Silicon rod slicing method and silicon rod slicing equipment

Abstract

The invention discloses a silicon rod slicing method and silicon rod slicing equipment, and relates to the technical field of silicon wafer processing. The silicon rod slicing method comprises the following steps that a silicon rod to be sliced is bonded with a bearing silicon plate, and the bearing silicon plate is fixed to a crystal support; the crystal support bonded with the silicon rod is installed above a cutting line; moving the silicon rod towards the direction of the cutting line and contacting with the cutting line, and cutting the silicon rod through the cutting line to form a silicon wafer; wherein along the cutting progress, the process of cutting the silicon rod by the cutting line sequentially comprises a first cutting stage, a second cutting stage and a third cutting stage; wherein the feeding distance of the third cutting stage is S13, the total feeding distance of the slicing process is S1, and S13 is smaller than or equal to 0.07 * S1; and the ratio of the average feeding speed V3 of the silicon rod in the third cutting stage to the average feeding speed V2 of the silicon rod in the second cutting stage is 0.3-0.5. By adopting the silicon rod slicing method provided by the invention, the yield of silicon wafers can be improved, and meanwhile, the slicing production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer processing technology, and in particular to a silicon rod slicing method and silicon rod slicing equipment. Background Technology

[0002] In recent years, with the rapid development of the photovoltaic power generation industry, the demand for photovoltaic modules has increased dramatically. Monocrystalline silicon wafers, as the foundation of photovoltaic modules, are one of the most important components in photovoltaic power generation. Currently, the industry generally uses diamond wire slicing machines to cut silicon rods into wafers with a thickness of about 100-150 micrometers. In the existing slicing process, before slicing begins, the crystal holder, resin plate, and silicon rod need to be glued together, and then clamped as a whole in the cutting chamber of the slicing machine for cutting. During slicing, the worktable moves the entire structure of the crystal holder, resin plate, and silicon rod towards the diamond wire, using the high-speed diamond wire to cut the silicon rod into several silicon wafers.

[0003] Because diamond wire is relatively thin and soft, during the silicon wafer dicing process, when the silicon ingot is pressed against the diamond wire, the wire bends downwards, forming an arc shape, commonly referred to in the industry as a wire bow. The presence of this wire bow results in a dicing kerf that is higher at the edges and lower in the middle. Therefore, to completely cut through the silicon ingot, it is necessary to cut into the resin substrate above the ingot to a certain depth at the end of the dicing process. However, due to the significant difference in hardness between the resin substrate and the silicon ingot, the cutting ability of the diamond wire differs greatly between the two. Silicon is harder and relatively more difficult to cut, while the resin substrate is very soft and easy to cut. This leads to a situation where, when the diamond wire cuts through the silicon ingot and into the resin substrate, the huge difference in cutting ability, coupled with the wire bow formed during the cutting process, causes the diamond wire to spring back like a stretched rubber band, resulting in severe tearing, chipping, or bright edges on the silicon wafer, leading to a significant decrease in wafer yield.

[0004] To reduce defects such as edge chipping during the diamond wire exit (the process of the diamond wire cutting from the silicon rod into the resin substrate, known in the industry as "exit") and improve silicon wafer yield, existing slicing methods typically require adjusting the process just before the diamond wire exits the silicon rod. This involves significantly reducing the feed rate of the silicon rod to minimize wire bowing, allowing for a smoother cut from the rod into the resin substrate—a step known in the industry as "retracting the wire." However, the average feed rate during the retracting process in existing slicing processes is very low, typically only 8% to 20% of the average feed rate of the cutting wire cutting the middle of the silicon rod. This results in a long retracting process, significantly extending the total cutting time and leading to low slicing production efficiency. Therefore, developing a silicon rod slicing method that can simultaneously improve silicon wafer yield and slicing production efficiency is of great significance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a silicon rod slicing method that can improve silicon wafer yield and simultaneously increase slicing production efficiency.

[0006] The technical problem to be solved by the present invention is to provide a silicon rod slicing device. Using the silicon rod slicing device of the present invention to slice silicon wafers can improve the yield of silicon wafers, increase the slicing efficiency, and quickly separate the supporting silicon plate and the crystal holder after slicing.

[0007] To address the aforementioned technical problems, this invention provides a method for slicing silicon rods, comprising the following steps: (1) Bond the silicon rod to be sliced ​​to the supporting silicon plate and fix the supporting silicon plate on the crystal holder; (2) Install the crystal holder with the silicon rod and the supporting silicon plate bonded together above the cutting line; (3) Move the silicon rod toward the cutting line and make it contact the cutting line, and cut the silicon rod through the cutting line to form a silicon wafer; wherein, along the cutting process, the process of the cutting line cutting the silicon rod includes the first cutting stage, the second cutting stage and the third cutting stage in sequence. The first cutting stage is the stage in which the silicon rod moves from the position of contacting the cutting line to the first feed position during the cutting process; the second cutting stage is the stage in which the silicon rod moves from the first feed position to the second feed position during the cutting process; and the third cutting stage is the stage in which the silicon rod moves from the second feed position to the position in which it is completely cut through by the cutting line during the cutting process. The distance S between the second feed position and the position where the silicon rod is completely cut through by the dicing line 13 The distance between the position where the silicon rod contacts the dicing line and the position where the silicon rod is completely cut through by the dicing line is S1, where S... 13 ≤0.07*S1; The average feed rate of the silicon rod in the second cutting stage is V2, and the average feed rate of the silicon rod in the third cutting stage is V3, wherein the ratio of V3 to V2 is 0.3 to 0.5.

[0008] As an improvement to the above technical solution, along the cutting process, the feed speed of the silicon rod gradually decreases in the third cutting stage; the ratio of the maximum feed speed of the silicon rod in the third cutting stage to the average feed speed of the silicon rod in the second cutting stage is 0.75~0.92, and the ratio of the minimum feed speed of the silicon rod in the third cutting stage to the average feed speed of the silicon rod in the second cutting stage is 0.08~0.2.

