Silicon wafer, square rod, processing method and equipment of silicon wafer, battery piece and photovoltaic module

Abstract

The invention provides a silicon wafer, a square rod, a processing method and equipment of the silicon wafer, a battery piece and a photovoltaic module. The surface roughness Ra of the side surface of the silicon wafer is 0.15 mu m-1 mu m. The square rod comprises two first surfaces which are oppositely arranged along a first direction; the two second surfaces are oppositely arranged in the second direction. The surface roughness Ra of the first surface and the surface roughness Ra of the second surface are both 0.35 [mu] m-0. 85 [mu] m. In the invention, the surface roughness Ra of the side surface of the silicon wafer is set to be 0.15-1 mu m, and the surface roughness Ra of the first surface and the surface roughness Ra of the second surface of the square rod are set to be 0.35-0.85 mu m in the cutting stage of the square rod, so that the requirements of the square rod for subsequent slicing and battery piece preparation can be met, and compared with an existing finished square rod, the production efficiency is improved, and the production cost is reduced. The surface roughness Ra of each surface of the square rod is obviously improved, the operation is convenient, and the bonding stability of the surfaces of the square rod is improved in the processes of slicing the square rod and preparing the battery piece, so that the yield of slices and the yield of the battery piece are increased.

Description

Technical Field

[0001] This application belongs to the technical field of monocrystalline silicon manufacturing, and in particular relates to a silicon wafer, a square bar, a processing method of the silicon wafer, equipment, a solar cell, and a photovoltaic module. Background Art

[0002] Solar cells have become one of the mainstreams of the world's new energy development, with huge development and demand space. Among them, solar cells are an important part of solar cells.

[0003] The production process of solar cells is a complex process, which specifically includes the following steps: selecting high-purity silicon raw materials; adding the high-purity silicon raw materials into a single crystal furnace for melting (the furnace temperature is usually about 1400 °C); then slowly cooling the molten silicon raw materials and pulling them into a single crystal ingot; cutting the single crystal ingot to produce a round bar; cutting the round bar into a semi-finished square bar; polishing the semi-finished square bar to produce a finished square bar; the finished square bar is further processed through processes such as slicing and sorting to produce a finished silicon wafer; finally, through processes such as texturing, diffusion, and etching, solar cells are obtained.

[0004] In the prior art, in order to improve the slicing yield of silicon wafers and solar cells and the cell yield, it is mainly adjusted by controlling the slicing process, while there is little research on the method of improving the yield by controlling the quality of square bars. Summary of the Invention

[0005] This application provides a silicon wafer, a square bar, a processing method of the silicon wafer, equipment, a solar cell, and a photovoltaic module, and improves the yield of the square bar in the processes of slicing and preparing solar cells by controlling the quality of the square bar.

[0006] According to the first aspect of this application, a silicon wafer is provided, and the surface roughness Ra of the side surface of the silicon wafer is 0.15 μm - 1 μm.

[0007] According to the second aspect of this application, a square bar for preparing the silicon wafer of the first aspect of this application is provided, which includes: two first surfaces, oppositely arranged along a first direction; two second surfaces, oppositely arranged along a second direction, and the first direction and the second direction are perpendicular to the length direction of the square bar. Wherein, a part of each of the first surfaces and a part of each of the second surfaces are respectively a corresponding side surface of the silicon wafer, and the surface roughness Ra of the first surface and the second surface is 0.35 μm - 0.85 μm.

[0008] According to a third aspect of the present application, a method for processing a silicon wafer is provided, which includes: providing a square bar to be processed, the square bar to be processed including two first surfaces oppositely arranged in a first direction and two second surfaces oppositely arranged in a second direction, the first direction and the second direction being perpendicular to the length direction of the square bar to be processed; performing surface polishing on the first surface and the second surface of the square bar to be processed to obtain the square bar described above; cutting the square bar after the surface polishing treatment to obtain the silicon wafer described above.

[0009] According to a fourth aspect of the present application, a processing device for a silicon wafer is provided, which includes: a surface polishing device for performing surface polishing on the first surface and the second surface of the square bar to be processed to obtain the square bar described above; a slicing device for slicing the square bar after the surface polishing treatment to obtain the silicon wafer described above.

[0010] According to a fifth aspect of the present application, a battery cell is provided, which is prepared by using the silicon wafer described above.

[0011] According to a sixth aspect of the present application, a photovoltaic module is provided, which includes the battery cell described above.

[0012] In summary, the silicon wafer, square bar, method for processing a silicon wafer, device, battery cell, and photovoltaic module provided by the present application at least have the following beneficial effects:

[0013] In the present application, the surface roughness Ra of the side surface of the silicon wafer is set to 0.15 μm - 1 μm, and in the square bar cutting stage, the surface roughness Ra of the square bar can be set at 0.35 μm - 0.85 μm, so that the bonding stability of the square bar surface is increased, which is not only convenient to operate, but also significantly improves the yield of slicing and the yield of subsequent battery cells. Description of the Drawings

[0014] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0015] Figure 1 A three-dimensional schematic diagram of the silicon wafer provided by the embodiment of the present application;

[0016] Figure 2 A schematic diagram of the side surface of the silicon wafer provided by the present application and a schematic diagram of the distribution of measurement points;

[0017] Figure 3It is a schematic structural diagram of a square bar provided in an embodiment of the present application;

[0018] Figure 4 It is a schematic diagram of the distribution of a kind of measurement points on the first surface of the square bar provided in an embodiment of the present application;

[0019] Figure 5 It is a schematic diagram of another distribution of measurement points on the first surface of the square bar provided in an embodiment of the present application;

[0020] Figure 6 It is a schematic diagram of the distribution of measurement points on the second chamfered surface of the square bar provided in an embodiment of the present application;

[0021] Figure 7 It is a schematic process flow diagram of a processing method of a silicon wafer provided in an embodiment of the present application;

[0022] Figure 8 It is a schematic diagram of the positional relationship of each mechanism in the surface polishing equipment of the square bar provided in an embodiment of the present application.

[0023] Among them, the reference numerals are as follows:

[0024] 20, silicon wafer; 21, front surface; 22, side surface; 23, first chamfer;

[0025] 10, square bar; 11, first surface; 12, second surface; 13, second chamfer; 14, end face;

[0026] 100, loading mechanism; 200, clamping mechanism; 300, detection mechanism; 310, detection probe; 400, grinding mechanism; 400A, grinding unit; 410, grinding wheel; 420, grinding wheel drive mechanism; 500, unloading mechanism;

[0027] X, first direction; Y, second direction; Z, length direction. Detailed implementation manners

[0028] In order to make the above and other features and advantages of the present application clearer, the present invention will be further described below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are only exemplary, not restrictive.

[0029] In the description of the present application, features defined with "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Features defined with "first" and "second" may explicitly or implicitly include at least one of the defined features. When the description of "a plurality" appears, it generally means at least including two, such as two, three, etc., unless otherwise specifically defined.

[0030] In this application, unless otherwise clearly specified and defined, terms such as "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection, it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] In the description of this application, terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean 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 this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0032] In this application, Ra is the arithmetic mean roughness, which represents the arithmetic mean of the absolute values of the profile offsets within the sampling length. Ry is the maximum profile height, which represents the distance between the profile peak line and the profile valley bottom line within the sampling length.

[0033] In this application, the roughness of the chamfers between the side surfaces of the silicon wafer and between adjacent side surfaces and the roughness of the chamfers between the square bar surface and adjacent surfaces are both measured by a stylus roughness meter. For example, it can be measured by an SJ-210 portable roughness meter or an FTAD3000 rough profile integrated measuring device.

[0034] An embodiment of the first aspect of this application provides a silicon wafer, which has two positive surfaces (i.e., large surfaces) oppositely arranged along its thickness direction and a plurality of side surfaces (i.e., narrow surfaces) arranged in sequence along the circumference of the silicon wafer. Among them, the surface roughness Ra of the side surfaces of the silicon wafer is 0.15 μm - 1 μm.

[0035] Exemplarily, the surface roughness Ra of the side surface of the silicon wafer can be 0.15 μm, 0.16 μm, 0.17 μm, 0.18 μm, 0.19 μm, 0.2 μm, 0.21 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.37 μm, 0.38 μm, 0.40 μm, 0.42 μm, 0.44 μm, 0.46 μm, 0.48 μm, 0.50 μm, 0.52 μm, 0.53 μm, 0.54 μm, 0.55 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, etc.

