Method for linearly cutting silicon wafer by adopting tungsten filament

Abstract

The invention provides a method for linearly cutting a silicon wafer by adopting a tungsten filament. The method comprises the steps of crystal bar pretreatment, crystal bar installation, wire net laying, cutting liquid adding, wire running, program setting and cutting starting which are carried out in sequence. Cutting wires adopted by the laying wire net are tungsten wires, and the comprehensive wire diameter of the tungsten wires is 42-48 microns. According to the invention, the tungsten wire with the superfine comprehensive wire diameter is used as the cutting wire, and through the adaptive cutting process, the high yield is ensured while the thin sheet cutting is realized, the wire breakage rate and the wire mark proportion are reduced, the sheet output number per kilogram and the silicon material utilization rate are improved, and the large-scale popularization and application are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells and relates to a method for cutting silicon wafers, in particular to a method for cutting silicon wafers using tungsten wires. Background Art

[0002] At present, the common method of silicon wafer cutting in the industry is carbon steel diamond wire cutting. This carbon steel diamond wire is composed of a carbon steel busbar substrate, a nickel coating and diamond powder particles. A layer of metal nickel is plated on the steel wire substrate by electroplating, and diamond particles are wrapped in the metal nickel layer, so that the diamond particles are consolidated on the steel wire substrate. The comprehensive wire diameter of the mainstream carbon steel wire is in the range of 48-58μm. After considerable development, the wire diameter of carbon steel diamond wire has evolved to a comprehensive wire diameter of 48μm. In order to ensure the tension required for cutting and the tension fluctuation margin during the cutting process, the thinning of carbon steel wire has approached the limit, and it is difficult to maintain the demand for cutting breakage rate. If we continue to explore wire diameters below 48μm, we need to convert the busbar material to complete the advancement of thinning.

[0003] As we all know, in the context of high silicon material prices, thinning and fine-wire are the most effective cost-reduction measures for silicon wafers. On the one hand, thinning of silicon wafers means an increase in the fragmentation rate, but under the same cutting process, diamond wires with thinner wire diameters cause less damage to the surface of silicon wafers during cutting, thereby bringing a higher yield rate; on the other hand, fine-wire has higher requirements for the cutting ability and tensile strength of diamond wires. In this industry context, tungsten wire came into being.

[0004] Compared with carbon steel wire, tungsten wire has high breaking force, high torsion value, high-density nickel coating and high corrosion resistance, so the excellent indicators of tungsten wire busbar are very suitable for the design requirements of ultra-fine wire and high-strength wire saw. With tungsten wire as the busbar matrix, matching with appropriate nickel coating and diamond powder particles, the comprehensive wire diameter range of tungsten wire can be controlled within 42-48μm, which is of great significance for thin-sheet cutting, increasing the number of pieces per kilogram, and improving the utilization rate of silicon materials.

[0005] Therefore, it can be seen that how to provide a method for cutting silicon wafers using tungsten wire to achieve thin-slice cutting and ensure a high yield rate by optimizing cutting conditions has become an urgent problem to be solved by people in this field. Summary of the invention

[0006] The purpose of the present invention is to provide a method for cutting silicon wafers using tungsten wire, which uses ultra-fine tungsten wire with a comprehensive wire diameter as the cutting wire. Through an adaptive cutting process, thin slice cutting is achieved while ensuring a high yield rate, reducing the wire breakage rate and wire mark ratio, and increasing the number of slices per kilogram and the utilization rate of silicon materials, which is conducive to large-scale promotion and application.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for cutting silicon wafers by using tungsten wire. The method comprises the following steps: pre-processing a crystal rod, installing a crystal rod, laying a wire net, adding a cutting fluid, running a wire, setting a program and starting cutting.

[0009] The cutting wire used for laying the wire mesh is tungsten wire, and the overall wire diameter of the tungsten wire is 42-48 μm, for example, it can be 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm or 48 μm, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0010] In the present invention, the tungsten wire is a tungsten wire commonly used in the art, which is different from the traditional carbon steel wire. The tungsten wire uses tungsten wire as a mother wire matrix, matched with a suitable nickel plating layer and diamond powder particles. For example, the tungsten wire disclosed in CN114480936A or CN113275659A can be used. As long as the purpose of tungsten wire cutting silicon wafers can be achieved, the specific structure of the tungsten wire is not particularly limited here.

[0011] The present invention adopts tungsten wire with ultra-fine comprehensive wire diameter as the cutting wire. Through the adaptive cutting process, it realizes thin slice cutting while ensuring a high yield rate, reduces the wire breakage rate and wire mark ratio, increases the number of slices per kilogram and the utilization rate of silicon materials, and is conducive to large-scale promotion and application.

[0012] Preferably, the crystal rod pretreatment comprises: selecting a crystal rod, and sequentially performing quality inspection and surface cleaning on the crystal rod to prevent impurities from adversely affecting the quality of the cut silicon wafers.

