Silicon wafer cutting method and apparatus

Abstract

This application relates to a silicon wafer cutting method and apparatus. The silicon wafer cutting method includes the following steps: setting a brand-new cutting wire on a main roller mechanism, driving the cutting wire in the cutting wire mesh to run cyclically through the main roller mechanism, cutting the silicon rod entering the cutting wire mesh into silicon wafers. The cyclical running includes an initial forward run, a reverse run, and a second forward run. The silicon wafer cutting method of this application, by making the cutting wire run cyclically during the cutting process, utilizes a cutting wire three times in a reasonable manner. In the three utilization processes, the cutting depth is maximized during the initial forward run with the highest wire speed, and the cutting depth is minimized during the second forward run with the lowest wire speed. This effectively controls the cutting wire speed and cutting depth according to the wear condition of the cutting wire, so as to make full use of the cutting wire while ensuring the normal operation of the wire bow, and thus ensuring the cutting quality and the quality of the silicon wafer.

Description

Technical Field

[0001] This application relates to the field of silicon wafer processing technology, and in particular to silicon wafer cutting methods and apparatus. Background Technology

[0002] In the manufacturing process of photovoltaic modules, a cutting machine is used to cut silicon rods into silicon wafers, and then the silicon wafers are processed and assembled to obtain photovoltaic modules.

[0003] In the silicon wafer dicing process, multi-wire dicing is typically used, which involves cutting the silicon rod using dicing wires. To ensure the efficient use of these dicing wires, most current silicon wafer dicing methods involve the dicing wires running in both forward and reverse directions in a cyclical manner, thereby maximizing their utilization.

[0004] However, the dicing wire will wear down during use and become thinner, resulting in a significant increase in the bow of the dicing wire during the dicing process. Abnormal bow directly affects the dicing quality of the silicon wafer, causing abnormalities in TTV (Total Thickness Variation), abnormal wire marks, abnormal wire breaks, or abnormal color differences, thus affecting the quality of the silicon wafer. Summary of the Invention

[0005] Therefore, it is necessary to provide a silicon wafer cutting method and apparatus to address the problem of abnormal wire bowing affecting silicon wafer quality.

[0006] In a first aspect, a silicon wafer dicing method includes the following steps:

[0007] Provide cut wire mesh;

[0008] Provide a silicon rod and move the silicon rod toward the dicing wire mesh;

[0009] The cutting wires in the cutting wire mesh are driven to run in a cyclic manner to cut the silicon rod entering the cutting wire mesh into silicon wafers;

[0010] The cyclical operation includes an initial forward run, a reverse run, and a subsequent forward run. The linear velocity of the initial forward run is greater than the linear velocity of the reverse run, the linear velocity of the reverse run is greater than the linear velocity of the subsequent forward run, the cutting depth of the initial forward run is greater than the cutting depth of the reverse run, and the cutting depth of the reverse run is greater than the cutting depth of the subsequent forward run. 。

[0011] In one embodiment, driving the cutting lines in the cutting wire mesh to operate cyclically includes:

[0012] The cutting wire is driven to perform an initial forward operation, such that the ratio between the cutting depth of the cutting wire on the silicon rod and the total cutting depth of the silicon rod is 14:19.

[0013] Driving the cutting line to run in reverse will make the ratio of the cutting depth of the cutting line on the silicon rod to the total cutting depth of the silicon rod 37:38;

[0014] The cutting line is driven to run forward again to cut the silicon rod into silicon wafers.

[0015] In one embodiment, the running length of the cutting line during its initial forward run is the same as its running length during its reverse run, and the running length of the cutting line during its subsequent forward run is less than its running length during its reverse run.

[0016] In one embodiment, the cutting line has a running length of 16km during its initial forward run, a running length of 16km during its reverse run, and a running length of 6km during its subsequent forward run.