[0009] As an improvement to the above technical solution, the distance between the position of the silicon rod contacting the cutting line and the first feed position is S. 11 , among which, S 11 The ratio of S1 to S1 is 0.03~0.08; The distance between the first feed position and the second feed position is S. 12 , among which, S 12 The ratio of S1 to S1 is 0.85~0.95; And S 11 +S 12 +S 13 =S1.

[0010] As an improvement to the above technical solution, the average feed rate of the silicon rod in the first cutting stage is V1, wherein the ratio of V1 to V2 is 0.5 to 0.65, and the feed rate of the silicon rod gradually increases in the first cutting stage along the cutting process.

[0011] As an improvement to the above technical solution, the average feed rate V2 of the silicon rod in the second cutting stage is 2200μm / min~2500μm / min.

[0012] As an improvement to the above technical solution, the average feed rate V3 of the silicon rod in the third cutting stage is 800μm / min~1100μm / min.

[0013] As an improvement to the above technical solution, the feed speed of the silicon rod in the third cutting stage is in the range of 200μm / min to 2200μm / min, and the feed speed of the silicon rod gradually decreases in the third cutting stage along the cutting process.

[0014] As an improvement to the above technical solution, the average feed rate of the silicon rod in the first cutting stage is 1300μm / min~1500μm / min, and the feed rate of the silicon rod gradually increases along the cutting process.

[0015] As an improvement to the above technical solution, the linear velocity of the cutting line in the third cutting stage is less than or equal to the linear velocity of the cutting line in the second cutting stage, and the linear velocity of the cutting line in the third cutting stage gradually decreases along the cutting process.

[0016] As an improvement to the above technical solution, the linear speed of the cutting line in the second cutting stage is 1900m / mm~2500m / mm; In the third cutting stage, the linear velocity of the cutting line is 1200m / mm to 2100m / mm, and the linear velocity of the cutting line gradually decreases along the cutting process.

[0017] As an improvement to the above technical solution, the linear speed of the cutting line in the first cutting stage is 800m / min to 2400m / min, and the linear speed of the cutting line gradually increases along the cutting process in the first cutting stage.

[0018] As an improvement to the above technical solution, in step (1), the silicon rod to be sliced ​​is bonded to the supporting silicon plate with glue, and the supporting silicon plate is bonded to the bottom of the crystal holder with glue, so that the silicon rod, the supporting silicon plate and the crystal holder are bonded together to form an integral structure.

[0019] As an improvement to the above technical solution, the silicon rod slicing method further includes the following steps: (4) Place the crystal holder, the supporting silicon plate and the silicon wafer formed after cutting in the first debinding liquid at a temperature of 50~80℃ so that the silicon wafer is separated from the supporting silicon plate and the silicon wafer is collected.

[0020] (5) Place the silicon wafer holder and the supporting silicon plate after removing the silicon wafer in a second degumming liquid at a temperature of 85~100℃ to separate the supporting silicon plate and the silicon wafer holder.

[0021] Accordingly, the present invention also provides a silicon rod slicing apparatus using the silicon rod slicing method described above, including a crystal holder and a supporting silicon plate bonded to the crystal holder, wherein one end of the supporting silicon plate away from the crystal holder is used to bond to the silicon rod to be sliced; The crystal holder includes an adhesive plate and a clamping mechanism, wherein the adhesive plate is mounted on the bottom of the clamping mechanism; The end of the adhesive plate away from the clamping mechanism is the adhesive end. At least one flow groove is provided on the adhesive end. The flow groove extends along the first direction and penetrates the entire adhesive end. The flow groove divides the adhesive end into several independent adhesive blocks. The end face of the adhesive segment away from the clamping mechanism forms an adhesive surface for connection with the supporting silicon plate.

[0022] As an improvement to the above technical solution, along the second direction, the width of several adhesive surfaces is ≤50mm.

[0023] As an improvement to the above technical solution, along the second direction, the widths of several adhesive surfaces are 30mm to 45mm respectively.

[0024] As an improvement to the above technical solution, in the second direction, the flow groove is provided in the middle of the adhesive end, and the flow groove extends along the first direction and penetrates the entire adhesive end, so that adhesive blocks of equal width are formed on both sides of the adhesive end in the second direction.

[0025] As an improvement to the above technical solution, the depth of the flow channel is 2mm~10mm.

[0026] Implementing this invention has the following beneficial effects: 1. This embodiment uses a carrier silicon plate instead of the resin plate used in traditional silicon rod slicing methods. Since the carrier silicon plate is made of the same material as the silicon rod, the cutting performance of the cutting line remains essentially unchanged when cutting the silicon rod and the carrier silicon plate. This avoids defects such as chipping, bright edges, and scratches caused by excessive hardness differences between the resin plate and the silicon rod, ensuring silicon wafer quality and improving slicing yield. Furthermore, because the hardness of the carrier silicon plate and the silicon rod are consistent in this embodiment, their physical properties are highly matched. This allows for a faster table feed speed at the end of the slicing process (corresponding to the third cutting stage in this embodiment), without significantly reducing the average feed speed at this stage. This greatly shortens the time spent on the retraction process, reducing the total cutting time and thus improving slicing production efficiency.

