of auxiliary guide wheels is two, corresponding to the two end faces of the single crystal silicon ingot respectively.

[0044] Specifically, multiple parallel annular grooves are formed on the circumference of the main cutting guide wheel. Steel wires sequentially pass around the corresponding grooves on two main cutting guide wheels, forming a uniformly spaced, parallel main wire mesh. The width of the main wire mesh is greater than the diameter of the single-crystal silicon ingot to ensure complete ingot cutting.

[0045] The preferred number of auxiliary guide wheels is two, corresponding to the two end faces (upper and lower) of the monocrystalline silicon ingot. The two auxiliary guide wheels can be controlled independently or in conjunction. Each auxiliary guide wheel is installed to the side of the main cutting guide wheel directly below its corresponding end face.

[0046] In terms of winding method, after the steel wire is led out from the feed drum, it passes sequentially through the tension control wheel and the wire feeding wheel before entering the first main cutting guide wheel. In the normal cutting area, the steel wire is wound sequentially in each annular groove in a conventional manner. When the steel wire travels to the groove area corresponding to the area directly below the ingot end face, if the system determines that an auxiliary wire mesh needs to be formed, it controls the corresponding auxiliary guide wheel to extend, lifting the steel wire in that part of the groove and guiding it into the groove of the auxiliary guide wheel. After the steel wire passes around the auxiliary guide wheel, it returns to the corresponding groove of the second main cutting guide wheel. In this way, two independent auxiliary wire meshes that do not participate in cutting are formed directly below the two end faces of the ingot. The other parts of the main wire mesh maintain their original shape and are cut normally.

[0047] In this way, the system can achieve active protection of both ends of the crystal ingot without increasing the complexity of the equipment.

[0048] Furthermore, as an optional embodiment of the present invention, the system further includes a monitoring unit, which includes at least one of the following sensors: a vision sensor for real-time monitoring of the position of the auxiliary guide wheel and the formation state of the auxiliary wire mesh to confirm whether the auxiliary wire mesh is accurately located directly below the end face of the monocrystalline silicon ingot; an acoustic sensor for listening to abnormal noise during the cutting process; and a tension sensor for real-time monitoring of the tension of the main wire mesh and the auxiliary wire mesh, wherein the tension value of the auxiliary wire mesh is lower than the tension value of the main wire mesh.

[0049] Specifically, a vision sensor, such as a CCD industrial camera, is mounted on the inner wall of the cutting frame in conjunction with an LED ring light source. Its field of view covers the area where the auxiliary guide rollers and auxiliary mesh are formed. The vision sensor is used to acquire real-time images of the position of the auxiliary guide rollers and the shape of the auxiliary mesh, and uses image processing algorithms to identify whether the auxiliary guide rollers have moved accurately to the extended position and whether the auxiliary mesh has been correctly formed. When the vision sensor detects that the auxiliary mesh is not accurately positioned directly below the ingot end face, the system will issue an alarm signal and pause cutting, awaiting manual intervention or automatic adjustment.

[0050] Furthermore, acoustic sensors, such as microphone arrays or piezoelectric acoustic emission sensors, are installed near the cutting area to monitor the acoustic signals generated during the cutting process in real time. During normal cutting, the friction between the steel wire and the ingot produces a smooth hissing sound. When a wire breaks, slots run out, or an abnormal impact occurs on the end face plate, a sharp crackling sound or a thud is produced. The acoustic sensors transmit the collected acoustic signals to the control system, which uses spectrum analysis and pattern recognition algorithms to determine whether there are abnormal events, thus providing early warning of wire breaks or slot runs. For example, when the characteristic acoustic signal of an end face plate impacting the auxiliary wire mesh is detected, the system can record the event without stopping the machine; when the characteristic acoustic signal of a main wire mesh break is detected, the system immediately performs an emergency stop.

[0051] Furthermore, tension sensors, such as piezoresistive or magnetoelectric tension detection wheels, are respectively installed in the main wire mesh circuit and the auxiliary wire mesh circuit. For the main wire mesh, the tension sensor monitors the running tension of the steel wire in real time. When the tension fluctuation exceeds a set threshold, the torque of the servo motor is automatically adjusted or deceleration is performed. For the auxiliary wire mesh, the tension sensor feeds back its actual tension value to the control system. The control system maintains the tension value of the auxiliary wire mesh at a preset low level through an independent tension adjustment mechanism, such as a magnetic powder brake on the auxiliary guide wheel. According to the aforementioned method embodiment, the tension value of the auxiliary wire mesh is set to be 50% lower than the tension value of the main wire mesh. When the tension sensor detects an abnormal increase in the tension of the auxiliary wire mesh, the system determines that there may be end face plate jamming or auxiliary guide wheel failure, and issues a corresponding alarm.

