Cutting device
By arranging the grooving laser, thermal cracking laser, and cooling structure at the same angle in the cutting device, the problem of low efficiency of solar cells caused by uneven silicon wafer cross-sections was solved, achieving directional cracking of silicon wafers and improving efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2026-03-24
AI Technical Summary
In existing technologies, the uneven cross-section of silicon wafers after dicing leads to low efficiency in solar cells.
A cutting apparatus is provided, comprising a stage, a grooving laser structure, a thermal cracking laser structure, and a cooling structure, all arranged in parallel directions and at the same angle to cut a silicon wafer at the same angle. After the grooving laser structure creates a groove on the silicon wafer, the thermal cracking laser structure applies a high-energy laser to the groove, and the cooling structure sprays cooling water at the same angle to form a directional temperature gradient field, causing the silicon wafer to crack along the directional direction.
This improves the flatness of the cross-section after the silicon wafer cracks, reduces the generation of dangling bonds, reduces carrier recombination, and improves the efficiency of solar cells.
Smart Images
Figure CN224026746U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of solar cell processing, in particular to a cutting device. BACKGROUND
[0002] In the preparation of solar cells, the existing laser scribing technology is to perform laser grooving on the silicon wafer at the middle position of the surface of the silicon wafer and along the direction perpendicular to the main grid. After the grooving, high-temperature laser scanning is performed on the grooving area by using a thermal cracking laser. After the thermal cracking laser scanning, the silicon wafer is cooled by a cooling liquid. The temperature gradient field generated by the thermal cracking laser and the cooling substance acting on the silicon wafer causes the silicon wafer to be subjected to thermal stress and then cracked, thereby completing the scribing of the silicon wafer. If the position or structure of the cooling spray device for the cooling liquid and the thermal cracking laser device is not properly arranged, it is easy to cause the temperature gradient field of the silicon wafer to be unevenly distributed, so that the direction of the thermal stress is not along the same direction. Other cracks may be generated at the cracking section of the silicon wafer, thereby exposing a large number of dangling bonds, increasing the damage degree of the section and the recombination of the carriers, and thereby reducing the cell efficiency of the finally formed solar cell. CONTENT
[0003] The main purpose of the present application is to provide a cutting device to solve the problem of low efficiency of solar cells caused by the uneven section of the silicon wafer after scribing in the prior art.
[0004] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a cutting device is provided, comprising: a carrier table having opposite first and second surfaces; a grooving laser structure located on the side of the first surface away from the second surface, the grooving laser structure having a first laser head, the first laser head having a first included angle with the first surface; a thermal cracking laser structure located on one side of the grooving laser structure, the arrangement direction of the thermal cracking laser structure and the grooving laser structure being parallel to the first surface, the thermal cracking laser structure having a second laser head, the central axis of the second laser head being parallel to the central axis of the first laser head; and a cooling structure located on the side of the thermal cracking laser structure away from the grooving laser structure, the cooling structure comprising a spray head, the central axis of the spray head being parallel to the central axis of the second laser head.
[0005] Optionally, the first included angle is 45°-80°.
[0006] Optionally, the cooling structure further comprises a cooling water delivery part, the water outlet of the cooling water delivery part being connected to the spray head, the spray head comprising water outlets, the cross-sectional area of the water outlets close to the cooling water delivery part being greater than the cross-sectional area of the water outlets away from the cooling water delivery part.
[0007] Optionally, the shower head further comprises at least one air outlet portion, which is located at the periphery of the water outlet hole, and is used for directing the cooling gas to be discharged.
[0008] Optionally, the air outlet portion is annular, and the central axis of the air outlet portion coincides with the central axis of the water outlet hole.
[0009] Optionally, the cross-sectional diameter of the water outlet hole away from the cooling water delivery portion is the same as the spot diameter of the hot-cracking laser beam emitted by the hot-cracking laser structure.
[0010] Optionally, the minimum distance between the center point of the cross section of the water outlet hole away from the cooling water delivery portion and the first surface is 2-6 mm.
[0011] Optionally, the minimum distance between the center point of the cross section of the light outlet of the second laser head and the first surface is 2-6 mm.
[0012] Optionally, the cutting device further comprises a temperature detection device, the first surface has a sample loading area, and the temperature detection device is used for detecting the temperature of the sample loading area when the cutting device is working.