[0036] It can be understood that silicon wafers are generally obtained by slicing square bars. In this application, since the surface roughness Ra of the side surface of the silicon wafer is 0.15 μm - 1 μm, the surface roughness Ra of the corresponding surface of the square bar used to prepare the silicon wafer will be set between 0.35 μm - 0.85 μm. If the roughness of the square bar is too low, the bonding stability of the square bar is slightly poor, resulting in a low yield in the slicing process; if the roughness of the square bar is too large, it will cause breakage of the edges of the subsequently cut silicon wafers, that is, defects such as chipping, cracks, and burrs are likely to occur at the edges of the silicon wafers. When the surface roughness Ra of the corresponding surface of the square bar used to prepare the silicon wafer is set to 0.35 μm - 0.85 μm, it can not only meet the requirements for subsequent slicing of the square bar and preparation of battery wafers, but also, compared with existing finished square bars, the surface roughness Ra of the corresponding surface of the square bar has been significantly improved. It is not only convenient to operate, but also increases the bonding stability of the square bar surface during the slicing of the square bar and the preparation of battery wafers, thereby increasing the slicing yield and the battery wafer yield.

[0037] Preferably, the surface roughness Ra of the side surface of the silicon wafer is 0.55 μm - 1 μm. Exemplarily, the surface roughness Ra of the side surface of the silicon wafer can be 0.55 μm, 0.56 μm, 0.57 μm, 0.58 μm, 0.59 μm, 0.6 μm, 0.62 μm, 0.64 μm, 0.66 μm, 0.68 μm, 0.7 μm, 0.72 μm, 0.74 μm, 0.76 μm, 0.78 μm, 0.8 μm, 0.82 μm, 0.84 μm, 0.86 μm, 0.88 μm, 0.9 μm, 0.92 μm, 0.94 μm, 0.96 μm, 0.98 μm, 1 μm, etc.

[0038] Since the surface roughness Ra of the side surface of the silicon wafer is 0.55 μm - 1 μm, the surface roughness Ra of the corresponding surface of the square bar used to prepare the silicon wafer will be set between 0.55 μm - 0.85 μm. Based on the surface roughness Ra of the corresponding surface of the square bar being set between 0.55 μm - 0.85 μm, the bonding effect of the square bar is the best and edge breakage will not occur.

[0039] In some embodiments, the surface roughness Ry of the side surface of the silicon wafer is uniformly 2 μm - 10 μm. Exemplarily, the surface roughness Ry of the side surface of the silicon wafer can be 2 μm, 2.1 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, 5.8 μm, 6 μm, 6.5 μm, 6.6 μm, 6.7 μm, 6.8 μm, 6.9 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm, 8 μm, 9 μm, 10 μm, etc.

[0040] In this application, since the surface roughness Ry of the side surface of the silicon wafer is uniformly 2 μm - 10 μm, the surface roughness Ry of the corresponding surface of the square bar used to prepare the silicon wafer will be set at 3 μm - 9 μm. If the surface roughness Ry of the corresponding surface of the square bar used to prepare the silicon wafer is set at 3 μm - 9 μm, if the roughness of the square bar is too low, the bonding stability of the square bar is slightly poor, resulting in a low yield during the slicing process; if the roughness of the square bar is too large, it will cause breakage of the edges of the subsequently cut silicon wafers, that is, defects such as chipping, cracks, and burrs are likely to occur at the edges of the silicon wafers. When the surface roughness Ry of the corresponding surface of the square bar used to prepare the silicon wafer is set at 3 μm - 9 μm, it can not only meet the requirements for subsequent slicing of the square bar and preparation of solar cells, but also compared with existing finished square bars, the surface roughness Ra of the corresponding surface of the square bar has been significantly improved. It is not only convenient to operate, but also increases the bonding stability of the surface of the square bar during the slicing of the square bar and the preparation of solar cells, thereby increasing the slicing yield and the solar cell yield.

[0041] Preferably, the surface roughness Ry of the side surface of the silicon wafer is uniformly 5 μm - 10 μm. Exemplarily, the surface roughness Ra of the side surface of the silicon wafer can be 5 μm, 5.1 μm, 5.3 μm, 5.4 μm, 5.6 μm, 5.9 μm, 6 μm, 6.4 μm, 7 μm, 7.5 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm, 9.9 μm, 10 μm, etc.

[0042] Since the surface roughness Ry of the side surfaces of the silicon wafer is 5 μm - 10 μm, the surface roughness Ry of the corresponding surfaces of the square bar used to prepare the silicon wafer will be set between 6 μm and 9 μm. Based on the surface roughness Ry of the corresponding surfaces of the square bar being set between 6 μm and 9 μm, the bonding effect of the square bar is the best and edge breakage will not occur.

[0043] In some embodiments, the surface roughness Ra of the first chamfer between every two adjacent side surfaces of the silicon wafer may be less than or equal to the surface roughness Ra of the side surfaces of the silicon wafer.

[0044] Setting the surface roughness Ra of the first chamfer between every two adjacent side surfaces of the silicon wafer to be less than or equal to the surface roughness Ra of the side surfaces of the silicon wafer can make the force during slicing more uniform, which is not only convenient for operation but also not likely to cause edge breakage, thereby increasing the slicing yield and the cell yield.

[0045] In some embodiments, the surface roughness Ra of the first chamfer between every two adjacent side surfaces of the silicon wafer is 0.15 μm - 1 μm. Exemplarily, the surface roughness Ra of the first chamfer between every two adjacent side surfaces of the silicon wafer can be 0.15 μm, 0.16 μm, 0.17 μm, 0.18 μm, 0.19 μm, 0.2 μm, 0.21 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.37 μm, 0.38 μm, 0.40 μm, 0.42 μm, 0.44 μm, 0.46 μm, 0.48 μm, 0.50 μm, 0.52 μm, 0.53 μm, 0.54 μm, 0.55 μm, 0.56 μm, 0.57 μm, 0.58 μm, 0.59 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, etc.

[0046] In some embodiments, the surface roughness Ry of the first chamfer between every two adjacent side surfaces of the silicon wafer is 2 μm - 10 μm. Exemplarily, the surface roughness Ry of the first chamfer between every two adjacent side surfaces of the silicon wafer can be 2 μm, 2.1 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, 5.8 μm, 6 μm, 6.5 μm, 6.6 μm, 6.7 μm, 6.8 μm, 6.9 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm, 8 μm, 9 μm, 10 μm, etc.

[0047] In some embodiments, the projection lengths of the first chamfer of the silicon wafer in the first direction X and the second direction Y are different, the first direction X and the second direction Y are perpendicular to the thickness direction of the silicon wafer, and the thickness direction of the silicon wafer is parallel to the length direction Z of the square bar used to prepare the silicon wafer.

[0048] In some embodiments, the absolute difference between the projection lengths of each first chamfer of the silicon wafer in the first direction X and the second direction Y is 0.05 mm - 0.1 mm.

[0049] In some embodiments, each first chamfer of the silicon wafer is an arc or a straight line.

[0050] Figure 1 A three-dimensional schematic diagram of the silicon wafer provided by the embodiments of the present application. Figure 2 A schematic diagram of the side surface of the silicon wafer provided by the present application and a schematic diagram of the distribution of measurement points.

[0051] Refer to Figure 1-2 , as can be seen from the figure, the silicon wafer 20 is generally a rectangular structure, for example, it can be a cube-like structure or a rectangle-like structure, and includes 2 positive surfaces 21, 4 side surfaces 22 and at least two first chamfers 23 opposite to each other along its thickness direction. The roughness tester for the side surface 22 of the silicon wafer 20 can use a stylus roughness meter to test. Three measurement segments are selected on the side surface 22 at intervals (the three measurement segments are the two end regions and the middle region of the side surface 22, for example, the center position of the side surface 22 and the positions at 1 / 2 of the distances from the center position to both sides); the roughness values Ra and / or Ry of at least one measurement point on the three measurement segments are detected by using a roughness measurement device; if only one value is measured, the tester can directly give the corresponding Ra and / or Ry value; if multiple values are measured, the average values Ra and / or Ry corresponding to the three measurement segments can be obtained by calculation.

[0052] An embodiment of the second aspect of the present application provides a square bar for preparing the silicon wafer of the first aspect of the present application. The surface roughness Ra of the first surface 11 and the second surface 12 of the square bar 10 is both 0.35 μm - 0.85 μm. Exemplarily, the surface roughness Ra of the first surface 11 of the square bar 10 can be 0.35 μm, 0.37 μm, 0.38 μm, 0.40 μm, 0.42 μm, 0.44 μm, 0.46 μm, 0.48 μm, 0.50 μm, 0.52 μm, 0.53 μm, 0.54 μm, 0.55 μm, etc., and the surface roughness Ra of the second surface 12 of the square bar 10 can be 0.35 μm, 0.37 μm, 0.38 μm, 0.40 μm, 0.42 μm, 0.44 μm, 0.46 μm, 0.48 μm, 0.50 μm, 0.52 μm, 0.53 μm, 0.54 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, etc.