[0052] Thus, by integrating the above monitoring units, not only can physical protection against end face drop be achieved, but also full-process status perception and intelligent response can be realized, significantly improving the stability of the cutting process and the yield.

[0053] like Figure 3 As shown, Figure 3 This is a schematic flowchart of another method for cutting a monocrystalline silicon ingot according to an embodiment of the present invention. Based on the monocrystalline silicon ingot cutting system mentioned in the above embodiment, it includes:

[0054] Step S301: Load and center the material to determine the spatial coordinates of the two end faces of the monocrystalline silicon ingot.

[0055] Specifically, the operator fixes the monocrystalline silicon ingot to be cut onto the support platform of the ingot clamping and feeding mechanism using resin bonding, and activates the clamping device for auxiliary fixation. Then, the system's centering calibration program is initiated. This program uses a vision sensor mounted on the cutting main frame to acquire position images of the monocrystalline silicon ingot, and uses image processing algorithms to identify the precise positions of the ingot's central axis, length direction, and two end faces. Based on feedback from the vision sensor, the fine-tuning platform of the ingot clamping mechanism or feeding mechanism is automatically adjusted so that the central axis of the ingot coincides with the central plane of the main mesh, i.e., centering. After centering, the control system calculates the spatial coordinates of the two end faces of the ingot in the cutting coordinate system based on the calibration results of the vision sensor and the known dimensions of the ingot (length and diameter). For example, using the main mesh plane as a reference and the feeding direction as the Y-axis, the coordinates of the upper end face are determined as Y1, and the coordinates of the lower end face as Y2. This coordinate data will be used for subsequent auxiliary mesh triggering and positioning.

[0056] Step S302: Start the main network to cut the monocrystalline silicon ingot.

[0057] Specifically, the control system activates the main wire mesh section. A pair of main cutting guide wheels, driven by servo motors, begin to rotate synchronously. The steel wire moves between the annular grooves of the main cutting guide wheels at a set reciprocating speed, forming a stable main wire mesh. Simultaneously, the slurry supply unit is activated, continuously spraying silicon carbide slurry into the contact area between the main wire mesh and the ingot. Subsequently, the ingot clamping and feeding mechanism drives the ingot to move vertically downward at a set feed speed, bringing the lower surface of the monocrystalline silicon ingot into contact with the moving main wire mesh, initiating grinding-type cutting. During this stage, the auxiliary guide wheels remain in the retracted position, the auxiliary wire mesh is not yet formed, and the main wire mesh cuts the main body of the ingot in its complete form.

[0058] Step S303: When the cutting position is close to the end face of the monocrystalline silicon ingot, control the auxiliary guide wheel to move to the extended position, and lead the target steel wire corresponding to the area directly below the end face of the monocrystalline silicon ingot from the main wire mesh and around the auxiliary guide wheel to form an overhead auxiliary wire mesh directly below the end face.

[0059] Specifically, during the cutting process, the control system monitors the ingot's feed stroke in real time and compares the current cutting position with the end face coordinates determined in the above steps. When it is determined that the current cutting position is close to the end face coordinates by a preset threshold, for example, 5mm-10mm away from the end face, the control system determines that the cutting position is close to the end face and then triggers the auxiliary wire mesh formation program. Specifically, the control system sends a command to the drive device of the auxiliary wire mesh section, driving the slider support to move along the guide rail until the slider support abuts against the first positioning block, so that the auxiliary guide wheel moves precisely to the extended position. At this extended position, the wheel surface of the auxiliary guide wheel is higher than the bottom surface of the annular groove of the main cutting guide wheel, thereby lifting the target steel wire in the main wire mesh corresponding to the area directly below the ingot end face from the groove of the main cutting guide wheel and guiding it to bypass the auxiliary guide wheel and return to the main wire mesh. Thus, an auxiliary wire mesh that is suspended and does not participate in the cutting is formed directly below the end face. The auxiliary mesh is located below the horizontal plane of the main mesh, and its vertical projection completely covers the area directly below the end face. A blank area without any mesh is formed between the top of the auxiliary mesh and the end face of the ingot.