[0013] Optionally, the cutting device further comprises a connecting structure, which is used for connecting the slotting laser structure, the hot-cracking laser structure and the cooling structure.
[0014] The technical scheme of the application provides a cutting device, which comprises a carrier, a slotting laser structure, a thermal cracking laser structure and a cooling structure, wherein the slotting laser structure, the thermal cracking laser structure and the cooling structure are located on the side of the carrier with a first surface and are arranged in parallel with the first surface, so that the slotting laser structure, the thermal cracking laser structure and the cooling structure can cut the silicon wafer on the carrier along the same preset path. The included angles between the central axes of the first laser head, the second laser head and the nozzle and the first surface are the same, that is, the three can work on the silicon wafer at the same angle. After the slotting laser beam emitted by the slotting laser structure forms a groove on the silicon wafer by slotting and scribing, the thermal cracking laser beam emitted by the thermal cracking laser structure also acts on the groove at the first included angle to generate high temperature in the groove. The cooling water sprayed by the nozzle of the cooling structure also cools the groove of the silicon wafer at the first included angle, so as to generate a directional temperature gradient field from the groove to the second surface of the silicon wafer in the first direction (the first direction is the direction in which the slotting laser structure, the thermal cracking laser structure and the cooling structure act on the silicon wafer when the included angle between the central axes of the slotting laser structure, the thermal cracking laser structure and the cooling structure and the first surface is the first included angle). The thermal stress generated by the temperature gradient field makes the silicon wafer crack in the first direction, improves the flatness of the cross section of the silicon wafer after cracking, reduces the generation of the suspended part at the cross section, and further reduces the recombination of carriers at the cross section of the battery, improves the effective carrier number in the battery, and further improves the efficiency of the solar cell wafer. The problem of low efficiency of the solar cell wafer caused by the uneven cross section of the silicon wafer after scribing in the prior art is solved. BRIEF DESCRIPTION OF DRAWINGS
[0015] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the specification explain the present application. The use of the same reference numerals in different drawings indicates similar or identical components.
[0016] Figure 1 A cross-sectional structure schematic diagram of a cutting device provided by an embodiment of the present application is shown;
[0017] Figure 2 A side view structure schematic diagram of the cutting device is shown Figure 1
[0018] Figure 3 A cross-sectional structure schematic diagram of a cutting device in the prior art after cutting a silicon wafer is shown;
[0019] Figure 4 A cross-sectional structure schematic diagram of a cutting device in another prior art after cutting a silicon wafer is shown;
[0020] Figure 5 A cross-sectional structure schematic diagram of a silicon wafer after being cut by a cutting device according to an embodiment of the present application is shown.
[0021] Figure 6 A cross-sectional structure schematic diagram of a cutting device according to an embodiment of the present application is shown. Figure 1
[0022] Figure 7 A cross-sectional structure schematic diagram of a cutting device according to an embodiment of the present application is shown. Figure 1
[0023] Figure 8 A cross-sectional structure schematic diagram of a cutting device according to an embodiment of the present application is shown. Figure 1
[0024] Figure 9 A cross-sectional structure schematic diagram of a cutting device according to an embodiment of the present application is shown.
[0025] Figure 10 A cross-sectional structure schematic diagram of a cutting device according to an embodiment of the present application is shown. Figure 9
[0026] Wherein, the above-mentioned drawings include the following reference signs:
[0027] 10, a stage; 20, a slotted laser structure; 21, a first laser head; 30, a thermal cracking laser structure; 31, a second laser head; 40, a cooling structure; 41, a spray head; 42, a cooling water delivery part; 43, an air outlet part; 44, a water outlet hole; 50, a connecting structure; 51, a support part; 52, a rotating part. DETAILED DESCRIPTION
[0028] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
[0029] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.
[0030] It should be noted that the terms "first", "second", and the like in the description and in the claims of the utility model and the above drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the utility model described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, the process, method, system, product or equipment including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.
[0031] It should be understood that when an element (such as a layer, film, region, or substrate) is described as "on" another element, it can be directly on the other element, or an intervening element can also be present. Also, when an element is referred to as being "connected" to another element, it can be "directly connected" to the other element, or "connected" to the other element by a third element.
