Method for rescuing broken wire loss of re-pressing cut silicon wafer
By adjusting the bottom surface of the silicon block to an inclined plane and combining it with low-speed forward lifting and segmented repressing and bouncing, the problem of high-level broken wires that cannot be repressed during silicon wafer cutting was solved, which improved cutting efficiency and yield, reduced color difference defect rate, and achieved a higher A-grade product rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YICHANG CSG POLYSILICON CO LTD
- Filing Date
- 2023-09-03
- Publication Date
- 2026-07-24
AI Technical Summary
In existing technologies, after a high-level wire breakage during silicon wafer cutting, effective re-pressing and cutting cannot be achieved, resulting in a decrease in cutting quality, a reduction in yield and A-grade yield, and the introduction of impurities from recycled silicon ingots, which affects the quality of ingot casting.
By employing a low-speed forward lifting method combined with segmented repressing and bouncing, and by adjusting the bottom surface of the silicon block to be inclined and making point contact with the wire mesh, combined with negative pressure cutting and liquid spray pipe position adjustment, the silicon block can be effectively repressed into the wire mesh, reducing the defect rate of broken wires and color difference, and improving cutting efficiency and yield.
It effectively solves the problem of not being able to re-pressure cut after high-level wire breakage, improves the efficiency of wire breakage recovery and re-pressure, reduces the color difference defect rate of negative pressure wire breakage cutting, improves silicon wafer cutting quality and A-grade rate, and increases the yield.
Smart Images
Figure CN117382008B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of silicon wafer cutting technology, and more particularly to a method for re-pressure cutting silicon wafers to recover from wire breakage losses. Background Technology
[0002] In the photovoltaic industry, the technological trend for both monocrystalline and polycrystalline silicon wafers is towards finer dicing lines and thinner wafers. Wire breakage during silicon wafer processing and cutting is a problem faced by all cutting companies. Currently, the traditional industry practice after a wire breakage occurs is to discard a portion of the silicon block and continue cutting with the wire, resulting in multiple breaks in a single operation or even causing the entire cut to have zero A-grade quality. Another approach is to use a wire bonding machine to weld the broken ends, then run the bonding head unidirectionally out of the wire mesh before cutting. This drastically changes the cutting mode from bidirectional to unidirectional cutting, resulting in significant color differences and downgrading of the salvaged wafers, thus affecting product quality.
[0003] Currently, the cutting of photovoltaic monocrystalline and polycrystalline silicon wafers, whether using diamond wire cutting on carbon steel substrates or new tungsten substrates, involves a single wire spirally wound around each groove of the main roller. The main roller is coated with resin and has 3,000-4,000 grooves. If the cutting wire breaks in even one groove during the cutting process, the entire cutting process will stop. Therefore, wire breakage is the biggest factor affecting the quality of monocrystalline and polycrystalline wafer cutting. Due to the continuous technological upgrades to thinner wires and wafers, especially when the wire breaks after the cutting depth exceeds 50%, the cut silicon wafers have already adhered to each other. The only way to salvage the wafers is to cut them from the broken point, sacrificing some of the smaller pieces or using a welding machine to weld the broken ends. This process affects the cutting quality, reduces the yield of finished wafers, and causes color differences in the wafers.
[0004] Existing technical solutions: When the cutting depth is <50%, the lifting rod re-pressing method is used. Because the silicon wafer itself is shallowly cut and the saw kerf is relatively independent, the re-pressing success rate is relatively high. Alternatively, wire bonding can be performed directly, reducing the grade of the silicon wafers due to color difference and minimizing scrap. When the cutting depth is ≥50%, because the cut silicon wafers are thin and the saw kerf is small, the cutting fluid between the wafers forms mutual adsorption, resulting in either sacrificing smaller wafers for larger ones or producing poor weld quality. This can only improve the yield rate, not the A-grade rate, thus affecting the overall silicon wafer cutting quality. With the development of silicon wafer cutting technology, silicon wafer cutting mainly focuses on three major directions: maximizing silicon wafer size, thinning silicon wafer thickness, and finer cutting wire diameter. As silicon wafer sizes increase, the entry kerf between the wire mesh and the silicon block also increases. With thinner wafers, their inherent toughness makes them prone to mutual adhesion. Finer wire diameters result in smaller kerfs, further intensifying the adhesion between wafers after cutting. These combined factors make the traditional wire pressing method unable to completely re-press the wires into the wafer. In the process, even a single overlapping wire out of over 3000 wires can lead to failure. Therefore, the traditional wire pressing method is completely incapable of recovering from depth errors (>50%). Recovery requires welding to repair broken ends, which negatively impacts cutting quality, reduces yield, and causes color variations. Directly salvaging smaller wafers for larger ones or welding can result in poor color quality, affecting the A-grade yield and ultimately hindering overall silicon wafer cutting quality improvement.
