Tungsten filament twisted cutting wire, preparation method and silicon wafer cutting method

Abstract

The invention provides a tungsten filament twisted cutting wire, a preparation method and a silicon wafer cutting method.The tungsten filament twisted cutting wire comprises a cutting wire body, a plurality of insulating layers and a plurality of diamond layers, the insulating layers and the diamond layers are arranged on the outer side of the cutting wire body, the cutting wire body comprises a plurality of tungsten filaments, and the tungsten filaments are spirally wound and twisted in the axial direction and the circumferential direction of the cutting wire body; a plurality of chip flutes are formed in the circumferential direction and the axial direction of the tangent line body, and the diamond layer is arranged at the maximum outer diameter position of the tangent line body. The cutting wire has the beneficial effects that the tungsten filament is adopted as the bus of the cutting wire, and compared with a conventional cutting wire adopting a carbon steel wire as the bus, the tungsten filament has higher tensile strength and higher flexibility, the wire breakage rate is reduced, the wire diameter of the drawn cutting wire is thinner, and the loss of a silicon wafer is reduced; the diamond layers are distributed in the axial direction of the cutting line body, so that the diamond layers fully participate in cutting, and the cutting capacity of the cutting line is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of silicon wafer cutting, and particularly relates to a tungsten wire twisted cutting line, a preparation method and a silicon wafer cutting method. BACKGROUND

[0002] The diamond wire saw cutting technology is widely applied to the machining process of hard and brittle materials such as monocrystalline silicon and sapphire due to high machining efficiency and small cutting loss. With the continuous fluctuation of the price of silicon material at the bottom of the "L" type, the competition between industries is fierce, and the industry accelerates cost reduction. Fine wire is the main means of current cost reduction, and the kilogram wafer output is improved by reducing the wire diameter. The tensile strength of the carbon steel wire itself has reached the limit, and the theoretical breaking gradually decreases. When the carbon steel wire diameter reaches 28 microns, the breaking force is basically limited to 4.8N, and the diameter of the single carbon steel wire cannot be further reduced to achieve fine wire cutting. Moreover, when the wire diameter is reduced, the liquid carrying capacity of the cutting wire is also reduced, resulting in problems such as color difference and large TTV in the cutting silicon wafer. SUMMARY

[0003] In view of the above problems, the application provides a tungsten wire twisted cutting line, a preparation method and a silicon wafer cutting method to solve the above or other previous problems existing in the prior art.

[0004] To solve the above technical problems, the technical scheme adopted by the application is as follows: a tungsten wire twisted cutting line, comprising a cutting wire body and a plurality of insulating layers and a plurality of diamond layers arranged on the outer side of the cutting wire body, the cutting wire body comprising a plurality of tungsten wires, the plurality of tungsten wires being spirally wound along the axial direction and the circumferential direction of the cutting wire body, and being twisted and arranged, a plurality of chip grooves being formed along the circumferential and axial directions of the cutting wire body, and the diamond layer being arranged at the maximum outer diameter of the cutting wire body.

[0005] Further, the ratio of the twisting pitch of the cutting wire body to the diameter of the tungsten wire is 8-10:1.

[0006] Further, the diameters of the plurality of tungsten wires are the same.

[0007] Further, the thickness of the insulating layer is less than the height of the diamond particles in the diamond layer.

[0008] A preparation method of a tungsten wire twisted cutting line, which is prepared by using a plurality of tungsten wires, comprising the following steps:

[0009] The plurality of tungsten wires are plied and twisted to form a cutting wire body;

[0010] The cutting wire body is subjected to insulation treatment to form an insulating layer on the outer surface of the cutting wire body;

[0011] The insulating layer at the maximum outer diameter of the cutting wire body is removed;

[0012] A diamond layer is prepared at the part of the tangent body without the insulating layer.

[0013] Further, before the plurality of tungsten wires are twisted, each tungsten wire is subjected to a surface activation treatment, which includes acid treatment or alkali treatment.

