Preparation method for photovoltaic silicon wafer, and photovoltaic silicon wafer

Abstract

A preparation method for a photovoltaic silicon (100) wafer. The preparation method comprises: S1, cutting out a scrapped silicon rod section (1) from a square silicon rod (2), and removing a scrapped portion (11) from the scrapped silicon rod section (1), so as to obtain silicon sub-rods (12); S2, bonding the plurality of the silicon sub-rods (12) along the thickness direction of the silicon sub-rods (12), so as to obtain a first preliminary silicon rod (13); S3, cutting the first preliminary silicon rod (13) along the length direction of the silicon sub-rods (12), so as to obtain a plurality of silicon rods (14); and S4, placing the silicon rods (14) in a cutting machine and performing cutting, so as to obtain a plurality of photovoltaic silicon wafers (100). The present invention also relates to a photovoltaic silicon wafer.

Description

Method for preparing photovoltaic silicon wafer and photovoltaic silicon wafer

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to the Chinese patent application No. 202410625584.5, filed on May 20, 2024, entitled “Method for preparing photovoltaic silicon wafer and photovoltaic silicon wafer”, to the State Intellectual Property Office of China, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of photovoltaic cells, and in particular to a method for preparing photovoltaic silicon wafer and photovoltaic silicon wafer. BACKGROUND

[0004] In the process of cutting a silicon rod, the cutting line may break, and due to the large cutting depth, the cutting line is evacuated, and it is difficult to rescue, etc., which may cause the partial area of the silicon rod to be scrapped and unable to be cut into a silicon wafer. In the related art, the silicon rod with the scrapped part is often degummed and cleaned, and then the entire silicon rod is returned to the crystal pulling factory to be used as silicon material for furnace charging. However, the above processing method may reduce the utilization rate of the silicon rod cut into a silicon wafer, and increase the cost of the photovoltaic silicon wafer.

[0005] SUMMARY

[0006] The present disclosure aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present disclosure is to provide a method for preparing photovoltaic silicon wafer, which can effectively utilize the unscrapped part of a square silicon rod, improve the utilization rate of the square silicon rod, and thus reduce the cost of the photovoltaic silicon wafer.

[0007] Another object of the present disclosure is to provide a photovoltaic cell wafer prepared by the above method for preparing photovoltaic silicon wafer.

[0008] According to the method for preparing photovoltaic silicon wafer of the first aspect of the present disclosure, the method comprises the following steps: S1, intercepting a scrapped silicon rod segment from a square silicon rod, and removing a scrapped part in the scrapped silicon rod segment to obtain a sub-silicon rod;

[0009] S2, bonding a plurality of the sub-silicon rods in a thickness direction of the sub-silicon rod to obtain a first primary silicon rod;

[0010] S3, cutting the first primary silicon rod in a length direction of the sub-silicon rod to obtain a plurality of silicon rods;

[0011] S4, placing the silicon rods in a cutting machine for cutting to obtain a plurality of photovoltaic silicon wafers.

[0012] According to the preparation method of the photovoltaic silicon wafer provided in the embodiments of the present disclosure, the scrapped silicon rod segments in the square silicon rod are processed multiple times to form a silicon rod suitable for cutting. Compared with the conventional processing method of the scrapped silicon rod, the method can effectively utilize the unscrapped part of the square silicon rod and improve the utilization rate of the square silicon rod, thereby reducing the cost of the photovoltaic silicon wafer.

[0013] According to some embodiments of the present disclosure, after the first preliminary silicon rod is cut in step S3, the surface of the silicon rod is polished, and the corner of the silicon rod is chamfered.

[0014] According to some embodiments of the present disclosure, before step S2, the preparation method further comprises: if the corner of the sub-silicon rod has a chamfer, determining whether the chamfer radius of the corner of the sub-silicon rod is greater than 2.5 mm,

[0015] if the determination result is yes, the sub-silicon rod is cut to remove the chamfer of the sub-silicon rod;

[0016] if the determination result is no, step S2 is performed.

[0017] According to some embodiments of the present disclosure, before step S1, the preparation method further comprises:

[0018] S0, cutting an arc segment of a circular silicon rod to obtain the square silicon rod;

[0019] S1', cutting the top of the arc segment, and bonding multiple arc segments along the thickness direction of the arc segment to obtain a second preliminary silicon rod;

[0020] S2', cutting all arc segments of the second preliminary silicon rod to obtain the square silicon rod.