[0005] The aforementioned problems arise because as silicon wafers become larger, the entry kerf between the wire mesh and the silicon block also increases. As silicon wafers become thinner, their direct toughness makes them prone to mutual adsorption. Furthermore, as the cutting wire diameter becomes finer, the kerf between the silicon wafers becomes smaller, further intensifying the adsorption force between the wafers after they are cut into wafers. The combination of these factors makes it impossible for the original pressing rod method to completely press the wires back into the silicon wafer one by one. During the process, if even one of the more than 3,000 wires overlaps, it will lead to failure. This not only prevents the continuous improvement of processing efficiency but also makes it very easy for new impurities to be introduced into the recycled silicon ingot material, which in turn worsens the ingot quality and prevents it from being improved. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a method for re-pressing and cutting silicon wafers to recover from wire breakage, which solves the problem that silicon ingots cannot be re-pressed and cut after high-level wire breakage during cutting in existing technologies.
[0007] According to an embodiment of the present invention, a method for recovering losses from wire breakage during complex-cutter silicon wafer cutting includes the following steps:
[0008] S1. Installation: Bond the processed silicon block to the bottom surface of the crystal drag;
[0009] S2. Determine if a wire breaks unexpectedly during silicon ingot cutting. Open the cutting chamber door and check the location of the broken wire. If the loss is small and the wire can be salvaged, cut the wire directly. If the loss is large or cannot be salvaged, use the negative pressure cutting method for silicon wafers.
[0010] S3. Cable management: If a broken cable is found, and it is determined that a re-pressure cutting rescue is needed, clean up the broken ends and residual wires.
[0011] S4. After marking, cleaning up broken and tangled wire, keep the cutting fluid running, lift the rod, and record the cutting depth and the amount of wire released and retrieved.
[0012] S5, Separation: After completing S4, lift the ingot to completely remove the uncut silicon block from the grid.
[0013] S6. Cool down. Adjust the output position of the spray pipe according to the cutting depth of the silicon block and turn on the cutting fluid circulation spray for 30-50 minutes.
[0014] S7. Wiring: After completing S6, close the spray pipe and re-lay the wire mesh. For areas with severe silicon block wire breakage damage, lay single wires at intervals of 3-6mm. Calculate the amount of wire needed based on the remaining depth and complete the wiring of the re-pressurized wire mesh.
[0015] S8. Insert the net. If the cutting entry point is on the right, restore the left nozzle of the spray pipe and shield the right nozzle. If the cutting entry point is on the left, restore the right nozzle and shield the left nozzle, and press the net in again.
[0016] S9. Adjust the screen: While running the wire, press down the silicon block until the silicon block is at zero position, then press down another 1-2mm to allow the silicon block to automatically enter the screen. During the process, there may be local or intermittent signs of abnormal screen entry. At this time, stop pressing down the silicon block and continue running the wire mesh at 0.06-0.1m / s. At the point where the screen did not enter the screen normally, the wire mesh will bounce and enter the blade due to inertia, so that the wire mesh will repeatedly enter the screen in a point-to-point pattern with small distances.
[0017] S10, repress, repeat S9 until all silicon blocks are successfully fed into the grid. Then press down the silicon blocks 5-10mm and confirm that all silicon blocks are successfully fed into the grid. If there is any abnormality, lift the ingot again and repeat S9. After confirming that all silicon blocks are successfully fed into the grid, press down the silicon blocks while routing according to the parameters of S8 until the wire breakage depth is less than 0.5-1mm.
