A process for cutting half a silicon block

Abstract

The present invention provides a process for cutting half a silicon block, belonging to the technical field of crystalline silicon slicing. In the present invention, a slicing method designed by the present invention adopts a four-roller (all driven) arrangement to control the roller length to 350-450mm. This method can reduce the number of wire meshes during wiring to 9-11, balancing the wire mesh tension while shortening the process time, so that the TTV rate of the prepared silicon wafer is less than 1%, and the high wire and wire break rate is less than 5%.

Description

Technical Field

[0001] The invention belongs to the technical field of crystalline silicon slicing, and in particular relates to a process for cutting a half-silicon block. Background Art

[0002] Silicon wafers are the primary raw material for solar cell production, and the quality of the cutting process directly impacts wafer quality and the conversion efficiency of solar cells. Currently, the cutting process for square silicon rods is stable and mature, and wafer quality can be guaranteed. However, in existing technologies, during the production of square silicon rods, because crystal growth is governed by thermodynamic laws and kinetic processes, the resulting square silicon rods are often not perfectly regular silicon blocks. Consequently, silicon material edge skin is present during the production process, requiring further processing to avoid waste of materials and resources.

[0003] Currently, the silicon shavings are further utilized by squaring half-slices from the silicon shavings and then slicing them into wafers. However, due to limitations of existing slicers, the slicing process for the silicon shavings is still the same as for the whole ingot. This requires bonding two rows of half-slices side by side to create a square ingot-like shape before slicing. Existing slicers typically consist of three rollers (two driven main rollers and one undriven secondary roller) arranged in an inverted triangle. Diamond wire is routed around these three rollers during slicing. During slicing, the two driven main rollers rotate, driving the diamond wire, which in turn drives the secondary roller to slice the shavings. However, because the length of all three rollers in a slicer is 850 ± 5 mm, multiple wire grids (20-22) are required to slice a fully loaded half-slice. However, the more wire grids there are, the greater the probability of wire breakage and high wire height during slicing. Currently, silicon wafers cut using the whole-wafer sawing process have a TTV (total thickness variation) rate greater than 2% and a wire breakage rate of 8-10%. Therefore, a cutting process suitable for half-wafer silicon ingots is needed to address the issues of uneven wire tension, high wire tension, and / or wire breakage caused by excessive wire separation during half-wafer sawing. Summary of the Invention

[0004] To address the existing issues in the prior art of slicing half-wafer silicon ingots, which can lead to uneven wire tension and / or wire breakage due to excessive wire separation during slicing, the present invention provides a process for slicing half-wafer silicon ingots. This design utilizes a slicing method using four rollers (all driven) to control the roller length to 350-450mm. This method reduces the number of wires required during slicing to 9-11, shortening the process time while balancing wire tension. The resulting silicon wafers have a TTV ratio of less than 1% and a wire breakage and breakage rate of less than 5%.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A process for cutting a half-silicon block, the cutting process comprising the following steps:

[0007] (1) The half silicon blocks are glued together to obtain silicon rods, which are then fixed on a cutting machine comprising four rollers. Wires are then routed around the four rollers according to the gaps between the half silicon blocks to obtain wired silicon rods.

[0008] (2) Circulate the cutting fluid in the working chamber and adjust the wire speed for preheating. After preheating, adjust the cutting parameters of the cutting machine: diamond wire speed 600-2000m / min, pay-off tension 3.5-4.5N, take-up tension 3.5-4.5N, cutting temperature controlled at 20-25°C, cutting fluid flow rate controlled at 150-220L / min, and overall process time at 60-120min;

[0009] (3) After the cutting is completed, the undebonded silicon wafer is obtained, and the undebonded silicon wafer is placed in a debonding machine for debonding, and then placed in a silicon wafer cleaning machine for cleaning, and finally a finished silicon wafer is obtained.

[0010] Furthermore, in step (1), the step of sticking the rods is as follows: sticking the resin plate to the crystal support with stick glue, and then sticking 10-12 half-sheet silicon blocks to the resin plate with stick glue after curing, and then completely curing to obtain silicon rods.

[0011] Furthermore, in step (1), the silicon rod is fixed by placing the silicon rod in parallel with the wire mesh of the cutting machine, with the silicon rod being 0.5-2 mm away from the wire mesh.

