CN108357002B - Solar-grade silicon wafer and production method thereof - Google Patents
Solar-grade silicon wafer and production method thereof Download PDFInfo
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- CN108357002B CN108357002B CN201810231704.8A CN201810231704A CN108357002B CN 108357002 B CN108357002 B CN 108357002B CN 201810231704 A CN201810231704 A CN 201810231704A CN 108357002 B CN108357002 B CN 108357002B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28D—WORKING STONE OR STONE-LIKE MATERIALS
- B28D5/00—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor
- B28D5/04—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by tools other than rotary type, e.g. reciprocating tools
- B28D5/042—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by tools other than rotary type, e.g. reciprocating tools by cutting with blades or wires mounted in a reciprocating frame
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28D—WORKING STONE OR STONE-LIKE MATERIALS
- B28D5/00—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor
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- B28D5/0082—Accessories specially adapted for use with machines for fine working of gems, jewels, crystals, e.g. of semiconductor material for supporting, holding, feeding, conveying or discharging work
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28D—WORKING STONE OR STONE-LIKE MATERIALS
- B28D5/00—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor
- B28D5/04—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by tools other than rotary type, e.g. reciprocating tools
- B28D5/045—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by tools other than rotary type, e.g. reciprocating tools by cutting with wires or closed-loop blades
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Abstract
The invention relates to a solar grade silicon chip and a production method thereof. At least one surface of the solar-grade silicon wafer is provided with a plurality of grooves (1). According to the invention, parameters such as loop rate and the like in the silicon wafer cutting process are improved and controlled, so that a novel solar-grade silicon wafer is obtained, and the surface of the novel solar-grade silicon wafer is provided with a groove with a certain size and shape; the surface of the silicon wafer is free of damage, scratches, stains, water stains and stains, and the size uniformity is within a certain range; the mechanical strength of the silicon wafer is excellent; the photoelectric conversion efficiency of the cell prepared on the basis of the silicon wafer is excellent; compared with the existing solar-grade silicon wafer, the specific surface area of the novel solar-grade silicon wafer is increased, and the unit area power generation of the cell is also remarkably improved. In conclusion, the invention has the advantages of high utilization rate of silicon materials, high utilization rate of solar energy, low process energy consumption, environmental protection and the like.
Description
Technical Field
The invention relates to the field of photovoltaic silicon wafer manufacturing, in particular to a solar-grade silicon wafer and a production method thereof.
Background
The photovoltaic industry is an upstream and downstream related industry formed by using the photovoltaic effect to enable solar energy to irradiate a silicon material to generate current and directly generate power. Photovoltaic power generation is a technology of directly converting light energy into electric energy by using the photovoltaic effect of a semiconductor interface. Due to the continuous manifestation of global warming, deterioration of ecological environment, and shortage of conventional energy, the development of renewable energy is receiving attention from various countries all over the world. Under the promotion of national policies and the introduction of new energy requirements, the newly increased installed photovoltaic capacity in China has been increased continuously since 2015. In the future, with the gradual deepening of new energy application, the photovoltaic industry in China will be further developed.
Silicon wafer cutting is an important ring in the photovoltaic industry, and solar grade silicon wafers cut by using diamond wires are an important means for reducing the production cost at present. The silicon wafer dicing process has hardly changed over the past decade. The method has the advantages of reducing cost, improving production efficiency and controlling the damage of silicon carbide to the environment, and is three major problems to be solved urgently by the wire cutting technology of high-hardness and brittle materials. With the expansion of industrial scale and the pressure of cost increase, the appeal for solving the problems becomes more and more severe, and the desire for solving the problems is realized by the arrival of the diamond wire cutting technology.
In addition, the existing solar grade silicon wafer product is mainly a silicon wafer with uniform thickness, no depth line mark or shallow line mark and uniform surface.
In the prior art, the silicon wafer produced by diamond wire cutting adopts linear unidirectional cutting, and the applicant of the invention applies and protects a diamond wire cutting polycrystalline silicon wafer device and a cutting method which can realize the reciprocating cutting of diamond wires in Chinese patent (application number: 201711129042.5).
Disclosure of Invention
The invention aims to provide a solar-grade silicon wafer and a production method thereof, and the solar-grade silicon wafer can be used for manufacturing a cell which can obviously improve the generated energy per unit area and has the advantages of high utilization rate of silicon materials, high utilization rate of solar energy, low process energy consumption, environmental protection and the like.
