Method for cutting silicon wafers and silicon wafer

Abstract

A method for cutting silicon wafers (2). The method comprises: providing a silicon rod (1) and a carrier plate (3); driving the silicon rod (1) to move downwards relative to a cutting wire (4), such that the silicon rod (1) is cut to obtain a plurality of silicon wafers (2); and lifting the silicon wafers (2) upwards relative to the cutting wire (4), and during the lifting of the silicon wafers (2), controlling the cutting wire (4) in contact with the silicon wafers (2) to alternately move in the forward and reverse directions in a cyclic manner. The cutting method can reduce the situation where the silicon wafers (2) fall off when lifted upwards, and has the advantages of a fast speed increase, a high surface quality of the silicon wafers (2), and little secondary damage. The present application further relates to a silicon wafer (2).

Description

Silicon wafer cutting method and silicon wafer

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese application No. 2023117541795, filed on December 19, 2023, entitled "A method for extracting a silicon wafer and a silicon wafer," Chinese application No. 2024108737679, filed on July 1, 2024, entitled "A method for cutting a silicon wafer," and Chinese application No. 2024118347797, filed on December 12, 2024, entitled "A method for cutting a silicon wafer and a silicon wafer," the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of crystalline silicon solar cell manufacturing, and in particular to a silicon wafer cutting method and a silicon wafer. Background Art

[0004] In the silicon wafer cutting process, silicon ingots are typically bonded to the lower surface of a carrier plate, which is in turn bonded to the lower surface of a wafer tray. A drive mechanism typically drives the wafer tray, moving the silicon ingot from top to bottom relative to a cutting line. This allows the cutting line to slice the silicon ingot, forming multiple silicon wafers. The silicon wafers are then lifted upward. Specifically, the drive mechanism drives the wafer tray upward, simultaneously raising the silicon wafer relative to the cutting line. Simultaneously, the cutting line moves, freeing the silicon wafer from the cutting line.

[0005] In the prior art, the silicon wafer is lifted up by moving the feed table upward at a certain speed, while the steel wire moves uniformly in one direction at another speed. The two components move in coordination to lift the cut silicon wafer upward and away from the wire mesh.

[0006] However, the above-mentioned method of lifting the silicon wafer upward is likely to cause the cutting line to break, the silicon wafer to fall when being lifted upward, and the silicon wafer surface to be scratched, thereby reducing the surface quality of the silicon wafer. Summary of the Invention

[0007] In a first aspect of the present application, a silicon wafer cutting method is provided, comprising:

[0008] Provide silicon rods and carrier plates;

[0009] driving the silicon rod to move downward relative to the cutting line so that the cutting line cuts the silicon rod to obtain a plurality of silicon wafers;

[0010] The silicon wafer is lifted upward relative to the cutting line. During the process of the silicon wafer being lifted, the cutting line in contact with the silicon wafer is controlled to move in alternating forward and reverse directions.

[0011] Optionally, controlling the cutting line to move alternately in forward and reverse directions includes:

[0012] In the reversing stage, the cutting line is controlled to switch the movement direction within 0 to 0.5 seconds and to accelerate to any value between 0.01 and 1 m / s within 4 to 7 seconds;

[0013] In the non-reversing stage, the cutting line is controlled to move at a constant speed of any one of 0.01 to 1 m / s.

[0014] Optionally, in each forward and reverse alternating cycle, the distance the cutting line moves in the forward direction is equal to the distance it moves in the reverse direction.

[0015] Optionally, in each forward and reverse alternating cycle, the distance that the cutting line moves in a single direction is any value between 0.05 and 30 m.

[0016] Optionally, controlling the silicon wafer to move upward includes:

[0017] Determining a feed speed according to the height to which the silicon wafer is lifted; wherein the feed speeds corresponding to different lifting heights are at least partially different;

[0018] According to the feeding speed, the silicon wafer is controlled to move upward.

[0019] When adopting the above technical solution, based on the fact that the friction force generated by the cutting line on the silicon wafer during the process of the silicon wafer being lifted upward is affected by the contact area between the cutting line and the silicon wafer, and the contact area between the cutting line and the silicon wafer is affected by the height of the upward lift, the feed speed of the silicon wafer is dynamically adjusted according to the situation that the height of the upward lift affects the contact area between the cutting line and the silicon wafer, so that the probability of scratches caused by the cutting line on the silicon wafer at different lifting heights tends to be consistent, thereby reducing the scratches formed by the cutting line on the silicon wafer, and at the same time can speed up the lifting speed of the silicon wafer, thereby improving production efficiency.

[0020] Optionally, before determining the feeding speed according to the height to which the silicon wafer is lifted, the method further includes:

[0021] Determining a correspondence between a height to which the silicon wafer is lifted and a feed speed; wherein, in the correspondence, the feed speeds corresponding to different lifting heights are at least partially different, so that when the silicon wafer is moved upwardly under the feed speed determined by the correspondence, scratches formed on the silicon wafer by the cutting line tend to be uniform;

[0022] Determining the feeding speed according to the lifting height of the silicon wafer includes:

[0023] The feeding speed is determined according to the lifting height and the corresponding relationship.

[0024] Optionally, the process of lifting the silicon wafer upwards includes a starting section, a middle section and an ending section in sequence;

[0025] Determining the feeding speed according to the lifting height of the silicon wafer includes:

[0026] Controlling a first feeding speed of the silicon wafer to be smaller than a second feeding speed, wherein the first feeding speed is a speed at which the silicon wafer moves upward in the initial section, and the second feeding speed is a speed at which the silicon wafer moves upward in the middle section;

[0027] The third feeding speed of the silicon wafer is controlled to be greater than or equal to the second feeding speed, and the third feeding speed is the upward moving speed of the silicon wafer in the end section.

[0028] Optionally, the first feed speed is any value between 20 and 40 mm / min, the second feed speed is any value between 40 and 80 mm / min, and the third feed speed is any value between 80 and 600 mm / min.

[0029] Optionally, the silicon wafer cutting method further includes:

[0030] The silicon wafer is lifted upward relative to the cutting line, and the movement mode of the cutting line within the carrier is different from the movement mode of the cutting line after it is separated from the carrier.

[0031] When the above technical solution is adopted, in the process of lifting the silicon wafer upward relative to the cutting line, the movement mode of the cutting line in the carrier is different from the movement mode of the cutting line after it is separated from the carrier. Due to the different materials of the carrier and the silicon wafer, as well as the different requirements for the protection of the carrier and the protection quality of the silicon wafer, a more suitable movement mode of the cutting line is selected according to the actual lifting environment of the cutting line in the carrier and the cutting line between the silicon wafers to ensure that the damage to the silicon wafer caused by the cutting line is reduced.

[0032] Optionally, the movement mode of the cutting line within the carrier plate and the movement mode of the cutting line after leaving the carrier plate are different and include:

[0033] When the cutting line is located in the carrier, the cutting line performs forward or reverse motion; when the cutting line is separated from the carrier, the cutting line performs alternating forward and reverse cyclic motion. When the above technical solution is adopted, when the cutting line is located in the carrier, the cutting line only performs unidirectional motion of winding up or unwinding. At this time, the cutting line will not swing back and forth in the horizontal direction perpendicular to the surface of the silicon wafer, so that the cutting line always remains in the position of cutting the carrier during the cutting process, that is, the cutting line will not deviate from either of the two adjacent silicon wafers. In this way, when the silicon wafer is lifted upward relative to the cutting line, it is not easy for the cutting line to hang on the side of the silicon wafer bonded to the carrier. Further, the situation of the cutting line being broken or the silicon wafer falling as the silicon wafer is lifted is effectively reduced. In addition, since the carrier does not require high protection, the unidirectional motion method is selected to reduce unnecessary switching of movement directions and improve the lifting efficiency of the cutting line in the carrier. Then, in the process of lifting the cutting line from the carrier to the silicon wafer, the cutting line alternates between winding and unwinding. The side of the cutting line relative to the silicon wafer changes as the direction of the cutting line movement changes. In this way, the cutting line bow caused by the cutting line entering only from one side of the silicon wafer can be reduced, and the cutting line is subjected to greater friction from the silicon wafer, making it difficult for the cutting line to separate the surfaces of two adjacent silicon wafers away from the side where the cutting line enters. This reduces the occurrence of scratches, bright lines, and even silicon wafer falling caused by the friction of the cutting line, which is difficult for the silicon wafer to be separated by the cutting line due to the strong suction. In addition, when the cutting line is located between two adjacent silicon wafers, the winding and unwinding movements are performed alternately, and the cutting line will swing back and forth in the horizontal direction perpendicular to the surface of the silicon wafer. At this time, the cutting line can be prevented from being in contact with any of the two adjacent silicon wafers. At the same time, during the horizontal swinging process of the cutting line, it is out of contact with the silicon wafer, shortening the contact time between the cutting line and the silicon wafer, reducing the friction on the silicon wafer, reducing the phenomenon of scratches on the surface of the silicon wafer, and reducing the breakage of the cutting line and the damage of the cutting line to the silicon wafer.

