Silicon wafer cutting line, cutting method and silicon wafer
By using a silicon wafer cutting wire structure with multiple single-wire spiral windings, the shortcomings of existing carbon steel and tungsten steel wires are overcome, improving cutting quality and efficiency, and achieving finer wires.
Patent Information
- Application Number
- CN202410464955.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-17
- Publication Date
- 2025-10-31
AI Technical Summary
The tensile strength of existing carbon steel wire has reached its limit and cannot support thinner wires. Tungsten steel wire is expensive and the reduced kerf depth decreases its liquid carrying capacity, affecting the quality of silicon wafer products.
The silicon wafer cutting wire is formed by multiple single-wire spiral windings. The outer surface of the substrate is wrapped with a consolidation layer and a cutting layer. It is equipped with chip grooves and diamond particles. The pitch and rotation speed are controlled to improve the flow of cutting fluid and chip discharge. The cutting layer is a diamond-plated layer.
It improved cutting quality, reduced wire marks and TTV, enhanced cutting capacity and production efficiency, and achieved finer wires.
Smart Images
Figure CN120862880A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of silicon single crystal production technology, and in particular relates to a silicon wafer cutting line, a cutting method, and a silicon wafer. Background Technology
[0002] Diamond wire saw cutting technology is widely used in the processing of hard and brittle materials such as monocrystalline silicon and sapphire due to its advantages such as high processing efficiency and low kerf loss.
[0003] With silicon material prices continuing to fluctuate at the bottom of an "L" shape, competition within the industry is fierce, and cost reduction is being accelerated. Wire diameter reduction is currently the main method for cost reduction, increasing wafer yield per kilogram by reducing wire diameter. Currently, the market offers two materials: carbon steel and tungsten steel. However, carbon steel wire's tensile strength has reached its limit, and its theoretical breaking strength is gradually decreasing. Specifically, carbon steel wire with a diameter of 28μm has a breaking strength of 4.8N, essentially reaching its limit and unable to support continued wire diameter reduction. Tungsten steel wire, with technological advancements, can achieve a tensile strength of over 7200MPa and can achieve a wire diameter of 22mm. However, the main problems are higher cost and reduced kerf depth, leading to decreased liquid carrying capacity, directly affecting silicon wafer product quality (TTV / line marks) and defect rate. Summary of the Invention
[0004] In view of the above problems, the present invention provides a silicon wafer dicing line, a dicing method, and a silicon wafer to solve the above or other problems existing in the prior art. To solve the above technical problems, the technical solution adopted by the present invention is: a silicon wafer dicing line, comprising a substrate and a bonding layer disposed on the outer surface of the substrate, wherein...
[0005] The matrix consists of multiple single wires, which are spirally wound and twisted together to form multiple chip grooves on the periphery of the matrix, so that cutting fluid can flow in and chips can be discharged during single crystal cutting.
[0006] The consolidation layer is wrapped around the outer surface of the substrate to fix multiple single wires.
[0007] Furthermore, multiple single wires are wound with a certain helix angle and a certain pitch. The relationship between the helix angle and the pitch is: h = πdtanα, where α is the helix angle, h is the pitch, and d is the diameter of the single wire.
[0008] Furthermore, the pitch is controlled by the rotational speed and wire feed speed of multiple single wires twisted together, and the pitch is 40-60 times the diameter of a single wire.
[0009] Furthermore, it also includes a cutting layer disposed on the outer surface of the consolidation layer, which covers the outer surface of the consolidation layer and is used to cut the single crystal.
[0010] Furthermore, the cutting layer is a diamond-coated layer, with multiple diamond particles distributed across the outer surface of the consolidation layer.
[0011] Furthermore, the particle density of the corundum particles is 250-350 particles / mm.
[0012] Furthermore, the effective abrasive particles of the diamond grit are 150-250 particles / mm.
[0013] Furthermore, the consolidation layer is a nickel plating layer formed by electroplating nickel.
[0014] Furthermore, the number of individual lines is greater than or equal to 3, and the diameter of each individual line is less than 30 μm.
[0015] Furthermore, multiple chip-collecting grooves are arranged sequentially along the axial and circumferential directions of the substrate.