[0021] According to some embodiments of the present disclosure, step S4 specifically comprises:

[0022] S41, bonding a resin cushion plate on one side of the workpiece plate in the thickness direction, and the resin cushion plate is arranged transversely to the workpiece plate;

[0023] S42, bonding the silicon rod on the side of the resin cushion plate away from the workpiece plate, and the silicon rod is parallel to the resin cushion plate;

[0024] S43, placing the silicon rod, the resin cushion plate and the workpiece plate as a whole in the cutting machine, and placing the silicon rod obliquely on the cutting line net.

[0025] According to some embodiments of the present disclosure, the cutting line is arranged on two parallel main rollers to form the cutting line net, and the included angle between the resin cushion plate and the workpiece plate is equal to the included angle between the silicon rod and the main roller.

[0026] According to some embodiments of the present disclosure, an included angle between the silicon rod and the main roller is α, wherein the α satisfies: 1°≤ɑ≤6°.

[0027] According to some embodiments of the present disclosure, in step S42, a plurality of the silicon rods are arranged on the resin cushion plate in a width direction of the resin cushion plate, and end portions of two adjacent silicon rods in a length direction of the resin cushion plate are staggered.

[0028] According to some embodiments of the present disclosure, in step S42, a minimum distance between two adjacent silicon rods in a width direction of the resin cushion plate is L, wherein the L satisfies: 1mm≤D≤3mm.

[0029] The photovoltaic silicon wafer according to the second aspect of the embodiments of the present disclosure is prepared by the method for preparing the photovoltaic silicon wafer according to the first aspect of the embodiments of the present disclosure.

[0030] Additional aspects and advantages of the present disclosure will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and / or additional aspects and advantages of the present disclosure will become apparent and be readily appreciated from the following description, including the appended drawings.

[0032] FIG. 1 is a flowchart of a method for preparing a photovoltaic silicon wafer according to an embodiment of the present disclosure;

[0033] FIG. 2 is a flowchart of a method for preparing a photovoltaic silicon wafer according to another embodiment of the present disclosure;

[0034] FIG. 3 is a partial flowchart of a method for preparing a photovoltaic silicon wafer according to an embodiment of the present disclosure;

[0035] FIG. 4 is another partial flowchart of a method for preparing a photovoltaic silicon wafer according to an embodiment of the present disclosure;

[0036] FIG. 5 is a schematic view of a scrap silicon rod segment according to an embodiment of the present disclosure;

[0037] FIG. 6 is a schematic view of a detailed processing method of a scrap silicon rod according to an embodiment of the present disclosure;

[0038] FIG. 7 is a schematic view of preparation of a first primary silicon rod according to an embodiment of the present disclosure;

[0039] FIG. 8 is a schematic view of cutting of a silicon rod according to an embodiment of the present disclosure;

[0040] FIG. 9 is a schematic view of a sub-silicon rod according to an embodiment of the present disclosure, wherein the sub-silicon rod has a chamfer;

[0041] Fig. 10 is a schematic diagram of preparation of a second primary silicon rod according to an embodiment of the present disclosure;

[0042] Fig. 11 is a schematic diagram of a silicon rod, a resin cushion plate and a workpiece plate according to an embodiment of the present disclosure;

[0043] Fig. 12 is a schematic diagram of a silicon rod and a cutting machine according to an embodiment of the present disclosure;

[0044] Fig. 13 is a schematic diagram of a silicon rod and a cutting machine from another angle according to an embodiment of the present disclosure;

[0045] Fig. 14 is a sectional view of a silicon rod according to an embodiment of the present disclosure;

[0046] Fig. 15 is a partial schematic diagram of two adjacent silicon rods according to an embodiment of the present disclosure.

[0047] Reference signs: 100: photovoltaic silicon wafer; 1: scrap silicon rod segment; 11: scrap portion; 12: sub silicon rod; 121: chamfer; 13: first primary silicon rod; 14: silicon rod; 2: square silicon rod; 3: arc-shaped segment; 31: second primary silicon rod; 4: resin cushion plate; 5: workpiece plate; 200: cutting line net; 201: cutting line; 202: main roller. DETAILED DESCRIPTION

[0048] The preparation method of the photovoltaic silicon wafer 100 according to the first aspect of the present disclosure will be described below with reference to Figs. 1-15.