[0018] S11. Cutting: After the re-pressing and wire insertion are completed, adjust the right nozzle of the spray pipe into position, perform a pre-cutting inspection, modify the short-cycle process by 2-3mm at the broken wire location, and finally start normal cutting to complete the re-pressing and wire insertion rescue.
[0019] Preferably, in step S9, when the spring wire mesh is inserted, the spring wire mesh is placed 10-20mm away from the edge of the silicon block on the right side of the silicon block entry point.
[0020] Preferably, in step S1, the originally flat bottom surface of the silicon block is processed into a slope, so that the silicon block changes from a line contact mesh to a point contact mesh, and at the same time, the lowest point of the silicon block is aligned with the direction of the cutting line.
[0021] Preferably, in step S4, the linear speed is set to 0.03-0.1 m / s, and the lifting speed is set to 30-60 mm / min.
[0022] Preferably, in step S5, the silicon block is completely lifted off the grid by manual lifting, and the flow rate of the cutting fluid is controlled to be 80-90% of the process cutting flow rate value.
[0023] Preferably, in step S8, when pressing the wire into the net, the wire speed is controlled at 0.08m / s, and the wire lifting speed is set at 10mm / min.
[0024] Preferably, in step S10, the short cycle is 50-70% of the normal cutting process stroke.
[0025] Preferably, in step S6, the nozzle position of the spray pipe is adjusted so that the spray point is 10-20mm away from the silicon block in the X-axis direction and 15-30mm away from the lower side of the broken line position in the Y-axis direction.
[0026] Preferably, in step S6, the cutting fluid flow rate is set to be 10-30% higher than the process cutting flow rate value.
[0027] Preferably, in step S7, an additional 10-15% of the amount of thread is added on top of the amount of thread used.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] 1. By combining low-speed forward lifting with segmented repressing and bouncing, the problem of not being able to repress cut at the high cutting position (50-80%) is effectively solved. It also effectively improves the efficiency of repressing to recover broken wires, reduces the color difference defect rate of negative pressure broken wire cutting, and improves the cutting quality of silicon wafers.
[0030] 2. Adhere the silicon block to the bottom surface of the crystallizer, and cut the bottom surface of the silicon block to transform the originally flat bottom surface into a slope, thereby changing the silicon block from a line contact wire mesh to a point contact wire mesh. At the same time, the lowest point is in the same direction as the cutting line. This not only covers the problem of slippage of the cutting wire mesh, but also improves the efficiency of wire breakage re-pressure recovery and cutting.
[0031] 3. Compared with existing salvage methods, when the cutting depth reaches 50-80%, this method achieves a salvage success rate of over 70%, improving efficiency by 40%, and can improve the quality of Grade A products by 3-5%. Attached Figure Description
[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0033] Figure 1 is a schematic diagram of the structure of an embodiment of the present invention.
[0034] In the above attached diagram: 1. Silicon block; 2. Main roller; 3. Spray pipe; 4. Crystal drag; 5. Plate. Detailed Implementation
[0035] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0036] As shown in Figure 1, this invention proposes a method for recovering losses from wire breakage during silicon wafer dicing, comprising the following steps:
[0037] S1. Installation: Bond the processed silicon block 1 to the bottom surface of the crystal drag 6, process the originally flat bottom surface of the silicon block 1 into a slope, so that the silicon block 1 changes from a line contact mesh to a point contact mesh, and at the same time make the low point of the silicon block 1 consistent with the direction of the cutting line.
[0038] S2. Determine if a wire breaks unexpectedly during the cutting of silicon block 1. Open the cutting chamber door and check the location of the broken wire. If the loss is small and the wire can be salvaged, then cut the wire directly. If the loss is large or cannot be salvaged, then use the negative pressure cutting method for silicon wafers.
[0039] S3. Cable management: If a broken cable is found, and it is determined that a re-pressure cutting rescue is needed, clean up the broken ends and residual wires.
[0040] S4. After marking, cleaning up broken and tangled wire, keep the cutting fluid running, set the wire speed to 0.03-0.1m / s, and set the rod lifting speed to 30-60mm / min. Record the cutting depth and the amount of wire released and retrieved.