[0016] A silicon wafer cutting method involves using a cutting device with silicon wafer cutting lines as described above to cut a single-crystal silicon rod to form a silicon wafer; during the cutting process of the single-crystal silicon rod, as the feed position increases, the feed speed, cutting line speed and cutting fluid flow rate are controlled to first increase and then decrease.
[0017] Furthermore, the feed rate is 0-3 mm / min, the cutting line speed is 0-50 m / s, and the cutting fluid flow rate is 100-260 L / min.
[0018] A silicon wafer, prepared using the silicon wafer cutting method described above, has a TTV of 7-9 μm and a wire mark diameter of 5-6 μm. Due to the adoption of the above technical solution, the substrate of the cutting wire used for cutting solar photovoltaic silicon wafers is composed of multiple single wires spirally wound and twisted together in a circular motion to form a spiral-shaped stranded wire structure. Multiple chip grooves are formed along the axial and circumferential directions of the substrate. Compared with the chip grooves of conventional cutting wires, the chip groove volume of the cutting wire is greatly increased, allowing the cutting fluid to reside within the chip grooves and flow along them to the cutting position. Simultaneously, the chip grooves can store chips and discharge them as the cutting wire moves, facilitating the inflow of cutting fluid and the discharge of chips. This avoids silicon powder obstruction leading to wire breakage or insufficient cutting capacity resulting in wire marks. The cutting surface exhibits more plastic shear characteristics, improving cutting quality. The number and diameter of the single wires can be selected according to the diameter of the cutting wire, increasing the number of diamond particles in the single wires to enhance the cutting capability and achieve finer wires. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the structure of an existing conventional cutting line;
[0020] Figure 2 This is a schematic diagram of the cutting line structure according to an embodiment of the present invention;
[0021] Figure 3 yes Figure 2A schematic diagram of the cross-sectional structure of AA;
[0022] Figure 4 This is a schematic diagram of the cross-sectional structure of a cutting line composed of four single lines according to an embodiment of the present invention.
[0023] Figure 5 This is a schematic diagram of the cross-sectional structure of a cutting line composed of five single lines according to an embodiment of the present invention.
[0024] Figure 6 This is a schematic diagram of the cross-sectional structure of a cutting line composed of six single lines according to an embodiment of the present invention.
[0025] Figure 7 This is a schematic diagram of the cross-sectional structure of a cutting line composed of seven single lines according to an embodiment of the present invention.
[0026] Figure 8 This is a schematic diagram of cutting a single crystal using a conventional wire cutting method;
[0027] Figure 9 This is a schematic diagram of a wire cutting single crystal according to an embodiment of the present invention;
[0028] Figure 10 This is a schematic diagram of the surface cutting quality of a single crystal when using conventional wire cutting.
[0029] Figure 11 This is a schematic diagram of the surface cutting quality of a single crystal during wire cutting of a single crystal according to an embodiment of the present invention.
[0030] In the picture:
[0031] 1. Single line 2. Chip groove 3. Emery particles
[0032] 4. Pitch D, Diameter Detailed Implementation
[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0034] Figure 2 The diagram shows a structural schematic of an embodiment of the present invention. This embodiment relates to a silicon wafer cutting wire, a cutting method, and a silicon wafer. The cutting wire is a twisted stranded wire installed on a wire cutter for cutting silicon single crystals into silicon wafers. It has chip grooves to facilitate the flow of cutting fluid into the cutting position along the chip grooves during the cutting process, and at the same time, to facilitate the flow of chips out along the chip grooves, avoiding silicon powder obstruction that could lead to wire breakage or insufficient cutting capacity that could cause wire marks, thereby improving the cutting quality of the cutting wire.
[0035] like Figure 1 As shown, Figure 1A schematic diagram of a conventional dicing wire structure for cutting silicon single crystals is shown. The conventional dicing wire is a single-wire structure. Under this structure, the limit of the single wire diameter is 30μm due to the influence of the tensile strength of the wire material. When the wire diameter of the conventional dicing wire is reduced, the kerf width is reduced, the fluid carrying capacity is reduced, the product quality (TTV / thickness) is reduced, the lubrication and cooling capacity of the dicing wire is reduced, the wire breakage problem increases, the chip removal capacity of the dicing wire is reduced, the product quality (line marks) is reduced, and the cutting capacity of the dicing wire is insufficient due to the reduction of the diamond particles per unit area after the wire diameter is reduced.