[0034] Optionally, during the alternating cyclic movement of the cutting line in forward and reverse directions, the cutting line alternately performs forward movement and reverse movement, the distance the cutting line performs the forward movement is any value between 0.05m and 0.2m, and the distance the cutting line performs the reverse movement is any value between 0.05m and 0.2m.

[0035] Optionally, during the process of the cutting line performing the forward movement and the reverse movement alternately, the distance of the forward movement of the cutting line is equal to the distance of the reverse movement of the cutting line.

[0036] Optionally, when the cutting line is located in the carrier board, during the forward or reverse movement of the cutting line, the average line speed of the cutting line during the forward or reverse movement is S1;

[0037] When the cutting line is separated from the carrier board and the cutting line alternately moves forward and reverse, the maximum line speed of the cutting line in the forward or reverse movement is S2, and S1<S2.

[0038] Optionally, when it is determined that the cutting line is located within the carrier board, the cutting line may gradually increase its routing speed during the forward or reverse movement of the cutting line.

[0039] Optionally, 3 m / min≤S1≤50 m / min and / or S2≤50 m / min.

[0040] Optionally, the speed of lifting the silicon wafer upward relative to the cutting line is any value between 15 mm / min and 60 mm / min.

[0041] In a second aspect of the present application, a silicon wafer is provided, wherein the silicon wafer has a first set of opposite sides and a second set of opposite sides, the first set of opposite sides including a first side and a second side disposed oppositely, the second set of opposite sides including a third side and a fourth side disposed oppositely, wherein the first side and / or the second side intersects with the third side and / or the fourth side; and the surface of the silicon wafer has two sets of scratches,

[0042] One group of the scratches is inclined in a first direction toward the third side, and the other group of the scratches is inclined in the first direction toward the fourth side, where the first direction is from the first side to the second side.

[0043] Optionally, the angle between the scratch mark and the cutting line mark is less than 20°.

[0044] Optionally, the scratch has a depth of 2 μm to 17 μm.

[0045] Optionally, the two groups of scratches are located on the same surface of the silicon wafer, and / or the two groups of scratches are located on two opposite surfaces of the silicon wafer.

[0046] Compared with the prior art, the embodiments of the present application have the following advantages:

[0047] In an embodiment of the present application, a silicon wafer cutting method is provided, which first uses a cutting wire to cut a silicon rod. After the silicon rod is cut into silicon wafers, the silicon wafer is controlled to move upward, and in the process of controlling the upward movement of the silicon wafer, the cutting wire is controlled to move in alternating cycles in the forward and reverse directions. The characteristic that the wire bow of the wire in the forward and reverse directions is smaller than that of the wire bow of the wire in the unidirectional direction is utilized, so that the contact area between the silicon wafer and the cutting wire is smaller. This not only reduces the probability of scratches on the surface of the silicon wafer caused by the cutting wire during the process of the silicon wafer being lifted upward, but also reduces the situation of the silicon wafer falling off when it is lifted upward. It has the advantages of fast speed increase, high surface quality of the silicon wafer, and small secondary damage. In addition, according to the actual pulling environment of the cutting wire in the carrier and the cutting wire between the silicon wafers, different movement modes of the cutting wire in the carrier and the cutting wire after leaving the carrier are selected, which further reduces the damage of the cutting wire to the silicon wafer.

[0048] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0050] FIG1 is a schematic structural diagram of the process of lifting a silicon wafer upward in the prior art;

[0051] FIG2 is a flow chart of a silicon wafer cutting method provided in Example 1 of the present application;

[0052] FIG3 is a schematic diagram showing the positional relationship between the silicon rod and the cutting wire during the process of the cutting wire cutting the silicon rod in one embodiment of the present application;

[0053] FIG4 is a schematic structural diagram of a process in which a silicon wafer is lifted upward in another embodiment of the present application;

[0054] FIG5 is a flow chart of a process of lifting a silicon wafer provided in Example 2 of the present application;

[0055] FIG6 is a flow chart of a process of lifting a silicon wafer provided in Example 3 of the present application;

[0056] FIG7 is an enlarged schematic diagram of the surface of a silicon wafer produced according to a method provided in one embodiment of the present application;

[0057] FIG8 is a schematic diagram showing the positional relationship between the silicon wafer and the cutting line when the silicon wafer obtained by cutting the silicon ingot is lifted upward relative to the cutting line, with the cutting line partially located within the carrier board, in the embodiment shown in FIG4 ;

[0058] FIG9 is a schematic diagram showing the positional relationship between the silicon wafer and the cutting line when the silicon wafer obtained by cutting the silicon ingot is lifted upward relative to the cutting line and the cutting line is separated from the carrier in the embodiment shown in FIG4 ;

[0059] FIG10 is a partial structural diagram showing a first group of scratches on a silicon wafer provided by the embodiment shown in FIG4 ;

[0060] FIG. 11 is a partial structural diagram showing a second set of scratches on the silicon wafer provided by the embodiment shown in FIG. 4 . DETAILED DESCRIPTION

[0061] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0062] It should be noted that in the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on this application.

[0063] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0064] The applicant of this application has discovered that in existing silicon wafer production technology, as shown in FIG1 , after the silicon wafer 20 is cut, it is moved upward at a certain speed by a feed table, while the cutting wire 10 is moved in one direction at a certain speed. The two work together to lift the cut silicon wafer from the wire mesh until the lower surface of the silicon wafer is free of the wire mesh. During the process of lifting the silicon wafer upward, because the wire mesh carries cutting fluid, the tension of the cutting fluid causes a strong adsorption force between the wire mesh and the silicon wafer, causing the steel wire to be adsorbed to the surface of the silicon wafer. As the silicon wafer is lifted, the steel wire is forced to stretch and form a reverse wire bow, which increases the contact area between the steel wire and the silicon wafer, increasing the probability of the silicon wafer falling due to separation from a carrier such as a resin board or adhesive stick when the silicon wafer is lifted upward. At the same time, the larger contact area easily scratches the silicon wafer surface, reducing the surface quality of the silicon wafer. In addition, the increased reverse wire bow causes the steel wire to contact the bottom edge of the mortar tube after being pulled up, which easily causes multiple breaks in the wire mesh, resulting in a large number of scratches on the silicon wafer, which has a significant impact on the yield rate. It should be noted that, in this field, lifting the silicon wafer upward is also called material lifting.

[0065] In order to solve the above problems, the embodiments of the present application provide a silicon wafer cutting method in the first aspect of the present application, which aims to reduce the scratches on the surface of the silicon wafer caused by the cutting line during the process of the silicon wafer being lifted upward, thereby improving the quality of the silicon wafer.

[0066] Please refer to Figures 2 and 3. Figure 2 shows a step flow chart of a silicon wafer cutting method in Example 1 of the present application. The method is applied to the process of cutting and lifting the silicon wafer. The method may include steps 100 to 300.

[0067] First of all, it should be noted that, as shown in Figure 3, the forward or reverse movement of the cutting line 4 is driven by the driving roller 5. During specific implementation, one end of the cutting line 4 is wound from the surface of the first driving roller 5 to the surface of the second driving roller 5, then to the surface of the third driving roller 5, and then to the surface of the first driving roller 5. In this winding method, a cutting line network is formed.

[0068] Step S100: providing a silicon rod 1 and a carrier plate 3.

[0069] Silicon ingot 1 is directly connected to carrier plate 3. A carrier plate 3 of corresponding size is selected based on the size of the silicon ingot 1 to be cut, as shown in Figure 3. The silicon ingot is then bonded to the lower surface of wafer support 6 via carrier plate 3. In practice, carrier plate 3 can be a resin or plastic plate. The thickness of carrier plate 3 can be selected based on actual conditions and is not specifically limited here.