[0032] As introduced in the background, in the process of laser scribing of silicon wafer, if the position or structure of the cooling spray device for emitting cooling liquid and the thermal cracking laser device is not properly arranged, it is easy to cause the temperature gradient field distribution of the silicon wafer to be uneven, so that the direction of thermal stress is not along the same direction, there can be other cracks at the cracking section of the silicon wafer, and then a large number of dangling bonds are exposed, the damage degree of the section and the recombination of electrons and holes are increased, and then the cell efficiency of the finally formed solar cell is reduced.
[0033] To solve the above technical problems, the application provides a cutting device, as shown in the figure, Figures 1-2 The cutting device includes a carrier 10, a slotting laser structure 20, a thermal cracking laser structure 30, and a cooling structure 40. The carrier 10 has opposite first and second surfaces. The slotting laser structure 20 is located on the side of the first surface away from the second surface, and the slotting laser structure 20 has a first laser head 21. The central axis of the first laser head 21 and the first surface have a first included angle a. The thermal cracking laser structure 30 is located on one side of the slotting laser structure 20, and the arrangement direction of the thermal cracking laser structure 30 and the slotting laser structure 20 is parallel to the first surface. The thermal cracking laser structure 30 has a second laser head 31, and the central axis of the second laser head 31 is parallel to the central axis of the first laser head 21. The cooling structure 40 is located on the side of the thermal cracking laser structure 30 away from the slotting laser structure 20, and the cooling structure 40 includes a spray head 41. The central axis of the spray head 41 is parallel to the central axis of the second laser head 31.
[0034] In the above scheme, the arrangement direction of the slotting laser structure, the thermal cracking laser structure and the cooling structure is parallel to the first surface, so that the three can cut the silicon wafer on the carrier along the same preset path. The central axes of the first laser head, the second laser head and the spray head are at the same angle with the first surface, so that the three can work on the silicon wafer at the same angle. After the slotting laser beam emitted by the slotting laser structure forms a groove on the silicon wafer at the first included angle, the thermal cracking laser beam emitted by the thermal cracking laser structure also acts on the groove at the first included angle to generate high temperature in the groove. The cooling water sprayed by the spray head of the cooling structure also cools the groove of the silicon wafer at the first included angle, thereby generating a directional temperature gradient field from the groove to the second surface of the silicon wafer in the first direction (the direction in which the slotting laser structure, the thermal cracking laser structure and the cooling structure act on the silicon wafer when the angle between the central axes of the slotting laser structure, the thermal cracking laser structure and the cooling structure and the first surface is the first included angle), and the thermal stress generated by the temperature gradient field makes the silicon wafer crack in the first direction. The flatness of the cross section of the silicon wafer after cracking is improved, the generation of the suspension at the cross section is reduced, thereby reducing the recombination of carriers at the cross section of the battery, increasing the number of effective carriers in the battery, and thereby improving the efficiency of the solar cell wafer. The problem of low efficiency of the solar cell wafer caused by the uneven cross section of the silicon wafer after slicing in the prior art is solved.
[0035] Figure 2 is Figure 1 the side view when the appearance, size and minimum distance from the carrier of the slotting laser structure 20 and the thermal cracking laser structure 30 are the same, the slotting laser structure 20 and the thermal cracking laser structure 30 are coincident from the side, Figure 2 The above-mentioned coincidence is schematically shown in the figure. The slotting laser structure 20 and the thermal cracking laser structure 30 can also be non-coincident from the side, which is not specifically limited in the present application.
[0036] In some embodiments, the carrier is a platform for carrying the material to be cut (such as a silicon wafer), which is taken as an example in the present application. The material to be cut can also be other semiconductor materials to be cut and other materials, and the specific type of the material to be cut is not specifically limited in the present application.
[0037] Specifically, the presence of the carrier can ensure the stability and accuracy of the silicon wafer during cutting. The first surface of the carrier is divided into a placement area, and the silicon wafer is placed in the area for slicing. In this way, the placement position of the silicon wafer can be accurately controlled, so that the slotting laser structure, the thermal cracking laser structure and the cooling structure can accurately act on the area to be sliced on the silicon wafer. The placement area can also have a clamping groove to fix the silicon wafer, reducing the slicing error caused by the displacement of the silicon wafer during slicing and improving the cutting efficiency.