[0036] Therefore, the dicing line structure is improved, and a silicon wafer dicing line is designed, such as... Figure 2 As shown, the device includes a substrate and a consolidation layer on the outer surface of the substrate. The substrate forms the main structure of the cutting wire. The substrate facilitates the installation of the consolidation layer. The substrate includes multiple single wires 1, which are spirally wound and twisted together to form the main structure of the cutting wire. The multiple single wires 1 are spirally wound in a circular motion. Due to the spiral winding of the multiple single wires 1, multiple chip grooves 2 are constructed on the peripheral side of the substrate to facilitate the inflow of cutting fluid and the discharge of chips during single crystal cutting. That is, the substrate is formed by twisting and twisting multiple single wires 1 together. The multiple single wires 1 move in a circular motion along the same rotation direction and are spirally wound to form the substrate structure. The consolidation layer wraps around the outer surface of the substrate. That is, the consolidation layer wraps around the outer surface of the multiple single wires 1 that constitute the substrate to fix the multiple single wires 1 and prevent them from loosening.
[0037] When in use, the silicon wafer cutting wire is installed on a wire cutter to cut silicon single crystals. The silicon single crystals are fed towards the cutting wire, the cutting wire moves, and the cutting wire cuts the silicon single crystals. During the cutting process, the cutting fluid flows along the chip groove 2 and into the cutting position. The chips are contained in the chip groove 2 and are discharged as the cutting wire moves.
[0038] Specifically, such as Figure 2 and 3As shown, the aforementioned substrate is formed by spirally winding multiple single wires 1 through circular motion, creating a wire structure of a certain length. This substrate is twisted together using a stranding machine. Under external force, the multiple single wires 1 simultaneously rotate in the same direction, forming a spiral wire structure. Each single wire 1 is a spiral; that is, multiple single wires 1 are twisted together in a spiral form to form a multi-twisted structure. The outer peripheral surface of the substrate is not a planar structure, but rather... The substrate has multiple grooves arranged sequentially along the axial and circumferential directions. These grooves are called chip collection grooves 2. The chip collection grooves 2 allow the cutting fluid to flow along the chip collection grooves 2 and into the cutting position when the cutting wire cuts the silicon single crystal, facilitating the flow of cutting fluid. At the same time, the chip collection grooves 2 create a gap between the cutting wire and the surface of the silicon single crystal. As the cutting wire cuts the silicon single crystal, the chips can be stored in the chip collection grooves 2, and as the cutting wire moves, the chips located in the chip collection grooves 2 can be discharged.
[0039] The diameter D of the aforementioned matrix is related to the diameter of each individual wire 1, such as... Figure 3 As shown, the substrate is cut at any position to obtain a cross-sectional structure diagram of the substrate. From the cross-sectional structure diagram of the substrate, it can be seen that multiple single lines 1 are arranged around the axis of the substrate as the center line. Multiple single lines 1 are arranged along the circumferential direction of the axis of the substrate. Multiple single lines 1 are located in the plane formed by the maximum outer diameter of the substrate.
[0040] The number of single wires 1 is greater than or equal to 3. Based on the design requirements of the substrate diameter D, the number and diameter of single wires 1 are selected. After determining the number and diameter of single wires 1, multiple single wires 1 are twisted and stranded together to prepare a cutting wire with a diameter D that meets the design requirements of the substrate diameter D. Depending on the size of different silicon single crystals, the corresponding cutting wire diameter D is selected to achieve the optimal cutting force, meeting the cutting requirements of the silicon single crystal. Here, the substrate diameter D is the maximum outer diameter of the substrate.
[0041] like Figure 3 As shown, there are 3 single wires. The 3 single wires are twisted together in a spiral to form a matrix structure. The 3 single wires are arranged around the axis of the matrix.
[0042] like Figure 4 As shown, there are 4 single wires. The 4 single wires are twisted together in a spiral to form a matrix structure. The 4 single wires are arranged around the axis of the matrix.