[0070] Step S200 : driving the silicon rod 1 to move downward relative to the cutting line 4 , so that the cutting line 4 cuts the silicon rod 1 to obtain a plurality of silicon wafers 2 .

[0071] It should be noted that, in the process of driving the silicon rod 1 downward relative to the cutting line 4 so that the cutting line 4 cuts the silicon rod 1 to obtain multiple silicon wafers 2, due to the presence of a line bow in the cutting line 4 during the cutting state, the cutting line 4 needs to be cut into the carrier 3 when cutting to the rear end of the silicon rod (the carrier 3 acts as a sacrificial plate in this case) so that the silicon rod 1 is completely cut through and the multiple silicon wafers are independent of each other. The cut-through state at this time refers to a state in which the silicon wafers 2 are independent of each other and the cutting line 4 is in the gap between the silicon wafers 2.

[0072] Step S300: the silicon wafer 2 is lifted upward relative to the cutting line 4. During the process of the silicon wafer 2 being lifted, the cutting line 4 in contact with the silicon wafer 2 is controlled to move in a forward and reverse direction in an alternating cycle.

[0073] Figures 8 and 9 illustrate the implementation step S300 in the first embodiment of the present application, while Figure 4 illustrates another embodiment of the implementation step S300 according to the present application. The embodiment shown in Figure 4 will be described first, and the embodiments shown in Figures 8 and 9 will be described in detail later.

[0074] As shown in FIG4 , in this embodiment, the cutting device is provided with two driving rollers, namely main rollers 30 , and the cutting line is wound from one main roller 30 to the other main roller 30 . The rotation of the main roller 30 can drive the cutting line 10 to move to cut the silicon rod.

[0075] Similarly, after the silicon rod is cut into silicon wafers, the silicon wafers are still located in the cutting wire mesh after the silicon rod is cut into silicon wafers, and the silicon wafers need to be separated from the cutting wire mesh. At this time, by controlling the feed table to move up, the silicon wafers can be driven to move up, so that the cutting wires can re-enter between adjacent silicon wafers from the resin plate until the lower surface of the silicon wafer is separated from the cutting wire mesh.

[0076] In the process of lifting the silicon wafer 20 relative to the cutting line 10, as shown in FIG4, the main rollers 30 on the left and right sides are controlled to act as active rollers in turn to control the cutting line 10 to move in alternating cycles in forward and reverse directions.

[0077] During unidirectional routing, the cutting line is continuously pulled in one direction, resulting in a larger deformation and a larger reverse wire bow. However, during forward and reverse routing, the deformation formed by the cutting line during the process of the silicon wafer being lifted upward is decomposed in two directions, resulting in a smaller reverse wire bow, making the contact area between the silicon wafer and the cutting line 10 smaller. This not only reduces the scratches on the surface of the silicon wafer caused by the cutting line during the process of the silicon wafer being lifted upward, but also reduces the chance of the silicon wafer falling when the silicon wafer is lifted upward. It has the advantages of fast speed increase, high surface quality of the silicon wafer produced, and less secondary damage.

[0078] Optionally, in one embodiment, controlling the upward movement of the silicon wafer includes steps 111 to 112:

[0079] Step 111: determining a feeding speed according to the height to which the silicon wafer is lifted; wherein the feeding speeds corresponding to different lifting heights are at least partially different;

[0080] Step 112: Control the silicon wafer to move upward according to the feeding speed.

[0081] In this embodiment, based on the fact that the friction force generated by the cutting line on the silicon wafer during the process of the silicon wafer being lifted upward is affected by the contact area between the cutting line and the silicon wafer, and the contact area between the cutting line and the silicon wafer is affected by the height at which the silicon wafer is lifted upward, the feed speed of the silicon wafer is dynamically adjusted according to the fact that the height at which the silicon wafer is lifted upward affects the contact area between the cutting line and the silicon wafer, so that the probability of scratches caused by the cutting line on the silicon wafer at different lifting heights tends to be consistent, thereby reducing the scratches formed on the silicon wafer by the cutting line, and at the same time can speed up the lifting speed of the silicon wafer, thereby improving production efficiency.

[0082] Optionally, in a specific embodiment, the process of lifting the silicon wafer upwards includes a starting section, a middle section, and an ending section in sequence;

[0083] The above step 111 specifically includes:

[0084] Controlling a first feeding speed of the silicon wafer to be smaller than a second feeding speed, wherein the first feeding speed is a speed at which the silicon wafer moves upward in the initial section, and the second feeding speed is a speed at which the silicon wafer moves upward in the middle section;

[0085] The third feeding speed of the silicon wafer is controlled to be greater than or equal to the second feeding speed, and the third feeding speed is the upward moving speed of the silicon wafer in the end section.

[0086] In this specific embodiment, the starting section is the stage from when the cutting line begins to enter the silicon wafer from the resin plate bonding the silicon wafer until it is completely inside the silicon wafer; the middle section is the stage from when the cutting line is completely inside the silicon wafer; and the ending section is the stage from when the cutting line begins to leave the silicon wafer until it is completely outside the silicon wafer. For example, for a 182*182mm silicon wafer, the starting section occurs when the height difference between the top of the main roller and the bottom of the silicon wafer is between 194 and 150mm; the middle section occurs when the height difference between the top of the main roller and the bottom of the silicon wafer is between 150 and -5mm; and the ending section occurs when the height difference between the top of the main roller and the bottom of the silicon wafer is between -5 and -20mm.

[0087] It should be noted that, in this embodiment, the bottom of the silicon wafer refers to the side of the silicon wafer opposite to the side close to the resin plate, and the top of the main roller here refers to the uppermost edge of the main roller or the cutting wire mesh, that is, the height difference between the top of the main roller and the bottom of the silicon wafer can be understood as the height difference between the cutting wire mesh and the bottom of the silicon wafer.

[0088] In this specific embodiment, when the cutting line enters the silicon wafer from the resin plate, the silicon wafer is lifted up at a slower speed, which can protect the edge surface of the silicon wafer. At the end section, the contact area between the cutting line and the silicon wafer becomes smaller, and the lifting speed is controlled to be faster at this time, which can not only reduce scratches, but also save the overall time required for the silicon wafer to be lifted up and improve the efficiency of the silicon wafer being lifted up.

[0089] Optionally, in a specific embodiment, the first feed speed can be any value between 20 and 40 mm / min, the second feed speed can be any value between 40 and 80 mm / min, and the third feed speed can be any value between 80 and 600 mm / min.

[0090] For example, the first feed speed may be one of 20 mm / min, 25 mm / min, 30 mm / min, 35 mm / min, 40 mm / min, or a value between any two of them; the second feed speed may be one of 40 mm / min, 45 mm / min, 50 mm / min, 55 mm / min, 60 mm / min, 70 mm / min, 80 mm / min, or a value between any two of them; and the third feed speed may be one of 80 mm / min, 100 mm / min, 150 mm / min, 200 mm / min, 250 mm / min, 300 mm / min, 350 mm / min, 400 mm / min, 450 mm / min, 500 mm / min, 550 mm / min, 600 mm / min, or a value between any two of them.

[0091] Optionally, the silicon wafer cutting method provided in the embodiment of the present application further includes:

[0092] In the process of controlling the cutting line to move in alternating cycles in forward and reverse directions, cutting liquid is sprayed onto the contact area between the silicon wafer and the cutting line.

[0093] When the silicon wafer is lifted upward, cutting fluid is sprayed onto the contact areas between the cutting lines on both sides of the silicon wafer, so that during the forward and reverse routing of the cutting lines, the cutting fluid is brought into the space between adjacent silicon wafers through the cutting lines, thereby utilizing the cutting fluid to act as a lubricant and further reducing the friction between the cutting lines and the silicon wafer.

[0094] Optionally, in one embodiment, the flow rate of the above-mentioned cutting fluid can be set to any value between 100 and 300 kg / min, for example, it can be one of 100 kg / min, 150 kg / min, 200 kg / min, 250 kg / min, 300 kg / min or a value between any two of them; in some embodiments, the flow rate of the above-mentioned cutting fluid is set to any value between 200 and 250 kg / min.