[0013] Preferably, the crystal ingot loading comprises: loading the crystal ingot into a clamping guide rail of a cutting machine workbench.

[0014] Preferably, the laying of the wire web comprises: laying the cutting wire on a main roller of a cutting machine.

[0015] Preferably, the laying tension of the cutting line is 3.7-3.8N, for example, it can be 3.7N, 3.71N, 3.72N, 3.73N, 3.74N, 3.75N, 3.76N, 3.77N, 3.78N, 3.79N or 3.8N, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] In the present invention, the laying tension of the cutting wire is adapted to the breaking tension (6.20-6.91N) of the tungsten wire itself, so as to reduce the risk of abnormal wire breakage of the tungsten wire during the silicon wafer cutting process.

[0017] Preferably, the cutting fluid is a mixture of coolant and water, and the mixing volume ratio of the coolant and water is (2.6-3.0):(450-500), for example, it can be 2.6:450, 2.7:450, 2.8:480, 2.9:500 or 3.0:500, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the components of the cooling liquid include any one of pentylene glycol, polyether, glycol polyoxyethylene ether or p-tert-butylbenzoic acid, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of pentylene glycol and polyether, a combination of polyether and glycol polyoxyethylene ether, a combination of glycol polyoxyethylene ether and p-tert-butylbenzoic acid, a combination of pentylene glycol, polyether and glycol polyoxyethylene ether, a combination of polyether, glycol polyoxyethylene ether and p-tert-butylbenzoic acid, or a combination of pentylene glycol, polyether, glycol polyoxyethylene ether and p-tert-butylbenzoic acid.

[0019] Preferably, the temperature of the cutting fluid is 22-24°C, for example, it can be 22°C, 22.2°C, 22.4°C, 22.6°C, 22.8°C, 23°C, 23.2°C, 23.4°C, 23.6°C, 23.8°C or 24°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the flow rate of the cutting fluid is 200-220 L / min, for example, it can be 200 L / min, 202 L / min, 204 L / min, 206 L / min, 208 L / min, 210 L / min, 212 L / min, 214 L / min, 216 L / min, 218 L / min or 220 L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Compared with the traditional carbon steel wire, the present invention uses a tungsten wire with a very fine wire diameter to cut silicon wafers. The matching guide wheel slot is significantly reduced, and the heat generated by the crystal rod increases due to the increase in saw seams per unit area. In this regard, the present invention increases the amount of cutting fluid used, effectively reducing the risk of dark cracks in the crystal rod due to excessive heat. At the same time, on this basis, the mixed volume ratio of coolant and water in the cutting fluid and the temperature range of the cutting fluid are further limited, thereby increasing the yield rate of the cut silicon wafers as much as possible.

[0022] In addition, during the process of tungsten wire cutting silicon wafers, due to the characteristic of small pitch of the guide wheel groove, the silicon powder generated in the cutting process is difficult to be brought out from the saw seam. In order to increase the amount of silicon powder brought out from the saw seam, the flow rate of the cutting fluid is limited to 200-220L / min in the present invention, which is significantly higher than the flow rate range of the cutting fluid used for traditional carbon steel wire, thereby fully bringing out the silicon powder in the saw seam.

[0023] Preferably, the line running comprises: utilizing a main roller of a cutting machine to run the cutting line used for cutting from a pay-off wheel to a take-up wheel.

[0024] Preferably, the setting procedure includes: setting the running speed of the cutting line in the cutting machine into three stages, including the knife entry stage, the mid-cutting stage and the knife closing stage, and the running acceleration of the cutting line in the three stages is 5-8m / s 2 , for example, it can be 5m / s 2 、5.5m / s 2 、6m / s 2 、6.5m / s 2 , 7m / s 2 , 7.5m / s 2 or 8m / s 2 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In the present invention, since the hardness of tungsten wire is generally about 67% higher than that of carbon steel wire, in order to reduce the risk of wire jumping during the cutting process, when matching the guide wheel, the depth of the guide wheel groove needs to be increased by 10-20μm, and at the same time, the circulation amount of the program wire is appropriately reduced, and the running speed of the cutting line is appropriately reduced.

[0026] Preferably, the knife entry stage is performed in a knife entry area, and the knife entry area is between 0-25 mm from the cutting starting point.

[0027] Preferably, the table speed in the knife entry stage is set to 1500-2600 μm / min, for example, it can be 1500 μm / min, 1600 μm / min, 1800 μm / min, 2000 μm / min, 2200 μm / min, 2400 μm / min or 2600 μm / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the amount of wire entering the knife stage is greater than the amount of wire returning, and the circulation amount is 20-100m, for example, it can be 20m, 25m, 30m, 35m, 40m, 45m, 50m, 55m, 60m, 65m, 70m, 75m, 80m, 85m, 90m, 95m or 100m, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the mid-stage cutting is performed in the main cutting area, and the main cutting area is between 25-150 mm from the cutting starting point.