[0014] Further, in the step of twisting the plurality of tungsten wires, the following steps are included:

[0015] Twisting: the plurality of tungsten wires are twisted simultaneously according to a certain twisting pitch with a certain twisting force;

[0016] Untwisting: the twisted wire after the twisting is untwisted with a certain tension, the direction of the tension is opposite to that of the twisting force, and the rotating force is released.

[0017] Further, the twisting force is 0.4-0.8 N;

[0018] And / or, the ratio of the twisting pitch to the diameter of the tungsten wire is 8-10:1;

[0019] And / or, the tension is 0.1-0.3 N.

[0020] Further, in the step of insulating the tangent body, the insulating treatment includes spraying method.

[0021] Further, the method of preparing the diamond layer includes electroplating method.

[0022] Further, the material of the insulating layer is polytetrafluoroethylene;

[0023] And / or, the thickness of the insulating layer is less than the height of the diamond particles in the diamond layer.

[0024] Further, along the circumferential direction of the maximum outer diameter of the tangent body, the tangent body is polished by polishing to remove the insulating layer at the maximum outer diameter of the tangent body.

[0025] A silicon wafer cutting method, using a cutting device with a tungsten wire twisted cutting line as described above to cut a single crystal silicon rod, during the cutting of the single crystal silicon, using only the feeding mode for cutting, as the feeding position increases, the feeding speed is first increased and then decreased, and the cutting wire speed is gradually increased.

[0026] Further, the feeding speed is 0.5-3 mm / min, and the cutting wire speed is 5-40 m / s.

[0027] Due to the adoption of the above technical solution, the tungsten wire twisted cutting wire is formed by twisting multiple tungsten wires of the same diameter. Using tungsten wire as the main wire of the cutting wire, compared with the conventional cutting wire which uses carbon steel wire as the main wire, tungsten wire has higher tensile strength and higher flexibility, reducing the wire breakage rate and making the drawn cutting wire thinner, thus reducing the wear on the silicon wafer. A diamond layer is set at the maximum outer diameter of the cutting wire body, and an insulating layer is set on the rest of the cutting wire body. Multiple diamond layers are distributed along the axial direction of the cutting wire body, so that the diamond layers fully participate in the cutting and improve the cutting ability of the cutting wire. Multiple chip grooves are set along the circumferential and axial directions of the cutting wire body to improve the liquid carrying capacity of the cutting wire. When cutting single crystal silicon rods, a wire-only cutting mode is used to reduce the color difference of the silicon wafer. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the cutting line structure according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the AA cross-sectional structure of the cutting line according to an embodiment of the present invention;

[0030] Figure 3 These are images of silicon wafers obtained using conventional wire cutting techniques.

[0031] Figure 4 This is an image of a silicon wafer obtained by tungsten wire twisting and tangential cutting.

[0032] In the picture:

[0033] 1. Tungsten wire 2. Chip groove Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] Figure 1 A schematic diagram of an embodiment of the present invention is shown. This embodiment relates to a tungsten wire twisted cutting wire, a preparation method, and a silicon wafer cutting method. The cutting wire is installed on a wire cutting machine for cutting silicon rods. The cutting wire is prepared by twisting multiple tungsten wires of the same diameter, and a diamond layer is provided on the periphery at the largest outer diameter, while the remaining parts are insulating layers, which improves the deformation resistance of the cutting wire and reduces the breakage rate.

[0036] A method for preparing tungsten wire twisted cutting wire, such as Figure 1 and 2As shown, the cutting wire is prepared using tungsten wire 1 with multiple diameters. That is, the main wire of the cutting wire is tungsten wire 1. Since tungsten wire 1 has higher tensile strength and higher flexibility than carbon steel wire, the diameter of conventional carbon steel cutting wire can be drawn up to 30 μm. If it is drawn further, it will break. Tungsten steel has better toughness, and the diameter of a single tungsten cutting wire can be drawn down to 10 μm and can still be used. Therefore, using tungsten wire 1 as the main wire of the cutting wire can make the diameter of the cutting wire smaller and enhance its resistance to deformation.