[0095] Optionally, in one embodiment, the slurry temperature of the cutting fluid is set to any value between 15 and 25°C, which can better play the role of the dispersant and lubricant in the cutting fluid and improve the lubrication effect; for example, the slurry temperature of the cutting fluid can be set to one of 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C or any value between two of them; in some embodiments, the slurry temperature of the cutting fluid is set to any value between 18 and 20°C.

[0096] In the embodiment of the present application, during the process of lifting the silicon wafer upward, the cutting line is controlled to move in alternating cycles in the forward and reverse directions, which can effectively alleviate the problems of silicon wafer falling and silicon wafer surface scratches that are easily caused by the existing method of lifting the silicon wafer upward.

[0097] The present application also proposes a silicon wafer, wherein the silicon wafer is processed by the above-mentioned silicon wafer cutting method.

[0098] Among them, because the cutting line is moved in alternating forward and reverse directions in the process of lifting the silicon wafer to prepare the above-mentioned silicon wafer, the reverse line bow formed by the cutting line can be reduced, making the contact area between the silicon wafer and the cutting line smaller, and the scratches on the surface of the silicon wafer caused by the cutting line during the process of lifting the silicon wafer can be significantly reduced. The surface quality of the silicon wafer produced is high and the secondary damage is small.

[0099] Example 2

[0100] 5 , which shows a flow chart of the steps of a silicon wafer cutting method in a second embodiment of the present application, the method is applied to a process in which a silicon wafer is lifted upwards, and the method may include steps 201 to 204:

[0101] Step 201: Determine a correspondence between the height to which the silicon wafer is lifted and the feed speed; wherein, in the correspondence, the feed speeds corresponding to different lifting heights are at least partially different, so that when the silicon wafer is controlled to move upward according to the feed speed determined by the correspondence, the scratches formed on the silicon wafer by the cutting line tend to be uniform.

[0102] In this step, based on the rule that the probability of the cutting line forming scratches on the silicon wafer during the process of the silicon wafer being lifted upward is affected by the size of the contact area, and the contact area between the cutting line and the silicon wafer changes with the height to which the silicon wafer is lifted upward, the lifting speed that changes continuously with the height to which the silicon wafer is lifted upward and controls the scratches formed on the silicon wafer by the cutting line during the process of the silicon wafer being lifted upward to tend to be uniform is calculated in advance, that is, the above-mentioned corresponding relationship is determined.

[0103] Step 202: Determine the feeding speed according to the lifting height and the corresponding relationship.

[0104] In this step, the above-mentioned corresponding relationship stipulates the silicon wafer feeding speed corresponding to different lifting heights, and when the silicon wafer is lifted upward and the feeding speed determined by the corresponding relationship is controlled to move the silicon wafer upward, the size of the reverse line arch formed by the cutting line tends to be uniform. Therefore, when the silicon wafer is controlled to move upward according to the above-mentioned feeding speed, the cutting line and the scratches on the silicon wafer tend to be uniform and the difference in scratches is small, which makes the silicon wafer less likely to fall and the silicon wafer quality is higher.

[0105] Step 203: Control the silicon wafer to move upward according to the feeding speed.

[0106] This step may be specifically referred to the above step 112 and will not be described in detail here.

[0107] Step 204: During the process of controlling the upward movement of the silicon wafer, the cutting line is controlled to move in alternating cycles in forward and reverse directions.

[0108] This step may be specifically referred to the above step 102 and will not be described in detail here.

[0109] Optionally, in one embodiment, in the above step 204, controlling the cutting line to move alternately in forward and reverse directions includes steps 2041 to 2042:

[0110] Step 2041: In the reversing stage, the cutting line is controlled to switch the movement direction within 0 to 0.5 seconds, and is accelerated to any value between 0.01 and 1 m / s within 4 to 7 seconds;

[0111] In step 2041, the reversing stage refers to the process of changing the active roller to switch the cutting line from forward motion to reverse motion, or switching the cutting line from reverse motion to forward motion; in the reversing stage, the cutting line is controlled to stop moving in the original motion direction within a short period of 0 to 0.5 seconds, and starts moving in the opposite direction to the original motion direction, and accelerates to any value between 0.01 and 1 m / s within 4 to 7 seconds, which can effectively reduce the reverse line bow and avoid increasing the burden on the driving roller rotation motor.

[0112] Step 2042: In the non-reversing stage, the cutting line is controlled to move at a constant speed of any one of 0.01 to 1 m / s.

[0113] In step 2042 , during the non-reversing phase, the cutting line is controlled to move at a uniform speed between 0.01 and 1 m / s, which can better match the rising speed of the silicon wafer and avoid forming horizontal scratches or vertical scratches.

[0114] Optionally, in a specific embodiment, in each alternating cycle of forward and reverse directions, the forward movement distance of the cutting line is equal to the reverse movement distance, which can more evenly offset the silicon wafer scratches caused by forward and reverse direction operation, further improving the quality of the silicon wafer.

[0115] Optionally, in a specific embodiment, in each alternating cycle of forward and reverse directions, the distance that the cutting line moves in a single direction is any value between 0.05 and 30 m, which can not only reduce the reverse bow of the cutting line, but also make full use of the forward and reverse directions of the cutting line to bring the cutting line into the silicon wafer, effectively reducing the contact area between the cutting line and the silicon wafer, thereby reducing scratches on the surface of the silicon wafer.

[0116] Optionally, in some embodiments, in each alternating cycle of forward and reverse directions, the distance that the cutting line moves in a single direction can be one of 0.05m, 0.1m, 0.2m, 0.4m, 0.6m, 0.8m, 1m, 1.2m, 1.5m, 1.8m, 2m, 2.2m, 2.5m, 2.8m, 3m, 5m, 8m, 10m, 15m, 20m, 25m, 30m or a value between any two of them.

[0117] In an embodiment of the present application, by controlling the routing distance, routing speed and acceleration / deceleration time of the cutting line in the forward and reverse directions, controlling the reversing frequency of the cutting line, and matching the feed table speed at different lifting heights, the wire bow formed by the cutting line being clamped by the silicon wafer can be made smaller, and the contact area between the silicon wafer and the cutting line can be made smaller, which has a positive effect on scratches on the surface of the silicon wafer.

[0118] Example 3

[0119] 6 , which shows a flow chart of the steps of a silicon wafer cutting method according to a third embodiment of the present application, wherein the method is applied to a process in which a silicon wafer is lifted upward, and the process in which the silicon wafer is lifted upward sequentially includes a starting section, a middle section, and an ending section;

[0120] The method may include steps 301 to 304:

[0121] Step 301: Determine the feed speed according to the lifting height of the silicon wafer; wherein, when the lifting height is at the starting section of the lifting process, the feed speed is any value between 20 and 40 mm / min, when the lifting height is at the middle section of the lifting process, the feed speed is any value between 40 and 80 mm / min, and when the lifting height is at the ending section of the lifting process, the feed speed is any value between 80 and 600 mm / min.

[0122] This step may be specifically referred to the above step 111 and will not be described in detail here.

[0123] Step 302: Control the silicon wafer to move upward according to the feeding speed.

[0124] This step may be specifically referred to the above step 112 and will not be described again here.

[0125] Step 303: In the process of controlling the upward movement of the silicon wafer, the cutting line is controlled to move in an alternating cycle in the forward and reverse directions; wherein, in the reversing stage, the cutting line is controlled to switch the movement direction within 0 to 0.5 seconds, and is accelerated to any value between 0.01 and 1 m / s within 4 to 7 seconds; in the non-reversing stage, the cutting line is controlled to move at a constant speed between 0.01 and 1 m / s, and in each alternating cycle in the forward and reverse directions, the distance of movement in a single direction is any value between 0.05 and 30 m.

[0126] This step may be specifically referred to the above step 204 and will not be described in detail here.

[0127] In an embodiment of the present application, by controlling the routing distance, routing speed and acceleration / deceleration time of the cutting line in the forward and reverse directions, and matching the feed table speed at different lifting heights, the wire bow formed by the cutting line being clamped by the silicon wafer can be made smaller, and the contact area between the silicon wafer and the cutting line can be made smaller, which can significantly reduce the probability of scratches forming on the silicon wafer surface.

[0128] In order to make the invention purpose, technical solution and beneficial effects of this application clearer, the present application is further described below in conjunction with examples. It should be understood that these examples are only used to illustrate this application and are not used to limit the scope of this application.