[0012] Furthermore, in step (1), the four rollers are all driven and can rotate on their own; the four rollers include a first main roller, a first auxiliary roller, a second main roller and a second auxiliary roller; an isosceles triangle with a vertex angle of 140 to 160 degrees is formed between the first main roller, the first auxiliary roller and the second main roller; an inverted isosceles triangle with a vertex angle of 100 to 120 degrees is formed between the first main roller, the second auxiliary roller and the second main roller.

[0013] Furthermore, the lengths of the four rollers are 350-450 mm, the diameters of the first main roller and the second main roller are 200±5 mm, the diameters of the first auxiliary roller and the second auxiliary roller are 150±5 mm; and the axial spacing between the first main roller and the second main roller is 900-1000 mm.

[0014] Furthermore, in step (1), a total of 9-11 wire meshes are formed, and the wiring is performed using diamond wires with a diameter of 35-43 μm.

[0015] Furthermore, in step (2), the cycle time is 10-20 minutes, and the line speed is 2000 m / min.

[0016] Furthermore, in step (2), when the cutting machine is cutting, the linear speed of the diamond wire changes to 1100→2600→100μm / min, and the rod lifting speed changes to 20→30→40mm / min

[0017] Furthermore, the cutting process performs horizontal or vertical cutting on half of the silicon block by adjusting the axis distance between the first main roller and the first auxiliary roller, and between the second main roller and the first auxiliary roller.

[0018] Furthermore, during the transverse cutting, the axial spacing between the first main roller and the first auxiliary roller, and between the second main roller and the first auxiliary roller is 400-450 mm; during the vertical cutting, the axial spacing between the first main roller and the first auxiliary roller, and between the second main roller and the first auxiliary roller is 300-350 mm.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] To address the existing issues of uneven wire tension, wire breakage, and wire breakage caused by excessive wire splitting during the prior art of slicing half a silicon block, the present invention employs four driven, self-rotating rollers to arrange the slices. The rollers are designed to be 350-450mm long. This method reduces the number of wire splits from 20-22 in the prior art to 9-11, significantly reducing the number of wire splits required during routing and the time and complexity of the slicing process.

[0021] In addition, the present invention also balances the tension of the wire mesh and adjusts the tension difference to 0.1-0.3N. The silicon wafer TTV rate obtained in this way is less than 1%, and the high wire and wire break rate is less than 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the silicon block bonding rod according to the present invention.

[0023] Figure 2 Schematic diagrams of cross-cutting (a) and vertical cutting (b) when cutting the silicon rod after wiring.

[0024] Reference numerals:

[0025] 1-first main roller; 2-first auxiliary roller; 3-second main roller; 4-second auxiliary roller. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0027] Example 1:

[0028] This embodiment specifically describes Figure 2 The vertical cutting process of a half-silicon block shown in the figure specifically includes the following steps:

[0029] 1. Adjustment of the axis spacing of the cutting machine:

[0030] The cutting machine in this embodiment improves upon existing commercially available cutting machines by replacing the existing rollers with four driven rollers. These four rollers include a first main roller 1, a first auxiliary roller 2, a second main roller 3, and a second auxiliary roller 4. The first main roller 1, the first auxiliary roller 2, and the second main roller 3 form an isosceles triangle with a vertex angle of 140°; the first main roller 1, the second auxiliary roller 2, and the second main roller 3 form an inverted isosceles triangle with a vertex angle of 100°. The roller length of each of the four rollers is 350mm. The diameters of the first main roller 1 and the second main roller 3 are 195mm, and the diameters of the first auxiliary roller 2 and the second auxiliary roller 4 are 145mm. The axial spacing between the first main roller 1 and the second main roller 3 is 900mm. During vertical cutting, the axial spacing between the first main roller 1 and the first auxiliary roller 2, and between the second main roller 3 and the first auxiliary roller 2, is 300mm.

[0031] 2. Vertical cutting process of half silicon block:

[0032] (1) Use epoxy AB glue to stick the resin plate to the crystal support. After curing, use epoxy AB glue to stick 10 half-piece silicon blocks to the resin plate. Wait until the curing is complete to obtain the following Figure 1 The silicon rod shown is then fixed on a cutting machine, with the silicon rod parallel to the wire mesh and 0.5 mm away from the wire mesh. A diamond wire with a diameter of 35 μm is then used to wrap around four rollers to divide the wire mesh according to the gap between the upper half of the silicon block. The wired silicon rod is divided into 9 wire meshes in total.