[0041] S5. Separation: After completing S4, set the cutting fluid flow rate to 80-90% of the process cutting flow rate value, manually lift the ingot, and completely remove the uncut silicon block 1 from the wire mesh.
[0042] S6. Cool down. Adjust the output position of the spray pipe according to the cutting depth of the silicon block and turn on the cutting fluid circulation spray for 30-50 minutes.
[0043] S7. Wiring: After completing S6, close the spray pipe 3 and re-lay the wire mesh. For areas with severe silicon block wire breakage damage, single wires can be laid at intervals of 3-6mm. Calculate the amount of wire needed based on the remaining depth and complete the wiring of the re-pressed wire mesh.
[0044] S8. Enter the net. If the cutting entry point is on the right, restore the left nozzle of the spray pipe 3 and shield the right nozzle. If the cutting entry point is on the left, restore the right nozzle and shield the left nozzle, and press the net in again. Set the line speed to 0.08m / s and the lifting speed to 10mm / min.
[0045] S9. Adjust the mesh while pressing down on silicon block 1. After the silicon block 1 is pressed down to zero, press down another 1-2mm to allow the silicon block to automatically enter the mesh. During the process, there may be local or intermittent signs of abnormal mesh entry. At this time, stop pressing down on silicon block 1 and continue running the mesh at 0.08m / s. At the point where the mesh has not entered normally, press the mesh 10-20mm away from the edge of the silicon block on the right side of the silicon block entry point. This will allow the mesh to repeatedly enter the mesh in a point-to-point pattern with small distances, and the inertia of the bouncing mesh will allow it to enter the mesh.
[0046] S10, repress, repeat S9 until all silicon blocks are successfully fed into the grid, then press down the silicon block 1 by 15-10mm, and confirm again that all silicon blocks 1 are successfully fed into the grid. If there is any abnormality, lift the ingot again and repeat S9. After confirming that all silicon blocks are successfully fed into the grid, press down the silicon block 1 while routing according to the parameters of S8 until it is less than 0.5-1mm to reach the wire breakage cutting depth.
[0047] S11. Cutting: After the re-pressing and wire insertion are completed, adjust the right nozzle of the spray pipe 3 into place, perform a pre-cutting inspection, modify the short-cycle process by 2-3mm at the broken wire position, and finally start normal cutting to complete the re-pressing and wire insertion rescue.
[0048] A plate 5 is installed at the bottom of the crystal drag 4. The silicon block 1 is bonded to the bottom surface of the plate 5, ensuring that the top surface of the silicon block 1 is in contact with the top surface of the plate 5. The crystal drag 4 is then tilted or the bottom surface of the silicon block 1 is cut to make the bottom surface of the silicon block 1 beveled. The two main rollers 2 that wind the contact wire are controlled to move synchronously to lift the rollers.
[0049] Furthermore, in S10, the short cycle is 50-70% of the normal cutting process stroke.
[0050] In normal processes, the cutting of the incoming and returning wire lengths is completed in one cycle. The wire breakage recovery process is changed from a long cycle to a short cycle, which can better restore the uniformity of wire mesh tension and improve the cutting texture at this point, reducing color difference defects.
[0051] Furthermore, in step S6, the nozzle position of the spray pipe 3 is adjusted so that the spray point is 10-20mm away from the silicon block in the X-axis direction and 15-30mm away from the lower side of the broken line position in the Y-axis direction.
[0052] Adjusting the spray position can salvage the re-pressed wire mesh, allowing the cutting fluid to spray more effectively, making the cutting kerf and the wire mesh bounce action more integrated, and thus improving the success rate of re-pressing.
[0053] Furthermore, in step S6, to improve cooling efficiency, the cutting fluid flow rate is set to be 10-30% higher than the process cutting flow rate value.
[0054] Furthermore, to avoid insufficient cable quantity due to broken wires, in step S7, an additional 10-15% of the cable quantity is added on top of the existing cable quantity.