[0038] In some embodiments, the slotting laser structure is used to preform a cutting path on the silicon wafer, i.e. to slot the silicon wafer. The slotting laser structure comprises a first laser head, and the slotting laser structure is capable of emitting a high-power slotting laser beam with a specific wavelength through the first laser head. The slotting laser structure is positioned in the middle of the silicon wafer, and moves in the vertical main grid direction, and a first included angle is formed between the emission direction of the slotting laser beam and the extension direction of the first surface of the silicon wafer, thereby providing a high-energy-density point in the first direction for the silicon wafer, and forming a narrow slot line on the first surface of the silicon wafer. A red nanosecond laser can be used as the slotting laser structure to slot the silicon wafer, the power can be 30-100 W, the frequency can be 50-200 kHz, and the spot diameter of the slotting laser beam can be 1-2 mm. The above parameters can effectively and accurately form the required slot line on the silicon wafer, while minimizing the thermal damage to the silicon wafer.
[0039] Specifically, the slotting laser structure can be a red nanosecond laser, a green skin laser, a green nanosecond laser, a purple skin laser, or the like, which is not limited in the present application.
[0040] In the prior art, the angles at which the thermal cracking laser structure and the slotting laser structure operate on the silicon wafer are different, and the thermal cracking laser beam emitted by the thermal cracking laser structure cannot completely act on the slot line region in the silicon wafer, and part of the thermal cracking laser beam acts on the region that has not been slotted, so that the silicon wafer outside the slotted region also generates high temperature, and when the cooling structure cools the silicon wafer, the silicon wafer outside the slotted region also generates thermal stress and thus produces different degrees of cracking in the unslotted region. Since the cracking direction deviates from the slotting direction, the cross section of the crack presents a corrugated morphology (as shown in Figure 3 and Figure 4 ). The thermal cracking laser structure and the slotting laser structure in the present application operate on the silicon wafer at the same angle, so that the thermal cracking laser beam completely acts on the slot line region, and thus when the cooling structure cools the silicon wafer, only the silicon wafer in the slotted region generates thermal stress and thus cracks, the cracking direction is the same as the slotting direction, and the cross section of the crack is relatively flat (as shown in Figure 5 ).
[0041] Specifically, the power of the thermal cracking laser structure can be 300-600 W, the frequency can be 50-200 kHz, and the scanning speed can be 500-800 mm / s. The above parameter range can rapidly heat the silicon wafer to a certain temperature, and thus generate sufficient thermal stress after cooling the silicon wafer, thereby promoting the silicon wafer to crack along the slot line. The circular spot diameter of the thermal cracking laser beam can be less than or equal to the circular spot diameter of the slotting laser beam, and can be 1-2 mm. In this way, the risk of the thermal cracking laser beam operating on the silicon wafer outside the slotted region can be reduced, and the process window is improved.
[0042] Specifically, the cross-sectional diameter of the water column of the cooling water discharged by the cooling structure can be equal to the slotted laser beam, and specifically can be 1-2 mm, so that the cooling water can more accurately and uniformly act on the silicon wafer in the slotted region, only the silicon wafer in the slotted region is cooled, thereby generating a directional temperature gradient field, and the silicon wafer is broken along the thermal stress generated by the temperature gradient field. Controlling the cross-sectional diameter of the water column within the above range can also control the flow of the cooling water, prevent the cooling water from overflowing the slotted region, and affect the temperature of other uncut regions, thereby causing the distribution range of the temperature gradient field to expand, the range of the silicon wafer receiving the thermal stress to increase, and more cracks to be generated.