[0017] In one embodiment, providing the silicon rod and moving the silicon rod toward the dicing wire mesh includes:

[0018] When the cutting depth of the dicing wire on the silicon rod is less than 20 mm, the relative moving speed of the silicon rod and the dicing wire mesh is a first speed; when the cutting depth of the dicing wire on the silicon rod is 20 mm to 80 mm, the relative moving speed of the silicon rod and the dicing wire mesh is a second speed; when the cutting depth of the dicing wire on the silicon rod is greater than 80 mm, the relative moving speed of the silicon rod and the dicing wire mesh is a third speed.

[0019] The second speed is greater than the first speed and the third speed.

[0020] In one embodiment, the first speed is 2.3 mm / min; the second speed is 2.8 mm / min; and the third speed gradually decreases as the cutting depth of the cutting line on the silicon rod gradually increases.

[0021] In one embodiment, the step of gradually decreasing the third speed as the cutting depth of the dicing wire on the silicon rod gradually increases includes:

[0022] When the cutting depth of the dicing wire on the silicon rod is 80mm-100mm, the relative moving speed of the silicon rod and the dicing wire mesh is 2.6mm / min; when the cutting depth of the dicing wire on the silicon rod is 100mm-120mm, the relative moving speed of the silicon rod and the dicing wire mesh is 2.3mm / min; when the cutting depth of the dicing wire on the silicon rod is 120mm-140mm, the relative moving speed of the silicon rod and the dicing wire mesh is 2mm / min. When the cutting depth of the dicing wire on the silicon rod is 140mm-160mm, the relative moving speed of the silicon rod and the dicing wire mesh is 1.7mm / min; when the cutting depth of the dicing wire on the silicon rod is 160mm-180mm, the relative moving speed of the silicon rod and the dicing wire mesh is 1.4mm / min; and when the cutting depth of the dicing wire on the silicon rod is 180mm-190mm, the relative moving speed of the silicon rod and the dicing wire mesh is 1mm / min.

[0023] In one embodiment, providing the cut wire mesh includes:

[0024] The cutting wire is wound around the first upper guide wheel, the second upper guide wheel and the lower guide wheel, and the cutting wire mesh is formed between the first upper guide wheel and the second upper guide wheel;

[0025] Adjust the height of the first upper guide wheel and the second upper guide wheel so that the height difference between the first upper guide wheel and the second upper guide wheel is greater than 0.3mm and less than 0.7mm;

[0026] Adjust the position of the lower guide wheel so that its axis intersects the perpendicular bisector of the line connecting the first upper guide wheel and the second upper guide wheel.

[0027] In one embodiment, adjusting the height of the first upper guide wheel and the second upper guide wheel includes: making the height difference between the first upper guide wheel and the second upper guide wheel 0.5mm.

[0028] The aforementioned silicon wafer cutting method utilizes a single cutting wire three times by cyclically performing an initial forward run, a reverse run, and a subsequent forward run during the cutting process. During these three runs, the initial forward run, with its highest wire speed, achieves the greatest cutting depth, while the subsequent forward run, with its lowest wire speed, minimizes the cutting depth. This effectively controls the cutting wire speed and depth based on the wear condition of the wire, ensuring both full utilization of the cutting wire and guaranteed cutting quality, thereby ensuring the quality of the silicon wafer, while maintaining proper wire bow operation.

[0029] In a second aspect, a silicon wafer cutting apparatus is provided for implementing the silicon wafer cutting method in any of the above embodiments, comprising an upper and lower worktable and a main roller mechanism, wherein the worktable is used to fix the silicon rod to be cut, and the main roller mechanism is used to install cutting wires to form a cutting wire mesh.

[0030] The main roller mechanism includes a first upper guide roller, a second upper guide roller, and a lower guide roller. The difference between the distance between the first upper guide roller and the worktable and the distance between the second upper guide roller and the worktable is greater than 0.3 mm and less than 0.7 mm. The lower guide roller is disposed below the first upper guide roller and the second upper guide roller, and the axis of the lower guide roller intersects the perpendicular bisector of the line connecting the first upper guide roller and the second upper guide roller.