[0030] Preferably, the table speed in the middle of the cutting is set to 2000-2700 μm / min, for example, it can be 2000 μm / min, 2100 μm / min, 2200 μm / min, 2300 μm / min, 2400 μm / min, 2500 μm / min, 2600 μm / min or 2700 μm / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the incoming line volume in the middle of the cutting is greater than the returning line volume, and the circulation volume is 100-300m, for example, it can be 100m, 120m, 140m, 160m, 180m, 200m, 220m, 240m, 260m, 280m or 300m, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the knife closing stage is performed in a knife closing area, and the knife closing area is between 150 mm from the cutting start point and the cutting end point.

[0033] Preferably, the table speed in the knife-retracting stage is set to 80-150 μm / min, for example, it can be 80 μm / min, 90 μm / min, 100 μm / min, 110 μm / min, 120 μm / min, 130 μm / min, 140 μm / min or 150 μm / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the amount of wire entering the knife closing stage is less than the amount of wire returning, and the circulation amount is 200-1500m, for example, it can be 200m, 300m, 400m, 500m, 600m, 700m, 800m, 900m, 1000m, 1100m, 1200m, 1300m, 1400m or 1500m, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, starting cutting includes: clicking a cutting confirmation button, and the cutting machine enters an automatic cutting state.

[0036] Preferably, the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically replenish recycled water, and at the same time, the original cutting fluid in the cylinder starts to flow out for overflow replacement; as the cutting depth increases, the overflow flow rate increases accordingly, and when the cutting depth is between 0-182mm, the cutting fluid concentration in the cylinder is always controlled to be stable in the range of 1-1.4wt%; when the cutting depth is between 182mm and the end of cutting, the cutting fluid concentration in the cylinder is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1-1.4 times the volume of the cylinder, and the cylinder is used to hold the cutting fluid.

[0037] In the present invention, the overflow scheme is formulated based on the characteristics that the sawing kerf of the tungsten wire cutting silicon wafer is very small and silicon powder is not easily brought out, so as to fully reduce the wire breakage rate and improve the cutting quality of the silicon wafer.

[0038] The present invention controls the concentration of the cutting fluid to be stable within the range of 1-1.4wt%, for example, it can be 1wt%, 1.05wt%, 1.1wt%, 1.15wt%, 1.2wt%, 1.25wt%, 1.3wt%, 1.35wt% or 1.4wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] For each cut made by the present invention, the displacement volume of the cutting fluid is 1-1.4 times of the cylinder volume, for example, it can be 1, 1.1, 1.2, 1.3 or 1.4 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the increasing interval of the overflow flow is 240-480L / h, for example, it can be 240L / h, 260L / h, 280L / h, 300L / h, 320L / h, 340L / h, 360L / h, 380L / h, 400L / h, 420L / h, 440L / h, 460L / h or 480L / h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] As a preferred technical solution of the present invention, the method comprises the following steps:

[0042] (1) Crystal ingot pretreatment: Select the crystal ingot, perform quality inspection and surface cleaning on the crystal ingot in turn;

[0043] (2) Crystal ingot installation: Load the crystal ingot into the clamping guide rail of the cutting machine workbench;

[0044] (3) Laying the wire mesh: Use tungsten wire with a comprehensive wire diameter of 42-48 μm as the cutting wire, lay the cutting wire on the main roller of the cutting machine, and control the laying tension to 3.7-3.8N;

[0045] (4) adding cutting fluid: the cutting fluid is a mixture of coolant and water in a volume ratio of (2.6-3.0):(450-500), the coolant component includes any one of pentanediol, polyether, glycol polyoxyethylene ether or p-tert-butylbenzoic acid or a combination of at least two thereof, the temperature of the cutting fluid is 22-24° C., and the flow rate is 200-220 L / min;

[0046] (5) Running line: Use the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel;

[0047] (6) Setting program: The running speed of the cutting line is set in the cutting machine in three stages, including the cutting entry stage, the mid-cutting stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 5-8m / s. 2 ; The knife entry stage is carried out between 0-25mm from the cutting starting point, the table speed is set to 1500-2600μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 20-100m; the mid-cutting stage is carried out between 25-150mm from the cutting starting point, the table speed is set to 2000-2700μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 100-300m; the knife closing stage is carried out between 150mm from the cutting starting point to the cutting end point, the table speed is set to 80-150μm / min, the wire feeding amount is less than the return wire amount, and the circulation amount is 200-1500m;

[0048] (7) Start cutting: Click the cutting confirmation button, and the cutting machine enters the automatic cutting state; the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically add recycled water, and at the same time, the original cutting fluid in the cylinder body starts to flow out, and overflow replacement is performed; as the cutting depth increases, the overflow flow rate increases accordingly, and the increasing range of the overflow flow rate is 240-480L / h; when the cutting depth is between 0-182mm, the cutting fluid concentration in the cylinder body is always controlled to be stable in the range of 1-1.4wt%; between the cutting depth of 182mm and the end of cutting, the cutting fluid concentration in the cylinder body is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1-1.4 times the volume of the cylinder body, and the cylinder body is used to hold the cutting fluid.