[0037] In some feasible embodiments, preferably, the multiple tungsten wires have the same diameter;

[0038] The method for preparing this tungsten wire twisted cutting wire includes the following steps:

[0039] Select the wire diameter and quantity of tungsten wire 1. According to the design requirements of the cutting wire, select the appropriate wire diameter and quantity of tungsten wire 1. Here, there are no specific requirements for the wire diameter and quantity of tungsten wire 1. Select according to actual needs.

[0040] Surface activation treatment is performed on each tungsten wire 1: This step of surface activation treatment on each tungsten wire 1 includes:

[0041] Each tungsten wire 1 is pre-cleaned by washing the surface of the tungsten wire 1 with pure water to remove impurities from the surface of the tungsten wire 1.

[0042] After pre-cleaning, each tungsten wire 1 undergoes surface activation treatment to remove impurities from its surface, facilitating subsequent insulation and electroplating processes. Surface activation treatment methods include acid treatment or alkali treatment. Acid treatment involves cleaning and immersing each tungsten wire 1 in an acid solution, specifically a nitric acid solution with a mass concentration of 10%-30%. Alkali treatment involves cleaning and immersing each tungsten wire 1 in an alkaline solution, specifically a sodium hydroxide solution or sodium carbonate solution with a concentration of 2-3%. The cleaning and immersion time for both acid and alkaline solutions is 10-20 minutes.

[0043] The surface-activated tungsten wire 1 is twisted into strands to form a tangent body. This tangent body has a wire structure of a certain length to meet the requirements of the cutting wire. The twisting step of the surface-activated tungsten wire 1 includes:

[0044] Twisting: Multiple tungsten wires 1 are simultaneously twisted with a certain twisting force and according to a certain twisting pitch to form a tangential main body. Multiple tungsten wires 1 of the same diameter are placed on a stranding machine, a certain twisting force is set, and multiple tungsten wires 1 are simultaneously spirally wound according to a certain twisting pitch. Multiple tungsten wires 1 move in a circular motion under the action of external force, rotating in the same direction of rotation. Multiple tungsten wires 1 rotate and wind simultaneously to form a spiral wire structure. Each tungsten wire 1 is a spiral wire, which is twisted together to form a knot of a certain length. The tangent body has a peripheral outer surface that is not planar but has multiple grooves arranged sequentially along the axial and circumferential directions of the substrate. These grooves are chip grooves 2. The chip grooves 2 allow cutting fluid to flow along the grooves and into the cutting position when the tangent cuts the silicon single crystal. Simultaneously, a gap exists between the tangent and the silicon single crystal surface, allowing chips to be stored in the chip grooves 2 as the tangent cuts the silicon single crystal, and to be discharged as the tangent moves. After twisting, multiple tungsten wires 1 are arranged around the axis of the tangent body, circumferentially along the axis of the tangent body. Cutting can be performed from any position on the tangent body. From its cross-sectional structure diagram, it can be seen that the multiple tungsten wires 1 are located within the plane formed by the maximum outer diameter of the tangent body. The cross-sectional plane of the tangent body is circular. Figure 2 As shown.

[0045] The twisting force mentioned above is a constant force, ranging from 0.4 to 0.8 N. The magnitude of this twisting force is selected based on actual needs, and no specific requirements are specified here.

[0046] The twist pitch is selected based on the diameter of the tungsten wire 1. In some feasible embodiments, the ratio of the twist pitch to the diameter of the tungsten wire 1 is 8-10:1. The twist pitch is selected according to actual needs, and no specific requirements are made here.

[0047] Untwisting: The twisted yarn after being twisted is untwisted with a certain tension. The tension is opposite to the twisting force, so that the gyratory forces generated between the individual tungsten wires cancel each other out. This allows the twisted cutting yarn to maintain a force balance in its natural state, and the rotational force is released, preventing the tangent matrix from spreading out.

