A method for cutting N-type single crystal silicon

Abstract

The application discloses a cutting method of N-type monocrystalline silicon and relates to the field of N-type monocrystalline silicon cutting, and comprises the following steps: step one, arranging a cutting line net; first, parallelly mounting a pay-off guide roller and a take-up guide roller on a workbench, and corresponding line grooves are formed in the pay-off guide roller and the take-up guide roller; a cutting line is obliquely arranged in the corresponding line grooves to form a cutting line net; step two, bonding a crystal bar; one side of a bonding plate is bonded with the crystal bar, and the other side of the bonding plate is connected with a crystal holder; step three, cutting the crystal bar; the crystal bar is cut with chamfers at four corners; and the crystal bar is segmented cut by setting different parameters; and step four, lifting the crystal bar; after the crystal bar is cut, a wafer bonded on the bonding plate is removed from the gap of the cutting line. The crystal bar is segmented cut, the line net blasting loss is reduced from 400 mm to 50 mm, and the probability of the tool mark is reduced by 1.5%.

Description

Technical Field

[0001] This invention relates to the field of N-type single crystal silicon cutting, and in particular to a method for cutting N-type single crystal silicon. Background Technology

[0002] Wire EDM of monocrystalline silicon utilizes a moving diamond wire as an electrode to perform pulsed spark discharge cutting on the workpiece. A fine diamond wire is used as the tool electrode for cutting, and a wire reservoir causes the wire to move alternately in both forward and reverse directions. The processing energy is supplied by a pulsed power source. A cutting fluid is poured between the diamond wire and the workpiece. The worktable moves in two horizontal coordinate directions according to a predetermined control program, performing servo feed movements based on the spark gap state, thereby synthesizing various curved trajectories to cut the workpiece into shape.

[0003] Existing N-type single-crystal carbon steel wire cutting is limited by the need for thinner wires. As the diameter of the carbon steel wire busbar decreases, its breaking force also decreases, resulting in a high wire breakage rate. This affects the yield of silicon wafers after a single cut, which refers to the yield of silicon wafers with a wire trace TTV < 13μm and no color difference on the surface after a complete cut of the crystal rod.

[0004] In existing monocrystalline silicon cutting processes, diamond wire is prone to breakage and large wire marks, affecting the quality of the silicon wafer. For example, patent CN 106584687 A discloses a monocrystalline silicon wafer cutting device, which includes a multi-groove wire roller and diamond wire stretched on the multi-groove wire roller. One disclosed monocrystalline silicon wafer cutting method first adheres a silicon rod to an adhesion plate, and then sets parameters to use the diamond wire of the monocrystalline silicon wafer cutting device to cut the silicon rod. However, this method sets a high cutting speed but does not consider the problem of wire breakage at different segments, resulting in a high loss rate in actual production. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for cutting N-type single crystal silicon, which addresses the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for cutting N-type monocrystalline silicon includes the following steps: Step 1, arranging the cutting wire mesh: First, the feed roller and take-up roller are installed parallel to each other on the worktable. Corresponding grooves are opened on both the feed roller and take-up roller. The cutting wires are laid obliquely in the corresponding grooves to form the cutting wire mesh; Step 2, bonding the crystal rod: One side of the bonding plate is bonded to the crystal rod, and the other side of the bonding plate is connected to the crystal holder; Step 3, cutting the crystal rod: Chamfers are cut at all four corners of the crystal rod. Different parameters are set to cut the crystal rod in segments; First, the crystal rod is aligned with the cutting wire mesh, and then the cutting of the crystal rod begins; First, the cutting wire mesh cuts from one chamfered side of the crystal rod, then the cutting wire mesh cuts the straight segments of the crystal rod, and finally the cutting wire mesh exits from the other chamfered side of the crystal rod; Step 4, lifting the crystal rod: After the crystal rod is cut, a wafer is formed bonded to the bonding plate. The wafer is removed from the gap of the cutting wires. By segmenting the crystal rod, the wire breakage loss was reduced from 400mm to 50mm, and the probability of wire marks was reduced by 1.5%.

[0008] As a further preferred embodiment of the present invention, in step one, the distance between the first cutting line and the second cutting line in the cutting wire mesh is greater than the distance between the second cutting line and the third cutting line. This reduces the cutting torque by 10-15 torques.

[0009] As a further preferred embodiment of the present invention, for crystal rods with a size of 182mm and a chamfer greater than 6mm, the cutting speed in step three, before the chamfering is completed, is 10-15m / s. The wire breakage loss is reduced from the original 400mm to 50mm.

[0010] As a further preferred embodiment of the present invention, in step three, the cutting speed is 35 m / s when the cutting depth is 181 mm and 184 mm, and 27 m / s when the cutting depth is 187 mm-192 mm. When the cutting depth is 181 mm-192 mm, the cutting flow rate is 10000 kg / h. The probability of blade marks is reduced by approximately 1.5%.