[0129] Example 1

[0130] After the M10 silicon wafer is cut, the wafer is lifted up and the steel wire used as the cutting line is controlled to move in alternating forward and reverse directions according to the parameters shown in Table 1, and cutting fluid is sprayed on both sides of the wafer. The cut wafer is lifted from the wire mesh until the bottom surface of the wafer is free of the wire mesh to obtain the wafer.

[0131] Table 1

[0132] Example 2

[0133] After the M10 silicon wafer is cut, the wafer is lifted up and the steel wire used as the cutting line is controlled to move in alternating forward and reverse directions according to the parameters shown in Table 2, and cutting fluid is sprayed on both sides of the wafer. The cut wafer is lifted from the wire mesh until the bottom surface of the wafer is free of the wire mesh to obtain the wafer.

[0134] Table 2

[0135] Example 3

[0136] After the M10 silicon wafer is cut, the wafer is lifted up and the steel wire used as the cutting line is controlled to move in alternating forward and reverse directions according to the parameters shown in Table 3, and cutting fluid is sprayed on both sides of the wafer. The cut wafer is lifted from the wire mesh until the bottom surface of the wafer is free of the wire mesh to obtain the wafer.

[0137] Table 3

[0138] Example 4

[0139] After the M10 silicon wafer is cut, the wafer is lifted up and the steel wire used as the cutting line is controlled to move in alternating forward and reverse directions according to the parameters shown in Table 4, and cutting fluid is sprayed on both sides of the wafer. The cut wafer is lifted from the wire mesh until the bottom surface of the wafer is free of the wire mesh to obtain the wafer.

[0140] Table 4

[0141] Comparative Example 1

[0142] After the M10 silicon wafer is cut, the wafer is lifted up and the steel wire used as the cutting line is controlled to move unidirectionally according to the parameters shown in Table 5, and cutting fluid is sprayed on both sides of the silicon wafer. The cut silicon wafer is lifted from the wire mesh until the lower surface of the silicon wafer is separated from the wire mesh to obtain the silicon wafer.

[0143] Table 5

[0144] The silicon wafers prepared in Examples 1 to 4 and Comparative Example 1 were subjected to surface scratch tests, respectively. The results are shown in Table 6.

[0145] Table 6

[0146] Experiments show that compared with the conventional process of controlling the unidirectional routing of the cutting line, the embodiment of the present application controls the alternating cyclic movement of the cutting line in the forward and reverse directions during the movement of the silicon wafer, and the scratches on the surface of the silicon wafer produced are significantly less than those produced by the conventional process. This shows that the method provided by the embodiment of the present application can effectively reduce the scratches formed on the surface of the silicon wafer during the process of lifting the silicon wafer, and the quality of the silicon wafer is significantly improved.

[0147] In addition, as shown in FIG7 , the surface of the silicon wafer prepared by the method provided by an embodiment of the present application shows scratches distributed along the direction of the cutting wire mesh, and the depth of the scratches is between 2 μm and 10 μm. Compared with the line marks, the depth of the scratches is significantly shallower. This depth control avoids the impact of excessively deep scratches on subsequent processing, thereby ensuring that high-quality silicon wafer surfaces can be obtained while ensuring improved efficiency. In addition, during the cutting process, by adopting a reciprocating silicon wafer lifting method, a specific pattern of scratches and line marks overlapping each other is formed on the surface of the silicon wafer. These patterns are similar to the "8"-shaped lines shown by the black dotted lines in FIG7. This pattern is evenly and symmetrically distributed and shows a high degree of consistency and regularity, providing high-quality guarantees for the mass production of silicon wafers.

[0148] As described above, referring to FIG3 , during the cutting process of the silicon wafer 2, the cutting line 4 needs to be cut into the carrier 3. Based on this, as shown in FIG8 and FIG9 , during the process of the silicon wafer being lifted upward, there are two movement modes: one in which the cutting line 4 is located within the carrier 3, and the other in which the cutting line 4 is separated from the carrier 3. It should be noted that the movement mode of the cutting line 4 actually refers to the routing direction of the cutting line, that is, the cutting line only performs a unidirectional movement of forward or reverse movement or a bidirectional movement of alternating forward and reverse movement. It should be noted that in this field, the forward movement can also be referred to as the winding movement, and the reverse movement can also be referred to as the unwinding movement, or the forward movement can also be referred to as the unwinding movement, and the reverse movement can also be referred to as the winding movement.

[0149] In this way, when the silicon wafer is lifted upward relative to the cutting line, the movement mode of the cutting line within the carrier is different from the movement mode of the cutting line after it is separated from the carrier. Due to the different materials of the carrier and the silicon wafer, as well as the different requirements for the protection of the carrier and the protection quality of the silicon wafer, a more appropriate movement mode of the cutting line is selected based on the actual lifting environment of the cutting line within the carrier and the cutting line between the silicon wafers. In actual situations, the movement mode of the cutting line within the carrier and the movement mode of the cutting line after it is separated from the carrier are selected to ensure that the damage to the silicon wafer caused by the cutting line is reduced. In one example, the movement mode of the cutting line 4 within the carrier 3 and the movement mode of the cutting line 4 after it is separated from the carrier 3 in step S300 are different, specifically including the following steps:

[0150] Step S310, determining that the cutting line 4 is located within the carrier 3, and the cutting line 4 performs forward or reverse motion;

[0151] Step S320 , determining that the cutting line 4 is separated from the carrier plate, and the cutting line 4 alternately moves forward and backward.

[0152] In this way, when the cutting line 4 is located in the carrier 3, the cutting line 4 only performs unidirectional motion in the forward or reverse direction. At this time, the cutting line 4 will not swing back and forth in the horizontal direction perpendicular to the surface of the silicon wafer, so that the cutting line 4 always remains in the position where the carrier 3 is cut during the cutting process, that is, the cutting line 4 will not be biased towards any of the two adjacent silicon wafers 2. In this way, in the process of lifting the silicon wafer 2 relative to the cutting line 4, it is not easy for the cutting line 4 to hang on the side of the silicon wafer 2 that is bonded to the carrier 3. Furthermore, the situation where the cutting line 4 is broken or the silicon wafer 2 falls as the silicon wafer 2 is lifted is effectively reduced. In addition, since the carrier does not have high protection requirements, the unidirectional motion method is selected to reduce unnecessary switching of movement directions and improve the lifting efficiency of the cutting line in the carrier. Then, in the process of lifting the cutting line 4 from the carrier plate 3 to the cutting line 4 being separated from the silicon wafer 2, the cutting line 4 alternates between forward and reverse motions, and the side where the cutting line 4 enters relative to the silicon wafer 2 changes as the direction of movement of the cutting line 4 changes. In this way, the large bow of the cutting line 4 caused by the cutting line 4 entering only from one side of the silicon wafer 2 can be reduced, and the cutting line 4 is subjected to a large friction force from the silicon wafer 2, and the cutting line 4 is not likely to separate the surfaces of the two adjacent silicon wafers 2 away from the side where the cutting line 4 enters. This reduces the occurrence of scratches, bright lines, and even the falling of the silicon wafer 2 caused by the friction of the cutting line 4, which is caused by the silicon wafer 2 being difficult to be separated by the cutting line 4 due to the large suction force. In addition, when the cutting line 4 is located between two adjacent silicon wafers 2, it alternates between forward and reverse motions, and the cutting line 4 swings back and forth in the horizontal direction perpendicular to the surface of the silicon wafer. At this time, the cutting line 4 can be prevented from being in constant contact with any of the two adjacent silicon wafers 2. At the same time, during the horizontal swinging process, the cutting line 4 is out of contact with the silicon wafer 2, shortening the contact time between the cutting line 4 and the silicon wafer 2, reducing the friction on the silicon wafer 2, reducing the phenomenon of scratches on the surface of the silicon wafer 2, and reducing the damage to the silicon wafer caused by the cutting line.

[0153] As shown in Figure 9, in one possible implementation, in step S320, it is determined that the cutting line is separated from the carrier. During the process of the cutting line alternating forward and reverse movements, the distance that the cutting line 4 moves forward is any value between 0.05m and 0.2m, and the distance that the cutting line 4 moves reversely is any value between 0.05m and 0.2m.