[0027] 2. In view of the material characteristics of the supporting silicon substrate, this embodiment improves the structure of the crystal holder by slotting the bonding end of the crystal holder, reducing the bonding area between the supporting silicon substrate and the crystal holder. During the debonding process, the adhesive layer between the adhesive surfaces of the supporting silicon substrate and the crystal holder can be softened by heat more quickly, thereby enabling the supporting silicon substrate to be debonded and separated quickly. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a silicon rod slicing method according to an embodiment of the present invention, in which the crystal holder, the supporting silicon plate, and the silicon rod are bonded together as a whole; Figure 2 yes Figure 1 Cross-sectional view; Figure 3 yes Figure 1 A schematic diagram of the bottom structure of the crystal holder shown; The components include: crystal tray 1, supporting silicon plate 2, silicon rod 3, bonding plate 11, clamping mechanism 12, flow channel 111, bonding block 112, and adhesive surface 1121. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0030] Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Raw materials whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0031] This embodiment discloses a method for slicing silicon rods, including the following steps: (1) Bond the silicon rod to be sliced ​​to the supporting silicon plate and fix the supporting silicon plate on the crystal holder; (2) The crystal holder with the silicon rod and the supporting silicon plate bonded together is installed above the cutting line; specifically, the whole formed by bonding the silicon rod, the supporting silicon plate and the crystal holder together is clamped on the worktable in the cutting chamber of the slicing machine and located directly above the cutting line; preferably, the cutting line is diamond wire, which can be the diamond wire commonly used in the existing silicon rod slicing method. The cutting principle of diamond wire is to use the diamond abrasive fixed on the surface to perform micro-cutting and grinding on hard and brittle materials such as silicon rods through high-speed motion, and finally cut the silicon rod into thin slices; (3) Move the silicon rod toward the cutting line and make it contact the cutting line, and cut the silicon rod through the cutting line to form a silicon wafer; specifically, the worktable drives the silicon rod, the supporting silicon plate and the crystal holder to move downward, thereby moving the silicon rod toward the cutting line and making it contact the cutting line; wherein, along the cutting process, the process of the cutting line cutting the silicon rod includes the first cutting stage, the second cutting stage and the third cutting stage in sequence; it should be noted that along the cutting process means along the cutting time or along the increase of the cutting depth; The first cutting stage is the stage in which the silicon rod moves from the position of contacting the cutting line to the first feed position during the cutting process; the second cutting stage is the stage in which the silicon rod moves from the first feed position to the second feed position during the cutting process; and the third cutting stage is the stage in which the silicon rod moves from the second feed position to the position in which it is completely cut through by the cutting line during the cutting process. The distance S between the second feed position and the position where the silicon rod is completely cut through by the dicing line 13 This distance is the feed distance of the silicon rod in the third dicing stage. The distance between the silicon rod's contact point with the dicing line and the point where the silicon rod is completely cut through by the dicing line is S1. This distance is the total feed distance of the silicon rod throughout the entire dicing process. 13 ≤0.07*S1; In some implementations, 0.02S1≤S 13 ≤0.06S1; In the second cutting stage, the average feed rate of the silicon rod is V2, and in the third cutting stage, the average feed rate of the silicon rod is V3, wherein the ratio of V3 to V2 is 0.3 to 0.5. It should be noted that the feed rate refers to the speed at which the silicon rod moves relative to the cutting line; in this embodiment, it refers to the speed at which the silicon rod moves downwards.

[0032] It is worth noting that the Mohs hardness of silicon rods is generally 6.5-7, while the Mohs hardness of the resin plates used in traditional silicon rod slicing methods is typically 2-4. Due to the significant difference in hardness, the cutting wire is prone to defects such as edge chipping during the cutting process. Existing technologies, in order to reduce edge chipping during the cutting process, require a significant reduction in the feed speed of the silicon rod during the retraction phase, resulting in a longer total cutting time and lower production efficiency. To solve the above problems, this embodiment uses a carrier silicon plate instead of the resin plate used in traditional silicon rod slicing methods. Since the carrier silicon plate is made of silicon, meaning the carrier silicon plate and the silicon rod are made of the same material, their physical properties, such as hardness and strength, are identical. The cutting performance of the cutting wire remains essentially unchanged when cutting the silicon rod and the carrier silicon plate, avoiding defects such as edge chipping, bright edges, and scratches caused by the large hardness difference between the resin plate and the silicon rod. This ensures the quality of the silicon wafers and improves the slicing yield. Furthermore, since the hardness of the silicon substrate and the silicon rod are basically similar in this embodiment, and their physical properties are highly matched, the silicon rod can withstand a faster table feed speed at the end of the slicing process (corresponding to the third cutting stage in this embodiment). The silicon rod can be cut out at a faster feed speed, which can significantly reduce the time spent in the retraction process (corresponding to the third cutting stage in this embodiment), shorten the total cutting time, and thus improve the slicing production efficiency.

[0033] Specifically, in this embodiment, S is limited. 13 ≤0.07*S1, and the ratio of the average feed speed V3 of the silicon rod in the third cutting stage to the average feed speed V2 of the silicon rod in the second cutting stage is 0.3~0.5. On the one hand, the feed distance in the third cutting stage is very short; on the other hand, compared with the average feed speed of the retraction process in the existing slicing method, which is usually only 8%~20% of V2, this embodiment significantly improves the average feed speed of the third cutting stage. The average feed speed V3 of the third cutting stage is 30%~50% of the average feed speed V2 of the silicon rod in the second cutting stage, which can significantly shorten the retraction time, thereby shortening the total cutting time and improving the slicing production efficiency. If S 13 If the ratio of S1 to V3 and / or V2 is less than 0.3, the efficiency improvement effect will be poor. If the ratio of V3 to V2 is greater than 0.5, it will lead to a decrease in the silicon wafer yield.

[0034] Further explanation: In this embodiment, the supporting silicon plate and silicon rod are made of the same material. The cutting performance remains unchanged when the silicon rod and supporting silicon plate are cut with diamond wire, avoiding problems such as edge chipping, bright edges, and reduced efficiency caused by differences in the material properties of the resin plate and silicon rod, thus improving the slicing yield. Specifically, the supporting silicon plate can be a monocrystalline silicon plate or a polycrystalline silicon plate. In one embodiment, the supporting silicon plate can be made from the edge material left after squaring a monocrystalline silicon rod and then machined; alternatively, it can be made from impure silicon materials such as waste material from the bottom of the crystal pulling pot, broken silicon wafers, and purified silicon sludge, which are simply cleaned, cast into ingots in a polycrystalline ingot furnace, and then machined. Using the edge material generated during silicon rod preparation and the waste silicon material from the silicon wafer production process to prepare the supporting silicon plate eliminates the need to purchase resin plates, effectively reducing production costs. Furthermore, the supporting silicon plate used for slicing can be recycled and recast, reducing the generation of solid waste.