[0011] As a further preferred embodiment of the present invention, in step four, when the ingot feed position is 192mm, the ingot lifting speed is 30mm / min and the cutting speed is 2m / min; when the ingot feed positions are 170mm, 100mm, and 30mm, the ingot lifting speed is 50mm / min and the cutting speed is 2m / min; when the feed position is 0mm, the ingot lifting speed is 500mm / min and the cutting speed is 2m / min. The ingot lifting torque is reduced by 20 Nm.

[0012] As a further preferred embodiment of the present invention, the adhesive board is a solid board. This reduces sheet breakage caused by deformation after the board is cut.

[0013] As a further preferred embodiment of the present invention, the cutting wire is a tungsten wire. Under the same breaking conditions, the tungsten wire diameter can be 30 mm, while carbon steel can only be 35 mm. The wire diameter is reduced by 5 μm, and the slot pitch can be reduced by 5 μm. Thus, with the same rod length, more wafers can be produced.

[0014] The present invention has the following beneficial effects:

[0015] 1. In this invention, the four corners of the crystal rod are all chamfered, and different parameters are set to cut the crystal rod into segments. First, the crystal rod is aligned with the cutting wire mesh, and then the cutting of the crystal rod begins. First, the cutting wire mesh enters from one chamfer of the crystal rod to cut, then the cutting wire mesh cuts the straight segments of the crystal rod, and finally the cutting wire mesh exits from the other chamfer of the crystal rod. By cutting the crystal rod into segments, the wire mesh breakage loss is reduced from 400mm to 50mm, and the probability of exiting the cutting wire mark is reduced by 1.5%.

[0016] 2. When the distance between the first and second cutting lines in the cutting wire mesh is greater than the distance between the second and third cutting lines, the cutting torque is reduced by 10-15 Nm.

[0017] 3. Under the same breaking conditions, tungsten wire diameter can be 30 wires, while carbon steel can only be 35 wires. With a 5μm reduction in wire diameter, the slot pitch can also be reduced by 5μm. Thus, with the same rod length, more wafers can be produced. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the crystal rod structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the cutting wire mesh structure of the present invention.

[0020] These include: 1. Feeding guide roller; 2. Take-up guide roller; 3. Cutting line; 4. Crystal rod; 5. Adhesive plate; 6. Wire groove; 7. Infeed chamfer; 8. Outfeed chamfer; 9. First cutting line; 10. Second cutting line; 11. Third cutting line. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0022] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0023] like Figure 1-2 As shown, a method for cutting N-type monocrystalline silicon includes the following steps: Step 1, arranging the cutting wire mesh: First, the feeding guide roller 1 and the take-up guide roller 2 are installed parallel to each other on the worktable. Corresponding grooves 6 are opened on both the feeding guide roller 1 and the take-up guide roller 2. The cutting wire 3 is inclinedly arranged in the corresponding grooves 6 to form the cutting wire mesh; Step 2, bonding the crystal rod 4: One side of the bonding plate 5 is bonded to the crystal rod 4, and the other side of the bonding plate 5 is connected to the crystal support; Step 3, cutting the crystal rod 4: The four edges of the crystal rod 4... All corners are chamfered. Different parameters are set to cut the crystal rod 4 into segments. First, the crystal rod 4 is aligned with the dicing wire mesh, and then the cutting of the crystal rod 4 begins. First, the dicing wire mesh cuts from one chamfered side of the crystal rod 4, then the dicing wire mesh cuts the straight segments of the crystal rod 4, and finally the dicing wire mesh exits from the other chamfered side of the crystal rod 4. Step four, lifting the rod: After the crystal rod 4 is cut, it forms a wafer bonded to the bonding plate 5. The wafer is then removed from the gap of the dicing wire 3. By cutting the crystal rod 4 into segments, the wire mesh breakage loss is reduced from 400mm to 50mm, and the probability of exiting the cutting wire mark is reduced by 1.5%.

[0024] In step one, the distance between the first cutting line 9 and the second cutting line 10 in the cutting wire mesh is greater than the distance between the second cutting line 10 and the third cutting line 11. To improve wire cutting capability while reducing wire diameter and increasing the number of blades per cut, different oblique wire mesh distances were verified, and cutting torque data were compared. When the distance between the first cutting line 9 and the second cutting line 10 in the cutting wire mesh is greater than the distance between the second cutting line 10 and the third cutting line 11, the cutting torque can be reduced by 10-15 Nm.