[0049] In the traditional single-cylinder cutting mode, as the cutting progress gradually increases, the concentration of silicon powder gradually increases. If the silicon powder concentration of the cutting water in the cutting cylinder is too high, the silicon powder carry-out rate in the saw seam will be limited, thereby reducing the cutting force of the wire and affecting the yield rate.

[0050] In the overflow cutting mode, as the cutting progress gradually increases, the overflow flow is adjusted to displace a portion of the cutting fluid in the cylinder, thereby controlling the concentration of the cutting fluid to be stable within the range of 1-1.4wt%, thereby fully utilizing the cutting force of the steel wire.

[0051] Preferably, the present invention starts overflowing from the 60mm feed position, the increasing interval of the overflow flow is 240-480L / h, and the concentration of the cutting fluid is controlled to be stable in the range of 1-1.4wt%. At the end of cutting, the concentration of the cutting fluid is stabilized at 1.25wt%, and for each cut, the displacement volume of the cutting fluid is 1.2 times the volume of the cylinder.

[0052] In the present invention, since the hardness of tungsten wire is generally about 67% higher than that of carbon steel wire, in order to reduce the risk of dark cracks during the cutting process, the running speed of the cutting wire should be appropriately reduced during the cutting process, and the temperature of the cutting fluid should be appropriately increased.

[0053] Preferably, the running speed of the mid-cutting cutting line of the present invention is 36 m / s, and the temperature of the cutting fluid is 24° C., which can effectively reduce the proportion of dark cracks.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The present invention adopts tungsten wire with ultra-fine comprehensive wire diameter as the cutting wire. Through the adaptive cutting process, it realizes thin slice cutting while ensuring a high yield rate, reduces the wire breakage rate and wire mark ratio, increases the number of slices per kilogram and the utilization rate of silicon materials, and is conducive to large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the structure of the tungsten wire used in the silicon wafer cutting method provided by the present invention;

[0057] Figure 2 This is a schematic diagram of the structure of the carbon steel wire used in the silicon wafer cutting method provided in Example 1-2.

[0058] Among them: 10-tungsten wire busbar; 11-carbon steel busbar; 20-nickel plating; 30-diamond powder particles. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0060] Example 1

[0061] This embodiment provides a method for cutting a silicon wafer using a tungsten wire. The structure of the tungsten wire is as follows: Figure 1 As shown, a tungsten wire busbar 10 is used as a substrate, matched with a suitable nickel coating 20 and diamond powder particles 30, and its model is a tungsten wire 28, and the overall wire diameter is 45 μm (tolerance ±3 μm).

[0062] The method provided in this implementation comprises the following steps:

[0063] (1) Crystal rod pretreatment: Select a single crystal rod with a cross-sectional size of 182 mm × 182 mm and a diameter of 247 mm, and perform quality inspection and surface cleaning on the single crystal rod in turn;

[0064] (2) Crystal ingot installation: Load the single crystal ingot into the clamping guide rail of the cutting machine workbench;

[0065] (3) Laying the wire mesh: Lay the cutting wire on the main roller of the cutting machine, and control the laying tension to 3.7N and the laying spacing to 198μm;

[0066] (4) adding cutting fluid: the cutting fluid is a mixture of coolant and water in a volume ratio of 3.0:450, the coolant comprises an equal volume combination of polyether and pentanediol, the temperature of the cutting fluid is 24° C., and the flow rate of the cutting fluid is 220 L / min;

[0067] (5) Running line: Use the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel;

[0068] (6) Setting program: The running speed of the cutting line is set in the cutting machine in three stages, including the cutting entry stage, the mid-cutting stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 5m / s. 2 ; The knife entry stage is carried out between 0-25mm from the cutting starting point, the knife is fed at 25mm, the table speed is set to 2300μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 90m; the mid-cutting stage is carried out between 25-150mm from the cutting starting point, the knife is fed at 150mm, the steel wire speed is 36m / s, the table speed is set to 2000μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 220m; the knife closing stage is carried out between 150mm from the cutting starting point to the cutting end point, the table speed is set to 80μm / min, the wire feeding amount is less than the return wire amount, and the circulation amount is 1300m;

[0069] (7) Start cutting: Click the cutting confirmation button, and the cutting machine enters the automatic cutting state; the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically add recycled water, and at the same time, the original cutting fluid in the cylinder body starts to flow out, and overflow replacement is performed; as the cutting depth increases, the overflow flow rate increases accordingly, and the increasing range of the overflow flow rate is 240-480L / h; when the cutting depth is between 0-182mm, the cutting fluid concentration in the cylinder body is always controlled to be stable in the range of 1-1.4wt%; between the cutting depth of 182mm and the end of cutting, the cutting fluid concentration in the cylinder body is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1.2 times the volume of the cylinder body, and the cylinder body is used to hold the cutting fluid.

