Substrate transfer method and solar cell manufacturing method

Abstract

The invention discloses a substrate transfer method and a solar cell manufacturing method, and relates to the technical field of cell production. According to the substrate transfer method, the vacuum pressure is calculated according to the surface average roughness and thickness of the coating layer, and then the vacuum pressure is calculated according to the adsorption area, the single-hole area, the number of the adsorption holes and the vacuum pressure of the vacuum chuck, so that the obtained vacuum pressure is appropriate, accurate and reliable, the situation that the substrate falls off is avoided, and the quality of the substrate is improved. Meanwhile, indentation marks cannot be formed on the surface of the substrate, the subsequent PL detection precision is guaranteed, and the battery quality is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of battery production, and in particular relates to a substrate transfer method and a solar cell manufacturing method. Background Art

[0002] At present, in the production process of solar cells, the substrate is generally transferred by adsorbing the substrate with a vacuum chuck. In this process, if the vacuum pressure of the vacuum chuck is too small, the adsorption force is insufficient, and the substrate is prone to fall off; if the vacuum pressure of the vacuum chuck is too large, an indentation will be formed on the surface of the substrate, affecting the subsequent PL detection accuracy and even directly affecting the quality of the battery.

[0003] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or known technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art that the vacuum pressure of the vacuum suction cup cannot be accurately controlled during the transfer process of the substrate, resulting in the substrate falling off or forming an indentation mark on the substrate surface, and provide a substrate transfer method and a solar cell manufacturing method. The substrate transfer method calculates the vacuum pressure by the surface average roughness and thickness of the coating layer, and then calculates the vacuum pressure by the adsorption area, single hole area, number of suction holes and vacuum pressure of the vacuum suction cup, so that the obtained vacuum pressure is appropriate, accurate and reliable, and the substrate falling off is avoided. At the same time, no indentation mark is formed on the substrate surface, thereby ensuring the subsequent PL detection accuracy and battery quality.

[0005] In order to achieve the above object, in a first aspect, the present invention provides a substrate transfer method, comprising: S1. Providing a substrate, wherein the substrate comprises a silicon wafer and a coating layer formed on the silicon wafer; S2. Obtaining the average surface roughness and thickness of the coating layer; S3. The vacuum pressure is calculated according to the average surface roughness and thickness by the first calculation formula, wherein the first calculation formula is: P = k*(D+25) / Ra; Wherein, P is the vacuum pressure, in pa; D is the thickness, in nm; Ra is the average surface roughness, in nm; k is the coefficient, and the value range of k is 100-140; S4. The vacuum pressure is calculated according to the adsorption area, single hole area, number of suction holes and vacuum pressure of the vacuum suction cup by the second calculation formula, wherein the vacuum suction cup is provided with an adsorption surface, a plurality of suction holes are provided on the adsorption surface, and the area of ​​a single suction hole is the single hole area. The second calculation formula is: F=P*(S1+S2*N); In the formula, F is the vacuum pressure, the unit is N; P is the vacuum pressure, the unit is pa; S1 is the adsorption area, the unit is m 2 ; S2 is the single hole area, unit is m 2 ; N is the number of suction holes; S5. Use a vacuum pump to provide vacuum pressure to the vacuum chuck so that the vacuum chuck can vacuum absorb the substrate.

[0006] Preferably, the vacuum suction cup includes a suction cup body and a buffer pad, the buffer pad is bonded to the suction cup surface of the suction cup body, the adsorption surface is arranged on the side of the buffer pad away from the suction cup surface, multiple suction holes are opened on the buffer pad, and multiple through holes are opened on the suction cup surface, and each through hole is aligned with a suction hole.

[0007] Preferably, the ratio of the area of ​​the adsorption surface to the area of ​​the suction cup surface is 1.3-2.5.

[0008] Preferably, the thickness of the cushion is 1 mm to 4 mm; And / or, the cushion is made of polypropylene, polyethylene, polyester fiber, polyvinyl chloride or polytetrafluoroethylene material.

[0009] Preferably, the number of vias is 2-15; And / or, the ratio of the total area of ​​the plurality of vias to the area of ​​the suction cup surface is 0.3-0.65.