[0033] (2) Use a cutting machine to cut the wired silicon rods. The cutting steps are as follows: After pouring the cutting fluid into the mortar tank, it needs to be fully circulated in the working chamber for 15 minutes, while the diamond wire runs back and forth at a line speed of 2000m / min. After preheating, adjust the cutting parameters of the cutting machine: table speed is 1100→2600→100μm / min, diamond wire line speed is 600m / min, wire tension is 3.5N, wire tension is 3.5N, cutting temperature is controlled at 20℃, cutting fluid flow is controlled at 150L / min, rod lifting speed is 20→30→40mm / min, and the overall process time is 60min.

[0034] (3) After the cutting is completed, the undebonded silicon wafer is obtained, and the undebonded silicon wafer is placed in a debonding machine for debonding, and then placed in a silicon wafer cleaning machine for cleaning, and finally a finished silicon wafer is obtained.

[0035] After being sorted by an automatic silicon wafer sorter, it was found that the TTV rate of the obtained silicon wafers was less than 1%, and the high line and broken line rates were less than 5%.

[0036] Example 2:

[0037] This embodiment specifically describes Figure 2 The vertical cutting process of a half-silicon block shown in the figure specifically includes the following steps:

[0038] 1. Adjustment of the axis spacing of the cutting machine:

[0039] In this embodiment, based on the cutting machine on the market, the rollers are improved to four rollers with drives, including the first main roller 1, the first auxiliary roller 2, the second main roller 3 and the second auxiliary roller 4; the first main roller 1, the first auxiliary roller 2 and the second main roller 3 form an isosceles triangle with a vertex angle of 160°; the first main roller 1, the second auxiliary roller 2 and the second main roller 3 form an inverted isosceles triangle with a vertex angle of 110°. The roller lengths of the four rollers are all 450mm, the diameters of the first main roller 1 and the second main roller 3 are 205mm, and the diameters of the first auxiliary roller 2 and the second auxiliary roller 4 are 155mm; the axial spacing between the first main roller 1 and the second main roller 3 is 1000mm. During vertical cutting, the axial spacing between the first main roller 1 and the first auxiliary roller 2, and between the second main roller 3 and the first auxiliary roller 2 is 350mm. 2. Vertical cutting process of half-chip silicon block:

[0040] (1) Use epoxy AB glue to stick the resin plate to the crystal support. After curing, use epoxy AB glue to stick 12 half-piece silicon blocks to the resin plate. Wait until the curing is complete to obtain the following Figure 1 The silicon rod shown is then fixed on a cutting machine, with the silicon rod parallel to the wire mesh and 2 mm away from the wire mesh. A diamond wire with a diameter of 43 μm is then used to wrap around four rollers to divide the wire mesh according to the gap between the upper half of the silicon block. The wired silicon rod is divided into 11 wire meshes in total.

[0041] (2) Use a cutting machine to cut the wired silicon rods. The cutting steps are as follows: After pouring the cutting fluid into the mortar tank, it needs to be fully circulated in the working chamber for 20 minutes, while the diamond wire runs back and forth at a line speed of 2000m / min. After preheating, adjust the cutting parameters of the cutting machine: table speed is 1100→2600→100μm / min, diamond wire line speed is 2000m / min, wire tension is 4.5N, wire tension is 4.5N, cutting temperature is controlled at 25℃, cutting fluid flow is controlled at 220L / min, rod lifting speed is 20→30→40mm / min, and the overall process time is 120min.

[0042] (3) After the cutting is completed, the undebonded silicon wafer is obtained, and the undebonded silicon wafer is placed in a debonding machine for debonding, and then placed in a silicon wafer cleaning machine for cleaning, and finally a finished silicon wafer is obtained.

[0043] After being sorted by an automatic silicon wafer sorter, it was found that the TTV rate of the obtained silicon wafers was less than 1%, and the high line and broken line rates were less than 5%.