[0035] In some embodiments, the feed rate of the silicon ingot gradually decreases during the third dicing stage. The ratio of the maximum feed rate of the silicon ingot in the third dicing stage to the average feed rate of the silicon ingot in the second dicing stage is 0.75~0.92, and the ratio of the minimum feed rate of the silicon ingot in the third dicing stage to the average feed rate of the silicon ingot in the second dicing stage is 0.08~0.2. Adopting a gradually decreasing feed rate in the third dicing stage helps to further reduce defects such as edge chipping, bright edges, and scratches, further improving product yield. Controlling the maximum and minimum feed rates of the silicon ingot within a defined range in the third dicing stage ensures that the average feed rate in the third dicing stage is within a relatively high range, while the minimum feed rate is relatively low. This shortens the third dicing stage time, improves slicing efficiency, and allows the dicing line to cut out of the silicon ingot more smoothly into the supporting silicon substrate, reducing defects such as edge chipping, bright edges, and scratches, and improving product yield.

[0036] In some embodiments, the distance between the position where the silicon rod contacts the dicing line and the first feed position is S. 11 This distance is the feed distance of the silicon rod in the first cutting stage, where S 11 The ratio of S1 to S1 is 0.03~0.08; the distance between the first feed position and the second feed position is S. 12 This distance is the feed distance of the silicon rod in the second cutting stage, where S 12 The ratio of S1 to S2 is 0.85~0.95; and S2... 11 +S 12 +S 13 =S1.

[0037] By further optimizing the ratio of the feed distance in the first and second cutting stages to the total feed distance of the silicon wafer, better cutting results can be achieved, the total cutting time can be further shortened, and production efficiency can be improved. Specifically, this embodiment uses a support silicon plate of the same material as the silicon rod instead of the resin plate in the traditional silicon rod slicing method. During the slicing process, S can be controlled. 12 The ratio of S1 to S1 is 0.85~0.95, which means that the feed distance in the second dicing stage accounts for a very large proportion. When the dicing wire cuts the silicon wafer in the second dicing stage, it can use a higher feed speed, which is beneficial to further shorten the total dicing time.

[0038] It should be noted that due to the presence of the dicing wire bow, in order to completely cut through the silicon ingot, it is necessary to cut into the supporting silicon plate on the silicon ingot to a certain depth at the end of the dicing process. Therefore, the total feed distance S1 from the contact of the silicon ingot with the dicing wire to the complete cutting of the silicon ingot is often greater than the thickness of the silicon ingot to be cut. In some embodiments, the total feed distance S1 from the contact of the silicon ingot with the dicing wire to the complete cutting of the silicon ingot is equal to the thickness of the silicon ingot to be cut plus 1mm to 10mm. The thickness of the silicon ingot to be cut is usually 100mm to 400mm, so S1 can be 101mm to 410mm. After obtaining S1, it can be calculated according to the above S... 11 S 12 and S 13 Determine S by comparing it with S1. 11 S 12 and S 13 The range.

[0039] For example, in one embodiment, the thickness of the silicon rod to be cut is 196 mm, then the total feed distance S1 of the silicon rod during slicing can be 196.5 mm to 206 mm, but is not limited to this. Then, based on S1, S can be determined. 11 S 12 and S 13 The range. For example, in one embodiment, the total feed distance S1 of the silicon rod during slicing is approximately 200 mm, then S 11 The range can be 6mm~16mm, S 12 The range can be 170mm~190mm, S 13 The range can be 4mm to 12mm.

[0040] In some embodiments, the average feed rate of the silicon rod in the first cutting stage is V1, wherein the ratio of V1 to V2 is 0.5 to 0.65, and the feed rate of the silicon rod gradually increases along the cutting process. The first cutting stage is the initial cutting stage. By controlling the ratio of V1 to V2 to 0.5 to 0.65, a lower feed rate can be used to cut into the silicon rod, which can reduce initial damage, further improve product yield, avoid instantaneous impact from high-speed feeding on the hard and brittle silicon rod, and prevent edge chipping or internal microcracks from forming. Preferably, the feed rate of the silicon rod gradually increases along the cutting process in the first cutting stage, which can achieve better cutting results and further reduce the overall defects of the silicon wafer.

[0041] In some embodiments, the average feed rate V2 of the silicon rod in the second cutting stage is 2200μm / min to 2500μm / min. Within this range, it is beneficial to shorten the total slicing time, improve production efficiency, ensure slice quality, and improve slicing yield.

[0042] Specifically, the feed rate of the silicon rod in the second cutting stage can be kept constant or can have a certain trend of variation. It is only necessary to control the average feed rate V2 of the silicon rod in the second cutting stage within the range of 2200μm / min to 2500μm / min.

[0043] In some implementation methods, during the cutting process, in the second cutting stage, the feed rate of the silicon rod can be slowly increased from 2000 μm / min to 2500 μm / min, and then the feed rate of 2500 μm / min is maintained for a period of time before the speed is slowly reduced to 2000 μm / min to enter the third cutting stage.

[0044] In some embodiments, the average feed rate V3 of the silicon rod in the third dicing stage is 800 μm / min to 1100 μm / min. Within this range, the average feed rate when the cutting line emerges from the end of the silicon rod and enters the supporting silicon substrate is relatively fast, which helps to shorten the cut-out time, improve dicing efficiency, and increase the yield of silicon wafers. If the average feed rate V3 of the silicon rod in the third dicing stage is too low, the improvement in production efficiency is not significant; if V3 is too high, the yield of silicon wafers will decrease.

[0045] In some embodiments, the feed rate of the silicon rod in the third cutting stage ranges from 200 μm / min to 2200 μm / min, and the feed rate of the silicon rod gradually decreases along the cutting process.

[0046] In some embodiments, the average feed rate of the silicon rod in the first cutting stage is 1300 μm / min to 1500 μm / min, and the feed rate of the silicon rod gradually increases along the cutting process, which helps to reduce initial damage and further improve product yield.

[0047] In some embodiments, the linear velocity of the cutting line in the third cutting stage is less than or equal to the linear velocity of the cutting line in the second cutting stage, and the linear velocity of the cutting line gradually decreases along the cutting process. It should be noted that the linear velocity refers to the moving speed of the cutting line itself.