[0060] Step S304: Continue the cutting process. When the end face of the single crystal silicon ingot falls under the action of gravity, the end face falls into the waste collection area after passing through the auxiliary wire mesh, and the falling path of the end face is spatially offset from that of the main wire mesh.

[0061] Specifically, after the auxiliary wire mesh is formed, the cutting process continues. The ingot continues to descend, and the main wire mesh cuts each part of the ingot sequentially. When the cutting reaches the end face, because the connection area between the end face and the main ingot is very small and cannot support its own weight, the end face will automatically detach from the ingot under gravity and fall downwards. Since there is a pre-set blank area and the suspended auxiliary wire mesh directly below the end face, the end face first freely passes through the blank area and then impacts the low-tension auxiliary wire mesh. Due to its low tension and flexible structure, the auxiliary wire mesh allows the end face to pass smoothly, and the end face continues to fall to the waste collection area at the bottom of the equipment. Throughout the entire fall, because the main wire mesh is located above the auxiliary wire mesh, and the fall path of the end face is completely confined to the auxiliary wire mesh and the blank area above it, the end face never comes into contact with the main wire mesh. The fall path of the end face piece is completely offset from that of the main wire network in space, thereby completely avoiding the impact, jamming or wear of the end face piece on the main wire network, and effectively preventing accidents such as wire breakage and slotting.

[0062] For example, in this embodiment of the invention, a single-crystal silicon ingot with a total length of 400mm and a diameter of 300mm is cut. The bottom axis rotation angle is 2°, meaning the ingot normal forms a 2° angle with the descent direction. After loading and centering, the system calculates the coordinates of the upper end face to be approximately Y=20mm and the lower end face to be approximately Y=420mm. During normal cutting to approximately Y=25mm, the control system extends the auxiliary guide wheel corresponding to the upper end face, forming an auxiliary mesh with a width of 5mm within the coordinate range of Y=15mm-20mm. Cutting continues, and when the ingot descends to Y=20mm, the upper end face detaches from the ingot and falls. This end face first passes through the blank area of ​​the Y=15mm-20mm region, then through the suspended auxiliary mesh, and falls into the waste collection area. Since the effective cutting area of ​​the main mesh is between Y=20mm and 420mm, the falling path of the end face piece is entirely within the space below Y=20mm and has no intersection with the main mesh. Therefore, the main mesh is not affected in any way, and the cutting process is completed smoothly.

[0063] Furthermore, as an optional embodiment of the present invention, forming an auxiliary wire mesh in an elevated state directly below the end face includes: calculating the required width of the auxiliary wire mesh and the extension distance of the auxiliary guide wheel based on the length, bottom shaft rotation angle and diameter information of the monocrystalline silicon ingot; adjusting the tension value of the steel wire of the auxiliary wire mesh to a preset value, the preset value being 50% lower than the tension value of the steel wire of the main wire mesh.

[0064] Specifically, when the system determines that the cutting position is close to the end face, it performs dynamic calculations based on the actual parameters of the current monocrystalline silicon ingot. Specifically, the system obtains the following input information: the length L of the monocrystalline silicon ingot, the diameter D of the monocrystalline silicon ingot, and the bottom axis rotation angle θ of the monocrystalline silicon ingot. The required width W of the auxiliary mesh is calculated based on geometric relationships. Due to the existence of the bottom axis rotation angle θ, the projected width of the incomplete silicon wafer at the ingot end face in the horizontal direction will increase. Therefore, in this embodiment of the invention, the width W of the auxiliary mesh is calculated using the following formula:

[0065]

[0066] In the above formula, This indicates the width of the auxiliary mesh. This indicates the basic width between wires, which can be preset to 3mm. For safety factors, such as 1.2. D represents the diameter of a single-crystal silicon ingot. Indicates the bottom axis rotation angle.

[0067] Furthermore, in this embodiment of the invention, the width value of the auxiliary net can also be obtained by directly looking up a table in an empirical database.