[0053] It should be noted that after the square bar is cut and cleaned, a finished silicon wafer will be obtained. One side surface 22 of the silicon wafer after cutting corresponds to a part of each first surface 11 or each second surface 12 of the square bar 10; the silicon wafer after cutting is cleaned with acid or alkali solution to remove organic impurities and particulate metal contaminants on the surface of the silicon wafer during the cutting process.

[0054] Since it is necessary to bond and fix the surface of the square bar during the slicing of the finished square bar and the preparation of the battery chip, the level of the surface roughness of each surface of the square bar will affect the bonding stability of the square bar surface. In the present application, the surface roughness Ra of the first surface 11 and the second surface 12 of the square bar 10 is both set to 0.35 μm - 0.85 μm. It can not only meet the requirements of subsequent slicing of the square bar and the preparation of the battery chip, but also compared with the existing finished square bar, the surface roughness Ra of each surface of the square bar 10 has been significantly improved. It is not only convenient to operate, but also increases the bonding stability of the square bar surface during the slicing of the square bar and the preparation of the battery chip, thereby increasing the slicing yield and the battery chip yield.

[0055] Preferably, the surface roughness Ra of the first surface 11 and the second surface 12 of the square bar 10 is 0.55 μm - 0.85 μm. Exemplarily, the surface roughness Ra of the first surface 11 and the second surface 12 of the square bar 10 can be 0.55 μm, 0.56 μm, 0.57 μm, 0.58 μm, 0.59 μm, 0.6 μm, 0.61 μm, 0.62 μm, 0.63 μm, 0.64 μm, 0.65 μm, 0.66 μm, 0.67 μm, 0.68 μm, 0.69 μm, 0.7 μm, 0.71 μm, 0.72 μm, 0.73 μm, 0.74 μm, 0.75 μm, 0.76 μm, 0.77 μm, 0.78 μm, 0.79 μm, 0.8 μm, 0.81 μm, 0.82 μm, 0.83 μm, 0.84 μm, 0.85 μm, etc.

[0056] Since the surface roughness Ra of the first surface 11 and the second surface 12 of the square bar 10 is 0.55 μm - 0.85 μm, the bonding effect of the square bar 10 can be the best, and the edge breakage will not be caused, thus not only the operation is convenient, but also the slicing yield and the cell yield are increased.

[0057] Figure 3 It is a schematic structural diagram of the square bar provided in the embodiment of the present application. Figure 4 It is a schematic diagram of the distribution of a kind of measurement points on the first surface of the square bar provided in the embodiment of the present application. Figure 5 It is another schematic diagram of the distribution of measurement points on the first surface of the square bar provided in the embodiment of the present application. Figure 6 It is a schematic diagram of the distribution of measurement points on the second chamfered surface of the square bar provided in the embodiment of the present application.

[0058] Please refer to Figure 3 , the square bar 10 provided in the present application includes two first surfaces 11 oppositely arranged along the first direction X, two second surfaces 12 oppositely arranged along the second direction Y, a second chamfer 13 located between two adjacent first surfaces 11 and second surfaces 12, and two end faces 14 oppositely arranged along the length direction Z of the square bar.

[0059] In other words, the two surfaces oppositely arranged along the first direction X are the first surfaces 11, and the two surfaces oppositely arranged along the second direction Y are the second surfaces 12. The number of the second chamfers 13 is at least two. For example, the number of the second chamfers 13 can be four. In this case, the second chamfer 13 is provided between each first surface 11 and the two second surfaces 12, and the square bar 10 at this time is a full bar. The number of the second chamfers 13 can also be two. In this case, the second chamfer 13 is only provided between one first surface 11 (or the second surface 12) and the two second surfaces 12 (or the two first surfaces 11), and the square bar 10 at this time is a half bar. The two end faces 14 can be clamped and fixed during the polishing process of the square bar.

[0060] Wherein, both the first direction X and the second direction Y are perpendicular to the length direction Z of the square bar, the first surfaces 11 and the second surfaces 12 are planes, and each second chamfer 13 can be a straight line or an arc.

[0061] In some embodiments, the surface roughness Ry of both the first surface 11 and the second surface 12 of the square bar 10 is 3μm - 9μm. Exemplarily, the surface roughness Ry of the first surface 11 of the square bar 10 can be 3μm, 3.2μm, 3.5μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.5μm, 5.8μm, 6μm, etc., and the surface roughness Ry of the second surface 12 of the square bar 10 can be 3μm, 3.2μm, 3.5μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.5μm, 5.8μm, 6μm, 7μm, 8μm, 9μm, etc.

[0062] In the present application, the surface roughness Ry of both the first surface 11 and the second surface 12 of the square bar 10 is set to 3μm - 9μm. This not only meets the requirements for subsequent slicing of the square bar and preparation of battery wafers, but also significantly improves the surface roughness Ry of each surface of the square bar 10 compared with the existing finished square bars. It is not only convenient to operate, but also increases the bonding stability of the square bar surface during the slicing of the square bar and the preparation of battery wafers, thereby increasing the slicing yield and the battery wafer yield.

[0063] Preferably, the surface roughness Ry of the first surface 11 and the second surface 12 of the square bar 10 is 6 μm - 9 μm. Exemplarily, the surface roughness Ry of the first surface 11 of the square bar 10 can be 6 μm, 6.1 μm, 6.2 μm, 6.3 μm, 6.4 μm, 6.5 μm, 6.6 μm, 6.7 μm, 6.8 μm, 6.9 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9 μm, etc.

[0064] By setting the surface roughness Ry of the first surface 11 and the second surface 12 of the square bar 10 to 6 μm - 9 μm, the bonding effect of the square bar 10 can be optimized, and edge breakage can be avoided. This not only simplifies the operation but also increases the slicing yield and the yield of solar cells.

[0065] In some embodiments, the surface roughness Ra of each second chamfer 13 of the square bar 10 is 0.35 μm - 0.55 μm. Exemplarily, the surface roughness Ra of each second chamfer 13 of the square bar 10 can be 0.35 μm, 0.37 μm, 0.38 μm, 0.40 μm, 0.42 μm, 0.44 μm, 0.46 μm, 0.48 μm, 0.50 μm, 0.52 μm, 0.53 μm, 0.54 μm, 0.55 μm, etc.

[0066] In some embodiments, the surface roughness Ry of each second chamfer 13 of the square bar 10 is 3 μm - 6 μm. Exemplarily, the surface roughness Ry of each second chamfer 13 of the square bar 10 can be 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, 5.8 μm, 6 μm, etc.

[0067] In the present application, by setting the surface roughness Ra of each second chamfer 13 of the square bar 10 to 0.35 μm - 0.55 μm and / or setting the surface roughness Ry of each second chamfer 13 to 3 μm - 6 μm, not only can the subsequent slicing and solar cell preparation requirements of the square bar be met, but also compared with existing finished square bars, the surface roughness Ry of each chamfer surface of the square bar 10 is significantly improved. This not only simplifies the operation but also increases the bonding stability of the square bar surface during slicing and solar cell preparation, thereby increasing the slicing yield and the yield of solar cells.

[0068] Understandably, for the first surface 11 of the square bar 10, measurements can be taken along the second direction Y and / or the length direction Z of the square bar; for the second surface 12 of the square bar 10, measurements can be taken along the first direction X and / or the length direction Z of the square bar; for each second chamfer 13 of the square bar 10, Ra and / or Ry measurements can be taken along the length direction Z of the square bar.

[0069] Moreover, for any measurement point on each surface of the square bar 10 in the measurement direction, a roughness measurement device with the specification of SJ-210 can be used, and the roughness measurement device can be placed at the measurement position on the surface to be measured. By detecting the probe expansion and contraction of the roughness measurement device, the roughness values Ra and / or Ry of the measurement position can be obtained.

[0070] Specifically, taking the first surface 11 of the square bar 10 as an example for illustration, refer to Figure 4 , along the length direction Z of the square bar, select 3 measurement regions (the 3 measurement regions are respectively located at the two end regions and the middle region in the length direction Z of the square bar) on the first surface 11 at intervals; and along the second direction Y of the square bar, select 3 measurement segments at intervals on each measurement region; then use the roughness measurement device to detect the roughness values of multiple measurement points on each measurement segment and obtain Ra and / or Ry corresponding to each measurement segment through average calculation, and then calculate the average value of Ra corresponding to the 9 measurement segments, that is, obtain the surface roughness Ra and / or Ry of the first surface 11 of the square bar 10. Of course, refer to Figure 5 , it is also possible to select 3 measurement regions (the 3 measurement regions are respectively located at the two end regions and the middle region in the second direction Y of the square bar) on the first surface 11 at intervals along the second direction Y of the square bar; and along the length direction Z of the square bar, select 3 measurement segments at intervals on each measurement region, then use the roughness measurement device to detect the roughness values of multiple measurement points on each measurement segment and obtain Ra and / or Ry corresponding to each measurement segment through calculation, and then calculate the average value of Ra and / or Ry corresponding to the 9 measurement segments, that is, obtain the surface roughness Ra and / or Ry of the first surface 11 of the square bar 10.