[0010] Preferably, the ratio of the adsorption area, the number of adsorption holes and the thickness is 1: (0.05-1.67): (0.27-16), where the unit of the adsorption area is cm 2 , the unit of the number of pores is pieces, and the unit of thickness is nm.

[0011] Preferably, the adsorption area, thickness and average surface roughness satisfy the following relationship: S1*D≥0.015Ra.

[0012] Preferably, S2 includes: Measure the height of multiple sampling points on the surface of the coating layer by laser interferometer, scanning electron microscope or atomic force microscope; The average surface roughness is calculated according to the heights of multiple sampling points using a third calculation formula, where the third calculation formula is: Ra=1 / n∑|Zi; Where n is the number of sampling points; Zi is the height of the i-th sampling point, in nm.

[0013] In a second aspect, the present invention provides a method for manufacturing a solar cell, comprising the above-mentioned substrate transfer method.

[0014] Beneficial effects: Through research, it is found that in the process of transferring the substrate by adsorbing the vacuum chuck, if the vacuum pressure of the vacuum chuck is too small, the adsorption force is insufficient and the substrate is prone to fall off; if the vacuum pressure of the vacuum chuck is too large, an indentation will be formed on the surface of the substrate, affecting the subsequent PL detection accuracy and even directly affecting the battery quality. Based on this, further research was conducted and the present invention was proposed.

[0015] The present invention adopts the above technical scheme, especially calculates the vacuum pressure through the surface average roughness and thickness of the coating layer, and then calculates the vacuum pressure through the adsorption area, single hole area, number of suction holes and vacuum pressure of the vacuum suction cup, so that the obtained vacuum pressure is appropriate, accurate and reliable, avoiding the situation of substrate falling, and at the same time, no indentation is formed on the substrate surface, thereby ensuring the subsequent PL detection accuracy and battery quality.

[0016] The solar cell manufacturing method of the present invention can stably and reliably transfer the substrate, has good transfer effect and good product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic structural diagram of a vacuum chuck used in a substrate transfer method provided in an embodiment of the present invention; Figure 2 A schematic structural diagram of a substrate transfer method provided in an embodiment of the present invention applied to a substrate.

[0019] Description of reference numerals: 100 - vacuum suction cup; 110 - suction cup body; 111 - suction cup surface; 112 - via hole; 120 - buffer pad; 121 - adsorption surface; 122 - suction hole; 200 - substrate; 210 - silicon wafer; 220 - coating layer. DETAILED DESCRIPTION

[0020] In the present invention, unless otherwise specified, directional words such as "upper, lower, left, right" are generally understood in conjunction with the directions shown in the drawings and actual applications.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0022] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. Among them, the terms "optional" and "optional" all mean that they may be included or not included (or may be present or not).

[0024] First, please refer to Figure 1 and Figure 2 The embodiment of the present invention provides a substrate transfer method, which calculates the vacuum pressure by the surface average roughness and thickness of the coating layer 220, and then calculates the vacuum pressure by the adsorption area, single hole area, number of suction holes 122 and vacuum pressure of the vacuum suction cup 100, so that the obtained vacuum pressure is appropriate, accurate and reliable, avoiding the substrate 200 from falling, and at the same time, no indentation is formed on the surface of the substrate 200, thereby ensuring the accuracy of subsequent PL detection and the quality of the battery.