[0043] The silicon wafer has three directions of the advantage crystal surface (the growth direction of the crystal), which are <100>, <110>, and <111>, and the breaking strength of the silicon wafer along the three crystal directions is small, and the silicon wafer can be broken under a small thermal stress. The direction in which the silicon wafer is most easily broken is the <111> crystal direction. In order to make the broken cross section of the silicon wafer more flat, in some embodiments of the present application, the first included angle between the slotted laser structure, the thermal cracking laser structure, and the cooling structure acting on the silicon wafer is 45°-80°, and when the silicon wafer is placed on the surface of the stage close to the slotted laser structure, the first direction is the same as the <111> crystal direction, that is, the first included angle matches the <111> crystal direction, so that the silicon wafer can be broken under a small temperature difference (small thermal stress), which can reduce the power intensity of the thermal cracking laser beam during preparation, and further reduce the thermal damage to the silicon wafer. Since the <111> crystal direction is the growth direction of the silicon wafer crystal, the cross section broken along the <111> crystal direction will be more flat, further reducing the cracks in the cross section and the depth of the cross section cracks. Experiments show that the above setting can reduce the depth of the existing cross section cracks from 1-20 μm to 0.1-3 μm (the depth refers to the depth of the cracks spreading in directions other than the direction of the first included angle), and the reduction of the depth of the cracks can reduce the formation of dangling bonds, reduce the carrier recombination on the cross section surface, improve the charge collection efficiency, and thus improve the fill factor of the battery. Reducing recombination can also improve the carrier concentration in the battery, and the improvement of the carrier concentration can improve the open-circuit voltage of the battery. The cross section broken along the <111> crystal direction will be more flat, which can also improve the passivation effect of the passivation process on the cross section, and further improve the efficiency of the battery wafer.
[0044] It should be noted that adjusting the range of the first included angle to make the silicon wafer break along the <100> or <110> crystal direction of the silicon wafer is also within the protection scope of the present application.
[0045] In some optional embodiments, as shown in FIG. 6, the slotted laser structure, the thermal cracking laser structure, and the cooling structure are arranged on the same plane, and the first included angle between the slotted laser structure, the thermal cracking laser structure, and the cooling structure acting on the silicon wafer is 45°-80°. Figure 1As shown, the cooling structure further comprises a cooling water delivery part 42, the outlet of the cooling water delivery part 42 is connected with the spray head 41, the spray head 41 comprises water outlet holes, the cross-sectional area of the water outlet holes close to the cooling water delivery part 42 is larger than the cross-sectional area of the water outlet holes far from the cooling water delivery part 42. The outlet of the cooling water delivery part 42 is connected with the spray head 41, the water outlet holes of the spray head 41 are used for directional emission of cooling water. The cross-sectional area of the water outlet holes close to the cooling water delivery part 42 is larger than the cross-sectional area of the water outlet holes far from the cooling water delivery part 42, the cooling water sequentially passes through the water outlet holes with large aperture and the water outlet holes with small aperture when being emitted, and then the pressure of the cooling water emitted from the water outlet holes with small aperture increases to be jetted, which can ensure that the cooling water flow forms more concentrated water column in a specific direction, more concentrated on the slotted area of the silicon wafer, and has better cooling effect.
[0046] In some embodiments, the cross-sectional area of the water outlet holes far from the cooling water delivery part 42 and the cross-sectional area of the water outlet holes close to the cooling water delivery part 42 are adjusted to control the size of the cross-sectional area of the water column of the emitted cooling water. For example, the cross-sectional area of the water outlet holes far from the cooling water delivery part 42 accounts for 20% of the cross-sectional area of the water outlet holes close to the cooling water delivery part 42, the water column pressure of the emitted cooling water is strong, and the water column is thin to be more concentrated in the slotted area of the silicon wafer; the cross-sectional area of the water outlet holes far from the cooling water delivery part 42 accounts for 50% of the cross-sectional area of the water outlet holes close to the cooling water delivery part 42, the water column pressure of the emitted cooling water is moderate, and the water column is moderate in thickness; the cross-sectional area of the water outlet holes far from the cooling water delivery part 42 accounts for 70% of the cross-sectional area of the water outlet holes close to the cooling water delivery part 42, the water column pressure of the emitted cooling water is small, and the water column is thick. The above-mentioned cross-sectional area of the water outlet holes far from the cooling water delivery part 42 and the cross-sectional area of the water outlet holes close to the cooling water delivery part 42 can be matched with the laser beams emitted by the slotted laser structure and the thermal cracking laser structure, which is not limited in the present application.
[0047] In some optional embodiments, as shown in Figure 6 and Figure 7 The spray head further comprises at least one gas outlet part 43, the gas outlet part 43 is located at the outer periphery of the water outlet hole 44, and the gas outlet part 43 is used for discharging cooling gas. By designing the gas outlet part 43 around the water outlet hole 44, the cooling gas can be introduced to assist cooling while the cooling water is emitted, and the heated area of the silicon wafer is uniformly cooled, so that the temperature gradient is more uniform and the cross-sectional damage is reduced.