[0071] Among them, the measurement of the surface roughness Ra and / or Ry of the second surface 12 of the square bar 10 is similar to that of the first surface 11, and will not be elaborated in detail in this application.

[0072] The measurement of the surface roughness Ra and / or Ry of any second chamfer 13 of the square bar 10 is described as follows: Refer to Figure 6, along the length direction Z of the square bar, three measurement segments are selected at intervals on the surface of the second chamfer 13 (the three measurement segments are respectively located at the two end regions and the middle region in the length direction Z of the square bar); the roughness values Ra and / or Ry of multiple measurement points on the three measurement segments are detected by using a roughness measurement device; and the roughness Ra and / or Ry corresponding to each measurement segment are obtained through calculation, and then the average value of the roughness means corresponding to the three measurement segments is calculated, that is, the surface roughness Ra and / or Ry of the second chamfer 13 of the square bar 10 are obtained.

[0073] In some embodiments, the projection lengths of the second chamfer 13 in the first direction X and the second direction Y are different, that is, the projection length of the second chamfer 13 in the first direction X can be greater than its projection length in the second direction Y, or the projection length of the second chamfer 13 in the first direction X is less than its projection length in the second direction Y. For example, the projection length of the second chamfer 13 in the first direction X is 1.41 mm or 1.34 mm, and the projection length of the second chamfer 13 in the second direction Y is 1.34 mm or 1.41 mm.

[0074] In this embodiment, setting the projection lengths of the second chamfer 13 in the first direction X and the second direction Y to be different can facilitate grinding the margin to the target requirement of the finished margin, thereby improving the surface margin accuracy of the square bar 10.

[0075] This is because if the margins on the first surface 11 or the second surface 12 are too different in the length direction Z of the square bar 10, it will necessarily affect the area of the first surface 11 or the second surface 12, thereby affecting the bonding performance of the first surface 11 or the second surface 12, and further affecting the stability of the square bar 10 during the processes of square bar slicing and battery wafer preparation.

[0076] It should be noted that the "margin on the first surface 11" refers to the distance between two opposite long sides in the second direction Y (i.e., the sides parallel to the length direction Z of the square bar 10), and can also be called the width of the first surface 11; the "margin on the second surface 12" refers to the distance between two opposite long sides in the first direction X (i.e., the sides parallel to the length direction Z of the square bar 10), and can also be called the width of the second surface 12.

[0077] In some embodiments, the absolute difference between the projected lengths of the second chamfer 13 in the first direction X and the second direction Y may be 0.05 mm - 0.1 mm. Exemplarily, the absolute difference between the projected lengths of the second chamfer 13 in the first direction X and the second direction Y may be 0.05 mm, 0.06 mm, 0.065 mm, 0.07 mm, 0.075 mm, 0.08 mm, 0.085 mm, 0.09 mm, 0.095 mm, 0.1 mm, etc. With such a setting, it is possible to avoid that the too large absolute difference between the projected lengths of the second chamfer 13 in the first direction X and the second direction Y affects the surface margin accuracy of the square bar 10, and that the too small absolute difference does not significantly improve the difference in the margins on the first surface 11 and the second surface 12 in the length direction Z of the square bar 10.

[0078] In some embodiments, the absolute value of the margin range difference between two opposite long sides on the first surface 11 is less than or equal to 0.02 mm. Exemplarily, the absolute value of the margin range difference between two opposite long sides on the first surface 11 may be 0.001 mm, 0.002 mm, 0.004 mm, 0.005 mm, 0.006 mm, 0.008 mm, 0.01 mm, 0.012 mm, 0.015 mm, 0.018 mm, 0.019 mm, 0.02 mm, etc.

[0079] The "margin range difference between two opposite long sides on the first surface 11" refers to the difference between the maximum value and the minimum value of the margins on the first surface 11 in the length direction Z of the square bar 10. By setting the margin range difference between two opposite long sides on the first surface 11 within the above range, it is possible to minimize the difference in the margins on the first surface 11 in the length direction Z of the square bar 10, so as to improve the surface margin accuracy of the square bar 10.

[0080] In some embodiments, the absolute value of the margin range difference between two opposite long sides on the second surface 12 is less than or equal to 0.02 mm. Exemplarily, the absolute value of the margin range difference between two opposite long sides on the second surface 12 may be 0.001 mm, 0.002 mm, 0.004 mm, 0.005 mm, 0.006 mm, 0.008 mm, 0.01 mm, 0.012 mm, 0.015 mm, 0.018 mm, 0.019 mm, 0.02 mm, etc.

[0081] The "margin range difference between two opposite long sides on the second surface 12" refers to the difference between the maximum value and the minimum value of the margins on the second surface 12 in the length direction Z of the square bar 10. By setting the margin range difference between two opposite long sides on the second surface 12 within the above range, it is possible to minimize the difference in the margins on the second surface 12 in the length direction Z of the square bar 10, so as to improve the surface margin accuracy of the square bar 10.

[0082] It should be noted that the measurement positions of the margins on the first surface 11 or the second surface 12 can be selected at several locations from the beginning to the end along the length direction Z of the square bar 10 for measurement, or the same as the roughness measurement positions of this surface.

[0083] An embodiment of the third aspect of the present application provides a method for processing a silicon wafer, which at least includes the following steps: providing a square bar to be processed, the square bar to be processed including two first surfaces 11 oppositely arranged along a first direction X and two second surfaces 12 oppositely arranged along a second direction Y, the first direction X and the second direction Y being perpendicular to the length direction Z of the square bar to be processed; performing surface polishing treatment on the first surface 11 and the second surface 12 of the square bar to be processed to obtain the square bar 10 described above; performing slicing treatment on the square bar 10 after the surface polishing treatment to obtain the silicon wafer 20 described above.

[0084] Figure 7 It is a schematic process flow diagram of the method for processing a silicon wafer provided in an embodiment of the present application.

[0085] Please refer to Figure 7 , the method for processing a silicon wafer provided in the embodiment of the present application includes steps S100 - S500.

[0086] S100, providing a square bar to be processed, the square bar to be processed including two first surfaces 11 oppositely arranged along a first direction X, two second surfaces 12 oppositely arranged along a second direction Y, and a second chamfer 13 located between two adjacent first surfaces 11 and second surfaces 12, the first direction X and the second direction Y being perpendicular to the length direction Z of the square bar to be processed.

[0087] Wherein, the second chamfer 13 located between two adjacent first surfaces 11 and second surfaces 12 is an arc chamfer or a straight chamfer.

[0088] S200, detecting the first surface 11, the second surface 12, and the second chamfer 13 of the square bar to be processed to determine the surface grinding parameters of the first surface 11, the second surface 12, and the second chamfer 13.

[0089] Specifically, when detecting the first surface 11, the second surface 12, and the second chamfer 13 of the square bar to be processed, mainly detecting the margin information on the first surface 11 of the square bar to be processed, the margin information on the second surface 12, and the margin information on the surface of the second chamfer 13, and then the surface grinding parameters of the first surface 11, the second surface 12, and the second chamfer 13 can be determined through these information. Among them, the surface grinding parameters include but are not limited to the grinding feed end position, the number of grinding tool divisions, etc.

[0090] S300. According to the surface grinding parameters of the first surface 11 and the second surface 12, use two oppositely arranged grinding wheels to grind the two first surfaces 11 and the two second surfaces 12 respectively. Each grinding wheel is a grinding wheel with a mesh number of 50 to 500.

[0091] Among them, the grinding wheels for grinding the two first surfaces 11 are the same, and the grinding wheels for grinding the two second surfaces 12 are the same. However, the grinding wheels for grinding the second surface 12 can be the same as or different from the grinding wheels for grinding the first surface 11, as long as the mesh number of the grinding wheel is within the above range.

[0092] Specifically, by using two oppositely arranged grinding wheels, one of the first surfaces 11 and the second surface 12 opposite to this first surface 11 can be ground simultaneously first. After the treatment is completed, the other first surface 11 and the second surface 12 opposite to this first surface 11 can be ground simultaneously. Moreover, the process of grinding any one of the first surfaces 11 and the second surface 12 opposite to it can include but is not limited to processes such as surface grinding and surface polishing.