[0070] Example 2

[0071] This embodiment provides a method for cutting a silicon wafer using a tungsten wire. The structure of the tungsten wire is as follows: Figure 1 As shown, a tungsten wire busbar 10 is used as a substrate, matched with a suitable nickel coating 20 and diamond powder particles 30, and its model is a tungsten wire 28, and the overall wire diameter is 45 μm (tolerance ±3 μm).

[0072] The method provided in this implementation comprises the following steps:

[0073] (1) Crystal rod pretreatment: Select a single crystal rod with a cross-sectional size of 182 mm × 182 mm and a diameter of 247 mm, and perform quality inspection and surface cleaning on the single crystal rod in turn;

[0074] (2) Crystal ingot installation: Load the single crystal ingot into the clamping guide rail of the cutting machine workbench;

[0075] (3) Laying the wire mesh: Lay the cutting wire on the main roller of the cutting machine, and control the laying tension to 3.8N and the laying spacing to 198μm;

[0076] (4) adding cutting fluid: the cutting fluid is a mixture of coolant and water in a volume ratio of 3.0:500, the coolant comprises an equal volume combination of polyether and pentanediol, the temperature of the cutting fluid is 24° C., and the flow rate is 220 L / min;

[0077] (5) Running line: Use the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel;

[0078] (6) Setting program: The running speed of the cutting line is set in the cutting machine in three stages, including the cutting entry stage, the mid-cutting stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 8m / s. 2; The knife entry stage is carried out between 0-25mm from the cutting starting point, the knife is fed at 25mm, the table speed is set to 2600μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 80m; the mid-cutting stage is carried out between 25-150mm from the cutting starting point, the knife is fed at 150mm, the steel wire speed is 38m / s, the table speed is set to 2300μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 200m; the knife closing stage is carried out between 150mm from the cutting starting point to the cutting end point, the table speed is set to 150μm / min, the wire feeding amount is less than the return wire amount, and the circulation amount is 1400m;

[0079] (7) Start cutting: Click the cutting confirmation button, and the cutting machine enters the automatic cutting state; the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically add recycled water, and at the same time, the original cutting fluid in the cylinder body starts to flow out, and overflow replacement is performed; as the cutting depth increases, the overflow flow rate increases accordingly, and the increasing range of the overflow flow rate is 240-480L / h; when the cutting depth is between 0-182mm, the cutting fluid concentration in the cylinder body is always controlled to be stable in the range of 1-1.4wt%; between the cutting depth of 182mm and the end of cutting, the cutting fluid concentration in the cylinder body is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1.2 times the volume of the cylinder body, and the cylinder body is used to hold the cutting fluid.

[0080] Example 3

[0081] This embodiment provides a method for cutting a silicon wafer using a tungsten wire. The structure of the tungsten wire is as follows: Figure 1 As shown, a tungsten wire busbar 10 is used as a substrate, matched with a suitable nickel coating 20 and diamond powder particles 30, and its model is a tungsten wire 28, and the overall wire diameter is 45 μm (tolerance ±3 μm).

[0082] The method provided in this implementation comprises the following steps:

[0083] (1) Crystal rod pretreatment: Select a single crystal rod with a cross-sectional size of 182 mm × 182 mm and a diameter of 247 mm, and perform quality inspection and surface cleaning on the single crystal rod in turn;

[0084] (2) Crystal ingot installation: Load the single crystal ingot into the clamping guide rail of the cutting machine workbench;

[0085] (3) Laying the wire mesh: Lay the cutting wire on the main roller of the cutting machine, and control the laying tension to 3.7N and the laying spacing to 198μm;

[0086] (4) adding cutting fluid: the cutting fluid is a mixture of coolant and water in a volume ratio of 3.0:450, the coolant comprises an equal volume combination of polyether and pentanediol, the temperature of the cutting fluid is 22° C., and the flow rate of the cutting fluid is 220 L / min;

[0087] (5) Running line: Use the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel;

[0088] (6) Setting program: The running speed of the cutting line is set in the cutting machine in three stages, including the cutting entry stage, the mid-cutting stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 5m / s. 2 ; The knife entry stage is carried out between 0-25mm from the cutting starting point, the knife is fed at 25mm, the table speed is set to 2300μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 90m; the mid-cutting stage is carried out between 25-150mm from the cutting starting point, the knife is fed at 150mm, the steel wire speed is 38m / s, the table speed is set to 2000μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 220m; the knife closing stage is carried out between 150mm from the cutting starting point to the cutting end point, the table speed is set to 80μm / min, the wire feeding amount is less than the return wire amount, and the circulation amount is 1300m;

[0089] (7) Start cutting: Click the cutting confirmation button, and the cutting machine enters the automatic cutting state; the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically add recycled water, and at the same time, the original cutting fluid in the cylinder body starts to flow out, and overflow replacement is performed; as the cutting depth increases, the overflow flow rate increases accordingly, and the increasing range of the overflow flow rate is 240-480L / h; when the cutting depth is between 0-182mm, the cutting fluid concentration in the cylinder body is always controlled to be stable in the range of 1-1.4wt%; between the cutting depth of 182mm and the end of cutting, the cutting fluid concentration in the cylinder body is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1.2 times the volume of the cylinder body, and the cylinder body is used to hold the cutting fluid.