[0154] In this way, the distance that the cutting line 4 moves in the forward direction and the distance that the cutting line 4 moves in the reverse direction are avoided to cause the cutting line 4 to have a larger line bow, thereby reducing the contact area between the cutting line 4 and the silicon wafer 2, reducing the friction between the cutting line 4 and the silicon wafer 2, and further reducing the occurrence of more scratches on the silicon wafer 2 caused by the cutting line 4, thereby reducing the damage to the silicon wafer caused by the cutting line.

[0155] For example, the distance that the cutting line 4 moves forward can be 0.05m, 0.08m, 0.1m, 0.12m, 0.15m, 0.18m, 0.2m, etc., and the distance that the cutting line 4 moves backward can be 0.05m, 0.06m, 0.08m, 0.1m, 0.12m, 0.16m, 0.17m, 0.2m, etc. Of course, this is just an example and not a specific limitation.

[0156] In one example, in step S320, it is determined that the cutting line 4 has separated from the carrier 3. During the process of the cutting line 4 alternating forward and reverse motions, the distance of the forward motion and the distance of the reverse motion of the cutting line 4 are equal. In this case, the two adjacent silicon wafers 2 are separated more evenly, thereby preventing the side of the silicon wafer 2 parallel to the cutting line from separating more slowly than the other side. This reduces the friction between the silicon wafer and the cutting line 4, and reduces the occurrence of scratches on the silicon wafer 2.

[0157] In some embodiments, when it is determined in step S310 that the cutting line 4 is located within the carrier 3 and the cutting line 4 is moving forward or backward, the forward or backward speed of the cutting line 4 is S1. When it is determined in step S320 that the cutting line 4 is separated from the carrier 3 and the cutting line 4 is moving alternately forward and backward, the maximum forward or backward speed of the cutting line 4 is S2, and S1 < S2. In this case, when it is determined in step S310 that the cutting line 4 is located within the carrier 3 and the cutting line is moving forward or backward, the forward or backward speed of the cutting line 4 is relatively low, thereby preventing the cutting line 4 from deviating toward one of the two adjacent silicon wafers 2 due to shaking, further reducing the possibility of the cutting line 4 getting caught on the side of the silicon wafer 2 bonded to the carrier 3. During the process from when the cutting line is separated from the carrier to when the cutting line is lifted from the silicon wafer, the forward or backward speed of the cutting line 4 is relatively high, thereby accelerating the separation of the two adjacent silicon wafers 2 and improving the efficiency of separating the silicon wafer 2 from the cutting line 4. It should be noted that due to the existence of a wire bow in the cutting line 4, the cutting line 4 defined in this application as being located inside the carrier board 3 indicates that at least part of the cutting line is located inside the carrier board 3; and the cutting line 4 being detached from the carrier board 3 indicates that all the cutting lines are detached from the carrier board 3.

[0158] As an optional method, in step S310, it is determined that the cutting line 4 is located within the carrier 3. During the forward or reverse movement of the cutting line 4, S1 gradually increases. When the cutting line 4 is completely within the carrier 3, the speed of the cutting line 4 is relatively low, preventing the cutting line 4 from deviating toward either of the two adjacent silicon wafers 2 due to shaking, thereby reducing the probability of the cutting line 4 getting caught on the side of the silicon wafer 2 bonded to the carrier 3. As the silicon wafer 2 is lifted relative to the cutting line 4, due to the existence of the cutting line 4 bow, when the cutting line 4 is partially located within the silicon wafer 2, as shown in Figure 8, the top of the cutting line 4 bow and the portion of the cutting line 4 near the top of the cutting line 4 bow are located within the carrier 3. The cutting line 4 near the side of the cutting line 4 that exits the silicon wafer 2 can drive the portion of the cutting line 4 located within the carrier 3, forcing the portion of the cutting line 4 located within the carrier 3 to move between the two adjacent silicon wafers 2, thereby preventing the cutting line 4 from getting caught on the side of the silicon wafer 2 bonded to the carrier 3.

[0159] In a specific implementation, 3 m / min ≤ S1 ≤ 50 m / min. For example, S1 can be 3 m / min, 10 m / min, 20 m / min, 25 m / min, 30 m / min, 40 m / min, 50 m / min, etc. S2 ≤ 50 m / min, S2 can be 20 m / min, 25 m / min, 30 m / min, 36 m / min, 42 m / min, 45 m / min, 50 m / min, etc.

[0160] It is understood that the direction of the curvature of the cutting line 4 is the same as the direction of movement of the carrier plate 3 relative to the cutting line 4. Specifically, as shown in Figure 3, during the cutting process, the carrier plate 3 drives the silicon ingot 1 from top to bottom relative to the cutting line 4. At this time, the cutting line 4 bends downward to form a curvature. Therefore, when the cutting line 4 cuts into the carrier plate 3, the curvature of the cutting line 4 is in a downward curved state. Referring to Figures 8 and 9, when the silicon wafer 2 obtained by cutting the silicon ingot 1 is lifted upward relative to the cutting line 4, the cutting line 4 bends upward to form a curvature. In this case, in order to separate the cutting line 4 from the carrier 3, the cutting line 4 gradually changes from a downward bend to an upward bend during the process of lifting the carrier 3 relative to the cutting line 4. To ensure that the cutting line 4 is completely separated from the carrier 3, the cutting line 4 is switched from a unidirectional motion mode to a bidirectional motion mode. In step S310, it is determined that the cutting line is located within the carrier. During the forward or reverse motion of the cutting line, the distance that the silicon wafer 2 is lifted upward relative to the cutting line 4 is 15%-25% of the vertical dimension of the silicon wafer. In this way, a suitable lifting distance is selected for silicon wafers of different sizes to ensure that the lifting distance completely separates the cutting line 4 from the carrier 3. In a specific implementation, the distance that the silicon wafer 2 is lifted upward relative to the cutting line 4 can be 30mm to 50mm, and specifically can be 30mm, 32mm, 40mm, 46mm, 50mm, etc.

[0161] In one optional embodiment, the silicon wafer 2 obtained by cutting the silicon ingot 1 is lifted upward relative to the cutting line 4 at a speed ranging from 15 mm / min to 60 mm / min. This prevents the silicon wafer 2 from being lifted upward relative to the cutting line 4 too quickly, which could cause the cutting line 4 to break or the silicon wafer 2 to break. Furthermore, it prevents the silicon wafer 2 from being lifted upward relative to the cutting line 4 too slowly, which could result in inefficient separation of the silicon wafer 2 from the cutting line 4.

[0162] In practice, during the process of lifting the silicon wafer 2 relative to the cutting line 4 in step S300, the silicon wafer cutting method provided in the embodiment of the present application further includes the step of spraying a cutting fluid onto the cutting line 4. The cutting fluid is preferably a mixed mortar, which can reduce the adsorption force between two adjacent silicon wafers 2 and facilitate the cutting line 4 to separate the two adjacent silicon wafers 2. In a specific implementation, the mixed mortar includes cutting fluid and silicon powder. The presence of silicon powder can reduce the adsorption force between two adjacent silicon wafers 2 and also enable the reuse of the cutting fluid, avoiding waste of resources.

[0163] In one possible implementation, in step S320, it is determined that the cutting line is separated from the carrier, and during the process in which the cutting line alternates forward and reverse motions, the silicon wafer cutting method further includes the step of: spraying clean water between the silicon wafers 2. The setting of the clean water, on the one hand, cleans the silicon wafers 2, and on the other hand, the clean water is sprayed between the silicon wafers 2, and the spray force of the clean water facilitates separating the two adjacent silicon wafers 2. The spray flow rate of the clean water is any value between 50L / min and 300L / min to ensure that the spray force of the clean water can separate the two adjacent silicon wafers 2. Exemplarily, the spray flow rate of the clean water can be 50L / min, 60L / min, 80L / min, 100L / min, 160L / min, 200L / min, 245L / min, 280L / min, 300L / min, etc.

[0164] The present application is further described below with reference to specific embodiments.

[0165] Example 1

[0166] In this embodiment 1, the cutting wire is wound around the surface of three cutting rollers to form a cutting wire net. The roller grooves of the three cutting rollers are V-shaped grooves. The cutting wire net is used to cut the silicon rods and then cut them into silicon wafers. The size of the silicon wafers obtained by cutting is 182.2mm*183.75mm*0.13mm. The cutting wire travel speed is 20mm / min, and the silicon wafer lifting speed is 30mm / min.