[0048] In this embodiment, the second cutting stage involves cutting the middle of the silicon rod. At this stage, the cutting resistance is relatively stable, and the cutting wire uses a higher linear speed to cut, which can improve the slicing efficiency. The third cutting stage uses a lower linear speed, and the linear speed of the cutting wire gradually decreases along the cutting process. This helps to further reduce the bowing of the cutting wire, allowing the cutting wire to cut out of the silicon rod more smoothly and enter the supporting silicon substrate, further improving the slicing effect and increasing the product yield.

[0049] In some embodiments, the linear velocity of the cutting line in the second cutting stage is 1900 m / mm to 2500 m / mm. Specifically, the linear velocity of the cutting line in the second cutting stage can remain constant or exhibit a certain trend of variation. In one embodiment, from the first feed position to a distance of 3 to 10 mm from the second feed position, the linear velocity of the cutting line in the second cutting stage can be a relatively high linear velocity of 2200 m / mm to 2500 m / mm, and the linear velocity can be kept constant; then, from a distance of 3 to 10 mm from the second feed position back to the second feed position, the linear velocity of the cutting line can be gradually reduced, allowing for a smoother transition between the second and third cutting stages, thereby further improving the slicing effect and reducing cutting defects.

[0050] In the third cutting stage, the linear velocity of the cutting line is 1200 m / mm to 2100 m / mm, and it gradually decreases along the cutting process. This helps to further improve the slicing effect and increase the product yield.

[0051] In one embodiment, the linear velocity of the cutting line in the first cutting stage is less than or equal to the linear velocity of the cutting line in the second cutting stage. Furthermore, the linear velocity of the cutting line in the first cutting stage gradually increases along the cutting process. The first cutting stage is the initial stage of the cutting line entering the silicon rod. At this time, a smaller linear velocity is used to cut into the silicon rod at a low speed, which helps to reduce the cutting damage to the starting section of the silicon wafer and further improve the yield.

[0052] In some embodiments, the linear velocity of the cutting line in the first cutting stage is 800m / min to 2400m / min, and the linear velocity of the cutting line gradually increases along the cutting process in the first cutting stage, which is beneficial to further improve the slicing effect and increase the product yield.

[0053] In one embodiment, in step (1), the silicon rod to be sliced ​​is bonded to the supporting silicon plate with adhesive, and the supporting silicon plate is bonded to the bottom of the crystal holder with adhesive, so that the silicon rod, the supporting silicon plate and the crystal holder are bonded together to form an integral structure.

[0054] In one embodiment, AB glue is used. Before slicing, the crystal tray, the supporting silicon plate, and the silicon rod are bonded together with AB glue to form a whole. Then, the whole is pushed into the cutting chamber of the slicing machine for fixation before slicing production can be carried out.

[0055] In one embodiment, the silicon rod slicing method further includes the following steps: (4) Place the crystal holder, the supporting silicon plate and the silicon wafer formed after cutting in the first debinding liquid at a temperature of 50~80℃ so that the silicon wafer is separated from the supporting silicon plate and the silicon wafer is collected.

[0056] (5) Place the removed silicon wafer and the supporting silicon plate in a second debinding solution at a temperature of 85~100℃ to separate the supporting silicon plate and the wafer. It should be noted that the supporting silicon plate will have wear and cutting marks after slicing, resulting in the bonding surface of the supporting silicon plate not being a complete plane. If it continues to be used, its bonding effect will be significantly reduced. Therefore, after slicing, the used supporting silicon plate needs to be removed to replace it with a new supporting silicon plate.

[0057] Specifically, after cutting, the adhesive between the silicon wafer and the supporting silicon plate is softened in a silicon wafer debonding machine using a first debonding liquid at a temperature of 50~80℃, thus separating the silicon wafer from the resin plate. Since the first debonding liquid in step (4) can penetrate the gap between the silicon wafers and contact the adhesive layer between the silicon wafer and the supporting silicon plate, and the silicon wafer is very thin, the adhesive layer between the silicon wafer and the supporting silicon plate can fully contact the first debonding liquid, thereby softening it quickly, so that the silicon wafer can be separated at a lower temperature. After the silicon wafer is separated, the crystal holder and the supporting silicon plate are still bonded together. The crystal holder and the supporting silicon plate need to be placed in a second debonding liquid at a higher temperature (85~100℃). Under the combined action of the high temperature and the second debonding liquid, the adhesive between the crystal holder and the supporting silicon plate will gradually soften, thereby separating the supporting silicon plate and the crystal holder.

[0058] In one embodiment, both the first degumming liquid and the second degumming liquid are hot water or both are hot water with a certain proportion of lactic acid added.

[0059] See Figures 1 to 3As shown, the present invention also provides an embodiment of a silicon rod slicing apparatus, using the above-described silicon rod slicing method, including a crystal holder 1 and a supporting silicon plate 2 bonded to the crystal holder 1, wherein one end of the supporting silicon plate 2 away from the crystal holder is used to bond to the silicon rod 3 to be sliced. The crystal holder 1 includes an adhesive plate 11 and a clamping mechanism 12. The adhesive plate 11 is mounted on the bottom of the clamping mechanism 12. Preferably, the adhesive plate 11 and the clamping mechanism 12 are integrally formed. It should be noted that the clamping mechanism 12 of the crystal holder 1 in this embodiment is a common structure in the art, so it will not be described in detail in this embodiment. The end of the adhesive plate 11 away from the clamping mechanism 12 is the adhesive end. At least one flow groove 111 is provided on the adhesive end. The flow groove 111 extends along the first direction and penetrates the entire adhesive end. The flow groove 111 divides the adhesive end into several independent adhesive blocks 112. The end face of the adhesive block 112 away from the clamping mechanism 12 forms an adhesive surface 1121 for connection with the carrier silicon plate 2.