[0048] The tension mentioned above is a constant force, ranging from 0.1 to 0.3 N. The magnitude of this tension can be selected based on actual needs, and no specific requirements are specified here.

[0049] Multiple tungsten wires 1 are twisted and untwisted to form a tangent body. Then, the tangent body is insulated to form an insulating layer on its outer surface. In this insulation treatment step, the insulation treatment method includes spraying. An insulating solution is sprayed onto the tangent body to form an insulating layer on its outer surface. During the spraying of the insulating solution onto the tangent body, there is relative movement between the tangent body and the nozzle of the spraying device. The nozzle moves along the circumference and axial direction of the tangent body, and spraying is performed along the circumference and axial direction of the tangent body, so that the entire outer surface of the tangent body is coated with an insulating solution, forming an insulating layer on its outer surface. Alternatively, the tangent body moves relative to the nozzle, moving along its own circumference and axial direction to spray the insulating solution, coating the entire outer surface of the tangent body with an insulating solution, forming an insulating layer on its outer surface. Of course, an insulating layer can also be formed on the outer surface of the tangent body by immersion or electroplating. The method of insulation treatment is selected according to actual needs, and no specific requirements are made here.

[0050] In some feasible embodiments, preferably, the insulating layer is made of polytetrafluoroethylene, and the thickness of the insulating layer is less than the height of the diamond particles in the diamond layer. The height of the diamond particles is 2-3 μm, so that when the tungsten wire twisted cutting wire cuts the single crystal silicon rod, the diamond particles in the diamond layer participate in the cutting.

[0051] After insulating the tangent body, it undergoes grinding to remove the insulation layer at the maximum outer diameter of the tangent body, facilitating subsequent electroplating. Diamond electroplating forms a diamond layer, which acts as a cutting layer, participating in the cutting process. The diamond particles are used as abrasives for cutting. In the step of removing the insulation layer at the maximum outer diameter of the tangent body, the tangent body is ground along the circumferential direction at the maximum outer diameter to remove the insulation layer. That is, the insulation layer on the peripheral outer surface of the tangent body at the maximum outer diameter is removed, exposing the tungsten wire 1 inside the tangent body for subsequent electroplating. This grinding method involves using a sharpening machine to grind and remove the insulation layer on the tangent body.

[0052] After removing the insulation layer at the maximum outer diameter of the tangent body, a diamond layer is prepared on the area of ​​the tangent body where no insulation layer is present. The diamond layer is located on the peripheral outer surface of the tangent body at the maximum outer diameter. The diamond layer is prepared by electroplating, meaning that the diamond layer is located at the position where the insulation layer of the tangent body has been removed. The diamond layer serves as the cutting layer, and the diamond particles act as abrasives. When the tangent wire cuts the silicon rod, the diamond particles participate in the cutting as abrasives. That is, the cutting position of the tangent wire is located at the maximum outer diameter of the tangent body, while the remaining part is an insulation layer without a diamond layer and does not participate in the cutting. Since only the outermost diamond layer of the tangent wire obtained by the twisting process is used for cutting, setting the diamond layer only on the outermost layer can fully utilize the diamond particles for cutting. Setting the diamond layer only on the outermost periphery of the tangent wire allows the space formed between two adjacent diamond layers to become a chip groove, further improving the liquid carrying capacity.

[0053] The diamond particles in the aforementioned diamond layer have a height of 2-3 μm and a density of 100-200 particles / mm.

[0054] The electroplated tangent body is dried by placing it in an oven to remove stress from the electroplated layer. The drying temperature is 80-100℃ and the drying time is 20-40 minutes.