[0043] like Figure 5 As shown, there are 5 single wires. The 5 single wires are twisted together in a spiral to form a matrix structure. The 5 single wires are arranged around the axis of the matrix.
[0044] like Figure 6 As shown, there are 6 single wires. The 6 single wires are twisted together in a spiral to form a matrix structure. The 6 single wires are arranged around the axis of the matrix.
[0045] like Figure 7 As shown, there are 7 single wires. The 7 single wires are twisted together in a spiral to form a matrix structure. One single wire is located on the axis of the matrix, and the other 6 single wires are arranged around the axis of the matrix.
[0046] When multiple single wires 1 are wound in rotation, they are wound with a certain helix angle and a certain pitch 4. The relationship between the helix angle and the pitch 4 is: h = πdtanα, where α is the helix angle, h is the pitch 4, and d is the diameter of the single wire 1. The pitch 4 is the straight-line distance that the single wire 1 travels along the axial direction of the substrate after rotating one revolution at the helix angle. The size of the pitch 4 affects the volume of the chip groove 2. During the twisting and stranding process of multiple single wires 1, the pitch 4 is controlled by the rotational speed and wire feed speed of the multiple single wires 1 during twisting and stranding. In some feasible embodiments, the pitch 4 is 40-60 times the diameter of the single wire.
[0047] The aforementioned helix angle is the angle between the axis of the single line 1 and the cross-section of the matrix. The size of the helix angle is controlled by the diameter of the single line 1 and the pitch 4. From the above calculation formula, it can be seen that the helix angle increases with the increase of the pitch 4 and decreases with the increase of the diameter D of the single line 1. The smaller the helix angle, the greater the bending deformation of the single line 1 and the greater the internal stress.
[0048] Based on the structure of the matrix formed by the twisting and stranding of multiple single wires 1, it can be known that there are multiple chip grooves 2. Multiple chip grooves 2 are arranged sequentially along the axial and circumferential directions of the matrix. The volume of the chip grooves 2 is determined by the pitch 4 and the diameter of the single wire 1. The chip grooves 2 can promote the inflow of cutting fluid and improve the discharge of chips, thus avoiding chip accumulation.
[0049] In some feasible embodiments, the single wire 1 mentioned above is a carbon steel cutting wire, and the diameter of the single wire 1 is less than 30μm. The diameter of the single wire 1 is selected according to actual needs, and no specific requirements are made here.
[0050] The aforementioned consolidation layer is a nickel plating layer formed by electroplating nickel. Multiple single wires 1 are twisted together to form a substrate. Multiple single wires 1 are spirally wound together under external force, and then nickel plating is performed on the substrate to form a nickel plating layer on the outer periphery of the substrate. The nickel plating layer wraps around the periphery of the substrate to fix the multiple single wires 1 that make up the substrate and prevent the multiple single wires 1 from loosening.
[0051] In some feasible embodiments, the thickness of the nickel plating layer is 1-3 μm, and the thickness of the nickel plating layer is selected according to actual needs.
[0052] In a further optimized design, the silicon wafer cutting line also includes a cutting layer located on the outer surface of the consolidation layer. The cutting layer covers the outer surface of the consolidation layer and is used to cut the single crystal.
[0053] In some feasible embodiments, the cutting layer is a diamond-coated layer, with multiple diamond particles 3 distributed on the outer surface of the consolidation layer. The particle density of the diamond particles 3 is 250-350 particles / mm. The particle density is the number of diamond particles 3 per unit area of the substrate surface, which directly determines the effective number of abrasive grains participating in the cutting of the cutting line, thereby affecting the cutting performance of the cutting line. The effective number of abrasive grains 3 is 150-250 particles / mm, and the effective abrasive grains are set at the outermost tangent of the single line 1.