[0167] The silicon wafer cutting method involved in this embodiment 1 includes the following steps: first, providing a silicon rod 1 and a carrier 3; second, driving the silicon rod 1 to move downward relative to the cutting line 4, so that the cutting line 4 cuts the silicon rod 1 to obtain multiple silicon wafers 2. At this time, the cutting line 4 needs to cut into the carrier to ensure that the silicon rod 1 is completely cut through; finally, the silicon wafer 2 is lifted upward relative to the cutting line 4. When the cutting line 4 is located on the carrier 3, the movement mode of the cutting line is unidirectional routing and lifting; when the cutting line completely enters the silicon rod and it is determined that the cutting line 4 is separated from the carrier, the cutting line performs bidirectional routing and lifting, that is, alternately performing forward and reverse movements. Specifically, the routing distance of the unidirectional routing and lifting is 4.2m, and the routing distance of the bidirectional routing and lifting is 0.6m.

[0168] Comparative Example 1

[0169] The difference from Example 1 is that during the entire process of the silicon wafer being lifted upward, the cutting line performs the unidirectional routing and lifting in Example 1, and when all unidirectional routing is lifted, the routing distance range is 17m. Other parts are the same as Example 1.

[0170] Comparative Example 2

[0171] The difference from Example 1 is that during the entire process of the silicon wafer being lifted upward, the cutting lines all perform the bidirectional routing lift in Example 1, and the routing distance of all bidirectional routing lifts is within 0.6 m. Other parts are the same as Example 1.

[0172] The following is a 2000-cut experiment conducted on 70 slicers of the same specifications. The breakage rate and wafer defect rate for Example 1 and Comparative Examples 1-2 are recorded. It should be noted that the wafer defect rate is the total number of defective wafers produced during the 2000-cut experiment divided by the total number of wafers produced. The wafer defect rate primarily refers to the percentage of defects such as scratches and chamfered chips that appear during the upward movement of the wafer. Specific comparative results are shown in Table 1.

[0173] Table 1

[0174] As shown in Table 1, the silicon wafer dicing method provided by this application can reduce the rate of wire breakage and the rate of silicon wafer abnormalities. Of course, the impact varies depending on the type of silicon wafer. Generally speaking, as the cutting line becomes thinner and the silicon wafer size increases, the silicon wafer dicing method provided by the embodiments of this application will show greater advantages.

[0175] As shown in Figures 8, 10 and 11, in the third aspect of the present application, an embodiment of the present application further provides a silicon wafer, the silicon wafer 2 having a first group of opposite sides and a second group of opposite sides, the first group of opposite sides including a first side 201 and a second side 202 arranged oppositely, the left and right sides of the silicon wafer 2 shown in Figure 8 are the first side 201 and the second side 202 respectively, the second group of opposite sides including a third side 203 and a fourth side 204 arranged oppositely, the upper and lower sides of the silicon wafer 2 shown in Figure 8 are the third side 203 and the fourth side 204 respectively, wherein the first side and / or the second side intersects with the third side and / or the fourth side; the surface of the silicon wafer 2 has a plurality of cutting lines 23 and two groups of scratches, the first group of scratches 21 shown in the rectangular box in Figure 10 and the second group of scratches shown in the rectangular box in Figure 11 Scratches 22, wherein the cutting lines 23 extend along the first set of opposite sides of the silicon wafer 2, that is, extend from the first side 201 to the second side 202 of the first set of opposite sides. The figure shows that the cutting lines 23 extend in the horizontal direction. Among the two groups of scratches, one group of scratches is inclined in the first direction toward the third side 203 of the silicon wafer 2, and the first direction is the direction from the first side 201 to the second side 202. As shown in FIG10 , the first side 201 is located on the left side in FIG10 and FIG11 , the second side 202 is located on the right side in FIG10 and FIG11 , and the third side 203 is located at the top in FIG10 and FIG11 . The other group of scratches is inclined in the first direction toward the fourth side 204 of the silicon wafer 2. As shown in FIG11 , the fourth side 204 is located at the bottom in FIG10 and FIG11 .

[0176] It should be noted that the cutting line marks 23 are formed when the cutting line 4 cuts the silicon rod 1. Specifically, the cutting line marks 23 are the grinding textures formed on the surface of the silicon wafer by the grinding between the cutting line 4 and the surface of the silicon wafer during the cutting process. As shown in Figure 3, since the silicon rod 1 is fed downward relative to the cutting line 4, the cutting line 4 is subjected to pressure from the silicon rod 1. While the cutting line 4 is reciprocating, it forms a certain degree of bending in the feeding direction. Each corresponding cutting line mark 23 appears as an arc visible to the naked eye on the surface of the silicon wafer. Figures 10 and 11 show the state of the cutting line marks 23 on the silicon wafer. It can be seen in the figure that multiple cutting line marks 23 are densely arranged along the cutting direction. The silicon wafer cutting method also includes lifting the silicon wafer 2 upward relative to the cutting line 4 after the silicon wafer is cut. During the process of lifting the silicon wafer 2, scratches will be formed on the surface of the silicon wafer 2 due to different degrees of contact between the cutting line 4 and the silicon wafer 2. That is, the scratches are traces formed by the contact between the cut silicon wafer 2 and the cutting line 4 when it is lifted upward relative to the cutting line 4. Each group of scratches has one, two or other smaller number of scratches, and each scratch in the same group of scratches has the same inclination direction relative to the cutting line mark 23, that is, as shown in Figures 10 and 11, it is inclined upward or downward relative to the cutting line mark 23 along the direction from left to right.

[0177] It can be understood that the intersection of the first side and / or the second side with the third side and / or the fourth side in the present application can be through chamfering and then intersecting with each other, or through intersecting with each side or its extension line, for example, for polygonal or other shaped silicon wafers, and the embodiments of the present application are not limited to this.

[0178] When using the above technical solution, both groups of scratches on the silicon wafer surface are formed by the dicing line scratching the silicon wafer as it is lifted relative to the dicing line. One group of scratches is formed by the dicing line randomly scratching the silicon wafer surface as it moves in one direction, for example, a first group of scratches 21 is formed by the dicing line scratching the silicon wafer surface as it moves forward between the silicon wafers. The other group of scratches is formed by the dicing line randomly scratching the silicon wafer surface as it moves in the opposite direction, for example, a second group of scratches 22 is formed by the dicing line scratching the silicon wafer surface as it moves in the opposite direction. Because the silicon wafer is lifted relative to the dicing line as it moves, the two groups of scratches are formed by the dicing line scratching in the two opposite directions of the dicing line. One group of scratches is inclined in the first direction relative to the dicing line mark 23 toward the third edge 203 of the silicon wafer, while the other group of scratches is inclined in the first direction relative to the dicing line mark 23 toward the fourth edge 204 of the silicon wafer, which is opposite the third edge 203. Since the silicon wafer cutting and slicing operations are performed according to the silicon wafer cutting method of the present application, scratches on the silicon wafer surface are reduced and damage to the silicon wafer caused by the cutting line is reduced. For details, please refer to the beneficial effects of the method, which will not be repeated here.

[0179] In some embodiments, the angle between the scratch and the cutting line mark 23 is less than 20°. For example, the angle can be 1°, 5°, 10°, 15°, 19°, etc. The angles between each scratch in the same group of scratches and the cutting line mark 23 can be the same or different. The angle refers to the angle between the scratch and the tangent on the cutting line mark 23, where the tangent is the tangent passing through the intersection of the scratch and the cutting line mark 23. Since the cutting line mark 23 is slightly arc-shaped as a whole, from the local view with the scratch, the cutting line mark 23 in the local view can be considered to be basically a straight line, and the scratch can also be considered to be basically a straight line.

[0180] The angle is related to the speed at which the silicon wafer is lifted relative to the cutting line and the line's travel speed. The greater the speed, the larger the angle between the scratch and the cutting line, leading to higher slicing efficiency but also increasing the number of scratches and wafer damage. Therefore, to ensure efficient slicing and minimize scratches and damage, a suitable speed is selected. The specific speed can be found in the method description. At this speed, the angle between the scratch on the silicon wafer and the cutting line 23 is less than 20°.

[0181] In some embodiments, the depth of the scratches is 2μm to 17μm, specifically 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, etc. The silicon wafer obtained by the above method has a smaller depth of scratches on its surface, which is beneficial to improving the surface passivation effect of the subsequently prepared solar cell and improving the photoelectric conversion efficiency.