[0048] The above-mentioned gas outlet part is also a hole, and the more specific shape is not limited in the present application, which can be circular, triangular or other irregular shapes. The skilled in the art can set the appropriate shape of the gas outlet part according to the actual situation.
[0049] Regarding the specific location of the air outlet, it only needs to be located outside the water outlet. The specific distance between it and the water outlet is not limited in this application, and those skilled in the art can set it according to the actual situation. In addition, this application does not limit the number of air outlets. They can be set outside the water outlet and can form a certain shape (the line connecting the centers of the air outlets forms this shape), such as a circle, a square, etc.
[0050] In some embodiments, the cooling gas can be nitrogen, and the cooling efficiency can be improved by using it in conjunction with cooling water to cool the silicon wafer. Figure 6 Multiple circular air outlets 43 are arranged around the water outlet 44. Figure 7 Two semi-annular air outlets 43 are arranged around the water outlet 44. This application does not specifically limit the specific shape and location of the air outlets 43.
[0051] To enhance the combined effect of cooling water and gas, the exhaust section can also be a complete ring shape. In some optional embodiments, such as... Figure 8 As shown, the air outlet 43 is annular, and the central axis of the air outlet 43 coincides with the central axis of the water outlet 44. This allows the gas discharged from the air outlet 43 to envelop the water column discharged from the water outlet 44. With the assistance of the gas flow, the water column is less likely to disperse after being sprayed a certain distance from the water outlet, making the cross-sectional diameter of the water column acting on the silicon wafer closer to the diameter of the water outlet of the water outlet 44. This allows the cooling water to act more precisely on the slotted area.
[0052] The aforementioned air outlet is a complete ring. However, this application does not limit its specific shape; it can be multiple rings, or an irregularly shaped air outlet forming a ring surrounding the water outlet. Those skilled in the art can design an air outlet of a suitable shape according to actual conditions.
[0053] In some optional embodiments, the cross-sectional diameter of the water outlet far from the cooling water supply section is the same as the spot diameter of the thermal cracking laser beam emitted by the thermal cracking laser structure. This ensures that the cooling water coverage area matches the laser's effective range, thereby achieving more precise and uniform cooling of the silicon wafer, generating a more uniform temperature gradient field, and realizing more precise temperature control. A more uniform temperature gradient field can generate thermal stress with essentially the same intensity and direction in the slotted area, allowing the silicon wafer to fracture precisely along the crystal orientation, effectively reducing cross-sectional damage and improving the subsequent passivation effect on the cross-section. Experiments have shown that matching the cross-sectional diameter of the water outlet far from the cooling water supply section to the spot diameter of the thermal cracking laser beam can improve the cell efficiency by 0.04%. The cross-sectional diameter of the water outlet far from the cooling water supply section can be 1–2 mm, such as 1 mm, 1.5 mm, or 2 mm.
[0054] In order to reduce the risk of damage to the silicon wafer caused by uneven laser heating, in some optional embodiments, the minimum distance between the center point of the cross section of the light outlet of the second laser head and the first surface is 2-6 mm. By precisely controlling the distance between the second laser head and the first surface, not only can the concentration of the hot cracking laser beam spot be ensured (too large distance will cause the spot to spread), but also the local silicon wafer will not be overheated and thus melted (too small distance will cause the hot cracking laser beam to be too close to the silicon wafer, and the laser intensity will be too strong). By adjusting the minimum distance between the center point of the cross section of the light outlet of the second laser head and the first surface, the distribution of laser energy is optimized, and the damage to the silicon wafer caused by uneven laser heating is reduced. The minimum distance between the center point of the cross section of the light outlet of the second laser head and the first surface can be 3 mm, 4 mm or 5 mm.
[0055] In order to match the hot cracking laser beam and improve the cooling effect and reduce the formation of cross-sectional cracks, in some optional embodiments, the minimum distance between the center point of the cross section of the water outlet hole of the cooling water delivery part and the first surface is 2-6 mm. In this way, the water flow intensity of the cooling water impacting the silicon wafer will not be too large, avoiding the situation that the silicon wafer is damaged due to the direct high-intensity impact of the cooling water on the surface of the silicon wafer due to too close distance, and the situation that the water column of the cooling water is dispersed due to too far distance, and the silicon wafer in the unheated area is cooled, so that the thermal stress is not only in the direction indicated by the first included angle, and thus more cracks are formed in the cross-sectional crack of the silicon wafer. The minimum distance between the center point of the cross section of the water outlet hole of the cooling water delivery part and the first surface can be 3 mm, 4 mm or 5 mm.