[0055] A tungsten wire twisted cutting wire is prepared using the method described above. It includes a cutting wire body and multiple insulating layers and multiple diamond layers disposed on the outside of the cutting wire body. The cutting wire body forms the main skeleton structure of the cutting wire, facilitating the placement of the insulating layers and diamond layers. The cutting wire body is a wire structure of a certain length, comprising multiple tungsten wires 1. These multiple tungsten wires 1 are spirally wound and twisted along the axial and circumferential directions of the cutting wire body. Since the cutting wire body is made of multiple tungsten wires 1 twisted together… Multiple grooves are formed on the outer surface of the tangent body, which are called chip grooves 2. That is, multiple chip grooves 2 are set along the circumferential and axial directions of the tangent body. The chip grooves 2 are set so that when the tangent cuts the single crystal silicon rod, the cutting fluid flows along the chip grooves 2 and flows into the cutting position. At the same time, there is a gap between the tangent and the surface of the single crystal silicon. As the tangent cuts the single crystal silicon, the chips can be stored in the chip grooves 2, and as the tangent moves, the chips in the chip grooves 2 can be discharged.

[0056] In some feasible embodiments, preferably, the plurality of tungsten wires 1 have the same wire diameter.

[0057] The diamond layer is located at the maximum outer diameter of the tangent body. The diamond particles in the diamond layer are abrasive grains that participate in cutting. Multiple diamond layers and multiple insulating layers are arranged sequentially along the axial direction of the tangent body, and the insulating layer is spaced apart from the diamond layer. That is, along the axial direction of the tangent body, a diamond layer is arranged on the circumferential side at each maximum outer diameter, and an insulating layer is arranged between two adjacent diamond layers.

[0058] The aforementioned tangential body is formed by twisting with a certain twisting force and a certain twisting pitch, so that the tangential body obtained after twisting has a certain pitch. The ratio of the pitch of the tangential body to the diameter of the tungsten wire 1 is 8-10:1. The ratio of the twisting pitch to the diameter of the tungsten wire 1 is selected according to actual needs, and no specific requirements are made here.

[0059] The insulating layer is made of polytetrafluoroethylene. The thickness of the insulating layer is less than the height of the diamond particles in the diamond layer, which is 2-3 μm high.

[0060] A silicon wafer cutting method involves using a cutting device with tungsten wire twisted cutting wires as described above to cut a monocrystalline silicon rod. The cutting wires are installed on the cutting device to form a cutting wire mesh. When cutting the monocrystalline silicon rod, the monocrystalline silicon rod moves relative to the cutting wire mesh for feeding. At the same time, the cutting wires move to cut the monocrystalline silicon rod, thereby cutting the monocrystalline silicon rod into multiple silicon wafers.

[0061] In the process of cutting monocrystalline silicon, a wire-only mode is adopted, that is, during the cutting process, only the wire is fed in and not withdrawn. As the feed position increases, the parameters of the feed speed and the cutting line speed are changed to make the feed speed and the cutting line speed suitable for different feed positions, thereby improving production efficiency while meeting the silicon wafer cutting quality requirements.

[0062] Specifically, as the single crystal feed position increases, the feed rate is first increased and then decreased, while the cutting line speed is gradually increased. 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 line mesh direction, the cutting depth of the cutting line gradually increases. For each additional feed position, the feed rate and cutting line speed of the single crystal change accordingly, so that the feed rate and cutting line speed of the single crystal are adapted to the feed position.

[0063] In some feasible embodiments, the feed rate is 0.5-3 mm / min, which can be selected according to actual needs, and no specific requirements are made here.

[0064] In some feasible embodiments, the cutting speed is 5-40 m / s, which can be selected according to actual needs, and no specific requirements are made here.

[0065] Different feed positions correspond to different feed speeds and cutting line speeds, as well as different cutting times. The cutting time ranges from 2 to 15 minutes, depending on the actual needs. No specific requirements are specified here.

[0066] The following is a specific embodiment for illustration.

[0067] 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 speed and cutting wire speed are selected according to the cutting position of the monocrystalline silicon rods.