[0093] S400. According to the surface grinding parameters of the second chamfer 13, use two grinding wheels to grind the surfaces of the four second chamfers 13, thereby obtaining the square bar 10 after surface polishing treatment. Each grinding wheel is a grinding wheel with a mesh number of 50 to 500.

[0094] Among them, the grinding wheels for grinding the surfaces of the second chamfers 13 can be the same as or different from the grinding wheels for grinding the first surface 11 or the second surface 12, as long as the mesh number of the grinding wheel is within the above range.

[0095] Specifically, by using two oppositely arranged grinding wheels, two opposite second chamfers 13 can be ground simultaneously first. After the treatment is completed, the other two opposite second chamfers 13 can be ground simultaneously. Moreover, the process of grinding any pair of second chamfers 13 can include but is not limited to processes such as surface grinding and surface polishing.

[0096] S500. Slice the square bar 10 after surface polishing treatment to obtain the silicon wafer 20 described above.

[0097] The current polishing process for semi-finished square bars is as follows: feeding → centering and clamping → blank detection → rough grinding → fine grinding → finished product detection → discharging. Since two grinding stages, namely rough grinding and fine grinding, are adopted, for a single arc or surface, it needs to be ground back and forth at least 14 times through the two stages of rough grinding and fine grinding to obtain a finished silicon bar. The processing process is cumbersome and the production capacity is low. Moreover, since tool setting is required once for both rough grinding and fine grinding, it increases the roughness difference of each surface of the silicon bar after treatment, thus affecting the overall performance of the silicon bar, and further reducing the finished product rate during the processes of slicing and preparing battery wafers.

[0098] In this application, since the grinding wheels for grinding each first surface 11, each second surface 12, and each second chamfer 13 are grinding wheels with a mesh number of 50 to 500, for example, they can be 50 mesh, 100 mesh, 150 mesh, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh, or 500 mesh; then it only needs to grind each first surface 11, each second surface 12, and each second chamfer 13 once respectively. This not only simplifies the surface polishing process of the square bar, but also avoids damage to the surface of the square bar due to multiple grindings, improves the surface grinding accuracy, thereby improving the surface roughness of the square bar 10, as well as the surface stability of the square bar 10, and reducing the process cost. Moreover, since tool setting is required again for each grinding, and in this application, each surface is only ground once, only tool setting is required once. Compared with the existing method of combining fine grinding and rough grinding, the number of tool setting times is reduced, thus further improving the grinding accuracy, thereby improving the edge distance accuracy on the first surface 11 and the second surface 12 of the square bar 10. Therefore, during the processes of slicing the square bar and preparing battery wafers, the surface bonding stability of the square bar 10 is increased, and further the slicing finished product rate and the battery wafer finished product rate are improved.

[0099] In some embodiments, the rotation speed of each grinding wheel during grinding treatment is greater than or equal to 3200 r / min. Exemplarily, the rotation speed of each grinding wheel during grinding treatment can be 3200 r / min, 3300 r / min, 3400 r / min, 3500 r / min, 3700 r / min, 3800 r / min, 3900 r / min, 4000 r / min, 4100 r / min, 4200 r / min, 4300 r / min, 4400 r / min, 4500 r / min, 4600 r / min, 4700 r / min, 4800 r / min, 4900 r / min, 5000 r / min, 5200 r / min, 5500 r / min, 6000 r / min, etc.

[0100] Since the number of stages of grinding by the grinding wheel has changed from two to one, and the mesh number of the grinding wheel has been improved, in order to improve the matching of the grinding capacity of the grinding wheel to the process of single-stage grinding by the grinding wheel, the rotational speed of each grinding wheel during grinding treatment is set to be greater than or equal to 3200 r / min. As a result, the surface roughness Ra of the first surface 11, the second surface 12, and the second chamfer 13 of the square bar 10 is 0.35 μm - 0.55 μm and can meet the requirements.

[0101] In step S300, according to the surface grinding parameters of the first surface 11 and the second surface 12, two relatively arranged grinding wheels are used to grind the two first surfaces 11 and the two second surfaces 12 respectively, including the following steps.

[0102] S310, according to the surface grinding parameters of the first surface 11, two grinding wheels are used to perform surface grinding and surface polishing on the two first surfaces 11 in sequence and control the feeding speed of the square bar during the surface grinding and surface polishing processes.

[0103] Among them, before grinding the two first surfaces 11, it is necessary to fix the square bar to be processed (for example, use a clamping mechanism to fix the two ends of the square bar to be processed in its length direction Z) and ensure that the two first surfaces 11 face the two grinding wheels respectively, so that the two grinding wheels can grind the two first surfaces 11 simultaneously.

[0104] S320, according to the surface grinding parameters of the second surface 12, two grinding wheels are used to perform surface grinding and surface polishing on the two second surfaces 12 in sequence and control the feeding speed of the square bar during the surface grinding and surface polishing processes.

[0105] Among them, before grinding the two second surfaces 12, it is necessary to rotate the square bar to be processed by 90 degrees so that the two second surfaces 12 face the two grinding wheels respectively.

[0106] In steps S310 and S320, the feeding speed of the square bar during surface grinding of the first surface 11 and the second surface 12 is 1500 - 1800 mm / min. For example, it can be specifically 1500 mm / min, 1550 mm / min, 1580 mm / min, 1600 mm / min, 1650 mm / min, 1680 mm / min, 1700 mm / min, 1750 mm / min, 1780 mm / min, 1800 mm / min, etc.; the single grinding amount during surface grinding of the first surface 11 and the second surface 12 is 0.1 - 0.2 mm. For example, it can be specifically 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, etc.

[0107] In steps S310 and S320, when performing surface polishing on the first surface 11 and the second surface 12, the feeding speed of the square bar is 2200 - 2500 mm / min. For example, it can be specifically 2200 mm / min, 2250 mm / min, 2280 mm / min, 2300 mm / min, 2350 mm / min, 2380 mm / min, 2400 mm / min, 2450 mm / min, 2480 mm / min, 2500 mm / min, etc.; when performing surface polishing on the first surface 11 and the second surface 12, the single grinding amount is 0.01 - 0.02 mm. For example, it can be specifically 0.01 mm, 0.011 mm, 0.012 mm, 0.013 mm, 0.014 mm, 0.015 mm, 0.016 mm, 0.017 mm, 0.018 mm, 0.019 mm, 0.02 mm, etc.

[0108] Since the grinding wheels for grinding the first surface 11 and the second surface 12 are grinding wheels with 50 - 500 meshes, compared with the grinding wheels used in the existing fine grinding process, the grinding ability of the grinding wheels in this application is relatively strong. By controlling the feeding speed of the square bar and the single grinding amount during the grinding process and the feeding speed of the square bar and the single grinding amount during the surface polishing process within the above ranges, the grinding accuracy of the grinding wheels in this application for grinding the first surface 11 and the second surface 12 can be significantly improved, and thus a square bar 10 with a surface roughness Ra of 0.35 μm - 0.55 μm for both the first surface 11 and the second surface 12 can be obtained.

[0109] In step S400, according to the surface grinding parameters of the second chamfer 13, two grinding wheels are used to grind the surfaces of the four second chamfers 13, including the following steps.

[0110] S410, according to the surface grinding parameters of the second chamfer 13, two grinding wheels are used to sequentially perform surface grinding and surface polishing on the surfaces of two relatively arranged second chamfers 13 and control the feeding speed of the square bar during the surface grinding and surface polishing processes.

[0111] Among them, after grinding the two first surfaces 11 and the two second surfaces 12, the square bar to be processed can be rotated by 45 degrees so that the surfaces of two of the second chamfers 13 face the two grinding wheels respectively, and then the surfaces of the two relatively arranged second chamfers 13 are ground.

[0112] S420, according to the surface grinding parameters of the second chamfer 13, two grinding wheels are used to sequentially perform surface grinding and surface polishing on the surfaces of the other two relatively arranged second chamfers 13 and control the feeding speed of the square bar during the surface grinding and surface polishing processes.

[0113] Among them, after grinding two of the second chamfers 13, the square bar to be processed can be rotated by 135 degrees so that the surfaces of the other two second chamfers 13 face the two grinding wheels respectively, and then the two relatively arranged second chamfers 13 are ground.

[0114] In steps S410 and S420, when grinding the surface of the second chamfer 13, the feeding speed of the square bar is 1500 - 1800 mm / min. For example, it can be specifically 1500 mm / min, 1550 mm / min, 1580 mm / min, 1600 mm / min, 1650 mm / min, 1680 mm / min, 1700 mm / min, 1750 mm / min, 1780 mm / min, 1800 mm / min, etc.; when grinding the surface of the second chamfer 13, the single grinding amount is 0.1 - 0.2 mm. For example, it can be specifically 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, etc.