[0025] The substrate transfer method comprises the following steps: S1. Providing a substrate 200, wherein the substrate 200 includes a silicon wafer 210 and a coating layer 220 formed on the silicon wafer 210; S2. Obtaining the average surface roughness and thickness of the coating layer 220; S3. The vacuum pressure is calculated according to the average surface roughness and thickness by the first calculation formula, wherein the first calculation formula is: P = k*(D+25) / Ra; Wherein, P is the vacuum pressure, in pa; D is the thickness, in nm; Ra is the average surface roughness, in nm; k is the coefficient, and the value range of k is 100-140; S4. The vacuum pressure is calculated by the second calculation formula according to the adsorption area, single hole area, number of suction holes 122 and vacuum pressure of the vacuum suction cup 100, wherein the vacuum suction cup 100 is provided with an adsorption surface 121, and a plurality of suction holes 122 are provided on the adsorption surface 121, the area of ​​a single suction hole 122 is the single hole area, and the area of ​​the adsorption surface 121 is the adsorption area. The second calculation formula is: F=P*(S1+S2*N); In the formula, F is the vacuum pressure, the unit is N; P is the vacuum pressure, the unit is pa; S1 is the adsorption area, the unit is m 2 ; S2 is the single hole area, unit is m 2 ; N is the number of suction holes 122; S5. Use a vacuum pump to provide vacuum pressure to the vacuum chuck 100 so that the vacuum chuck 100 performs vacuum adsorption on the substrate 200.

[0026] The vacuum suction cup 100 includes a suction cup body 110 and a buffer pad 120. The buffer pad 120 is bonded to the suction cup surface 111 of the suction cup body 110. The suction cup body 110 is used to absorb the substrate 200, and the buffer pad 120 is used to buffer the substrate 200 to avoid forming an indentation mark on the surface of the substrate 200. Specifically, the suction surface 121 is arranged on the side of the buffer pad 120 away from the suction cup surface 111, and a plurality of suction holes 122 are all opened on the buffer pad 120. The suction cup surface 111 is provided with a plurality of through holes 112, and each through hole 112 is aligned with a suction hole 122. The plurality of through holes 112 and the plurality of suction holes 122 work together to achieve the vacuum adsorption function. When the vacuum suction cup 100 is working, air can pass through the suction holes 122 of the buffer pad 120 and the through holes 112 of the suction cup body 110 in sequence to adsorb the coating layer 220 of the substrate 200 onto the adsorption surface 121 of the buffer pad 120, thereby realizing vacuum adsorption of the substrate 200 and facilitating the transfer operation of the substrate 200. During this process, the buffer pad 120 buffers the coating layer 220 to prevent the coating layer 220 from generating indentations under the action of vacuum pressure.

[0027] Preferably, the area of ​​the buffer pad 120 is larger than the area of ​​the suction cup body 110, and the ratio of the area of ​​the adsorption surface 121 to the area of ​​the suction cup surface 111 is 1.3-2.5. A reasonable ratio of the area of ​​the adsorption surface 121 to the area of ​​the suction cup surface 111 can fully reduce the pressure exerted by the adsorption surface 121 on the coating layer 220 on the surface of the silicon wafer 210, thereby preventing the substrate 200 from being damaged during the transfer process.

[0028] Preferably, the thickness of the buffer pad 120 is 1 mm-4 mm. A reasonable thickness of the buffer pad 120 can buffer the pressure exerted by the suction cup body 110 on the coating layer 220 , thereby helping to reduce the imprint on the surface of the coating layer 220 .

[0029] Preferably, the buffer pad 120 is made of polypropylene, polyethylene, polyester fiber, polyvinyl chloride or polytetrafluoroethylene. The buffer pad 120 has low hardness and good buffering effect, can reduce the compressive stress on the coating layer 220, and is conducive to reducing damage to the surface of the coating layer 220.

[0030] Preferably, the number of the through holes 112 is 2-15, and the number of the suction holes 122 is the same as the number of the through holes 112 . Reasonable numbers of the through holes 112 and the suction holes 122 can improve the adsorption capacity, which is conducive to taking into account both the adsorption effect and the pressure reduction.

[0031] In this embodiment, the number of the through holes 112 and the suction holes 122 are both 9, and the 9 through holes 112 are arranged in a rectangular array on the suction cup surface 111 of the suction cup body 110, and the 9 suction holes 122 are arranged in a rectangular array on the suction surface 121 of the buffer pad 120, and the position of each through hole 112 corresponds to the position of a suction hole 122. However, this is not limited to this, and in other embodiments, the number of the through holes 112 and the suction holes 122 can be 4 or 12, and the number and arrangement of the through holes 112 and the suction holes 122 are not specifically limited.