[0060] It should be noted that since silicon rods are brittle materials, they cannot be directly clamped onto the slicing machine's worktable for slicing. Therefore, a wafer holder is needed to fix the silicon rod. The wafer holder is firmly attached to the end face of the silicon rod with adhesive, thus stably fixing the silicon rod to the wafer holder. Due to the presence of the cutting wire bow, in order to completely cut through the silicon rod, a certain distance needs to be cut out of the silicon rod at the end of the slicing process. Since the manufacturing cost of wafer holders is relatively high, a support plate is often required between the wafer holder and the silicon rod to prevent the cutting wire from cutting into the wafer holder and causing damage or scrap. One end of the support plate is bonded to the wafer holder, and the other end is bonded to the silicon rod, so that during slicing, the cutting wire cuts into the support plate instead of the wafer holder, thereby protecting the wafer holder. Currently used support plates are generally resin plates. Using resin plates for slicing makes it difficult to simultaneously achieve high slicing yield and slicing efficiency. The silicon rod slicing equipment of this invention uses a silicon plate instead of the traditional resin plate, which can improve silicon wafer yield and simultaneously increase slicing production efficiency.

[0061] It is worth noting that the crystal tray 1 is generally made of iron. Without slotting, the bond strength between the crystal tray 1 and the supporting silicon plate 2 is very high, making it difficult to separate the supporting silicon plate 2 later. This invention reduces the contact area between the supporting silicon plate 2 and the iron plate surface of the crystal tray 1 by slotting the crystal tray 1. This increases the contact area between the adhesive layer between the supporting silicon plate 2 and the crystal tray 1 and the hot water during debonding, allowing the adhesive layer to be heated more quickly and evenly. The cut silicon plate and crystal tray 1 can then be successfully debonded, solving the problem of being unable to debond due to the high bond strength between the silicon plate and the iron plate. This allows the technology of using silicon plates instead of resin plates in the slicing process to be put into production practice. In addition, because the adhesive area is reduced after slotting the crystal tray 1, the amount of glue used can be saved, reducing costs.

[0062] Specifically, in traditional wafer trays, the adhesive surface used to bond the resin substrate is a single flat surface. The resin substrate is bonded to the wafer tray using adhesive. Because resin has a high coefficient of thermal expansion and is easily deformed by heat, after dicing and separating the silicon wafer, the bonded wafer tray and resin substrate are soaked in hot water. The adhesive at the joint between the resin substrate and the wafer tray softens under the influence of hot water. Combined with the thermal deformation of the resin substrate, the hot water gradually penetrates into the gap between the resin substrate and the wafer tray, softening the adhesive. After a period of time, the adhesive between the resin substrate and the wafer tray will be completely softened, allowing the wafer tray and resin substrate to be separated. The wafer tray can be recycled, and the removed resin substrate is disposed of as solid waste.

[0063] Because this embodiment uses a supporting silicon plate 2 instead of a resin plate, the silicon plate has a small coefficient of thermal expansion and minimal thermal deformation. If existing crystal trays are used for slicing, during the debonding process, even after the adhesive at the joint between the silicon plate and the crystal tray softens to a certain depth, the adhesive at the center of the bonding surface of the silicon plate still has strong bonding force, preventing the silicon plate and the crystal tray from separating. It requires heating in an oven at temperatures above 250°C to degrade the adhesive and allow separation. To solve this problem, this embodiment improves the structure of the crystal tray 1 by creating at least one flow groove 111 at the bonding end of the crystal tray 1. Since the flow groove 111 extends through the entire bonding end, it divides the bonding end into several independent bonding blocks 112, thus dividing the adhesive surface of the crystal tray 1 into several smaller adhesive surfaces 1121. During debonding, the contact area between the debonding liquid and the adhesive layer is increased, allowing the adhesive between the bonding end and the supporting silicon plate 2 to soften quickly, enabling successful debonding of the supporting silicon plate 2 and the crystal tray 1. At the same time, since the adhesive surface 1121 is reduced, the amount of glue used during adhesive bonding is also reduced accordingly, saving the amount of adhesive used and reducing glue costs.

[0064] It should be noted that, when using the improved crystal tray 1 of this embodiment, a silicon plate is required as the slicing consumable during slicing; the two are complementary, and a resin plate cannot be used for slicing. Because the improved crystal tray 1 has a flow groove 111 at the bonding end, and the resin plate is relatively soft, it is prone to deformation when the adhesive surface area 1121 is small. This increases edge chipping defects during slicing, leading to a decrease in slicing yield. Especially when a relatively wide flow groove 111 is only provided in the middle of the bonding end, with adhesive surfaces 1121 on both sides of the flow groove 111, the cutting pressure will deform the resin plate when both sides of the silicon rod 3 are cut through, leaving only the middle part of the silicon rod 3, causing edge chipping of the entire silicon wafer. This embodiment uses a silicon plate instead of a resin plate. The supporting silicon plate 2 has high hardness and strength, is not easily deformed, and avoids the above problems.

[0065] It should be noted that the silicon rod slicing equipment of the present invention also includes components such as a cutting chamber, a cutting line, and a worktable that drives the crystal tray to move in the direction of the cutting line. These all adopt existing structures in the art, and therefore will not be described in detail in this embodiment. During slicing, the crystal tray 1, the supporting silicon plate 2, and the silicon rod 3 are bonded together with adhesive and then pushed into the cutting chamber of the slicing machine. The crystal tray 1 is then fixed to the worktable by the clamping mechanism 12 of the crystal tray 1, and then slicing production is carried out.

[0066] Specifically, in this embodiment, the first direction is the length direction of the adhesive plate 11, the second direction is the width direction of the adhesive plate 11, and the first direction and the second direction are perpendicular to each other.

[0067] In one embodiment, along the second direction, the widths of the plurality of adhesive surfaces 1121 are ≤50mm, so that during debonding, the heated debonding liquid can smoothly soften the adhesive layer between the supporting silicon plate 2 and the adhesive surface 1121, so that the supporting silicon plate 2 and the crystal holder 1 can be smoothly debonded and separated.

[0068] In one embodiment, along the second direction, the widths of the plurality of adhesive surfaces 1121 are 30mm to 45mm respectively. Further limiting the width of the adhesive surfaces 1121 to within the above range allows for faster softening of the adhesive layer between the supporting silicon substrate 2 and the adhesive surfaces 1121 during debonding, enabling rapid separation of the supporting silicon substrate 2 and the crystal holder 1. Furthermore, the width of the adhesive surfaces 1121 should not be less than 30mm. If the width of the adhesive surfaces 1121 is small, when both ends of the dicing line are cut through the silicon rod 3, but the middle of the dicing line has not yet cut through the silicon rod 3, the smaller bonding area will easily lead to edge chipping, resulting in a decrease in silicon wafer yield.