[0115] In steps S410 and S420, when surface polishing the surface of the second chamfer 13, the feeding speed of the square bar is 2200 - 2500 mm / min. For example, it can be specifically 2200 mm / min, 2250 mm / min, 2280 mm / min, 2300 mm / min, 2350 mm / min, 2380 mm / min, 2400 mm / min, 2450 mm / min, 2480 mm / min, 2500 mm / min, etc.; when surface polishing the surface of the second chamfer 13, the single grinding amount is 0.01 - 0.02 mm. For example, it can be specifically 0.01 mm, 0.011 mm, 0.012 mm, 0.013 mm, 0.014 mm, 0.015 mm, 0.016 mm, 0.017 mm, 0.018 mm, 0.019 mm, 0.02 mm, etc.

[0116] Since the grinding wheels for grinding the first surface 11 and the second surface 12 are 50 - 500 - mesh grinding wheels, compared with the grinding wheels used in the existing fine grinding process, the grinding ability of the grinding wheels in this application is relatively strong. Then in step S400, by controlling the feeding speed and single grinding amount during grinding and the feeding speed and single grinding amount during surface polishing within the above ranges, the grinding accuracy of the grinding wheels in this application for grinding the surface of the second chamfer 13 can be significantly improved, and thus a square bar 10 with a surface roughness Ra of 0.35 μm - 0.55 μm for the second chamfer 13 is obtained.

[0117] In step S200, the first surface 11, the second surface 12, and the second chamfer 13 of the square bar to be processed are detected, and the steps for determining the surface grinding parameters of the first surface 11, the second surface 12, and the second chamfer 13 are as follows.

[0118] S210, detect the first surface 11, the second surface 12, and the second chamfer 13 of the square bar to be processed, and obtain multiple sets of margin information of the first surface 11, the second surface 12, and the second chamfer 13 at different positions respectively.

[0119] Specifically, along the length direction Z of the square bar to be processed, three different positions (such as both ends and the middle of the square bar in its length direction Z) can be selected on each surface for detection, and 3 sets of margin information on each surface are obtained.

[0120] S220, determine the surface grinding parameters of the first surface 11 according to the mean value of multiple sets of margins on the first surface 11 and the target margin value.

[0121] S230, determine the surface grinding parameters of the second surface 12 according to the mean value of multiple sets of margins on the second surface 12 and the target margin value.

[0122] S240, determine the surface grinding parameters of the second chamfer 13 according to the mean value of multiple sets of margins on the second chamfer 13 and the target margin value.

[0123] Among them, for any one of the surfaces of the first surface 11, the second surface 12, and the second chamfer 13, its grinding process at least includes surface grinding and surface polishing, and the surface grinding parameters include the number of grinding tool divisions, and the number of grinding tool divisions includes the number of surface grinding tool divisions and the number of surface polishing tool divisions.

[0124] Specifically, taking the first surface 11 as an example, the mean value of multiple sets of margins on the first surface 11 can be calculated first; then, according to the mean value of multiple sets of margins and the target margin value on the first surface 11, the total unilateral grinding allowance of the first surface 11 is determined; then, according to the total unilateral grinding allowance of the first surface 11 and the set single grinding amount during surface grinding and the single grinding amount during surface polishing, the number of surface grinding tool divisions and the number of surface polishing tool divisions of the first surface 11 are determined. Among them, the number of surface polishing tool divisions, the single grinding amount during surface polishing, and the single grinding amount during surface grinding can all be set.

[0125] Exemplarily, the number of dividing cuts for surface polishing is set to 1, the single grinding amount during surface grinding is set to 0.1 mm, and the single grinding amount during surface polishing is set to 0.01 mm. Taking the total unilateral grinding allowance of the first surface 11 as 0.6 mm as an example, according to the total unilateral grinding allowance of the first surface 11 (0.6 mm), the single grinding amount during surface grinding (0.1 mm), and the single grinding amount during surface polishing (0.01 mm), the number of dividing cuts for surface grinding of the first surface 11 can be determined as (0.6 - 0.01) / 0.1 = 6 cuts.

[0126] Therefore, during the grinding process, the first surface 11 can be ground 6 cuts first according to the number of dividing cuts for surface grinding and the single grinding amount during surface grinding; and after the surface grinding is completed, the first surface 11 can be ground 1 cut according to the set number of dividing cuts for surface polishing and the single grinding amount during surface polishing.

[0127] Among them, the grinding process of the second surface 12 of the square bar 10 and the surface of the second chamfer 13 and the determination process of the surface grinding parameters are similar to those of the first surface 11, and will not be elaborated in detail in this application.

[0128] An embodiment of the fourth aspect of this application provides a processing device for silicon wafers, including: a surface polishing device for performing surface polishing on the first surface 11 and the second surface 12 of a square bar to be processed to obtain the square bar 10 described above; and a slicing device for slicing the square bar after surface polishing to obtain the silicon wafer 20 described above.

[0129] Figure 8 It is a schematic diagram of the positional relationship of each mechanism in the surface polishing device of the square bar provided in an embodiment of this application.

[0130] Please refer to Figure 8 , the surface polishing device 1000 of the square bar provided in the embodiment of this application includes a loading mechanism 100, a clamping mechanism 200, a detection mechanism 300, and a grinding mechanism 400.

[0131] The loading mechanism 100 is used to receive the square bar to be processed and transfer the square bar to the clamping area corresponding to the clamping mechanism 200. Specifically, the loading mechanism 100 may include a loading table, a centering adjustment device, and a servo motor moving device, which play the role of material transportation and centering adjustment.

[0132] Specifically, the semi-finished square bar after square cutting can be placed on the loading table of the loading mechanism 100 by manual or mechanical handling, and then the servo motor moving device of the loading mechanism 100 is used to make the square bar to be processed enter the clamping area of the clamping mechanism 200, and the semi-finished square bar is centered and placed relative to the clamping mechanism 200 through the centering adjustment device of the loading mechanism 100.

[0133] The clamping mechanism 200 is used to clamp the two end faces 14 of the square bar to be processed in the clamping area in the length direction Z thereof and transfer the square bar to be processed to the detection area corresponding to the detection mechanism 300.

[0134] Specifically, the clamping mechanism 200 includes a servo motor clamping device, a harmonic reducer rotating device, and a servo motor guide rail moving device. The servo motor clamping device plays a role in clamping and transporting the square bar to be processed, the servo motor guide rail moving device plays a role in transporting the square bar to be processed, and the harmonic reducer rotating device plays a role in rotating and positioning the square bar to be processed.

[0135] The detection mechanism 300 is used to detect the first surface 11, the second surface 12, and the second chamfer 13 of the square bar to be processed in its detection area. After the detection mechanism 300 finishes the detection, the clamping mechanism 200 is further used to transfer the square bar to be processed to the grinding area corresponding to the grinding mechanism 400.

[0136] Specifically, the detection mechanism 300 includes detection probes 310 and a cylinder-driven extension device, which play a role in detecting the dimensions of the square bar to be processed. Further, the detection probes 310 are arranged in three groups. Two detection probes 310 in each group are respectively located on both sides of the detection area. The detection probes 310 are driven by the cylinder-driven extension device. Based on the reciprocating telescoping of the detection probes 310 and the forward and backward movement and rotation of the square bar to be processed, multiple groups of margin information on each surface of the square bar can be detected. Furthermore, the surface grinding parameters of the first surface 11, the second surface 12, and the second chamfer 13 can be determined through this information.

[0137] The grinding mechanism 400 includes two grinding units 400A. Each grinding unit 400A includes a grinding wheel 410 and a grinding wheel driving mechanism 420 for driving the grinding wheel 410 to rotate. The two grinding wheels 410 of the grinding mechanism 400 are arranged oppositely. Each grinding wheel 410 is a grinding wheel with a mesh number of 50 to 500. The two grinding wheels 410 are used to grind the surfaces of the two first surfaces 11, the two second surfaces 12, and the four second chamfers 13 in the grinding area to obtain the square bar 10 in the above embodiment.

[0138] Specifically, before the grinding mechanism 400 grinds, the clamping mechanism 200 makes one first surface 11 of the square bar to be processed and the second surface 12 opposite thereto face the left and right grinding wheels 410. The grinding wheel driving mechanism 420 (such as a motor) drives the grinding wheel 410 to rotate at a high speed and approach the first surface 11 and the second surface 12. At the same time, the clamping mechanism 200 drives the square bar to be processed to move back and forth for grinding. After the grinding is completed, the clamping mechanism 200 rotates the square bar to be processed by 90 degrees so that the other first surface 11 and the second surface 12 opposite thereto face the left and right grinding wheels 410, and then grind in the same way to realize the grinding of the two first surfaces 11 and the two second surfaces 12.