[0049] As shown in Figs. 1-15, the preparation method of the photovoltaic silicon wafer 100 according to the first aspect of the present disclosure comprises:

[0050] S1, referring to Figs. 1, 2, 5 and 6, a scrap silicon rod segment 1 in a square silicon rod 2 is cut off, and a scrap portion 11 in the scrap silicon rod segment 1 is removed to obtain a sub silicon rod 12. Wherein, the square silicon rod 2 has a scrap portion 11 due to the fracture of the cutting line 201 during cutting, and the scrap portion 11 needs to be removed, and the part that can be normally used (i.e. the sub silicon rod 12) is left, which is beneficial to subsequent processing of the sub silicon rod 12. Compared with the traditional processing method of the scrap silicon rod, the unscraped part of the square silicon rod 2 can be effectively utilized, and the utilization rate of the square silicon rod 2 is improved, so that the cost of the photovoltaic silicon wafer 100 can be reduced.

[0051] According to the relative relationship between the length (a) and the height (b) of the scrapped silicon rod and the side length (L, L / 2) of the silicon wafer, five kinds of processing logic can be divided, referring to FIG. 6, the positions of cutting processing are different in the five cases of a>L and b>L / 2, a>L and b<L / 2, L>a>L / 2 and b>L / 2, L>a>L / 2 and b<L / 2, a<L / 2 and b>L / 2, and the processed silicon rods are re-bonded into semi-rods with random lengths. When the length a of the scrapped silicon rod is much larger than L: if b>L / 2, the semi-rod can be directly processed; if b<L / 2, the semi-rod can be processed by stacking multiple pieces, so as to save processing cost, as shown in FIG. 7 and FIG. 10.

[0052] If the non-cutting surface of the scrapped silicon rod is damaged, the size of the multi-spliced semi-rod can be adjusted according to the depth of the damage. For example, in the case of a scrapped silicon rod with a side length of 210 mm and no damage to the non-cutting surface, if a<L / 2 and b>L / 2 (L=210 mm), the scrapped silicon rod can be processed into a semi-rod with the same size as the silicon wafer, for example, assuming a=50 mm and b=120 mm, the scrapped silicon rod can be processed into a semi-rod with a size of 105*210*50 mm. In the case of a scrapped silicon rod with a side length of 210 mm and a 10 mm deep damage to the non-cutting surface, the silicon rod can be processed into a semi-rod with a size of 105*182*50, 95.8*182*50, etc. (the semi-rod can obtain semi-rod sizes including but not limited to 105*210 mm, 105*182 mm, 95.8*182 mm, 91*182 mm, etc. after cutting).

[0053] S2, a plurality of sub-silicon rods 12 are bonded along the thickness direction (for example, the up-down direction in FIG. 7) of the sub-silicon rods 12 to obtain a first primary silicon rod 13. In the description of the present disclosure, the meaning of "a plurality of" is two or more than two. For example, in the examples of FIG. 1, FIG. 2 and FIG. 7, two adjacent sub-silicon rods 12 are bonded by using a bonding layer. Eight sub-silicon rods 12 are sequentially bonded along the thickness direction of the sub-silicon rods 12, so as to facilitate subsequent processing of the eight sub-silicon rods 12 at the same time, simplify the subsequent processing process, and improve the processing efficiency of the plurality of sub-silicon rods 12.

[0054] FIG. 7 shows eight sub-silicon rods 12 for illustrative purposes, but a person skilled in the art can obviously understand that this scheme can be applied to other numbers of sub-silicon rods 12 after reading the technical scheme of the present application, which also falls within the protection scope of the present disclosure.

[0055] S3, cutting the first primary silicon rod 13 along the length direction (for example, the left-right direction in FIG. 7) of the sub-silicon rod 12 to obtain a plurality of silicon rods 14. The first primary silicon rod 13 (i.e., the eight sub-silicon rods 12 bonded together) is cut along the length direction of the sub-silicon rod 12 to cut out the silicon rods 14 which can be used to cut the photovoltaic silicon wafer 100.

[0056] S4, placing the silicon rod 14 in the cutting machine for cutting to obtain a plurality of photovoltaic silicon wafers 100. Thus, the reuse of the sub-silicon rod 12 is realized, and the cost of the photovoltaic silicon wafer 100 is reduced.

[0057] According to the preparation method of the photovoltaic silicon wafer 100 of the embodiment of the present disclosure, the discarded silicon rod segment 1 in the square silicon rod 2 is processed multiple times to form the silicon rod 14 suitable for cutting. Compared with the conventional processing method of the discarded silicon rod, the unused part of the square silicon rod 2 can be effectively utilized, and the utilization rate of the square silicon rod 2 is improved, so that the cost of the photovoltaic silicon wafer 100 can be reduced.