[0056] In some optional embodiments, the cutting device further comprises a temperature detection device, and the first surface has a wafer loading area. The temperature detection device is used to detect the temperature of the wafer loading area when the cutting device is working. In this way, the temperature change during the cutting of the silicon wafer can be monitored in real time, and the cooling strategy can be adjusted in time to ensure that the temperature gradient field is uniform and consistent during the entire cutting process of the silicon wafer. The temperature detection device can be an infrared temperature sensor or other devices that can detect temperature, which is not limited in the present application.
[0057] Specifically, the temperature detection device can be placed directly below the stage of the cutting path of the silicon wafer, or placed on both sides of the stage of the cutting path of the silicon wafer, or placed inside the stage so that the temperature detection device is located directly below the cutting path of the silicon wafer. In this way, the instantaneous temperature of the heated area of the silicon wafer and the temperature change during the action of the cooling water can be directly monitored, providing reference data for subsequent adjustment of the cooling parameters.
[0058] Specifically, a temperature detection device can also be added near the water outlet of the nozzle to monitor the temperature of the cooling water. The temperature detection device near the water outlet and the temperature detection device on the platform can work together to more accurately monitor the temperature of the cooling water and the heated area of the silicon wafer, and then control it.
[0059] In some embodiments, the temperature difference between the upper and lower surfaces of the silicon wafer reaches 150-250°C, and the silicon wafer will break along the crystal direction. For example, when the temperature detection device at the bottom of the platform detects that the temperature of the area of the silicon wafer scanned by the hot cracking laser beam is higher than a certain threshold, combined with the temperature of the cooling water detected by the temperature detection device at the water outlet, the water flow of the cooling structure is increased or the moving speed of the cooling structure is slowed down to better cool the silicon wafer, so that the temperature difference between the upper and lower surfaces of the silicon wafer reaches 150-250°C, and then the silicon wafer breaks along the crystal direction to form a flat cross section.
[0060] In some embodiments, as shown in Figure 9 and Figure 10 The cutting device also includes a connecting structure 50 for connecting the slotting laser structure 20, the hot cracking laser structure 30, and the cooling structure 40. The connecting structure 50 includes a support part 51 (only shown in Figure 10 ) connected to the platform 10 for supporting the slotting laser structure 20, the hot cracking laser structure 30, and the cooling structure 40. One end of the rotating part 52 is connected to the support part 51, and the other end is connected to the slotting laser structure 20, the hot cracking laser structure 30, and the cooling structure 40. Figure 10 In some embodiments, the rotating part 52 has three rotating parts, each corresponding to the slotting laser structure 20, the hot cracking laser structure 30, and the cooling structure 40. The rotating part 52 can adjust the working angle of the slotting laser structure 20, the hot cracking laser structure 30, and the cooling structure 40, so that the direction of the three structures working on the silicon wafer can be consistent.
[0061] Specifically, the rotating part can be independently adjusted to allow the angle of each structure relative to the silicon wafer to be fine-tuned within a range of 20°-160°, and the working angles of the slotting laser structure, the hot cracking laser structure, and the cooling structure can be adjusted so that the included angle between the three structures and the first surface of the silicon wafer is a first included angle. This can accurately match the laser action direction and the cooling direction with the crystal lattice direction inside the silicon wafer, achieving efficient and low-damage cutting.
[0062] In some embodiments, the rotating part can also be equipped with an angle sensor to monitor and feedback the angle of the rotating part in real time. Combined with the control system, the working angles of the slotting laser structure, the hot cracking laser structure, and the cooling structure can be dynamically adjusted to ensure the consistency of the working angles of the three structures during the entire cutting process.