[0069] See Figure 3As shown, in one embodiment, a flow groove 111 is formed along the adhesive end, and the flow groove 111 is located in the middle of the adhesive end along the second direction, so that the adhesive end forms two independent adhesive blocks of equal width on both sides in the second direction. This embodiment only has one flow groove 111, which is more conducive to machining. The two sides of the flow groove 111 in the second direction are adhesive surfaces 1121. Compared with more adhesive surfaces 1121 but smaller area, this embodiment is more convenient to apply and spread the adhesive evenly. Furthermore, by controlling the width of the two adhesive surfaces 1121 to ≤50mm, the width of the flow groove 111 is larger, which facilitates the flow of the de-adhesive liquid in the flow groove 111, so as to heat and soften the adhesive more quickly, and enable the supporting silicon plate 2 and the crystal holder 1 to be successfully de-adhesive and separated.

[0070] In some embodiments, the total width of the bonding plate 11 is 180mm~200mm. When a flow channel 111 is provided, the width of the flow channel 111 can be 100mm~110mm, so that the width of the two adhesive surfaces 1121 formed is ≤50mm. Due to the provision of the flow channel 111, during debonding, the heated debonding liquid can smoothly soften the adhesive, and the silicon substrate and the crystal holder 1 can be successfully debonded. At the same time, since the adhesive surface 1121 is reduced, the amount of adhesive used during bonding is correspondingly reduced, saving the cost of adhesive for silicon substrate bonding.

[0071] In another embodiment, two flow grooves 111 may be formed on the adhesive end, with the two flow grooves 111 spaced apart at the middle of the adhesive end, so that the two flow grooves 111 divide the adhesive end into three independent adhesive blocks 112. In this embodiment, the total width of the adhesive plate 11 is 180mm~200mm, in which case the width of the two flow grooves 111 can be 40mm~45mm respectively, and the width of the three independent adhesive surfaces 1121 formed can be 30mm~40mm respectively.

[0072] In one embodiment, the depth of the flow channel 111 is 2mm to 10mm. Controlling the depth of the flow channel 111 within this range facilitates the entry of the desiccant into the flow channel 111 and softens the adhesive layer between the die holder 1 and the silicon substrate. The depth of the flow channel 111 is exemplary to be 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm, but is not limited thereto.

[0073] The technical solution of the present invention will be further described below through embodiments and comparative examples.

[0074] Example 1 This embodiment provides a method for slicing silicon rods, including the following steps: (1) The silicon rod to be sliced ​​is bonded to the supporting silicon plate, and the supporting silicon plate is fixed on the crystal holder; in this embodiment, the thickness S1 of the silicon rod to be sliced ​​is 196mm; (2) Install the crystal holder with the silicon rod attached above the dicing line; (3) Move the silicon rod toward the cutting line and make it contact the cutting line, and cut the silicon rod through the cutting line to form a silicon wafer; wherein, along the cutting process, the process of the cutting line cutting the silicon rod includes the first cutting stage, the second cutting stage and the third cutting stage in sequence. In this embodiment, the total feed distance S1 of the silicon rod from the contact dicing line to the point where it is completely cut through the dicing line is 200.8 mm. The first cutting stage is the stage in which the silicon rod moves from the position of contact with the cutting line (0mm) to the first feed position (10mm) during the cutting process. The second cutting stage is the stage in which the silicon rod moves from the first feed position (10mm) to the second feed position (195mm) during the cutting process. The third cutting stage is the stage in which the silicon rod moves from the second feed position (195mm) to the position where it is completely cut through by the cutting line (200.8mm) during the cutting process. The feed rates and linear velocities for the first, second, third, and fourth cutting stages in this embodiment are shown in Table 1 below: Table 1 Cutting parameters of Example 1

[0075] Comparative Example 1 This comparative example provides a method for slicing silicon rods, including the following steps: (1) The silicon rod to be sliced ​​is bonded to the supporting silicon plate, and the supporting silicon plate is fixed on the crystal holder; in this embodiment, the thickness S1 of the silicon rod to be sliced ​​is 196mm; (2) Install the crystal holder with the silicon rod attached above the dicing line; (3) Move the silicon rod toward the cutting line and make it contact the cutting line. Cut the silicon rod through the cutting line to form a silicon wafer. In Comparative Example 1, the total feed distance S1 from contact with the cutting line to being completely cut through the cutting line is about 200.8 mm. The process of the cutting line cutting the silicon rod in Comparative Example 1 and the feed speed and linear speed at each stage are shown in Table 2 below: Table 2 Cutting parameters for Comparative Example 1

[0076] Specifically, silicon wafers obtained from Example 1 and Comparative Example 1 were collected, and the presence of defects such as tearing, chipping, or bright edges on the silicon wafers obtained from Example 1 and Comparative Example 1 was detected. The proportion of qualified silicon wafers (i.e., yield) was counted, and the yield improvement value of the Example was calculated based on Comparative Example 1, wherein the yield improvement value = yield of the Example - yield of Comparative Example 1. Meanwhile, the total cutting time of Example 1 and Comparative Example 1 was statistically analyzed, and the efficiency improvement rate of Example 1 was calculated based on Comparative Example 1. The formula for calculating the efficiency improvement rate is as follows: Efficiency improvement rate = (Total cutting time of Comparative Example 1 - Total cutting time of Example) / Total cutting time of Comparative Example 1.