[0025] For crystal rod 4 with a size of 182mm and a chamfer greater than 6mm, the cutting speed in step three is 10-15m / s before the chamfer 7 is completed. To address the issue of low-segment wire breakage during the cutting of the 182mm large chamfer, the cutting speed and feed process were optimized. Low-segment wire breakage refers to wire mesh breakage occurring during cutting depths of 3-15mm without exceeding the chamfer. Analysis of collected wire breakage and breakage cases revealed that the breakage rate for the 210mm small chamfer size was lower than that for the 182mm large chamfer size; the difference lies in the chamfer size. Through process matching adjustments, for the 182mm large chamfer size, the cutting speed was stabilized at 10-15m / s before the chamfer 7 is completed, reducing wire mesh breakage loss from 400mm to 50mm.

[0026] To prevent the degradation of wafer B due to line marks at the chamfer 8 point, the cutting speed at the exit and retraction points is adjusted. Wafer B is defined as a single silicon wafer with a line mark value >13μm. In step three, the cutting speed is 35m / s for cutting depths of 181mm and 184mm, and 27m / s for cutting depths of 187mm-192mm. At cutting depths of 181mm-192mm, the cutting flow rate is 10000kg / h, which is the average hourly water supply. This reduces the probability of line marks at the exit point by approximately 1.5%.

[0027] To address issues such as wire jamming and wafer drop during rod lifting after cutting, the rod lifting process was refined. Rod lifting refers to the slow withdrawal of ingot 4 from the slit of cutting line 3 after cutting. In step four, when the feed position of ingot 4 is 192mm, the rod lifting speed is 30mm / min, and the cutting line speed is 2m / min; when the feed positions of ingot 4 are 170mm, 100mm, and 30mm, the rod lifting speed is 50mm / min, and the cutting line speed is 2m / min; when the feed position is 0mm, the rod lifting speed is 500mm / min, and the cutting line speed is 2m / min. The rod lifting torque is reduced by 20 Nm.

[0028] The adhesive plate 5 is a solid plate. This reduces wafer loss caused by deformation after the plate is cut. The cutting line 3 is a tungsten wire. Under the same breaking conditions, the tungsten wire diameter can be 30 mm, while carbon steel can only be 35 mm. Reducing the wire diameter by 5 μm allows for a 5 μm reduction in the slot pitch, thus enabling the production of more wafers for the same rod length.

[0029] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A method of slicing N-type single crystal silicon, characterized by: It comprises the following steps: Step one, arranging the cutting line net: firstly, install the wire feeding guide roller (1) and the wire collecting guide roller (2) in parallel on the workbench, both the wire feeding guide roller (1) and the wire collecting guide roller (2) are provided with corresponding wire grooves (6), the cutting line (3) is arranged in the corresponding wire groove (6) to form the cutting line net; the distance between the first cutting line (9) and the second cutting line (10) in the cutting line net is greater than the distance between the second cutting line (10) and the third cutting line (11); Step two, bonding the crystal bar (4): one side of the adhesive plate (5) is bonded with the crystal bar (4), and the other side of the adhesive plate (5) is connected with the crystal holder; Step three, cutting the crystal bar (4): the crystal bar (4) is provided with chamfers at four corners, different parameters are set to cut the crystal bar (4) in sections; align the crystal bar (4) with the cutting line net, and then start cutting the crystal bar (4); Firstly, the cutting line net cuts from one chamfer of the crystal bar (4), then the cutting line net cuts the straight section of the crystal bar (4), and finally the cutting line net cuts out from the other chamfer of the crystal bar (4); For the crystal bar (4) with a size of 182mm and a chamfer greater than 6mm, the cutting line speed is 10-15m / s before cutting the chamfer (7); Step four, lifting the rod: after the crystal bar (4) is cut, the wafer bonded on the adhesive plate (5) is removed from the gap of the cutting line net.

2. The method of cutting N-type single crystal silicon as defined in claim 1, wherein: The cutting line speed is 35m / s when the cutting depth is 181mm and 184mm, and the cutting line speed is 27m / s when the cutting depth is 187mm-192mm.

3. The method of dicing N-type single crystal silicon as defined in claim 2, wherein: When the cutting depth is 181mm-192mm, the cutting flow is 10000kg / h.

4. The method of cutting N-type single crystal silicon as defined in claim 1, wherein: When the feeding position of the crystal bar (4) is 192mm in step four, the lifting speed is 30mm / min, and the cutting line speed is 2m / min; when the feeding position of the crystal bar (4) is 170mm, 100mm and 30mm, the lifting speed is 50mm / min, and the cutting line speed is 2m / min; when the feeding position is 0mm, the lifting speed is 500mm / min, and the cutting line speed is 2m / min.

5. The method of cutting N-type single crystal silicon as defined in claim 1, wherein: The adhesive plate (5) is a solid plate.

6. The method of cutting N-type single crystal silicon as defined in claim 1, wherein: The cutting line (3) is a tungsten wire.

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