[0054] During the preparation of the cutting wire for cutting solar photovoltaic silicon wafers, the diameter and number of individual wires 1 are selected according to the required diameter D of the cutting wire. Multiple individual wires 1 simultaneously perform circular motion, spirally wind and twist together. During twisting, the pitch 4 is controlled by adjusting the twisting speed and wire feed speed of the individual wires 1 to ensure that the pitch 4 meets the design requirements and forms the structure of the substrate. Then, nickel is electroplated onto the substrate to form a nickel plating layer on the outer peripheral side of the substrate. Then, a diamond abrasive layer is plated on the outer peripheral side of the nickel plating layer. Multiple diamond abrasive particles 3 are distributed on the peripheral side of the substrate along the circumferential and axial directions. The diamond abrasive particles 3 act as abrasive grains and have cutting ability so that the cutting wire can cut silicon single crystals. When the diamond abrasive particles 3 are arranged, the particle density of the diamond abrasive particles 3 is determined according to actual needs to ensure that the cutting wire meets the cutting performance requirements.
[0055] The cutting wire is installed on the wire cutting machine. When cutting silicon single crystal, the cutting wire moves horizontally and the silicon single crystal is fed vertically. The chip groove 2 contains the cutting fluid and the cutting fluid flows along the chip groove 2, which promotes the inflow of cutting fluid and allows the cutting fluid to flow into the cutting position. The chips are located in the chip groove 2 on the side of the substrate facing the silicon single crystal. As the cutting wire moves, the chips in the chip groove 2 that are separated from the silicon single crystal are discharged, improving the chip removal of the cutting wire.
[0056] like Figure 8 and 9 As shown, compared with twisted strands composed of multiple single wires, conventional cutting wires have chip grooves and fewer effective diamond particles 3 participating in cutting than conventional cutting wires. During the cutting process, silicon powder will not cause the cutting wire to break or the cutting ability to be insufficient, resulting in wire marks, thus improving the cutting ability of the cutting wire.
[0057] like Figure 10 and 11 As shown, compared with twisted stranded wire composed of multiple single wires, under the same cutting process conditions, the brittle plasticity removal ratio of twisted stranded wire is higher than that of single-wire cutting wire. The main reason is that the effective cutting part of the twisted stranded wire is helical, and some abrasive grains do not exert a cutting force perpendicular to the contact area on the workpiece during cutting. The reduction of the cutting force perpendicular to the cutting part is more conducive to plastic shearing. Therefore, the cutting surface of the twisted stranded wire has more plastic shearing characteristics, and the cutting surface quality is better than that of the conventional cutting wire.
[0058] A silicon wafer cutting method involves using a cutting device with silicon wafer cutting lines as described above to cut a monocrystalline silicon rod into silicon wafers. The cutting lines are installed on the cutting device to form a cutting line mesh. When cutting the monocrystalline silicon rod, the monocrystalline silicon rod moves relative to the cutting line mesh for feeding. At the same time, the cutting lines move to cut the monocrystalline silicon rod into multiple silicon wafers.
[0059] In the process of cutting monocrystalline silicon rods, as the feed position increases, the parameters of feed speed, cutting line speed and cutting fluid flow rate are changed to make the feed speed, cutting line speed and cutting fluid flow rate parameters suitable for different feed positions. While meeting the silicon wafer cutting quality, the feed speed and cutting line speed are increased, thereby improving production efficiency.
[0060] Specifically, as the single crystal feed position increases, the feed rate, cutting line speed, and cutting fluid flow rate are all first increased and then decreased. Here, the feed position is the cutting depth. During the single crystal silicon rod cutting process, as the single crystal silicon rod feeds towards the cutting wire mesh direction, the cutting depth of the cutting line gradually increases. For each additional feed position, the single crystal feed rate, cutting line speed, and cutting fluid flow rate all change accordingly, so that the single crystal feed rate, cutting line speed, and cutting fluid flow rate are adapted to the feed position.
[0061] In some feasible embodiments, the feed rate described above is 0-3 mm / min, which can be selected according to actual needs, and no specific requirements are made here.
[0062] The cutting speed is 0-50m / s, which can be selected according to actual needs; no specific requirements are given here.
[0063] The cutting fluid flow rate is 100-260L / min, which can be selected according to actual needs; no specific requirements are given here.
[0064] A silicon wafer is prepared by the silicon wafer cutting method described above, wherein the silicon wafer has a TTV of 7-9 μm and a line mark of 5-6 μm.