The invention provides a solar-grade silicon wafer, wherein at least one surface of the solar-grade silicon wafer is provided with a plurality of grooves.
In the solar-grade silicon wafer, the grooves are formed in the upper surface and the lower surface of the solar-grade silicon wafer.
In the solar-grade silicon wafer, a plurality of grooves on the same surface are parallel to each other; the upper surface and the lower surface of the solar-grade silicon wafer are parallel to each other.
In the solar-grade silicon wafer, each groove is linear or curved; the wire tension adjusting device can be specifically adjusted by adjusting the wire speed and the tension of the diamond wire (the speed of the diamond wire can be adjusted through the rotation of a guide wheel, and the tension of the diamond wire is adjusted through a tension system sensor).
And/or the section perpendicular to the extending direction of the groove is arc-shaped or U-shaped;
the dimensions of the arc may be: the chord length is 0.1-0.4 mm;
and/or each of said trenches has a maximum depth of less than 15 μm,
and/or the distance (spacing) between the adjacent edges of two adjacent grooves is 0.1-0.8 mm.
In the solar-grade silicon wafer, the solar-grade silicon wafer is rectangular, four corners of the rectangle are provided with chamfers,
the chamfer is a straight chamfer or an arc chamfer;
the degree of the straight chamfer is 30-45 degrees, and the size is 0.5-2 mm;
in the production process of the silicon wafer, 4 corners of the silicon rod are the cutting edges for diamond wire cutting, and the silicon rod is processed into the chamfer angle, so that the defect of the silicon wafer in the cutting process can be prevented, the edge breakage in the carrying and production processes can be effectively prevented, and the fracturing in the process of manufacturing the battery piece can be prevented.
In the solar-grade silicon wafer, the technical parameters of the solar-grade silicon wafer are as follows:
the shape is square, the side length is 156.75 + -0.25 mm, the thickness is 200 + -20 μm, and the single crystallite is smaller than 3 × 3mm2The whole microcrystalline region is less than 3 x 3cm2；
The oxygen content is less than or equal to 8.0 multiplied by 1017atoms/cm3(16ppma) and carbon content of less than or equal to 6.0X 1017atoms/cm3(12ppma), a resistivity of 1-3 omega cm, and a minority carrier lifetime of more than or equal to 1.0 mus.
The invention also provides a production method of the solar grade silicon wafer, which comprises the following steps: cutting a silicon material (such as a solid silicon block of monocrystalline silicon or polycrystalline silicon) by using a metal wire to obtain any one of the solar-grade silicon wafers;
wherein, during the cutting, the metal wire is cut back and forth, and the loop rate is 70-97%; the proper loop rate can generate a proper depth groove, which is also a key factor of cost control, and the loop rate is too high to obtain the solar grade silicon wafer; the loop rate is too low and the cost is too high.
In the above production method, the metal wire is a steel wire, preferably a diamond wire, more preferably a plated diamond wire,
the outer diameter of the diamond wire is 65-75 mu m,
the diamond grain diameter of the diamond wire is 6-10 mu m;
more specifically, the height of the diamond exposed outside the coating is 4-6 μm, the diamonds on the diamond wire are uniformly spaced, and the number of single-sided diamond particles is 60-80.
In the prior art, the grain diameter of diamond grains is usually controlled to be 15-50 mu m, but the loss of single crystal materials is large, the invention reduces the outer diameter of a diamond wire and the grain diameter of the diamond grains, can reduce the material loss, increases the number of silicon wafers produced by silicon materials with unit length, and reduces the processing cost.
In the above production method, the linear speed of the cutting is 1000 to 1400 m/min.
In the above production method, the tension of the wire is 8 to 14 newtons; the temperature of the cutting cooling liquid is 20-30 ℃; the cooling water flow is 100-150L/min.
The invention has the following beneficial effects:
according to the invention, parameters such as loop rate and the like in the silicon wafer cutting process are improved and controlled, so that a novel solar-grade silicon wafer is obtained, and the upper surface and the lower surface of the novel solar-grade silicon wafer are provided with grooves with certain depth and shape; the surface of the silicon wafer is free of damage, scratches, stains, water stains and stains, and the size uniformity is within a certain range; the mechanical strength of the silicon wafer is excellent; the photoelectric conversion efficiency of the cell prepared on the basis of the silicon wafer is excellent; compared with the existing solar-grade silicon wafer, the specific surface area of the novel solar-grade silicon wafer is increased, and the unit area power generation of the cell is also remarkably improved. In conclusion, the invention has the advantages of high utilization rate of silicon materials, high utilization rate of solar energy, low process energy consumption, environmental protection and the like.