[0090] Example 4

[0091] This embodiment provides a method for cutting a silicon wafer using a tungsten wire. The structure of the tungsten wire is as follows: Figure 1 As shown, a tungsten wire busbar 10 is used as a substrate, matched with a suitable nickel coating 20 and diamond powder particles 30, and its model is a tungsten wire 28, and the overall wire diameter is 45 μm (tolerance ±3 μm).

[0092] The method provided in this implementation comprises the following steps:

[0093] (1) Crystal rod pretreatment: Select a single crystal rod with a cross-sectional size of 182 mm × 182 mm and a diameter of 247 mm, and perform quality inspection and surface cleaning on the single crystal rod in turn;

[0094] (2) Crystal ingot installation: Load the single crystal ingot into the clamping guide rail of the cutting machine workbench;

[0095] (3) Laying the wire mesh: Lay the cutting wire on the main roller of the cutting machine, and control the laying tension to 3.7N and the laying spacing to 198μm;

[0096] (4) adding cutting fluid: the cutting fluid is a mixture of coolant and water in a volume ratio of 3.0:450, the coolant comprises an equal volume combination of polyether and pentanediol, the temperature of the cutting fluid is 24° C., and the flow rate of the cutting fluid is 220 L / min;

[0097] (5) Running line: Use the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel;

[0098] (6) Setting program: The running speed of the cutting line is set in the cutting machine in three stages, including the cutting entry stage, the mid-cutting stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 5m / s. 2 ; The knife entry stage is carried out between 0-25mm from the cutting starting point, the knife is fed at 25mm, the table speed is set to 2300μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 90m; the mid-cutting stage is carried out between 25-150mm from the cutting starting point, the knife is fed at 150mm, the steel wire speed is 36m / s, the table speed is set to 2000μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 220m; the knife closing stage is carried out between 150mm from the cutting starting point to the cutting end point, the table speed is set to 80μm / min, the wire feeding amount is less than the return wire amount, and the circulation amount is 1300m;

[0099] (7) Start cutting: Click the cutting confirmation button, and the cutting machine enters the automatic cutting state; the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically add recycled water, and at the same time, the original cutting fluid in the cylinder body starts to flow out, and overflow replacement is performed; as the cutting depth increases, the overflow flow rate increases accordingly, and the increasing range of the overflow flow rate is 300-480L / h; between the cutting depth of 0-182mm, the cutting fluid concentration in the cylinder body is always controlled to be stable in the range of 1-1.4wt%; between the cutting depth of 182mm and the end of cutting, the cutting fluid concentration in the cylinder body is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1.2 times the volume of the cylinder body, and the cylinder body is used to hold the cutting fluid.

[0100] Example 5

[0101] This embodiment provides a method for cutting a silicon wafer using a tungsten wire. The structure of the tungsten wire is as follows: Figure 1 As shown, a tungsten wire busbar 10 is used as a substrate, matched with a suitable nickel coating 20 and diamond powder particles 30, and its model is a tungsten wire 28, and the overall wire diameter is 45 μm (tolerance ±3 μm).

[0102] The method provided in this implementation comprises the following steps:

[0103] (1) Crystal rod pretreatment: Select a single crystal rod with a cross-sectional size of 182 mm × 182 mm and a diameter of 247 mm, and perform quality inspection and surface cleaning on the single crystal rod in turn;

[0104] (2) Crystal ingot installation: Load the single crystal ingot into the clamping guide rail of the cutting machine workbench;

[0105] (3) Laying the wire mesh: Lay the cutting wire on the main roller of the cutting machine, and control the laying tension to 3.7N and the laying spacing to 198μm;

[0106] (4) adding cutting fluid: the cutting fluid is a mixture of coolant and water in a volume ratio of 3.0:450, the coolant comprises an equal volume combination of polyether and pentanediol, the temperature of the cutting fluid is 24° C., and the flow rate of the cutting fluid is 220 L / min;

[0107] (5) Running line: Use the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel;