[0044] Example 3:

[0045] This embodiment specifically describes Figure 2 The cross-cutting process of a half-silicon block shown in FIG. 1 includes the following steps:

[0046] 1. Adjustment of the axis spacing of the cutting machine:

[0047] In this embodiment, based on the cutting machine on the market, the rollers are improved to four rollers with drives, including the first main roller 1, the first auxiliary roller 2, the second main roller 3 and the second auxiliary roller 4; the first main roller 1, the first auxiliary roller 2 and the second main roller 3 form an isosceles triangle with a vertex angle of 150°; the first main roller 1, the second auxiliary roller 2 and the second main roller 3 form an inverted isosceles triangle with a vertex angle of 120°. The roller lengths of the four rollers are all 400mm, the diameters of the first main roller 1 and the second main roller 3 are 200mm, and the diameters of the first auxiliary roller 2 and the second auxiliary roller 4 are 150mm; the axial spacing between the first main roller 1 and the second main roller 3 is 950mm. During vertical cutting, the axial spacing between the first main roller 1 and the first auxiliary roller 2, and between the second main roller 3 and the first auxiliary roller 2 is 400mm. 2. Vertical cutting process of half-chip silicon block:

[0048] (1) Use epoxy AB glue to stick the resin plate to the crystal support. After curing, use epoxy AB glue to stick 11 half-piece silicon blocks to the resin plate. Wait until the curing is complete to obtain the following Figure 1 The silicon rod shown is then fixed on a cutting machine, with the silicon rod parallel to the wire mesh and 1 mm away from the wire mesh. A diamond wire with a diameter of 40 μm is then used to wrap around four rollers to divide the wire mesh according to the gap between the upper half of the silicon block. The wired silicon rod is divided into 10 wire meshes in total.

[0049] (2) Use a cutting machine to cut the wired silicon rods. The cutting steps are as follows: After pouring the cutting fluid into the mortar tank, it needs to be fully circulated in the working chamber for 18 minutes, while the diamond wire runs back and forth at a line speed of 2000m / min. After preheating, adjust the cutting parameters of the cutting machine: table speed is 1100→2600→100μm / min, diamond wire line speed is 1000m / min, wire tension is 4.0N, wire tension is 4.0N, cutting temperature is controlled at 23℃, cutting fluid flow is controlled at 200L / min, rod lifting speed is 20→30→40mm / min, and the overall process time is 100min.

[0050] (3) After the cutting is completed, the undebonded silicon wafer is obtained, and the undebonded silicon wafer is placed in a debonding machine for debonding, and then placed in a silicon wafer cleaning machine for cleaning, and finally a finished silicon wafer is obtained.

[0051] After being sorted by an automatic silicon wafer sorter, it was found that the TTV rate of the obtained silicon wafers was less than 1%, and the high line and broken line rates were less than 5%.

[0052] Example 4:

[0053] This embodiment specifically describes Figure 2 The cross-cutting process of a half-silicon block shown in FIG. 1 includes the following steps:

[0054] 1. Adjustment of the axis spacing of the cutting machine:

[0055] In this embodiment, based on a commercially available cutting machine, the rollers are improved to consist of four driven rollers: a first main roller 1, a first auxiliary roller 2, a second main roller 3, and a second auxiliary roller 4. The first main roller 1, the first auxiliary roller 2, and the second main roller 3 form an isosceles triangle with a vertex angle of 160°; the first main roller 1, the second auxiliary roller 2, and the second main roller 3 form an inverted isosceles triangle with a vertex angle of 110°. All four rollers have a length of 430 mm. The diameters of the first main roller 1 and the second main roller 3 are 205 mm, and the diameters of the first auxiliary roller 2 and the second auxiliary roller 4 are 145 mm. The axial spacing between the first main roller 1 and the second main roller 3 is 900 mm. During cross-cutting, the axial spacing between the first main roller 1 and the first auxiliary roller 2, and between the second main roller 3 and the first auxiliary roller 2, is 450 mm.

[0056] 2. Vertical cutting process of half silicon block:

[0057] (1) Use epoxy AB glue to stick the resin plate to the crystal support. After curing, use epoxy AB glue to stick 12 half-piece silicon blocks to the resin plate. Wait until the curing is complete to obtain the following Figure 1The silicon rod shown is then fixed on a cutting machine, parallel to the wire mesh, with a distance of 1 mm between the silicon rod and the wire mesh. Diamond wire with a diameter of 40 μm is then used to wrap around four rollers to divide the wire mesh according to the gap between the upper half of the silicon block. The wired silicon rod is divided into 11 wire meshes in total.