[0068] When the feed position is 0mm, the single crystal feed rate is 0.8mm / min, the cutting line speed is 8m / s, and the cutting time is 3.25min;

[0069] When the feed position is 2mm, the single crystal feed rate is 1.5mm / min, the cutting line speed is 10m / s, and the cutting time is 1.33min;

[0070] When the feed position is 4mm, the single crystal feed rate is 1.5mm / min, the cutting line speed is 28m / s, and the cutting time is 3.5min;

[0071] When the feed position is 10mm, the single crystal feed rate is 2.1mm / min, the cutting line speed is 35m / s, and the cutting time is 9.83min;

[0072] When the feed position is 30mm, the single crystal feed rate is 2.8mm / min, the cutting line speed is 35m / s, and the cutting time is 13.67min;

[0073] When the feed position is 60mm, the single crystal feed rate is 3.0mm / min, the cutting line speed is 35m / s, and the cutting time is 13.17min;

[0074] When the feed position is 90mm, the single crystal feed rate is 3.0mm / min, the cutting line speed is 35m / s, and the cutting time is 13.17min;

[0075] When the feed position is 120mm, the single crystal feed rate is 3.0mm / min, the cutting line speed is 35m / s, and the cutting time is 13.17min;

[0076] When the feed position is 150mm, the single crystal feed rate is 3.0mm / min, the cutting line speed is 35m / s, and the cutting time is 13.17min;

[0077] When the feed position is 180mm, the single crystal feed rate is 3.0mm / min, the cutting line speed is 35m / s, and the cutting time is 8.83min;

[0078] When the feed position is 200mm, the single crystal feed rate is 2.3mm / min, the cutting line speed is 35m / s, and the cutting time is 6min;

[0079] When the feed position is 210mm, the single crystal feed rate is 1.2mm / min, the cutting line speed is 35m / s, and the cutting time is 9.67min;

[0080] When the feed position is 217mm, the single crystal feed rate is 0.4mm / min, the cutting line speed is 15m / s, and the cutting time is 7min;

[0081] When the feed position is 219mm, the single crystal feed rate is 0.2mm / min, the cutting line speed is 15m / s, and the cutting time is 11.5min;

[0082] When the feed position is 220.5mm, the single crystal feed rate is 0.08mm / min, the cutting line speed is 37m / s, and the cutting time is 12.5min;

[0083] When the feed position is 221.3mm, the single crystal feed rate is 0.05mm / min, the cutting line speed is 37m / s, the cutting time is 0min, and the cutting is completed.

[0084] The above cutting parameters are summarized in the table below:

[0085]

[0086]

[0087] Using the above parameters to cut monocrystalline silicon rods, the resulting silicon wafers show reduced color difference compared to those obtained by cutting monocrystalline silicon rods with conventional dicing lines. Figure 3 and Figure 4 As shown, Figure 3 The silicon wafers are cut using conventional dicing techniques, and there may be color variations. Figure 4 The silicon wafers are cut using the aforementioned tungsten wire twisting and cutting method. The silicon wafers have no obvious color difference, and the color difference rate has been reduced from the original 3%-5% to below 0.5%.

[0088] The silicon wafers obtained by cutting monocrystalline silicon rods using the aforementioned tungsten wire twisting cutting wire have a reduced color difference compared to silicon wafers obtained by cutting monocrystalline silicon rods using conventional cutting wires.

[0089] Due to the adoption of the above technical solution, the tungsten wire twisted cutting wire is formed by twisting multiple tungsten wires of the same diameter. Using tungsten wire as the main wire of the cutting wire, compared with the conventional cutting wire which uses carbon steel wire as the main wire, tungsten wire has higher tensile strength and higher flexibility, reducing the wire breakage rate and making the drawn cutting wire thinner, thus reducing the wear on the silicon wafer. A diamond layer is set at the maximum outer diameter of the cutting wire body, and an insulating layer is set on the rest of the cutting wire body. Multiple diamond layers are distributed along the axial direction of the cutting wire body, so that the diamond layers fully participate in the cutting and improve the cutting ability of the cutting wire. Multiple chip grooves are set along the circumferential and axial directions of the cutting wire body to improve the liquid carrying capacity of the cutting wire. When cutting single crystal silicon rods, a wire-only cutting mode is used to reduce the color difference of the silicon wafer.