[0108] (6) Setting program: The running speed of the cutting line is set in the cutting machine in three stages, including the cutting entry stage, the mid-cutting stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 5m / s. 2 ; The knife entry stage is carried out between 0-25mm from the cutting starting point, the knife is fed at 25mm, the table speed is set to 2300μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 90m; the mid-cutting stage is carried out between 25-150mm from the cutting starting point, the knife is fed at 150mm, the steel wire speed is 36m / s, the table speed is set to 2000μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 220m; the knife closing stage is carried out between 150mm from the cutting starting point to the cutting end point, the table speed is set to 80μm / min, the wire feeding amount is less than the return wire amount, and the circulation amount is 1300m;

[0109] (7) Start cutting: Click the cutting confirmation button, and the cutting machine enters the automatic cutting state; the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically add recycled water, and at the same time, the original cutting fluid in the cylinder body starts to flow out, and overflow replacement is performed; as the cutting depth increases, the overflow flow rate increases accordingly, and the increasing range of the overflow flow rate is 360-540L / h; between the cutting depth of 0-182mm, the cutting fluid concentration in the cylinder body is always controlled to be stable in the range of 1-1.4wt%; between the cutting depth of 182mm and the end of cutting, the cutting fluid concentration in the cylinder body is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1.2 times the volume of the cylinder body, and the cylinder body is used to hold the cutting fluid.

[0110] Comparative Example 1

[0111] This comparative example provides a method for cutting silicon wafers using a carbon steel wire. The structure of the carbon steel wire is as follows: Figure 2 As shown, a carbon steel busbar 11 is used as a substrate, and a suitable nickel coating 20 and diamond powder particles 30 are matched. The model is carbon steel 35, and the comprehensive wire diameter is 48 μm. Except for setting the cutting fluid temperature to 20° C., the other steps and conditions are the same as those in Example 3, so they are not repeated here.

[0112] Comparative Example 2

[0113] This comparative example provides a method for cutting silicon wafers using a carbon steel wire. The structure of the carbon steel wire is as follows: Figure 2 As shown, a carbon steel busbar 11 is used as a substrate, and a suitable nickel coating 20 and diamond powder particles 30 are matched. The model is carbon steel 35, and the comprehensive wire diameter is 48 μm. Except for setting the steel wire speed in the middle of cutting to 38 m / s and the cutting fluid temperature to 20° C., the other steps and conditions are the same as those in Example 4, so they are not repeated here.

[0114] The cutting data obtained in Examples 1-5 and Comparative Examples 1-2 are shown in Table 1 below.

[0115] Table 1

[0116]

[0117] It can be seen from Table 1 that compared with Comparative Examples 1-2, Examples 1-5 have obvious advantages in wire breakage rate (reduced by 1.4%-2.7%) under the same cutting mode. In particular, when the overflow flow rate matching the overflow cutting is in the increment range of 240-480L / h, the steel wire speed in the middle of cutting is 36m / s, and the temperature of the cutting liquid is 24°C, the wire breakage rate and dark crack ratio are the lowest, and the yield of cutting silicon wafers is the best; when the overflow flow is too large, due to the reduction in the concentration of the effective components of the coolant, the abnormal wire breakage rate during the cutting process will increase significantly; when the overflow flow is too low, the silicon powder concentration of the cutting water in the cutting cylinder cannot be effectively reduced, which will result in a limited rate of silicon powder removal in the saw seam, thereby reducing the cutting force of the wire.

[0118] It can be seen that the present invention adopts ultra-fine tungsten wire with a comprehensive wire diameter as the cutting wire. Through an adapted cutting process, compared with carbon steel wire, the yield of cutting silicon wafers can be greatly improved (A rate is increased by 1%-2%), and the number of wafers per kilogram can be increased by more than 2500pcs / T.

[0119] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for cutting silicon wafers using tungsten wire, characterized in that: The method includes sequentially performing crystal rod pretreatment, crystal rod installation, wire mesh laying, cutting fluid addition, wire running, program setting and cutting start; The cutting wire used for laying the wire mesh is a tungsten wire, and the overall wire diameter of the tungsten wire is 42-48 μm.

2. The method according to claim 1, characterized in that The crystal rod pretreatment includes: selecting a crystal rod, and performing quality inspection and surface cleaning on the crystal rod in sequence.

3. The method according to claim 1 or 2, characterized in that: The crystal rod installation includes: installing the crystal rod into the clamping guide rail of the cutting machine workbench.

4. The method according to any one of claims 1 to 3, characterized in that: The laying of the wire mesh comprises: laying the cutting wire on the main roller of the cutting machine; Preferably, the laying tension of the cutting line is 3.7-3.8N.

5. The method according to any one of claims 1 to 4, characterized in that: The cutting fluid is a mixture of coolant and water, and the mixing volume ratio of the coolant and water is (2.6-3.0):(450-500); Preferably, the components of the cooling liquid include any one or a combination of at least two of pentanediol, polyether, glycol polyoxyethylene ether or p-tert-butylbenzoic acid; Preferably, the temperature of the cutting fluid is 22-24°C; Preferably, the flow rate of the cutting fluid is 200-220 L / min.