[0065] The following is a specific embodiment for illustration.
[0066] When cutting monocrystalline silicon rods, the monocrystalline silicon rods are mounted on wire cutting machines, and the cutting wires are wound and mounted on the wire cutting machines to form a cutting wire mesh. When cutting monocrystalline silicon rods, the appropriate monocrystalline feed rate, cutting wire speed and cutting fluid flow rate are selected according to the cutting position of the monocrystalline silicon rods.
[0067] When the feed position is 0mm (the cutting line is in contact with the outer surface of the single crystal silicon rod), the single crystal feed rate is 1.2mm / min, the cutting line speed is 8m / s, and the cutting fluid flow rate is 160L / min.
[0068] When the feed position is 2mm, the single crystal feed rate is 1.5mm / min, the cutting line speed is 15m / s, and the cutting fluid flow rate is 160L / min;
[0069] When the feed position is 4mm, the single crystal feed rate is 1.5mm / min, the cutting line speed is 30m / s, and the cutting fluid flow rate is 180L / min;
[0070] When the feed position is 10mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 35m / s, and the cutting fluid flow rate is 180L / min;
[0071] When the feed position is 20mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 35m / s, and the cutting fluid flow rate is 200L / min;
[0072] When the feed position is 60mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 40m / s, and the cutting fluid flow rate is 200L / min;
[0073] When the feed position is 97mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 40m / s, and the cutting fluid flow rate is 240L / min;
[0074] When the feed position is 126mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 40m / s, and the cutting fluid flow rate is 240L / min;
[0075] When the feed position is 152mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 40m / s, and the cutting fluid flow rate is 250L / min;
[0076] When the feed position is 175mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 40m / s, and the cutting fluid flow rate is 250L / min;
[0077] When the feed position is 178mm, the single crystal feed rate is 2.6mm / min, the cutting line speed is 40m / s, and the cutting fluid flow rate is 180L / min;
[0078] When the feed position is 188mm, the single crystal feed rate is 0.3mm / min, the cutting line speed is 35m / s, and the cutting fluid flow rate is 120L / min;
[0079] When the feed position is 189mm, the single crystal feed rate is 0.05mm / min, the cutting line speed is 15m / s, and the cutting fluid flow rate is 120L / min;
[0080] When the feed position is 190mm, the single crystal feed rate is 0.05mm / min, the cutting line speed is 20m / s, and the cutting fluid flow rate is 120L / min;
[0081] Once the cutting is complete, the cutting line contacts the resin plate, and the single crystal and the cutting line stop moving. At this point, the feed position is 0mm, the single crystal feed rate is 0mm / min, the cutting line speed is 0m / s, and the cutting fluid flow rate is 0L / min.
[0082] The above parameters are summarized in the table below:
[0083] Feed position / mm Feed rate / mm / min Cutting line speed / m / s Cutting fluid flow rate / L / min 0 1.2 8 160 2 1.5 15 160 4 1.5 30 180 10 2.6 35 200 20 2.6 35 200 60 2.6 40 200 97 2.6 40 240 126 2.6 40 240 152 2.6 40 250 175 2.6 40 250 178 2.6 40 180 188 0.3 35 120 189 0.05 15 120 190 0.05 20 120 0 0 0 0
[0084] Using the above parameters to cut the single-crystal silicon rod, the resulting silicon wafer has an average TTV of 8µm and an average line mark of 5.5µm.
[0085] When using a conventional wire cutter to cut a single-crystal silicon rod, the following table shows the changes in single-crystal feed rate, wire cutter speed, and slurry flow rate as the feed position increases:
[0086]
[0087]
[0088] Using the above parameters to cut the single-crystal silicon rod, the average TTV of the resulting silicon wafer was 10.71 μm, and the average line mark was 7.63 μm.
[0089] As can be seen from the above, when cutting a single crystal silicon rod using the aforementioned cutting wire and when cutting a single crystal silicon rod using a conventional cutting wire, the feed rate of the single crystal, the cutting wire speed, and the flow rate of the cutting fluid are all different at the same feed position. When cutting a single crystal silicon rod using the aforementioned twisted cutting wire, the feed rate of the single crystal is increased, the cutting wire speed is increased, and the flow rate of the cutting fluid is not much different. The TTV and wire marks of the prepared silicon wafer are reduced, thus improving the cutting quality of the silicon wafer.