[0090] 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 tungsten wire twisted cutting wire, characterized in that: The device includes a tangent body and multiple insulating layers and multiple diamond layers disposed on the outside of the tangent body. The tangent body includes multiple tungsten wires, which are spirally wound and twisted along the axial and circumferential directions of the tangent body. Multiple chip-receiving grooves are constructed along the circumferential and axial directions of the tangent body. The diamond layers are disposed at the maximum outer diameter of the tangent body.

2. The tungsten wire twisted cutting wire according to claim 1, characterized in that: The ratio of the twisting pitch of the tangential body to the diameter of the tungsten wire is 8-10:

1.

3. The tungsten wire twisted cutting wire according to claim 1 or 2, characterized in that: The tungsten wires mentioned above have the same diameter.

4. The tungsten wire twisted cutting wire according to claim 1 or 2, characterized in that: The thickness of the insulating layer is less than the height of the diamond particles in the diamond layer.

5. A method for preparing tungsten wire twisted cutting wire, characterized in that: The process involves preparing the material using multiple tungsten wires, including the following steps: Multiple tungsten wires are twisted together to form a tangential body; The tangent body is insulated, and an insulating layer is formed on the outer surface of the tangent body; Remove the insulation layer at the maximum outer diameter of the tangent body; A diamond layer is prepared in the area of ​​the tangent body where no insulating layer is provided.

6. The method for preparing tungsten wire twisted cutting wire according to claim 5, characterized in that: Before twisting multiple tungsten wires together, each tungsten wire undergoes a surface activation treatment, which may include acid treatment or alkali treatment.

7. The method for preparing tungsten wire twisted cutting wire according to claim 5 or 6, characterized in that: The step of twisting multiple tungsten wires together includes: Twisting: Twisting multiple tungsten wires simultaneously with a certain twisting force and a certain twisting pitch; Untwisting: Untwisting the twisted yarn after it has been twisted with a certain tension, the tension being opposite to the twisting force, to release the rotational force.

8. The method for preparing tungsten wire twisted cutting wire according to claim 7, characterized in that: The twisting force is 0.4-0.8N; And / or, the ratio of the twisting pitch to the diameter of the tungsten wire is 8-10:1; And / or, the tension is 0.1-0.3N.

9. The method for preparing tungsten wire twisted cutting wire according to claim 5, 6, or 8, characterized in that: In the step of insulating the tangent body, the insulation treatment method includes spraying.

10. The method for preparing tungsten wire twisted cutting wire according to claim 9, characterized in that: Methods for preparing diamond layers include electroplating.

11. The method for preparing tungsten wire twisted cutting wire according to claim 5, characterized in that: The insulating layer is made of polytetrafluoroethylene; And / or, the thickness of the insulating layer is less than the height of the diamond particles in the diamond layer.

12. The method for preparing tungsten wire twisted cutting wire according to any one of claims 5-6, 8 and 10-11, characterized in that: Along the circumferential direction at the maximum outer diameter of the tangent body, the tangent body is ground to remove the insulating layer at the maximum outer diameter of the tangent body.

13. A method for cutting silicon wafers, characterized in that: A single-crystal silicon rod is cut using a cutting device with tungsten wire twisting tangent as described in any one of claims 1-4. During the single-crystal silicon cutting process, a wire-only cutting mode is used. As the feed position increases, the feed speed is controlled to first increase and then decrease, and the cutting wire speed is controlled to gradually increase.

14. The silicon wafer cutting method according to claim 13, characterized in that: The feed rate is 0.5-3 mm / min, and the cutting line speed is 5-40 m / s.

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