[0139] Before grinding the surface of the second chamfer 13, the square bar to be processed can be rotated 45 degrees by the clamping mechanism 200, so that the surfaces of two opposite second chamfers 13 face the left and right grinding wheels 410. The grinding wheel driving mechanism 420 (such as a motor) drives the grinding wheel 410 to rotate at a high speed and approach the surface of the second chamfer 13, and the clamping mechanism 200 drives the square bar to be processed to move back and forth for grinding; after the surfaces of the two second chamfers 13 are ground, the square bar to be processed is rotated 135 degrees by the clamping mechanism 200, so that the surfaces of the other two opposite second chamfers 13 face the left and right grinding wheels 410, and then the grinding process is carried out in the same way to realize the grinding of the surfaces of the four second chamfers 13.

[0140] Moreover, after the grinding process of the square bar to be processed is completed, the processed square bar can be transported to the detection area again through the clamping mechanism 200. The detection method can be the same as that before grinding, and each surface of the processed square bar can be detected to obtain multiple sets of margin and dimension information on each surface, so as to judge whether the margin and dimension information of the processed square bar meet the requirements.

[0141] In this embodiment, the surface polishing device 1000 of the square bar of the present application uses the feeding mechanism 100, the clamping mechanism 200, the detection mechanism 300 and the grinding mechanism 400 to realize the grinding process of each surface of the processed square bar, and obtain the square bar 10 in the above embodiment. Since each grinding wheel in the grinding mechanism 400 is a grinding wheel with a mesh number of 50 to 500, it only needs to grind each first surface 11, each second surface 12 and each second chamfer 13 once respectively. This not only simplifies the surface polishing process of the square bar, but also avoids the damage to the surface of the square bar caused by multiple grindings, improves the surface grinding accuracy, thereby improving the surface roughness of the square bar 10, the surface stability of the square bar 10, and reducing the process cost. Moreover, since the present application only grinds each surface once, it only needs to perform tool setting once. Therefore, compared with the existing method of combining fine grinding and rough grinding, the number of tool setting times is reduced, thereby further improving the grinding accuracy, thus improving the margin accuracy on the first surface 11 and the second surface 12 of the square bar 10. Therefore, during the process of slicing the square bar and preparing the battery chip, the surface bonding stability of the square bar 10 is increased, and then the slicing yield and the battery chip yield are improved.

[0142] In some embodiments, the surface polishing device 1000 of the square bar provided by the present application further includes a blanking mechanism 500. After the finished product detection of the processed square bar is completed, the processed square bar can be transported to the clamping area through the clamping mechanism 200. At the same time, the blanking table of the blanking mechanism 500 moves horizontally to the clamping area. The clamping mechanism 200 places the processed square bar on the blanking table, and then the blanking table moves horizontally out of the clamping area, and then the processed square bar is transferred to the next process by manual or mechanical handling.

[0143] In the fifth aspect of the present application, a solar cell is provided, which is prepared by using the silicon wafer provided in the first aspect of the present application.

[0144] In the sixth aspect of the present application, a photovoltaic module is provided, which includes the solar cell provided in the fifth aspect of the present application.

[0145] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific examples and comparative examples. However, the specific examples described are only used to explain the present invention and are not used to limit the present invention.

[0146] Twelve groups of square bars are selected. The size specifications of the square bars are 182 mm × 191.75 mm. The square bars have four linear chamfers, and the arc length projection of each chamfer is 1.41 mm × 1.34 mm (the projection length of the long side is 1.41 mm, and the projection length of the short side is 1.34 mm). Each group of square bars includes two sister square bars. One square bar of the twelve groups of sister square bars is used to prepare the examples, and the other is used to prepare the comparative examples. Different polishing processes are performed on the twelve groups of square bars, and slicing is performed using the same slicing equipment with the same process. The slicing yield of the twelve square bars is counted; then cleaning and detection are performed using the same equipment and process to obtain the finished silicon wafers; then the finished silicon wafers of different groups are used to prepare the same solar cells, and the difference in the solar cell yield between the examples and the comparative examples is counted. Among them, the slicing yield is equal to the actual number of silicon wafers / the theoretically calculated number of silicon wafers; the difference in the solar cell yield is equal to the solar cell yield of the examples minus the solar cell yield of the comparative examples; the solar cell yield is equal to the final number of solar cells / the number of silicon wafers before solar cell preparation.

[0147] It can be understood that after pulling single-crystal silicon, a crystal bar will be formed. After each crystal bar is squared and truncated, multiple square bars will be formed. Adjacent square bars cut from the same crystal bar are sister square bars. Since sister square bars come from the same crystal bar and have undergone the same process treatment before grinding, it can be considered that they have the same performance before the grinding stage.

[0148] Example: One group of twelve square bars is subjected to one-time grinding wheel polishing. The grinding wheel mesh number is 350 mesh; the grinding wheel rotation speed is 3500 r / min, the feeding speed of the square bar during surface grinding is 1500 mm / min; the feeding speed of the square bar during surface polishing is 2500 mm / min; the feeding speed of the square bar during arc grinding is 1500 mm / min; the feeding speed of the square bar during arc polishing is 2500 mm / min; the single grinding amount during surface grinding is 0.2 mm, the single grinding amount during arc grinding is 0.5 mm, the single grinding amount during surface polishing is 0.02 mm, and the single grinding amount during arc polishing is 0.02 mm.

[0149] The roughness of the square bar after surface polishing was tested, and the Ra and Ry values of the first surface, the second surface, and the chamfered surface were measured. Among them, the Ra of the first surface, the second surface, and the chamfered surface of 12 square bars was between 0.35 μm and 0.55 μm, and the Ry of the first surface, the second surface, and the chamfered surface of 12 square bars was between 3 μm and 6 μm.

[0150] Comparative example: Another group of 12 square bars was polished twice with grinding wheels. First, a coarse grinding wheel with a mesh number of 200 was used, and then a fine grinding wheel with a mesh number of 800 was used; the rotational speed of the grinding wheel was 2800 r / min, the feeding speed of the square bar during surface grinding was 1000 mm / min; the feeding speed of the square bar during surface polishing was 2200 mm / min; the feeding speed of the square bar during arc grinding was 1100 mm / min; the feeding speed of the square bar during arc polishing was 2200 mm / min; the single grinding amount during surface grinding was 0.01 mm, the single grinding amount during arc grinding was 1.3 mm, the single grinding amount during surface polishing was 0.01 mm, and the single grinding amount during arc polishing was 0.01 mm.

[0151] The roughness of the ingot bar after surface polishing was tested, and the Ra and Ry values of the first surface, the second surface, and the chamfered surface were measured. Among them, the Ra of the first surface, the second surface, and the chamfered surface of 12 square bars was between 0.08 μm and 0.12 μm, and the Ry of the first surface, the second surface, and the chamfered surface of 12 square bars was between 1 μm and 4 μm.

[0152] Table 1 shows the results of the yield rates of the examples and the comparative example. Among them, the roughness range refers to the range interval between the maximum and minimum values of all data points measured for 12 ingot bars; the value range of the slicing yield rate refers to the range interval between the maximum and minimum values of the yield rates when slicing 12 square bars; the average value of the slicing yield rate refers to the average value of the slicing yield rates of these 12 square bars. The value range of the battery yield rate refers to the range interval between the maximum and minimum values of the yield rates when preparing battery wafers from 12 square bars; the average value of the battery yield rate refers to the average value of the yield rates when preparing battery wafers from these 12 square bars.

[0153] As can be seen from the table, by controlling the roughness Ra of the square bar within 0.35 - 0.55 μm and Ry within 3 μm - 6 μm, both the slicing yield rate and the battery wafer yield rate have increased.

[0154] Table 1 Results of the yield rates of the examples and the comparative example

[0155]

[0156] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A silicon wafer, characterized in that, The surface roughness Ra of the side surfaces of the silicon wafers is 0.15 μm - 1 μm; preferably, the surface roughness Ra of the side surfaces of the silicon wafers is 0.55 μm - 1 μm.

2. The silicon wafer according to claim 1, characterized in that, The surface roughness Ry of the side surfaces of the silicon wafers is 2 μm - 10 μm; preferably, the surface roughness Ry of the side surfaces of the silicon wafers is 5 - 10 μm.

3. The silicon wafer according to claim 1, characterized in that, The surface roughness Ra of the first chamfer between every two adjacent side surfaces of the silicon wafer is less than or equal to the surface roughness Ra of the side surface of the silicon wafer.

4. The silicon wafer according to claim 3, wherein the surface roughness Ra of the first chamfer between every two adjacent side surfaces of the silicon wafer is 0.15 μm - 1 μm; and / or the surface roughness Ry of the first chamfer between every two adjacent side surfaces of the silicon wafer is 2 μm - 10 μm.