[0182] In some possible implementations, the two groups of scratches are located on the same surface of the silicon wafer, and / or the two groups of scratches are located on two opposite surfaces of the silicon wafer. Since the scratches formed by the cutting line on the silicon wafer are random, scratches may be formed only on one surface of the silicon wafer, or scratches may be formed on both sides of the silicon wafer. When scratches are formed on only one surface of the silicon wafer, there are two groups of scratches on the one surface, including a first group of scratches 21 and a second group of scratches 22. When scratches are formed on both sides of the silicon wafer, one surface may have only one group of scratches (such as the first group of scratches 21), and the other surface may have only the other group of scratches (such as the second group of scratches), or one surface may have only one group of scratches, such as the first group of scratches 21 or the second group of scratches 22, and the other surface may have both groups of scratches, or both surfaces may have both groups of scratches.

[0183] It should be noted that the scratches in different groups mentioned above have different inclination directions, that is, the scratches in the first group 21 and the scratches in the second group 22 have different inclination directions, and the scratches in the same group have the same inclination direction.

[0184] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0185] In summary, in this embodiment, the silicon wafer cutting method provided is to first cut the silicon rod with a cutting wire, and after the silicon rod is cut into silicon wafers, the silicon wafer is controlled to move upward, and in the process of controlling the upward movement of the silicon wafer, the cutting wire is controlled to move in alternating cycles in the forward and reverse directions; wherein, the wire bow of the wire in the forward and reverse directions is smaller than the wire bow of the wire in the unidirectional direction, so that the contact area between the silicon wafer and the cutting wire is smaller, which not only reduces the probability of the cutting wire forming scratches on the surface of the silicon wafer during the upward lifting of the silicon wafer, but also reduces the situation of the silicon wafer falling off when the silicon wafer is lifted upward, and has the advantages of fast speed increase, high surface quality of the silicon wafer produced, and low secondary damage. In addition, according to the actual pulling environment of the cutting wire in the carrier and the cutting wire between the silicon wafers, different movement modes of the cutting wire in the carrier and the cutting wire after leaving the carrier are selected, which further reduces the damage of the cutting wire to the silicon wafer.

[0186] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic inventive concepts. Therefore, the claims are intended to include the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0187] The above is a detailed introduction to the silicon wafer cutting method and silicon wafer provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A silicon wafer cutting method, wherein: include: Provide silicon rods and carrier plates; Driving the silicon rod to move downward relative to the cutting line so that the cutting line cuts the silicon rod to obtain a plurality of silicon wafers; The silicon wafer is lifted upward relative to the cutting line. During the process of the silicon wafer being lifted, the cutting line in contact with the silicon wafer is controlled to move in a positive and negative alternating circular motion.

2. The silicon wafer cutting method according to claim 1, wherein: Controlling the cutting line to move alternately in forward and reverse directions includes: In the reversing stage, the cutting line is controlled to switch the moving direction within 0 to 0.5 seconds, and is accelerated to any value between 0.01 and 1 m / s within 4 to 7 seconds; In the non-reversing stage, the cutting line is controlled to move at a uniform speed of any one of 0.01 to 1 m / s.

3. The silicon wafer cutting method according to claim 1, wherein: In each positive and negative alternating cycle, the distance of the cutting line moving in the positive direction is equal to the distance of the cutting line moving in the negative direction.

4. The silicon wafer cutting method according to claim 3, wherein: In each forward and reverse direction alternating cycle, the distance that the cutting line moves in a single direction is any value between 0.05 and 30 m.

5. The silicon wafer cutting method according to claim 1, wherein: Controlling the silicon wafer to move upward includes: Determining a feeding speed according to the height to which the silicon wafer is lifted upward; wherein the feeding speeds corresponding to different lifting heights are at least partially different; According to the feeding speed, the silicon wafer is controlled to move upward.

6. The silicon wafer cutting method according to claim 5, wherein: Before determining the feeding speed according to the height by which the silicon wafer is lifted upward, the method further includes: Determine a correspondence between the height to which the silicon wafer is lifted and the feed speed; wherein, in the correspondence, the feed speeds corresponding to different lifting heights are at least partially different, so that when the silicon wafer is moved upwardly by controlling the feed speed determined by the correspondence, the scratches formed on the silicon wafer by the cutting line tend to be uniform; According to the lifting height of the silicon wafer, the feeding speed is determined, including: The feeding speed is determined according to the lifting height and the corresponding relationship.

7. The silicon wafer cutting method according to claim 5, wherein: The process of lifting the silicon wafer upwards includes a starting section, a middle section and an ending section in sequence; According to the lifting height of the silicon wafer, the feeding speed is determined, including: Controlling a first feeding speed of the silicon wafer to be smaller than a second feeding speed, wherein the first feeding speed is a silicon wafer upward moving speed in the starting section, and the second feeding speed is a silicon wafer upward moving speed in the middle section; The third feeding speed of the silicon wafer is controlled to be greater than or equal to the second feeding speed, and the third feeding speed is the upward moving speed of the silicon wafer in the end section.

8. The silicon wafer cutting method according to claim 7, wherein: The first feed speed is any value in the range of 20 to 40 mm / min, the second feed speed is any value in the range of 40 to 80 mm / min, and the third feed speed is any value in the range of 80 to 600 mm / min.

9. The silicon wafer cutting method according to claim 1, wherein: The silicon wafer cutting method further comprises: The silicon wafer is lifted upward relative to the cutting line, and the movement mode of the cutting line within the carrier is different from the movement mode of the cutting line after it is separated from the carrier.

10. The silicon wafer cutting method according to claim 9, wherein: The difference between the motion mode of the cutting line within the carrier and the motion mode of the cutting line after leaving the carrier includes: When the cutting line is located in the carrier, the cutting line performs forward movement or reverse movement; when the cutting line is separated from the carrier, the cutting line performs alternating forward and reverse circular movement.

11. The silicon wafer cutting method according to claim 10, wherein: During the alternating cyclic movement of the cutting line in forward and reverse directions, the cutting line alternately performs forward movement and reverse movement, the distance of the forward movement of the cutting line is any value between 0.05m and 0.2m, and the distance of the reverse movement of the cutting line is any value between 0.05m and 0.2m.

12. The silicon wafer cutting method according to claim 11, wherein: During the process of the cutting line performing the forward movement and the reverse movement alternately, the distance of the forward movement and the distance of the reverse movement of the cutting line are equal.

13. The silicon wafer cutting method according to claim 11, wherein: When the cutting line is located in the carrier board and the cutting line is moving forward or backward, the average line speed of the cutting line is S1; When the cutting line is separated from the carrier board, the cutting line alternately performs forward movement and reverse movement, and the maximum line speed of the cutting line for the forward movement or reverse movement is S2, and S1<S2.

14. The silicon wafer cutting method according to claim 13, wherein: When it is determined that the cutting line is located in the carrier board, the line routing speed gradually increases during the process of the cutting line moving forward or backward.

15. The silicon wafer cutting method according to claim 13, wherein: 3m / min≤S1≤50m / min and / or S2≤50m / min.

16. The silicon wafer cutting method according to claim 9, wherein: The speed of lifting the silicon wafer upward relative to the cutting line is any value between 15 mm / min and 60 mm / min.

17. A silicon wafer, wherein: The silicon wafer has a first set of opposite edges and a second set of opposite edges, the first set of opposite edges includes a first edge and a second edge arranged oppositely, the second set of opposite edges includes a third edge and a fourth edge arranged oppositely, wherein the first edge and / or the second edge intersects with the third edge and / or the fourth edge; the surface of the silicon wafer has two sets of scratches, One group of the scratches is inclined toward the third side in a first direction, and another group of the scratches is inclined toward the fourth side in the first direction, wherein the first direction is a direction from the first side to the second side.

18. The silicon wafer according to claim 17, wherein: The angle between the scratch mark and the cutting line mark is less than 20°.

19. The silicon wafer according to claim 17, wherein: The depth of the scratch is any value between 2 μm and 17 μm.

20. The silicon wafer according to any one of claims 17 to 19, wherein: The two groups of scratches are located on the same surface of the silicon wafer, and / or the two groups of scratches are located on two opposite surfaces of the silicon wafer.

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