[0063] The technical solution of the present application can be applied to photovoltaic cells such as full back electrode contact cells of zero busbar (0BB) or multi-busbar (MBB) technology, interdigitated back contact (IBC) cells, all back contact (ABC) cells, hybrid passivated back contact (HPBC) cells, passivated emitter and rear cell (PERC) cells, tunnel oxide passivated contact (TOPcon) cells, TOPcon-IBC cells, heterojunction with intrinsic thin-layer (HJT) cells, perovskite stacked cells, flexible cells, and the like.
[0064] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:
[0065] 1) The cutting device of the present application makes the arrangement direction of the slotting laser structure, the thermal cracking laser structure, and the cooling structure parallel to the first surface, so that the three can cut the silicon wafer on the carrier along the same preset path. The central axes of the first laser head, the second laser head, and the spray head have the same angle with the first surface, so that the three can work on the silicon wafer in the first direction. The thermal stress generated by the temperature gradient field makes the silicon wafer crack in the first direction, improves the flatness of the cross section of the silicon wafer after cracking, reduces the generation of overhangs at the cross section, and further reduces the recombination of carriers at the cross section of the cell, thereby increasing the number of effective carriers in the cell and improving the efficiency of the solar cell.
[0066] 2) Since the central axes of the slotting laser structure, the thermal cracking laser structure, and the cooling structure have a first included angle with the extension direction of the first surface, the three act on the silicon wafer in the first direction. Since the first direction is basically consistent with the crystal direction of the silicon wafer, the silicon wafer cracks along the crystal direction under the action of thermal stress, improves the flatness of the cross section of the silicon wafer after cracking, reduces the generation of overhangs at the cross section, and further reduces the recombination of electrons and holes at the cross section of the cell, thereby reducing the number of effective carriers in the cell and improving the efficiency of the solar cell.
[0067] 2) The cutting device of the present application can make the water column emitted from the water outlet hole more difficult to disperse by arranging the water outlet hole in the nozzle of the cooling structure and the air outlet part around the water outlet hole, and then concentrate the water column to accurately cool the grooving area of the silicon wafer.
[0068] The above only is the preferred embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A cutting device, characterized in that, include: The stage has opposing first and second surfaces; A slotted laser structure is located on the side of the first surface away from the second surface. The slotted laser structure has a first laser head, and the central axis of the first laser head has a first angle with the first surface. A hot-splitting laser structure is located on one side of the slotted laser structure. The hot-splitting laser structure and the slotted laser structure are arranged in a direction parallel to the first surface. The hot-splitting laser structure has a second laser head, and the central axis of the second laser head is parallel to the central axis of the first laser head. A cooling structure is located on the side of the thermal cracking laser structure opposite to the slotting laser structure. The cooling structure includes a nozzle, the central axis of which is parallel to the central axis of the second laser head.
2. The cutting device according to claim 1, characterized in that, The first included angle is 45° to 80°.
3. The cutting device according to claim 1, characterized in that, The cooling structure also includes a cooling water delivery unit, the outlet of which is connected to the nozzle. The nozzle has an outlet hole inside, and the cross-sectional area of the outlet hole near the cooling water delivery unit is larger than the cross-sectional area of the outlet hole away from the cooling water delivery unit.
4. The cutting device according to claim 3, characterized in that, The nozzle also includes at least one air outlet located on the outer periphery of the water outlet, the air outlet being used to directionally discharge cooling gas.
5. The cutting device according to claim 4, characterized in that, The air outlet is annular, and the central axis of the air outlet coincides with the central axis of the water outlet.
6. The cutting device according to claim 3, characterized in that, The cross-sectional diameter of the water outlet hole, which is away from the cooling water delivery section, is the same as the spot diameter of the thermal cracking laser beam emitted by the thermal cracking laser structure.
7. The cutting device according to claim 3, characterized in that, The minimum distance between the center point of the cross-section of the water outlet hole away from the cooling water conveying section and the first surface is 2mm to 6mm.
8. The cutting device according to claim 1, characterized in that, The minimum distance between the center point of the cross-section of the light outlet of the second laser head and the first surface is 2mm to 6mm.
9. The cutting device according to claim 1, characterized in that, The cutting device further includes a temperature detection device, and the first surface has a loading area. The temperature detection device is used to detect the temperature of the loading area when the cutting device is in operation.
10. The cutting device according to claim 1, characterized in that, The cutting device further includes a connecting structure for connecting the grooving laser structure, the hot cracking laser structure, and the cooling structure.