[0032] Preferably, the ratio of the total area of ​​the plurality of vias 112 to the area of ​​the suction cup surface 111 is 0.3-0.65. A reasonable ratio of the total area of ​​the plurality of vias 112 to the area of ​​the suction cup surface 111 can reduce the adsorption pressure and help alleviate transfer damage to the coating layer 220 .

[0033] Preferably, the area of ​​the adsorption surface 121 on the vacuum suction cup 100 is the adsorption area, and the ratio of the adsorption area, the number of the suction holes 122 and the thickness of the coating layer 220 is 1: (0.05-1.67): (0.27-16), wherein the unit of the adsorption area (the area of ​​the adsorption surface 121) is cm 2 The unit of the number of the suction holes 122 is pieces, and the unit of the thickness of the coating layer 220 is nm. A reasonable ratio of the adsorption area, the number of the suction holes 122 and the thickness of the coating layer 220 is beneficial to avoid the vacuum pressure generated in the via 112 from damaging the coating layer 220, reducing or even eliminating the indentation mark, ensuring the accuracy of subsequent PL detection, and ensuring the quality of the battery.

[0034] Preferably, the adsorption area, the thickness of the coating layer 220 and the average surface roughness of the coating layer 220 satisfy the following relationship: S1*D≥0.015Ra. By controlling the reasonable proportional relationship between the adsorption area, thickness and average surface roughness, it is helpful to alleviate the damage to the coating layer 220 caused by the vacuum pressure of the vacuum suction cup 100.

[0035] It should be noted that, in S1, the front surface of the silicon wafer 210 is first textured, and then the rough textured surface on the front surface of the silicon wafer 210 is coated to form a coating layer 220 to form the substrate 200. The silicon wafer 210 is preferably an N-type single crystal silicon wafer, and the silicon wafer 210 can be a CZ single crystal silicon wafer or a cast single crystal silicon wafer.

[0036] In S2, the surface average roughness and thickness of the coating layer 220 are measured in sequence, wherein the process of measuring the surface average roughness is divided into two stages, namely: Phase 1: The heights of multiple sampling points on the surface of the coating layer 220 are measured by laser interferometer, scanning electron microscope or atomic force microscope.

[0037] The second stage: the average surface roughness is calculated according to the height of multiple sampling points through the third calculation formula, where the third calculation formula is: Ra=1 / n∑|Zi; Where n is the number of sampling points; Zi is the height of the i-th sampling point, in nm.

[0038] In S3, the vacuum pressure is calculated by the first calculation formula according to the surface average roughness of the coating layer 220 and the thickness of the coating layer 220, and the first calculation formula is: P=k*(D+25) / Ra. In the formula, 25 is a thickness compensation value, which is an empirical thickness compensation value obtained through experimental testing and verification; the value range of k is 100-140, preferably k=120, and a reasonable value of k can properly evaluate the pressure on the coating layer 220 and control the suction force of the vacuum chuck 100, which is conducive to avoiding damage or imprinting that may be caused by the transfer of the substrate 200.

[0039] In S4, the vacuum pressure is calculated according to the adsorption area of ​​the vacuum suction cup 100, the single hole area, the number of suction holes 122 and the vacuum pressure through the second calculation formula. The second calculation formula is: F=P*(S1+S2*N). The vacuum pressure calculated by the second calculation formula is appropriate, accurate and reliable, and avoids the substrate 200 from falling. At the same time, no indentation is formed on the surface of the substrate 200, thereby ensuring the accuracy of subsequent PL detection and the quality of the battery.

[0040] In S5, a vacuum pump is used to provide the vacuum pressure calculated in S4 to the vacuum suction cup 100, so as to adsorb the substrate 200 through the vacuum suction cup 100. During this process, the coating layer 220 of the substrate 200 is adsorbed and adhered to the adsorption surface 121 of the buffer pad 120. The buffer pad 120 can buffer the coating layer 220, and the vacuum pressure is appropriate, which can avoid the situation that the adsorption force is insufficient and the substrate 200 falls due to the vacuum pressure is too small, and can also avoid the situation that the vacuum pressure is too large, the indentation is formed on the surface of the substrate 200, and the subsequent PL detection accuracy is affected.