5. The silicon wafer according to claim 4, characterized in that, The projection lengths of the first chamfer in the first direction (X) and the second direction (Y) are different, and the first direction (X) and the second direction (Y) are perpendicular to the thickness direction of the silicon wafer.

6. The silicon wafer according to claim 5, characterized in that, The absolute difference between the projection lengths of the first chamfer in the first direction (X) and the second direction (Y) is 0.05 mm - 0.1 mm.

7. The silicon wafer according to claim 4, characterized in that, Each of the first chamfers is an arc or a straight line.

8. A square bar for preparing the silicon wafer according to any one of claims 1-7, characterized in that, Comprising: two first surfaces (11), oppositely arranged along the first direction (X); two second surfaces (12), oppositely arranged along the second direction (Y), and the first direction (X) and the second direction (Y) are perpendicular to the length direction (Z) of the square bar; wherein, a part of each of the first surfaces (11) and a part of each of the second surfaces (12) are respectively a corresponding side surface of the silicon wafer, and the surface roughness Ra of the first surfaces (11) and the second surfaces (12) is 0.35 μm - 0.85 μm; Preferably, the surface roughness Ra of the first surfaces (11) and the second surfaces (12) is 0.55 μm - 0.85 μm.

9. The square bar according to claim 8, wherein the surface roughness Ry of the first surfaces (11) and the second surfaces (12) is 3 μm - 9 μm; Preferably, the surface roughness Ry of the first surfaces (11) and the second surfaces (12) is 6 μm - 9 μm.

10. The square bar according to claim 8, wherein the absolute value of the margin range difference between two opposite long sides on the first surface (11) is less than or equal to 0.02 mm; and / or, the absolute value of the margin range difference between two opposite long sides on the second surface (12) is less than or equal to 0.02 mm.

11. The square bar according to any one of claims 8 - 10, wherein the square bar further comprises at least two second chamfers (13), and each of the second chamfers (13) is arranged between two adjacent first surfaces (11) and the second surfaces (12); Among them, the surface roughness Ra of each of the second chamfers (13) is 0.35 μm - 0.55 μm; and / or, the surface roughness Ry of each of the second chamfers (13) is 3 μm - 6 μm.

12. A processing method for a silicon wafer, characterized in that, Comprising: Providing a square bar to be processed, the square bar to be processed includes two first surfaces (11) oppositely arranged along a first direction (X) and two second surfaces (12) oppositely arranged along a second direction (Y), the first direction (X) and the second direction (Y) are perpendicular to the length direction (Z) of the square bar to be processed; Performing surface polishing treatment on the first surface (11) and the second surface (12) of the square bar to be processed to obtain the square bar according to any one of claims 8 - 11; Performing slicing treatment on the square bar after surface polishing treatment to obtain the silicon wafer according to any one of claims 1 - 7.

13. The processing method of the silicon wafer according to claim 12, wherein, The performing surface polishing treatment on the first surface (11) and the second surface (12) of the square bar to be processed includes: Detecting the first surface (11) and the second surface (12) of the square bar to be processed to determine the surface grinding parameters of the first surface (11) and the second surface (12); According to the surface grinding parameters of the first surface (11) and the second surface (12), using two oppositely arranged grinding wheels to respectively perform grinding treatment on the two first surfaces (11) and the two second surfaces (12), wherein each of the grinding wheels is a grinding wheel with a mesh number of 50 - 500 meshes.

14. The processing method of the silicon wafer according to claim 13, wherein The rotation speed of each of the grinding wheels during grinding treatment is greater than or equal to 3200 r / min.

15. The processing method of the silicon wafer according to claim 13, wherein, The according to the surface grinding parameters of the first surface (11) and the second surface (12), using two oppositely arranged grinding wheels to respectively perform grinding treatment on the two first surfaces (11) and the two second surfaces (12) includes: According to the surface grinding parameters of the first surface (11), using the two grinding wheels to simultaneously perform surface grinding treatment and surface polishing treatment on the two first surfaces (11) in sequence and controlling the feeding speed of the square bar during the surface grinding treatment and the surface polishing treatment; According to the surface grinding parameters of the second surface (12), using the two grinding wheels to perform surface grinding treatment and surface polishing treatment on the two second surfaces (12) in sequence and controlling the feeding speed of the square bar during the surface grinding treatment and the surface polishing treatment; Among them, the feeding speed of the square bar during surface grinding treatment on the first surface (11) and the second surface (12) is 1500 - 1800 mm / min, the single grinding amount is 0.1 - 0.2 mm, and the feeding speed of the square bar during surface polishing treatment on the first surface (11) and the second surface (12) is 2200 - 2500 mm / min, the single grinding amount is 0.01 - 0.02 mm.

16. The processing method of the silicon wafer according to any one of claims 13 - 15, characterized in that The square bar to be processed further includes a second chamfer (13) located between two adjacent first surfaces (11) and the second surface (12); Before slicing the square bar after surface polishing treatment, the processing method of the silicon wafer further includes: detecting the second chamfer (13) to determine the surface grinding parameters of the second chamfer (13); According to the surface grinding parameters of the second chamfer (13), use two oppositely arranged grinding wheels to grind the surfaces of the four second chamfers (13), wherein each grinding wheel is a grinding wheel with a mesh number of 50 to 500.

17. The processing method of the silicon wafer according to claim 16, wherein, The step of using two oppositely arranged grinding wheels to grind the surfaces of the four second chamfers (13) according to the surface grinding parameters of the second chamfer (13) includes: According to the surface grinding parameters of the second chamfer (13), use the two grinding wheels to successively perform surface grinding and surface polishing on the surfaces of two oppositely arranged second chamfers (13) and control the feeding speed of the square bar during the surface grinding and surface polishing processes; According to the surface grinding parameters of the second chamfer (13), use the two grinding wheels to successively perform surface grinding and surface polishing on the surfaces of the other two oppositely arranged chamfers (13) and control the feeding speed of the square bar during the surface grinding and surface polishing processes; Wherein, the feeding speed of the square bar during surface grinding of the surface of the second chamfer (13) is 1500 - 1800 mm / min, the single grinding amount is 0.1 - 0.2 mm, and the feeding speed of the square bar during surface polishing of the surface of the chamfer (13) is 2200 - 2500 mm / min, the single grinding amount is 0.01 - 0.02 mm.

18. The processing method of the silicon wafer according to claim 16, wherein Detecting the first surface (11) and the second surface (12) of the square bar to be processed to determine the surface grinding parameters of the first surface (11) and the second surface (12) includes: detecting the first surface (11) and the second surface (12) of the square bar to be processed to obtain multiple sets of margin information of the first surface (11) and the second surface (12) at different positions; determining the surface grinding parameters of the first surface (11) according to the mean value of the multiple sets of margins on the first surface (11) and the target margin value; determining the surface grinding parameters of the second surface (12) according to the mean value of the multiple sets of margins on the second surface (12) and the target margin value; and / or Detecting the second chamfer (13) of the square bar to be processed to determine the surface grinding parameters of the second chamfer (13) includes: detecting the second chamfer (13) of the square bar to be processed to obtain multiple sets of margin information of the second chamfer (13) at different positions; determining the surface grinding parameters of the second chamfer (13) according to the mean value of the multiple sets of margins on the second chamfer (13) and the target margin value.

19. A processing device for a silicon wafer, characterized in that, including: A surface polishing device for performing surface polishing treatment on the first surface (11) and the second surface (12) of the square bar to be processed to obtain the square bar according to any one of claims 8 - 11; A slicing device for slicing the square bar after surface polishing to obtain the silicon wafer according to any one of claims 1-7.

20. The processing equipment for silicon wafers according to claim 19, wherein The surface polishing device includes: A loading mechanism for receiving the square bar to be processed and transferring the square bar to be processed to the clamping area; A clamping mechanism for clamping the two end faces (14) of the square bar to be processed in its length direction in the clamping area and transferring the square bar to be processed to the detection area; A detection mechanism for detecting the first surface (11) and the second surface (12) of the square bar to be processed in the detection area, and after the detection mechanism finishes the detection, the clamping mechanism is further used to transfer the square bar to be processed to the grinding area; and A grinding mechanism includes two relatively arranged grinding wheels, each grinding wheel is a grinding wheel with a mesh number of 50 to 500, and the two grinding wheels are used to grind the two first surfaces (11) and the two second surfaces (12) in the grinding area to obtain the square bar according to any one of claims 8-11.

21. A battery cell, characterized in that, Prepared by using the silicon wafer according to any one of claims 1-7.

22. A photovoltaic module, characterized in that, Including the battery chip according to claim 21.

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