Drawings
FIG. 1 is a schematic structural diagram of a solar-grade silicon wafer.
Fig. 2 is an enlarged view of fig. 1 at a rectangular frame.
Fig. 3 is a cross-sectional view along AA of fig. 1 (the groove is arcuate).
The reference numerals in fig. 1-3 are as follows:
1. groove, 2, upper surface, 3, lower surface, 4, chamfer.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Loop rate: when the diamond wire cutting machine cuts, the diamond wire is cut back and forth, and the return wire length of the diamond wire accounts for the percentage of the wire feeding length. If the electroplated diamond wire runs forwards (the wire feeding length) by 500 meters and runs backwards (the wire returning length) by 350 meters, the wire returning rate is 70 percent.
Examples 1-3 production of solar grade silicon wafers
Cutting a silicon material (a monocrystalline silicon rod or a polycrystalline silicon block with the size of 156.75 +/-0.25 mm) by using an electroplating diamond wire to obtain a solar-grade silicon wafer (shown in figures 1 and 2) with a plurality of grooves 1 on the surface, and specifically comprising the following steps:
(1) and (3) chamfering: the four edges of the qualified silicon material are machined into a chamfer 4 (shown in fig. 1 and 2) with certain shape and size by using a chamfering machine.
(2) Stick sticking: and gluing the chamfered silicon material according to the process requirement.
(3) Wire cutting: loading the glued silicon material on an electroplating diamond wire cutting machine, cutting the silicon material by using an electroplating diamond wire, and processing the silicon material into a silicon wafer;
wherein, the electroplating diamond wire is cut back and forth during cutting, the loop rate is 70-97%, and the wire speed is 1000-1400 m/min; controlling the tension of the electroplated diamond wire to be 8-14 newtons according to the diamond wire of the parent metal with the outer diameter of 70 mu m; the temperature of cutting cooling liquid is controlled between 20 ℃ and 30 ℃, and the flow of cooling water is controlled between 100L/min and 150L/min; to control the shape, size and wafer quality of the trenches 1.
(4) Degumming: after the silicon rod is processed into the silicon wafer by the electroplating diamond wire cutting machine, removing a glue layer between the silicon wafer and a resin plate;
(5) inserting sheets: after degumming, inserting the degummed silicon wafer into a silicon wafer box with fixed specification through a wafer inserting machine;
(6) cleaning: putting the silicon wafer box inserted with the silicon wafer into a cleaning machine, cleaning and drying the silicon wafer;
(7) and (4) checking: and (4) inspecting the silicon wafer by using an inspector, and warehousing the qualified silicon wafer.
And (3) silicon wafer inspection results:
the silicon chip is square, and the upper surface 2 and the lower surface 3 are both provided with a plurality of mutually parallel grooves 1 (shown in figures 1 and 2) which are linear in shape;
the side length of the square is 156.75 +/-0.25 mm, the thickness is 200 +/-20 mu m, the depth of each groove 1 is less than 15 mu m, and the single microcrystal is less than 3 multiplied by 3mm2The whole microcrystalline region is less than 3 x 3cm2(ii) a The surface of the silicon chip is not damaged, scratched or smeared, and has no water stain or stain; the size uniformity of the silicon wafer can be ensured within a certain range;
the oxygen content of the silicon chip is less than or equal to 8.0 multiplied by 1017atoms/cm3(16ppma) and carbon content of less than or equal to 6.0X 1017atoms/cm3(12ppma), the resistivity is 1-3 omega cm, and the minority carrier lifetime is more than or equal to 1.0 mu s; so as to ensure that the mechanical strength of the silicon chip is excellent, and the electrical performance parameters can ensure that the photoelectric conversion efficiency of the cell has an excellent manufacturing foundation.
The solar grade silicon wafer obtained by the method and corresponding process parameters are detailed in table 1.
TABLE 1
In table 1, the diamond wires have a height of 4 to 6 μm, the diamonds are uniformly spaced, and the number of single-side diamond particles is 60 to 80.