[0041] In a second aspect, an embodiment of the present invention provides a method for manufacturing a solar cell, including the above-mentioned substrate transfer method.

[0042] The substrate transfer method provided by the embodiment of the present invention calculates the vacuum pressure by the surface average roughness and thickness of the coating layer 220, and then calculates the vacuum pressure by the adsorption area, single hole area, number of suction holes 122 and vacuum pressure of the vacuum chuck 100, so that the obtained vacuum pressure is appropriate, accurate and reliable, and the substrate 200 is prevented from falling off, and at the same time, no indentation is formed on the surface of the substrate 200, so as to ensure the subsequent PL detection accuracy and the battery quality. The solar cell manufacturing method can stably and reliably transfer the substrate 200, with good transfer effect and good product quality.

[0043] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A substrate transfer method, characterized in that: include: S1. Providing a substrate, wherein the substrate comprises a silicon wafer and a coating layer formed on the silicon wafer; S2 obtains the average surface roughness and thickness of the coating layer; S3. The vacuum pressure is calculated according to the average surface roughness and the thickness by a first calculation formula, wherein the first calculation formula is: P = k*(D+25) / Ra; Wherein, P is the vacuum pressure, in pa; D is the thickness, in nm; Ra is the average surface roughness, in nm; k is a coefficient, and the value range of k is 100-140; S4. The vacuum pressure is calculated according to the adsorption area, single hole area and number of suction holes of the vacuum suction cup and the vacuum pressure by a second calculation formula, wherein the vacuum suction cup is provided with an adsorption surface, a plurality of suction holes are provided on the adsorption surface, the area of ​​a single suction hole is the single hole area, and the second calculation formula is: F=P*(S1+S2*N); Wherein, F is the vacuum pressure, in N; P is the vacuum pressure, in pa; S1 is the adsorption area, in m 2 ; S2 is the single hole area, unit is m 2 ; N is the number of suction holes; S5. Using a vacuum pump to provide the vacuum pressure to the vacuum chuck, so that the vacuum chuck performs vacuum adsorption on the substrate.

2. The substrate transfer method according to claim 1, characterized in that: The vacuum suction cup includes a suction cup body and a buffer pad, the buffer pad is bonded to the suction cup surface of the suction cup body, the adsorption surface is arranged on the side of the buffer pad away from the suction cup surface, a plurality of suction holes are opened on the buffer pad, a plurality of through holes are opened on the suction cup surface, and each of the through holes is aligned with a suction hole.

3. The substrate transfer method according to claim 2, characterized in that: The ratio of the area of ​​the adsorption surface to the area of ​​the suction cup surface is 1.3-2.

5.

4. The substrate transfer method according to claim 2, characterized in that: The thickness of the buffer pad is 1mm-4mm; And / or, the buffer pad is made of polypropylene, polyethylene, polyester fiber, polyvinyl chloride or polytetrafluoroethylene.

5. The substrate transfer method according to claim 2, characterized in that: The number of the vias is 2-15; And / or, the ratio of the total area of ​​the plurality of via holes to the area of ​​the suction cup surface is 0.3-0.

65.

6. The substrate transfer method according to claim 1, characterized in that: The ratio of the adsorption area, the number of the adsorption holes and the thickness is 1: (0.05-1.67): (0.27-16), wherein the unit of the adsorption area is cm 2 , the unit of the number of the suction holes is piece, and the unit of the thickness is nm.

7. The substrate transfer method according to claim 1, characterized in that: The adsorption area, the thickness and the average surface roughness satisfy the following relationship: S1*D≥0.015Ra.

8. The substrate transfer method according to claim 1, characterized in that S2 include: Measuring the heights of multiple sampling points on the surface of the coating layer by using a laser interferometer, a scanning electron microscope or an atomic force microscope; The surface average roughness is calculated according to the heights of the plurality of sampling points by using a third calculation formula, wherein the third calculation formula is: Ra=1 / n∑|Zi; Wherein, n is the number of the sampling points; Zi is the height of the i-th sampling point, in nm.

9. A method for manufacturing a solar cell, characterized in that: The method comprises a substrate transfer method as claimed in any one of claims 1 to 8.

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