[0090] Due to the adoption of the above technical solution, the substrate of the cutting wire used for cutting solar photovoltaic silicon wafers is made of multiple single wires spirally wound and twisted together in a circular motion to form a spiral stranded wire structure. Multiple chip grooves are formed along the axial and circumferential directions of the substrate. Compared with the chip grooves of conventional cutting wires, the chip groove volume of the cutting wire is greatly increased, allowing the cutting fluid to be located in the chip grooves and flow along the chip grooves to the cutting position. At the same time, the chip grooves can store chips and discharge them as the cutting wire moves, which is conducive to the inflow of cutting fluid and the discharge of chips. It avoids silicon powder obstruction that could lead to wire breakage or insufficient cutting ability that could result in wire marks. The cutting surface has more plastic shear characteristics, improving the cutting quality. The number and diameter of the single wires can be selected according to the diameter of the cutting wire, and the number of diamond particles in the single wires can be increased to improve the cutting ability of the cutting wire and achieve finer wires.
[0091] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.
Claims
1. A silicon wafer dicing wire, characterized in that: Includes a matrix and a consolidation layer disposed on the outer surface of the matrix, wherein, The substrate includes multiple single wires, which are spirally wound and twisted together to form multiple chip grooves on the peripheral side of the substrate, so as to allow the inflow of cutting fluid and the discharge of chips during single crystal cutting. The consolidation layer is wrapped around the outer surface of the substrate to fix the multiple single wires.
2. The silicon wafer dicing wire according to claim 1, characterized in that: The multiple single wires are wound with a certain helix angle and a certain pitch. The relationship between the helix angle and the pitch is: h = πdtanα, where α is the helix angle, h is the pitch, and d is the diameter of the single wire.
3. The silicon wafer dicing wire according to claim 2, characterized in that: The pitch is controlled by the rotational speed and wire feed speed of the multiple strands twisted and rotated, and the pitch is 40-60 times the diameter of the single strand.
4. The silicon wafer dicing wire according to any one of claims 1-3, characterized in that: It also includes a cutting layer disposed on the outer surface of the consolidation layer, the cutting layer being distributed throughout the outer surface of the consolidation layer, for cutting single crystals.
5. The silicon wafer dicing wire according to claim 4, characterized in that: The cutting layer is a diamond-coated layer, with multiple diamond particles distributed across the outer surface of the consolidation layer.
6. The silicon wafer dicing wire according to claim 5, characterized in that: The particle density of the diamond abrasive particles is 250-350 particles / mm.
7. The silicon wafer dicing wire according to claim 6, characterized in that: The effective abrasive particles of the diamond abrasive are 150-250 particles / mm.
8. The silicon wafer dicing wire according to any one of claims 1-3 and 5-7, characterized in that: The consolidation layer is a nickel plating layer formed by electroplating nickel.
9. The silicon wafer dicing wire according to claim 1, characterized in that: The number of single lines is greater than or equal to 3, and the diameter of the single line is less than 30 μm.
10. The silicon wafer dicing wire according to claim 8, characterized in that: The plurality of chip-receiving grooves are arranged sequentially along the axial and circumferential directions of the substrate.
11. A method for cutting silicon wafers, characterized in that: A single-crystal silicon rod is cut into a silicon wafer using a cutting device having a silicon wafer cutting line as described in any one of claims 1-10; during the cutting process of the single-crystal silicon rod, as the feed position increases, the feed speed, cutting line speed and cutting fluid flow rate are controlled to increase first and then decrease.
12. The silicon wafer cutting method according to claim 11, characterized in that: The feed rate is 0-3 mm / min, the cutting line speed is 0-50 m / s, and the cutting fluid flow rate is 100-260 L / min.
13. A silicon wafer, characterized in that: The silicon wafer is prepared by the silicon wafer cutting method as described in any one of claims 11-12, wherein the TTV of the silicon wafer is 7-9 μm and the line marks are 5-6 μm.