[0058] According to some embodiments of the present disclosure, in step S3, after the first initial silicon rod 13 is cut to obtain the silicon rod 14, the surface of the silicon rod 14 is polished, and the corner of the silicon rod 14 is chamfered. Thus, by polishing the surface of the silicon rod 14 (physical friction and chemical reaction double action), a silicon rod 14 with a highly flat and scratch-free, defect-free super-smooth surface is obtained, so that the surface of the silicon rod 14 meets the flatness requirement for cutting the photovoltaic silicon wafer 100.

[0059] In the formula, the size of the cross section of the silicon rod 14 can be greater than half the size of the cross section of the square silicon rod 2, so as to polish the reserved part of the silicon rod 14, and the size of the cross section of the obtained silicon rod 14 is half the size of the cross section of the square silicon rod 2. For example, when the size of the cross section of the square silicon rod 2 is 182*182mm, the size of the cross section of the silicon rod 14 is 91*182mm; when the size of the cross section of the square silicon rod 2 is 210*210mm, the size of the cross section of the silicon rod 14 is 105*182mm. The width of the silicon rod 14 before polishing needs to be reserved by 0.3-0.5mm, so as to facilitate the size of the cross section of the silicon rod 14 after polishing to be suitable for cutting the photovoltaic silicon wafer 100.

[0060] According to some embodiments of the present disclosure, referring to FIG. 2 and FIG. 9, before step S2, if the corner of the sub-silicon rod 12 has a chamfer 121, it is judged whether the radius of the chamfer 121 at the corner of the sub-silicon rod 12 is greater than 2.5mm,

[0061] If the judgment result is yes, the sub-silicon rod 12 is cut to remove the chamfer 121 of the sub-silicon rod 12;

[0062] If the judgment result is no, step S2 is performed.

[0063] That is, if the corner of the sub-silicon rod 12 does not have a chamfer 121, step S2 is performed. If the corner of the sub-silicon rod 12 has a chamfer 121, the radius of the chamfer 121 needs to be judged to reduce the influence of the chamfer 121 on the cutting of the silicon rod 14.

[0064] When the radius of the chamfer 121 at the corner of the sub-silicon rod 12 is less than 2.5 mm, the chamfer 121 has no effect on the cutting of the photovoltaic silicon wafer 100, that is, the corresponding silicon rod 14 at the chamfer 121 meets the cutting size requirements of the photovoltaic silicon wafer 100. When the radius of the chamfer 121 at the corner of the sub-silicon rod 12 is greater than 2.5 mm, it will affect the size of the photovoltaic silicon wafer 100 cut, and it is difficult to meet the use requirements of the photovoltaic silicon wafer 100, so the sub-silicon rod 12 needs to be processed, that is, the chamfer 121 of the sub-silicon rod 12 is removed, which is beneficial to the cutting of the silicon rod 14 to obtain the designed photovoltaic silicon wafer 100.

[0065] In addition, referring to FIG. 3, the preparation method further includes the following steps before step S1:

[0066] S0, cutting the arc-shaped segments 3 of the circular silicon rod 14 to obtain a square silicon rod 2.

[0067] S1', referring to FIGS. 3 and 10, the top of each arc-shaped segment 3 is cut off, and a plurality of arc-shaped segments 3 are bonded along the thickness direction of the arc-shaped segment 3 (for example, the up-down direction in FIG. 10) to obtain a second primary silicon rod 31. The top of each arc-shaped segment 3 is cut off to make the two sides in the thickness direction of the arc-shaped segment 3 parallel, thereby facilitating the bonding of the plurality of arc-shaped segments 3. For example, in the example of FIG. 10, after the top of each of the eight arc-shaped segments 3 is cut off, the eight arc-shaped segments 3 are stacked and bonded in the thickness direction of the arc-shaped segment 3 in turn to obtain the second primary silicon rod 31.

[0068] S2', referring to FIGS. 3 and 10, all arc-shaped segments of the second primary silicon rod 31 are cut off to obtain a square silicon rod 2. In this step, a plurality of arc-shaped segments 3 in the second primary silicon rod 31 can be processed at the same time, which is beneficial to ensuring the consistency of the processing of the plurality of arc-shaped segments 3, simplifying the preparation method of the square silicon rod 2, and improving the preparation efficiency of the square silicon rod 2.