Comparative example 1 detection of amount of generated Power per Unit area of cell
According to the same steps of the conventional cell preparation method, the solar grade silicon wafers prepared in the embodiments 1 to 3 are used for preparing the cell, and meanwhile, the conventional solar grade silicon wafers (the surfaces of which are all provided with no grooves, but other technical parameters are the same as those of the solar grade silicon wafers prepared in the embodiments 1 to 3) are used as a reference, and the same method is used for detecting the generated energy.
As a result, the power generation per unit area of the solar-grade silicon wafers prepared in examples 1 to 3 was 1.2 to 1.5 times that of the conventional solar-grade silicon wafers.
Those not described in detail in this specification are within the skill of the art.
Claims (7)
1. A solar-grade silicon wafer is characterized in that at least one surface of the solar-grade silicon wafer is provided with a plurality of grooves (1); the grooves (1) on the same surface are parallel to each other, and the upper surface (2) and the lower surface (3) of the solar-grade silicon wafer are parallel to each other;
wherein each groove (1) is linear or curved in shape; the section of the groove (1) is arc-shaped, and the chord length of the arc is 0.1-0.4 mm;
and/or the maximum depth of each groove (1) is less than 15
，
And/or the distance between the adjacent edges of two adjacent grooves (1) is 0.1-0.8 mm;
the technical parameters of the solar-grade silicon wafer are as follows:
the shape is square, the side length is 156.75 plus or minus 0.25mm, and the thickness is 200 plus or minus 20
Single crystallite of less than 3X 3mm2The whole microcrystalline region is less than 3 x 3cm2；
The oxygen content is less than or equal to 8.0 multiplied by 1017atoms/cm3Carbon content is less than or equal to 6.0 x 1017atoms/cm3Resistivity of 1-3 omega cm, minority carrier lifetime of 1.0 or more
。
2. The solar-grade silicon wafer according to claim 1, wherein the grooves (1) are formed in the upper surface (2) and the lower surface (3) of the solar-grade silicon wafer.
3. The solar-grade silicon wafer according to any one of claims 1 to 2, wherein the solar-grade silicon wafer is rectangular, four corners of the rectangle are chamfered (4),
the chamfer (4) is a straight chamfer or an arc chamfer;
the degree of the straight chamfer is 30-45 degrees, and the size is 0.5-2 mm.
4. A production method of a solar grade silicon wafer comprises the following steps: cutting the silicon material by using a metal wire to obtain the solar-grade silicon wafer as claimed in any one of claims 1 to 3;
wherein, during the cutting, the metal wire is cut back and forth, and the loop rate is 70-97%.
5. The production method according to claim 4, wherein: the metal wire is a diamond wire which is provided with a plurality of metal wires,
the outer diameter of the diamond wire is 65-75
，
The diamond wire has diamond particles with a particle size of 6-10
。
6. The production method according to claim 4 or 5, wherein: the linear speed of the cutting is 1000-1400 m/min.
7. The production method according to claim 4 or 5, wherein: the tension of the metal wire is 8-14 newtons; the temperature of the cutting cooling liquid is 20-30 ℃; the cooling water flow is 100-150L/min.
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| CN109049371A (en) * | 2018-08-11 | 2018-12-21 | 山西潞安太阳能科技有限责任公司 | A kind of technique of 60 μm of Buddha's warrior attendant wire cuttings, 180 μ m thick monocrystalline silicon piece |
| CN109435085A (en) * | 2019-01-08 | 2019-03-08 | 天津中环领先材料技术有限公司 | A kind of technique of diamond wire cutting semi-conductor silicon chip |
| CN112157830B (en) * | 2020-10-26 | 2022-07-12 | 青岛高测科技股份有限公司 | Diamond wire cutting equipment with compensation function |
| CN114361273A (en) * | 2021-12-03 | 2022-04-15 | 宁夏隆基乐叶科技有限公司 | Silicon wafer, preparation method thereof and solar cell |
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| CN100565935C (en) * | 2008-03-21 | 2009-12-02 | 常州有则科技有限公司 | Ultra-thin solar silicon slice and cutting technique thereof |
| CN106938504A (en) * | 2017-03-31 | 2017-07-11 | 江苏美科硅能源有限公司 | A kind of efficient, low cost diamond wire work sheet polysilicon chip method |
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