[0068] Furthermore, based on the required width W of the auxiliary wire mesh, the diameter of the auxiliary guide wheel, and the geometry of the guide wheel groove, the required extension distance S of the auxiliary guide wheel is calculated, which is the displacement from the retracted position to the extended position. The extension distance S is positively correlated with the width W, and the specific relationship is determined by the radius of the guide wheel and the winding angle, which can be calculated using the pre-calibrated function S=f(W).

[0069] Furthermore, during the formation of the auxiliary wire mesh, or after its formation but before the end face sheet falls off, the tension of the steel wire in the auxiliary wire mesh is independently adjusted. Specifically, the control system monitors the current tension value of the auxiliary wire mesh in real time using a tension sensor and compares it with a preset target tension value. This preset target tension value is 50% lower than the tension value of the main wire mesh.

[0070] In a specific example, the tension of the steel wire used for cutting the main body of the wire mesh is set to 30N. The system then presets the tension of the auxiliary wire mesh to 30N × 50% = 15N. In a more preferred embodiment, to further increase the flexibility and buffering capacity of the auxiliary wire mesh, the preset value is set to 30%-40% of the main wire mesh tension, i.e., 9N-12N. The system stabilizes the actual tension of the auxiliary wire mesh near the preset value by adjusting the torque of the magnetic powder brake on the auxiliary guide wheel or an independent servo motor.

[0071] Thus, by reducing the tension of the auxiliary wire mesh to less than 50% of the tension of the main wire mesh, when the end piece falls and impacts the auxiliary wire mesh, the low-tension steel wire is more prone to elastic bending and displacement, effectively absorbing impact energy and preventing the steel wire from breaking due to overload. The low tension also reduces the obstruction of the wire mesh on the end piece, making it easier for the end piece to pass through the mesh and fall without jamming. The tension difference between the auxiliary and main wire mesh forms a soft connection; the vibration generated by the impact of the end piece is absorbed by the auxiliary wire mesh and is almost not transmitted to the main wire mesh, thereby ensuring stable cutting of the main wire mesh.

[0072] The above embodiments of the present invention focus on describing the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be described in detail here.

[0073] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A method of slicing a single crystal silicon ingot, characterized by, Applications include: mortar wire cutting equipment The target steel wire corresponding to the area directly below the end face of the monocrystalline silicon ingot is drawn out from the cutting area of ​​the main wire mesh, goes around the auxiliary guide wheel and returns to the main wire mesh to form an auxiliary wire mesh. The auxiliary mesh is located below the horizontal plane where the main mesh is located. The vertical projection of the auxiliary mesh covers at least the area directly below the end face of the single crystal silicon ingot, and the area directly above the auxiliary mesh forms a blank area. When the end face of the single crystal silicon ingot falls, the end face falls vertically, passes through the blank area and the auxiliary wire mesh, and falls into the waste collection area. The falling path of the end face is spatially offset from that of the main wire mesh. The process of drawing the target steel wire corresponding to the area directly below the end face of the monocrystalline silicon ingot from the cutting area of ​​the main wire mesh, passing through the auxiliary guide wheel, and returning to the main wire mesh to form the auxiliary wire mesh includes: The position coordinates of the end face of the single crystal silicon ingot are determined based on the three-dimensional model of the single crystal silicon ingot; The cutting path of the monocrystalline silicon ingot is determined based on the position coordinates, and a virtual blank path is generated at the position directly below the end face of the monocrystalline silicon ingot. The auxiliary guide wheel is moved to the extended position, and the target steel wire located in the area directly below the end face of the monocrystalline silicon ingot in the main wire mesh is lifted from the main cutting guide wheel and guided to the auxiliary guide wheel. After passing around the auxiliary guide wheel, it returns to the main wire mesh. The target steel wire forms a continuous but non-cutting overhead wire mesh segment in the area directly below the end face of the monocrystalline silicon ingot, thus obtaining the auxiliary wire mesh.

2. The method of slicing a single crystal silicon ingot according to claim 1, wherein The tension value of the steel wire in the auxiliary wire mesh is lower than that of the steel wire in the main wire mesh.

3. The method of slicing a single crystal silicon ingot according to claim 2, wherein The tension value of the steel wire in the auxiliary wire mesh is 50% lower than that of the steel wire in the main wire mesh.