[0069] For example, the sub-silicon rod 12 can be processed from the edge waste of the square silicon rod 2 with a size of 210, and the size of the sub-silicon rod 12 can be 182.2 mm x 95.8 mm x 33 mm.

[0070] Therefore, the utilization of the arc-shaped segments 3 of the circular silicon rod 14 is improved, and the plurality of arc-shaped segments 3 are bonded and stacked after the top of each arc-shaped segment 3 is cut off, that is, the plurality of arc-shaped segments 3 are bonded into the second primary silicon rod 31, and then all the arc-shaped segments 3 are cut off, which avoids the overflow problem of the square silicon rod 2, and improves the preparation efficiency of the square silicon rod 2.

[0071] According to some embodiments of the present disclosure, referring to FIG. 4, step S4 specifically includes:

[0072] S41, referring to FIG. 11, the resin pad plate 4 is bonded on one side of the workpiece plate 5 in the thickness direction (for example, the up-down direction in FIG. 15), and the resin pad plate 4 is arranged crossing the workpiece plate 5. That is, a certain angle is formed between the extension direction of the workpiece plate 5 and the extension direction of the resin pad plate 4.

[0073] S42, referring to FIG. 11, the silicon rod 14 is bonded on the side of the resin pad plate 4 away from the workpiece plate 5, and the silicon rod 14 is parallel to the resin pad plate 4. The resin pad plate 4 can completely cover the side of the silicon rod 14 facing the workpiece plate 5, which is conducive to the protection of the silicon rod 14 by the resin pad plate 4, and at the same time increases the stability of the silicon rod 14 during cutting, so as to increase the cutting consistency of the photovoltaic silicon wafer 100. In addition, since the mass of the resin pad plate 4 is small, the resin pad plate 4 is first bonded on the workpiece plate 5, and then the silicon rod 14 is connected, which is conducive to improving the assembly efficiency.

[0074] S43, as shown in FIGS. 11-13, the silicon rod 14, the resin pad plate 4 and the workpiece plate 5 are placed as a whole in the cutting machine, and the silicon rod 14 is placed on the cutting line net 200 at an angle. In this way, the silicon rod 14, the resin pad plate 4 and the workpiece plate 5 can be operated as a whole, so as to improve the cutting stability of the cutting machine to the silicon rod 14. Among them, an angle is formed between the silicon rod 14 and the cutting line net 200, which can avoid the cutting line net 200 passing through the bonding layer completely, and reduce the risk of breaking of the cutting line net 200.

[0075] Further, referring to FIG. 12, the cutting line 201 is wound around two parallel arranged main rollers 202 to form the cutting line net 200, and the angle between the resin pad plate 4 and the workpiece plate 5 is equal to the angle between the silicon rod 14 and the main roller 202.

[0076] The resin pad plate 4 and the workpiece plate 5 are arranged crossing, and since the resin pad plate 4 is parallel to the silicon rod 14, the silicon rod 14 and the workpiece plate 5 are arranged crossing, so that when the silicon rod 14, the resin pad plate 4 and the workpiece plate 5 are placed as a whole in the cutting machine, the axis of the workpiece plate 5 is parallel to the axis of the main roller 202 of the cutting machine, and then an angle is formed between the extension direction of the silicon rod 14 and the resin pad plate 4 and the axis of the main roller 202. In this way, when the silicon rod 14 is cut, there is a cutting mode of full silicon wafer-bonding layer-full silicon wafer, which reduces the risk of breaking of the cutting line 201 at the bonding layer during the cutting of the silicon rod 14, so that the cutting line net 200 in the cutting machine can not be operated, and the preparation efficiency of the photovoltaic silicon wafer 100 is improved.

[0077] Further, referring to FIG. 11 and FIG. 12, the included angle between the silicon rod 14 and the main roller 202 is α, wherein α satisfies: 1°≤α≤6°. When α<1°, the included angle between the silicon rod 14 and the main roller 202 is small, which leads to that the included angle between the bonding layer of the silicon rod 14 and the cutting line 201 is too small, and the cutting line 201 passes through most of the bonding layer in the cutting process, which leads to that the breakage rate of the cutting line 201 increases, thereby causing the cutting yield to decrease. When α>6°, since the included angle between the bonding layer of the silicon rod 14 and the cutting line 201 is too large, it also leads to that the breakage rate of the cutting line 201 increases, and the cutting yield and the process loss (i.e., the part of the silicon rod 14 which fails to be processed into the photovoltaic silicon wafer 100) are not advantageous. Therefore, by making the included angle α between the silicon rod 14 and the main roller 202 satisfy 1°≤α≤6°, the cutting process is ensured to be normal, the breakage rate of the cutting line 201 is at a normal level, and the cutting yield and the process loss are advantageous.