6. The method according to any one of claims 1 to 5, characterized in that: The line running comprises: utilizing the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel.

7. The method according to any one of claims 1 to 6, characterized in that: The setting procedure includes: setting the running speed of the cutting line in the cutting machine into three stages, including the cutting entry stage, the cutting mid-stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 5-8m / s 2 .

8. The method according to claim 7, characterized in that The knife entry stage is performed in the knife entry area, and the knife entry area is between 0-25 mm from the cutting starting point; Preferably, the table speed in the knife entry stage is set to 1500-2600 μm / min; Preferably, the incoming wire volume in the knife entry stage is greater than the return wire volume, and the circulation volume is 20-100m; Preferably, the mid-stage cutting is performed in the main cutting area, and the main cutting area is between 25-150 mm from the cutting starting point; Preferably, the table speed in the mid-cutting period is set to 2000-2700 μm / min; Preferably, the incoming wire volume in the middle of the cutting is greater than the returning wire volume, and the circulation volume is 100-300m; Preferably, the knife closing stage is carried out in a knife closing area, and the knife closing area is between 150 mm from the cutting start point and the cutting end point; Preferably, the table speed in the knife closing stage is set to 80-150 μm / min; Preferably, the incoming wire volume in the knife closing stage is less than the returning wire volume, and the circulation volume is 200-1500m.

9. The method according to any one of claims 1 to 8, characterized in that: The starting cutting includes: clicking a cutting confirmation button, and the cutting machine enters an automatic cutting state; Preferably, the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically replenish recycled water, and at the same time, the original cutting fluid in the cylinder starts to flow out for overflow replacement; as the cutting depth increases, the overflow flow rate gradually increases accordingly, and when the cutting depth is between 0-182mm, the concentration of the cutting fluid in the cylinder is always controlled to be stable within the range of 1-1.4wt%; when the cutting depth is between 182mm and the end of cutting, the concentration of the cutting fluid in the cylinder is controlled to be stable at 1.25wt%; for each cutting, the replacement volume of the cutting fluid is 1-1.4 times the volume of the cylinder, and the cylinder is used to contain the cutting fluid; Preferably, the increasing range of the overflow flow rate is 240-480 L / h.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) Crystal ingot pretreatment: Select the crystal ingot, perform quality inspection and surface cleaning on the crystal ingot in turn; (2) Crystal ingot installation: Load the crystal ingot into the clamping guide rail of the cutting machine workbench; (3) Laying the wire mesh: Use tungsten wire with a comprehensive wire diameter of 42-48 μm as the cutting wire, lay the cutting wire on the main roller of the cutting machine, and control the laying tension to 3.7-3.8N; (4) adding cutting fluid: the cutting fluid is a mixture of coolant and water in a volume ratio of (2.6-3.0):(450-500), the coolant component includes any one of pentanediol, polyether, glycol polyoxyethylene ether or p-tert-butylbenzoic acid or a combination of at least two thereof, the temperature of the cutting fluid is 22-24° C., and the flow rate is 200-220 L / min; (5) Running line: Use the main roller of the cutting machine to run the cutting line used for cutting from the pay-off wheel to the take-up wheel; (6) Setting program: The running speed of the cutting line is set in the cutting machine in three stages, including the cutting entry stage, the mid-cutting stage and the cutting end stage, and the running acceleration of the cutting line in the three stages is 5-8m / s. 2 ; The knife entry stage is carried out between 0-25mm from the cutting starting point, the table speed is set to 1500-2600μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 20-100m; the mid-cutting stage is carried out between 25-150mm from the cutting starting point, the table speed is set to 2000-2700μm / min, the wire feeding amount is greater than the return wire amount, and the circulation amount is 100-300m; the knife closing stage is carried out between 150mm from the cutting starting point to the cutting end point, the table speed is set to 80-150μm / min, the wire feeding amount is less than the return wire amount, and the circulation amount is 200-1500m; (7) Start cutting: Click the cutting confirmation button, and the cutting machine enters the automatic cutting state; the automatic cutting state is matched with an overflow scheme, and the overflow scheme includes: when the cutting depth reaches 60mm, the machine starts to automatically add recycled water, and at the same time, the original cutting fluid in the cylinder body starts to flow out, and overflow replacement is performed; as the cutting depth increases, the overflow flow rate increases accordingly, and the increasing range of the overflow flow rate is 240-480L / h; when the cutting depth is between 0-182mm, the cutting fluid concentration in the cylinder body is always controlled to be stable in the range of 1-1.4wt%; between the cutting depth of 182mm and the end of cutting, the cutting fluid concentration in the cylinder body is controlled to be stable at 1.25wt%; for each cut, the replacement volume of the cutting fluid is 1-1.4 times the volume of the cylinder body, and the cylinder body is used to hold the cutting fluid.

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