[0077] The slicing results of Example 1 and Comparative Example 1 are shown in Table 3 below: Table 3 Slicing effect

[0078] As can be seen from the data in Table 3, this embodiment can effectively improve the slicing efficiency and the yield of silicon wafers by using silicon wafers instead of resin wafers and optimizing the cutting process.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method of slicing a silicon rod, characterized by, The method comprises the following steps: (1) bonding a silicon rod to be sliced to a bearing silicon plate, and fixing the bearing silicon plate on a crystal holder; (2) installing the crystal holder with the bonded silicon rod and bearing silicon plate above a cutting line; (3) moving the silicon rod to the direction of the cutting line and contacting the cutting line, and cutting the silicon rod by the cutting line to form a silicon wafer; wherein, along the cutting process, the cutting of the silicon rod by the cutting line comprises a first cutting stage, a second cutting stage and a third cutting stage in sequence; wherein, the first cutting stage is a stage in which the silicon rod moves from the position contacting the cutting line to a first feeding position during the cutting process, the second cutting stage is a stage in which the silicon rod moves from the first feeding position to a second feeding position during the cutting process, and the third cutting stage is a stage in which the silicon rod moves from the second feeding position to a position completely cut through by the cutting line during the cutting process; The distance between the second feeding position and the position where the silicon rod is completely cut through by the cutting line is S 13 The distance between the position where the silicon rod contacts the cutting line and the position where the silicon rod is completely cut through by the cutting line is S1, wherein S 13 ≤ 0.07 * S1 the average feeding speed of the silicon rod in the second cutting stage is V2, and the average feeding speed of the silicon rod in the third cutting stage is V3, wherein the ratio of V3 to V2 is 0.3-0.

5.

2. The method of slicing a silicon rod according to claim 1, wherein Along the cutting process, the feeding speed of the silicon rod in the third cutting stage gradually decreases; the ratio of the maximum feeding speed of the silicon rod in the third cutting stage to the average feeding speed of the silicon rod in the second cutting stage is 0.75-0.92, and the ratio of the minimum feeding speed of the silicon rod in the third cutting stage to the average feeding speed of the silicon rod in the second cutting stage is 0.08-0.

2.

3. The method of slicing a silicon rod according to claim 1, wherein The distance between the position where the silicon rod contacts the cutting line and the first feeding position is S 11 wherein S 11 The ratio of S and S1 is 0.03-0.

08. The distance between the first feeding position and the second feeding position is S 12 wherein S 12 The ratio of S and S1 is 0.85-0.

95. and S 11 + S 12 + S 13 = S1.

4. The method of slicing a silicon rod according to claim 3, wherein The average feeding speed of the silicon rod in the first cutting stage is V1, wherein the ratio of V1 to V2 is 0.5-0.65, and along the cutting process, the feeding speed of the silicon rod in the first cutting stage gradually increases.

5. The method of slicing a silicon rod according to claim 1, wherein The average feeding speed V2 of the silicon rod in the second cutting stage is 2200 μm / min-2500 μm / min.

6. The method of slicing a silicon rod according to claim 1, wherein The average feeding speed V3 of the silicon rod in the third cutting stage is 800 μm / min-1100 μm / min.

7. The method of slicing a silicon rod according to claim 6, wherein The feeding speed range of the silicon rod in the third cutting stage is 200 μm / min-2200 μm / min, and along the cutting process, the feeding speed of the silicon rod in the third cutting stage gradually decreases.

8. The method of slicing a silicon rod according to claim 1, wherein The average feeding speed of the silicon rod in the first cutting stage is 1300 μm / min-1500 μm / min, and along the cutting process, the feeding speed of the silicon rod in the first cutting stage gradually increases.

9. The method of claim 1 wherein, The linear speed of the cutting line in the third cutting stage is ≤ the linear speed of the cutting line in the second cutting stage, and along the cutting process, the linear speed of the cutting line in the third cutting stage gradually decreases.

10. The method of slicing a silicon rod according to claim 9, wherein, The linear speed of the cutting line in the second cutting stage is 1900 m / mm-2500 m / mm; The linear speed of the cutting line in the third cutting stage is 1200 m / mm-2100 m / mm.

11. The method of slicing a silicon rod according to claim 10, wherein, The linear speed of the cutting line in the first cutting stage is 800 m / min-2400 m / min, and in the first cutting stage, the linear speed of the cutting line gradually increases along the cutting process.

12. The method of claim 1, wherein, In step (1), the silicon rod to be sliced is bonded to the bearing silicon plate with glue, and the bearing silicon plate is bonded to the bottom of the crystal holder with glue, so that the silicon rod, the bearing silicon plate and the crystal holder are bonded to form an integral structure.

13. The method of slicing a silicon rod according to claim 12, wherein, The silicon rod slicing method further comprises the following steps: (4) The crystal holder, the bearing silicon plate and the silicon wafer formed after cutting are placed in a first degumming liquid with a temperature of 50-80°C, so that the silicon wafer is separated from the bearing silicon plate, and the silicon wafer is collected. (5) The crystal holder and the bearing silicon plate after the silicon wafer is taken out are placed in a second degumming liquid with a temperature of 85-100°C, so that the bearing silicon plate and the crystal holder are separated.

14. A silicon rod slicing apparatus characterized by, The silicon rod slicing method according to any one of claims 1-13, comprising a crystal holder and a bearing silicon plate bonded to the crystal holder, wherein one end of the bearing silicon plate away from the crystal holder is used to bond to a silicon rod to be sliced; The crystal holder comprises a bonding plate body and a clamping mechanism, and the bonding plate body is installed at the bottom of the clamping mechanism; The end of the bonding plate body away from the clamping mechanism is a bonding end, and at least one flow-through groove is formed in the bonding end, the flow-through groove extends along a first direction and penetrates through the entire bonding end, and the flow-through groove separates the bonding end into a plurality of independent bonding sub-blocks; The end surface of the bonding sub-block away from the clamping mechanism constitutes a bonding surface for connecting the bearing silicon plate.

15. The silicon-rod slicing apparatus of claim 14, wherein In a second direction, the widths of the bonding surfaces are respectively ≤50mm.

16. The silicon-rod slicing apparatus of claim 15, wherein In a second direction, the widths of the bonding surfaces are respectively 30-45mm.

17. The silicon-rod dicing apparatus of claim 14, wherein In the second direction, the flow-through groove is formed in the middle of the bonding end, and the flow-through groove extends along the first direction and penetrates through the entire bonding end, so that the two sides of the bonding end in the second direction respectively form the bonding sub-blocks with equal widths.

18. A silicon-rod slicing apparatus according to any one of claims 14-17, characterized in that The depth of the flow-through groove is 2-10mm.

Images