[0078] Optionally, α further satisfies: 1°≤α≤2°. By setting in this way, the included angle α between the silicon rod 14 and the main roller 202 is more reasonable, the cutting process is ensured to be normal, the breakage rate of the cutting line 201 is at a normal level, the cutting yield can be further improved, and the process loss is further reduced.

[0079] The comparison of the specific processing data of the silicon rod according to the embodiments of the present disclosure is as follows:

[0080] Embodiment 1

[0081] Referring to Table 1, the thickness of the bonding layer between the two adjacent sub-silicon rods 12 is in the range of 50μm to 250μm, the included angle between the silicon rod 14 and the main roller 202 is 0.5°, at this time, the included angle between the joint and the cutting line 201 is too small, and in the cutting process, a plurality of high lines appear at the joint, which leads to that the breakage rate increases sharply (25.3%), and the cutting yield also decreases sharply.

[0082] Embodiment 2

[0083] Referring to Table 1, the thickness of the bonding layer between the two adjacent sub-silicon rods 12 is in the range of 50μm to 250μm, the included angle between the silicon rod 14 and the main roller 202 is 2°, in the cutting process, the joint is normal, the breakage rate is at a normal level (10.5%), and the cutting yield and the process loss are advantageous.

[0084] Embodiment 3

[0085] Referring to Table 1, the thickness of the bonding layer between the two adjacent sub-silicon rods 12 is in the range of 50μm to 250μm, the included angle between the silicon rod 14 and the main roller 202 is 5°, in the cutting process, the joint is normal, the breakage rate increases (15.2%), and the cutting yield and the process loss are not advantageous.

[0086] Example 4

[0087] Double-row vertical cutting line screen cutting, silicon rod 14 is parallel to the main roller 202, the thickness of the bonding layer between the two adjacent sub-silicon rods 12 is less than 150 μm, in the cutting process, the joint is not passed through the cutting line 201, affected by the alignment of the two rows of joints, the process loss is 13.57%, the breakage rate is at the normal level (12.07%), and the cutting yield is general.

[0088] Table 1

[0089] Referring to FIG. 15, according to some embodiments of the present disclosure, in step S42, a plurality of silicon rods 14 are arranged on the resin cushion plate 4 along the width direction (for example, the left-right direction in FIG. 15) of the resin cushion plate 4, and the end portions of the two adjacent silicon rods 14 are staggered in the length direction (for example, the up-down direction in FIG. 15) of the resin cushion plate 4. Arranging a plurality of silicon rods 14 along the width direction of the resin cushion plate 4, and arranging a plurality of silicon rods 14 along the length direction of the resin cushion plate 4, is beneficial to improve the space utilization rate in the cutting machine. Staggering the end portions of the two adjacent silicon rods 14 is beneficial to reduce the thickness and quantity of the scrapped silicon wafers cut at the connection position of the two adjacent silicon rods 14 in the length direction of the resin cushion plate 4, thereby reducing the process loss.

[0090] The comparison of the specific processing data of the silicon rod 14 according to the embodiments of the present disclosure is as follows:

[0091] Example 5

[0092] For a silicon rod 14 with a specification of 12 joints and a thickness of 33 mm, a 4*12 joint double-row vertical bonding mode is adopted, and a screen cutting without line is used by using an oblique cutting mode, the inclination is set to 1° to 2°, the actual inclination of the joint (the total inclined length of the joint between the two silicon rods 14 arranged in the length direction of the resin cushion plate 4 in the extension direction of the cutting line 201) is 5.5 mm, the process loss is 9.79%; the actual inclination of the joint is 5.0 mm, the process loss is 8.96%; the actual inclination of the joint is 4.5 mm, the process loss is 8.14%; the actual inclination of the joint is 4.0 mm, the process loss is 7.32%; the actual inclination of the joint is 3.5 mm, and the process loss is 6.5%.