[0058] (2) Use a cutting machine to cut the wired silicon rods. The cutting steps are as follows: After pouring the cutting fluid into the mortar tank, it needs to be fully circulated in the working chamber for 20 minutes, while the diamond wire runs back and forth at a line speed of 2000m / min. After preheating, adjust the cutting parameters of the cutting machine: table speed is 1100→2600→100μm / min, diamond wire line speed is 1500m / min, wire tension is 4.5N, wire tension is 4.5N, cutting temperature is controlled at 25℃, cutting fluid flow is controlled at 220L / min, rod lifting speed is 20→30→40mm / min, and the overall process time is 120min.

[0059] (3) After the cutting is completed, the undebonded silicon wafer is obtained, and the undebonded silicon wafer is placed in a debonding machine for debonding, and then placed in a silicon wafer cleaning machine for cleaning, and finally a finished silicon wafer is obtained.

[0060] After being sorted by an automatic silicon wafer sorter, it was found that the TTV rate of the obtained silicon wafers was less than 1%, and the high line and broken line rates were less than 5%.

[0061] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A process for cutting a half-piece silicon block, characterized in that: The cutting process includes: S1. The half-sheet silicon block is glued to a rod and then fixed on a cutting machine comprising four rollers. The wire mesh is then routed around the four rollers according to the gaps between the half-sheet silicon blocks to obtain the silicon rod after routing. The steps for fixing the silicon rod are as follows: the silicon rod is parallel to the wire mesh of the cutting machine, and the silicon rod is 0.5-2mm away from the wire mesh; The four rollers are all driven and can rotate on their own; the four rollers include a first main roller (1), a first auxiliary roller (2), a second main roller (3) and a second auxiliary roller (4); an isosceles triangle with a vertex angle of 140 to 160 degrees is formed between the first main roller (1), the first auxiliary roller (2) and the second main roller (3); an inverted isosceles triangle with a vertex angle of 100 to 120 degrees is formed between the first main roller (1), the second auxiliary roller (4) and the second main roller (3); The lengths of the four rollers are all 350-450 mm, the diameters of the first main roller (1) and the second main roller (3) are 200 ± 5 mm, the diameters of the first auxiliary roller (2) and the second auxiliary roller (4) are 150 ± 5 mm; the distance between the first main roller (1) and the second main roller (3) is 900-1000 mm. It is divided into 9-11 wire nets, and the wiring uses diamond wire with a wire diameter of 35-43μm; S2. Circulate the cutting fluid in the work chamber and adjust the wire speed to preheat. After preheating, adjust the cutting machine's cutting parameters: wire speed 600-2000 m / min, pay-off tension 3.5-4.5 N, take-up tension 3.5-4.5 N, cutting temperature 20-25°C, cutting fluid flow rate 150-220 L / min, and total process time 60-120 min. During cutting, the wire table speed changes from 1100 to 2600 to 100 μm / min, and the wire raising speed changes from 20 to 30 to 40 mm / min. S3. After the cutting is completed, the undebonded silicon wafer is obtained, and the undebonded silicon wafer is placed in a debonding machine for debonding, and then placed in a silicon wafer cleaning machine for cleaning, to finally obtain a finished silicon wafer.

2. The process for cutting a half silicon block according to claim 1, wherein: In step S1, the sticking step is: sticking the resin plate on the wafer support with sticking glue, and then sticking 10-12 half-sheet silicon blocks on the resin plate with sticking glue after curing, and then completely curing to obtain silicon rods.

3. The process for cutting a half silicon block according to claim 1, wherein: In step S2, during preheating, the cycle time is 10-20 minutes and the line speed is 2000 m / min.

4. The process for cutting a half silicon block according to claim 1, wherein: The cutting process is to perform horizontal or vertical cutting on a half-sheet silicon block by adjusting the axis spacing between the first main roller (1) and the first auxiliary roller (2), and between the second main roller (3) and the first auxiliary roller (2).

5. The process for cutting a half silicon block according to claim 4, wherein: During the transverse cutting, the axial spacing between the first main roller (1) and the first auxiliary roller (2), and between the second main roller (3) and the first auxiliary roller (2) is 400-450 mm; during the vertical cutting, the axial spacing between the first main roller (1) and the first auxiliary roller (2), and between the second main roller (3) and the first auxiliary roller (2) is 300-350 mm.

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