Claims
1. A method for recovering losses from wire breakage during complex-state silicon wafer cutting, characterized in that, Includes the following steps: S1. Installation: Bond the processed silicon block (1) to the bottom surface of the crystal drag (4); S2. Determine if a wire breaks unexpectedly during the cutting of silicon block (1). Open the cutting chamber door and check the location of the broken wire. If the loss is small and there is a wire to salvage, then cut the wire directly. If the loss is large or cannot be salvaged, then use the double-pressure cutting method for silicon wafers. S3. Cable management: If a broken cable is found, and it is determined that a re-pressure cutting rescue is needed, clean up the broken ends and residual wires. S4. After marking, cleaning up broken and tangled wire, keep the cutting fluid running, lift the rod, and record the cutting depth and the amount of wire released and retrieved. S5, Separation: After completing S4, lift the rod to completely remove the uncut silicon block (1) from the grid. S6. Cool down. Adjust the output position of the spray pipe according to the cutting depth of the silicon block and turn on the cutting fluid circulation spray for 30-50 minutes. S7. Wiring: After completing S6, close the spray pipe (3), re-lay the wire mesh, and lay single wires at intervals of 3-6mm in areas with severe silicon block wire breakage damage. Calculate the amount of wire needed based on the remaining depth and complete the wiring of the re-pressed wire mesh. S8, enter the net. If the cutting entry point is on the right, restore the left nozzle of the spray pipe (3) and shield the right nozzle. If the cutting entry point is on the left, restore the right nozzle and shield the left nozzle, and press the net again. S9. Adjust the mesh, press down the silicon block (1) while running the wire, so that the silicon block (1) is pressed down to the zero point and then press down 1-2mm to let the silicon block automatically enter the mesh. During the process, there will be local or intermittent signs of not entering the mesh normally. At this time, stop pressing down the silicon block (1) and run the wire mesh at 0.06-0.1m / s. At the point where the mesh does not enter normally, the wire mesh bounces and enters the knife by inertia, so that the wire mesh enters the mesh repeatedly in a point mode with small distances. S10, repress, repeat S9 until all are entered into the grid, then press down the silicon block (1) by 5-10mm, confirm that all silicon blocks (1) are entered into the grid normally. If there is any abnormality, lift the rod again and repeat S9. After confirming that all are entered into the grid, press down the silicon block (1) while routing according to the parameters of S8 until it is less than 0.5-1mm to reach the wire breakage cutting depth. S11, Cutting: After the re-pressing and netting are completed, adjust the right nozzle of the spray pipe (3) into place, do a pre-cutting inspection, modify the short cycle process of 2-3mm at the broken wire position, and finally start normal cutting to complete the re-pressing and netting rescue. In step S9, when the wire mesh is spring-loaded, the wire mesh is spring-loaded 10-20mm away from the edge of the silicon block (1) on the right side of the silicon block (1) when the knife enters; In step S4, the linear speed is set to 0.03-0.1 m / s, and the lifting speed is set to 30-60 mm / min; In step S8, when pressing the wire into the net, the wire speed is controlled at 0.08m / s, and the wire lifting speed is set at 10mm / min; In step S11, the short cycle is 50-70% of the normal cutting process stroke.
2. The method for recovering losses from wire breakage during silicon wafer cutting as described in claim 1, characterized in that: In step S1, the originally flat bottom surface of the silicon block (1) is processed into a slope, so that the silicon block (1) changes from a line contact wire mesh to a point contact wire mesh, and at the same time, the low point of the silicon block (1) is aligned with the direction of the cutting line.
3. The method for recovering losses from wire breakage during silicon wafer cutting as described in claim 1, characterized in that: In step S5, the silicon block (1) is completely lifted off the grid by manual lifting, and the flow rate of the cutting fluid is controlled to be 80-90% of the process cutting flow rate value.
4. The method for recovering losses from wire breakage during silicon wafer dicing as described in claim 1, characterized in that: In step S6, the nozzle position of the spray pipe (3) is adjusted so that the spray point is 10-20mm away from the silicon block in the X-axis direction and 15-30mm away from the lower side of the broken line position in the Y-axis direction.
5. The method for recovering losses from wire breakage during silicon wafer cutting as described in claim 1, characterized in that: In step S6, the cutting fluid flow rate is set to be 10-30% higher than the process cutting flow rate value.
6. The method for recovering losses from wire breakage during silicon wafer dicing as described in claim 1, characterized in that: In step S7, an additional 10-15% of the amount of wire is added on top of the amount of wire used.