[0093] Example 6

[0094] For the silicon rods 14 with a size of 12 pieces and a thickness of 33 mm, a 4*12 pieces double-row vertical bonding mode is adopted, the slant cutting mode is used for non-separation line net cutting, the slope is set to 1° to 2°, the actual slope of the joint seam is 5.0 mm, the process loss is 8.96%, by splicing the joint seam between the end portions of the adjacent two silicon rods 14 and staggering the arrangement of the end portions thereof, the process loss is reduced by 1.64%, and the process loss obtained is 7.32%.

[0095] When the photovoltaic silicon wafer 100 is processed, the two silicon rods 14 can be vertically arranged and placed, a gap is left between the two silicon rods 14, and the end portions of the adjacent two silicon rods 14 in the length direction of the resin cushion plate 4 are staggered and arranged in sequence, and finally the plurality of silicon rods 14 are placed on the cutting line net 200 of the cutting machine, at this time, there is an included angle between the silicon rod 14 and the cutting line net 200, and the silicon rod 14 is approximately in the middle of the cutting line net 200. When the silicon rod 14 is cut, the part of the silicon rod 14 at the bonding layer after cutting, there is a through bonding layer on one of the two silicon rods 14 obtained, and the above-mentioned through bonding layer also changes with the change of the cutting position (as shown in FIG. 14), there is a cutting mode of full silicon wafer-bonding layer-full silicon wafer, which makes there is no any abnormality in the cutting process of the silicon rod 14, and reduces the risk of fracture of the cutting line net 200.

[0096] In addition, the reduction of the number of silicon rods 14 along the length direction of the resin cushion plate 4 in the cutting machine also reduces the space utilization rate in the cutting machine and improves the process loss.

[0097] Example 7

[0098] For example, the plurality of silicon rods 14 are arranged along the length direction of the resin cushion plate 4 in sequence, the actual slope of the joint gap between the end portions of the two adjacent silicon rods 14 in the extension direction of the cutting line 201 is 4mm, the number of the silicon rods 14 is reduced from 12 to 11, the process loss is 7.44%; the number of the silicon rods 14 is reduced from 12 to 10, the process loss is 7.58%; the number of the silicon rods 14 is reduced from 12 to 9, the process loss is 7.74%. Further, as shown in FIG. 12, in step S42, the minimum distance between the two adjacent silicon rods 14 along the width direction of the resin cushion plate 4 is L, wherein L satisfies: 1mm≤L≤3mm. When L<1mm, the minimum distance between the two adjacent silicon rods 14 is small, firstly, in the cutting process, the two silicon rods 14 move towards the adjacent silicon rod 14, thereby colliding with each other, reducing the stability of the cutting of the silicon rods 14, secondly, it is difficult to install the baffle between the two adjacent silicon rods 14 after the cutting is completed, and in the process of separating the photovoltaic silicon wafer 100 from the resin cushion plate 4, the baffle is easy to tilt to the middle. When L>3mm, the minimum distance between the two adjacent silicon rods 14 is large, and it is difficult to realize the simultaneous cutting of the two silicon rods 14 in the limited space of the cutting machine. Therefore, by making the minimum distance L between the two adjacent silicon rods 14 satisfy 1mm≤L≤3mm, the two adjacent silicon rods 14 are spaced apart in the limited space of the cutting machine, so as to avoid affecting each other in the cutting process, improve the stability of the cutting, and at the same time, facilitate the installation of the baffle between the two adjacent silicon rods 14 after the cutting is completed, and improve the stability of the photovoltaic silicon wafer 100 cut by the two silicon rods 14 in the process of separating the photovoltaic silicon wafer 100 from the resin cushion plate 4.

[0099] Optionally, the viscosity of the adhesive layer is less than 10 Pa·s, and the strength of the adhesive layer is greater than 10 Mpa. The thickness of the adhesive layer is less than 300 μm, and preferably ranges from 50 μm to 250 μm.

[0100] Optionally, the adhesive layer can be an epoxy resin glue. However, it is not limited thereto.

[0101] The photovoltaic silicon wafer 100 according to the second aspect of the present disclosure is prepared by using the preparation method of the photovoltaic silicon wafer 100 according to the first aspect of the present disclosure.

[0102] The photovoltaic silicon wafer 100 according to the present disclosure is prepared by using the above preparation method of the photovoltaic silicon wafer 100, which is beneficial to improve the utilization rate of the silicon rod 14, thereby reducing the cost of the photovoltaic silicon wafer 100.

[0103] Other operations of the preparation method of the photovoltaic silicon wafer 100 according to the present disclosure are known to those skilled in the art, and will not be described in detail here.