4. A cutting system of a single crystal silicon ingot, characterized by, A method for cutting a single-crystal silicon ingot according to any one of claims 1 to 3, comprising: Cutting main frame; A crystal ingot clamping and feeding mechanism is provided on the cutting main frame and is used to fix the single crystal silicon ingot and control the feeding movement of the single crystal silicon ingot. The main wire mesh section is located on the cutting host frame. The main wire mesh section includes a pair of main cutting guide wheels. The steel wire is reciprocally wound on the pair of main cutting guide wheels to form the main wire mesh. The main wire mesh is located directly below the monocrystalline silicon ingot and is used to cut the monocrystalline silicon ingot. An auxiliary wire mesh section, provided on the cutting main frame, includes at least one auxiliary guide wheel, which is configured to move between a retracted position and an extended position; When the auxiliary guide wheel is in the extended position, the target steel wire in the main wire mesh corresponding to the area directly below the end face of the monocrystalline silicon ingot is lifted by the auxiliary guide wheel to form an auxiliary wire mesh located below the main wire mesh. The auxiliary mesh is located below the horizontal plane where the main mesh is located. The vertical projection of the auxiliary mesh covers at least the area directly below the end face of the single crystal silicon ingot, and the area directly above the auxiliary mesh forms a blank area. When the end face of the single crystal silicon ingot falls, the end face falls vertically, passes through the blank area and the auxiliary wire mesh, and falls into the waste collection area. The falling path of the end face is spatially offset from that of the main wire mesh.

5. The single crystal silicon ingot slicing system of claim 4, wherein The auxiliary wire mesh section also includes: Guide rails are fixed to the cutting main frame; A slider bracket is slidably engaged with the guide rail, and the auxiliary guide wheel is mounted on the slider bracket; The first positioning block and the second positioning block are sequentially arranged on the guide rail along the sliding direction; when the slider bracket abuts against the first positioning block, the auxiliary guide wheel is in the extended position, and its wheel surface is higher than the bottom surface of the groove of the main cutting guide wheel, so as to lift the target steel wire; When the slider bracket abuts against the second positioning block, the auxiliary guide wheel is in the retracted position, and its wheel surface is lower than the bottom surface of the groove of the main cutting guide wheel, thus disengaging from the target steel wire.

6. The single-crystal silicon ingot cutting system according to claim 4, characterized in that, The main cutting guide wheel is provided with multiple parallel annular grooves, and the steel wire forms a main wire mesh with uniform spacing in each of the parallel annular grooves. The number of auxiliary guide wheels is two, corresponding to the two end faces of the single crystal silicon ingot respectively.

7. The single-crystal silicon ingot cutting system according to claim 4, characterized in that, The system further includes a monitoring unit, which includes at least one of the following sensors: A visual sensor is used to monitor the position of the auxiliary guide wheel and the formation state of the auxiliary wire mesh in real time to confirm whether the auxiliary wire mesh is accurately located directly below the end face of the monocrystalline silicon ingot. Acoustic sensors are used to monitor abnormal noises during the cutting process; A tension sensor is used to monitor the tension of the main wire mesh and the auxiliary wire mesh in real time, wherein the tension value of the auxiliary wire mesh is lower than the tension value of the main wire mesh.

8. A method for cutting a single-crystal silicon ingot, characterized in that, The single-crystal silicon ingot cutting system according to any one of claims 4 to 7 comprises: Load and center the material to determine the spatial coordinates of the two end faces of the monocrystalline silicon ingot; The main network is activated to cut the single-crystal silicon ingot; When the cutting position approaches the end face of the monocrystalline silicon ingot, the auxiliary guide wheel is controlled to move to the extended position, and the target steel wire corresponding to the area directly below the end face of the monocrystalline silicon ingot is led out from the main wire mesh and wrapped around the auxiliary guide wheel to form an overhead auxiliary wire mesh directly below the end face. As the cutting process continues, when the end face of the single crystal silicon ingot falls under the influence of gravity, the end face falls through the auxiliary wire mesh and into the waste collection area, and the falling path of the end face is spatially offset from that of the main wire mesh.

9. The method for cutting a single-crystal silicon ingot according to claim 8, characterized in that, The auxiliary wire mesh that forms an overhead state directly below the end face includes: Based on the length, bottom shaft rotation angle, and diameter information of the single crystal silicon ingot, calculate the required width of the auxiliary wire mesh and the extension distance of the auxiliary guide wheel; The tension value of the steel wire in the auxiliary wire mesh is adjusted to a preset value, which is 50% lower than the tension value of the steel wire in the main wire mesh.

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