[0104] In the description of the disclosure, it needs to be understood that the terms "center", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the disclosure.

[0105] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

[0106] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present application, the exemplary description of the above terms does not necessarily refer to the same embodiment or example.

[0107] Although the embodiments of the present disclosure have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present disclosure, and the scope of the present disclosure is defined by the claims and their equivalents.

Claims

1. A method of producing a photovoltaic silicon wafer (100), characterized in that, The method comprises the following steps: S1, cutting off a scrap silicon rod segment (1) from a square silicon rod (2) and removing a scrap portion (11) from the scrap silicon rod segment (1) to obtain a sub silicon rod (12); S2, bonding a plurality of the sub silicon rods (12) along the thickness direction of the sub silicon rod (12) to obtain a first primary silicon rod (13); S3, cutting the first primary silicon rod (13) along the length direction of the sub silicon rod (12) to obtain a plurality of silicon rods (14); S4, placing the silicon rods (14) in a cutting machine for cutting to obtain a plurality of photovoltaic silicon wafers (100). In step S3, after the first primary silicon rod (13) is cut to obtain the silicon rods (14), the surface of the silicon rod (14) is polished, and the corner of the silicon rod (14) is chamfered.

2. The method of producing a photovoltaic silicon wafer (100) according to claim 1, characterized in that, Before step S2, further comprising: if there is a chamfer at the corner of the sub silicon rod (12), judging whether the chamfer radius at the corner of the sub silicon rod (12) is greater than 2.5mm, 3. The method of producing a photovoltaic silicon wafer (100) according to claim 1 or 2, characterized in that if the judgment result is yes, cutting the sub silicon rod (12) to remove the chamfer of the sub silicon rod (12); if the judgment result is no, executing step S2. Before step S1, further comprising:

4. The method of producing a photovoltaic silicon wafer (100) according to any one of claims 1 to 3, characterized in that, S0, cutting off an arc segment of a circular silicon rod to obtain a square silicon rod (2); S1', cutting off the top of the arc segment and bonding a plurality of the arc segments along the thickness direction of the arc segment to obtain a second primary silicon rod (31), and S2', cutting off all arc portions of the second primary silicon rod (31) to obtain the square silicon rod (2). Step S4 specifically comprises:

5. The method of producing a photovoltaic silicon wafer (100) according to any one of claims 1 to 4, characterized in that, S41, bonding a resin cushion plate (4) on one side of a workpiece plate (5) in the thickness direction, and the resin cushion plate (4) and the workpiece plate (5) are cross arranged; S42, bonding the silicon rods (14) on the side of the resin cushion plate (4) away from the workpiece plate (5), and the silicon rods (14) are parallel to the resin cushion plate (4); and S43, placing the silicon rods (14), the resin cushion plate (4) and the workpiece plate (5) as a whole in the cutting machine, and the silicon rods (14) are placed on the cutting line net (200) in an inclined manner. The cutting line is wound around two parallel arranged main rollers (202) to form the cutting line net (200), 6. The method of producing a photovoltaic silicon wafer (100) according to claim 5, characterized in that, the included angle between the resin cushion plate (4) and the workpiece plate (5) is equal to the included angle between the silicon rods (14) and the main rollers (202). The included angle between the silicon rods (14) and the main rollers (202) is α, wherein the α satisfies: 1°≤ɑ≤6°.

7. The method of producing a photovoltaic silicon wafer (100) according to claim 6, characterized in that, In step S42, a plurality of the silicon rods (14) are arranged on the resin cushion plate (4) in the width direction of the resin cushion plate (4), and the end portions of two adjacent silicon rods (14) in the length direction of the resin cushion plate (4) are arranged in a staggered manner.

8. The method of producing a photovoltaic silicon wafer (100) according to any one of claims 5 to 7, characterized in that, In step S42, the minimum distance between two adjacent silicon rods (14) in the width direction of the resin cushion plate (4) is L, wherein the L satisfies: 1mm≤D≤3mm.

9. The method of producing a photovoltaic silicon wafer (100) according to claim 8, characterized in that, ​ 10. A photovoltaic silicon wafer (100), characterized in that The photovoltaic silicon wafer (100) is prepared by the method for preparing the photovoltaic silicon wafer (100) according to any one of claims 1-9. The photovoltaic silicon wafer (100) is prepared by the method for preparing the photovoltaic silicon wafer (100) according to any one of claims 1-9.

Images