[0031] The aforementioned silicon wafer cutting device fixes the silicon rod to be cut on a worktable and installs a cutting wire through a main roller mechanism to cut the silicon rod. During the cutting process, the silicon wafer cutting method described in the embodiment can effectively control the cutting wire speed and cutting depth according to the wear condition of the cutting wire. This ensures that the cutting wire is fully utilized while maintaining normal wire bow condition, thus guaranteeing the cutting quality and ultimately ensuring the quality of the silicon wafer. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the steps of a silicon wafer cutting method according to some embodiments of this application.

[0033] Figure 2 This is a partial structural schematic diagram of a silicon wafer cutting apparatus according to some embodiments of this application.

[0034] Figure label:

[0035] 1. Worktable; 2. Main roller mechanism; 21. First upper guide roller; 22. Second upper guide roller; 23. Lower guide roller. Detailed Implementation

[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0037] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and 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 orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0038] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0040] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0042] See Figure 1 One embodiment of this application provides a silicon wafer cutting method, including the following steps:

[0043] A new cutting line is set on the main roller mechanism to form a cutting line mesh.

[0044] Specifically, the main roller mechanism includes a first upper guide roller and a second upper guide roller. Both the first upper guide roller and the second upper guide roller are provided with multiple wire grooves. The cutting wire is sequentially wound around the multiple wire grooves of the first upper guide roller and the second upper guide roller to form a cutting wire mesh.

[0045] The silicon rod to be cut is fed into the cutting wire mesh, causing the silicon rod and the cutting wire mesh to move towards each other.

[0046] Specifically, a worktable is provided above the main roller mechanism. After the silicon rod to be cut is fixed, the worktable can drive the silicon rod to move, so as to shorten the distance between the silicon rod and the cutting wire mesh. When the silicon rod comes into contact with the cutting wire mesh, the silicon rod can be cut into silicon wafers by the cutting wire mesh.

[0047] The main roller mechanism drives the cutting wires in the cutting wire mesh to run in a reciprocating cycle, cutting the silicon rods entering the cutting wire mesh into silicon wafers.

[0048] Specifically, the main roller mechanism also includes a take-up and untake-up mechanism and a drive mechanism. The take-up and untake-up mechanism includes an untake-up roller and a take-up roller, which can take up and untake the cutting wire during the cutting process. The drive mechanism is used to drive the main roller mechanism and the take-up and untake-up mechanism, so that the first upper guide wheel, the second upper guide wheel, the untake-up roller and the take-up roller rotate alternately in the forward and reverse directions, so as to drive the cutting wire in the cutting wire mesh on the first upper guide wheel and the second upper guide wheel to run in a cyclic reciprocating motion. The untake-up roller and the take-up roller alternately perform take-up and untake-up operations during the reciprocating motion of the cutting wire.

[0049] The cyclical operation includes an initial forward run, a reverse run, and a second forward run. The linear speed of the initial forward run is greater than that of the reverse run, the linear speed of the reverse run is greater than that of the second forward run, the cutting depth of the initial forward run is greater than that of the reverse run, and the cutting depth of the reverse run is greater than that of the second forward run.

[0050] Specifically, when cutting the silicon rod through the cutting lines in the cutting wire mesh, the drive mechanism first drives the feed roller, take-up roller, first upper guide roller, and second upper guide roller to rotate forward for the first stage of cutting the silicon rod. After the first stage of cutting is completed, the drive mechanism then drives the feed roller, take-up roller, first upper guide roller, and second upper guide roller to rotate in the opposite direction for the second stage of cutting the silicon rod. After the second stage of cutting is completed, the drive mechanism then drives the feed roller, take-up roller, first upper guide roller, and second upper guide roller to rotate forward for the third stage of cutting the silicon rod, thus cutting the silicon rod into silicon wafers. The cutting speed in the first stage is greater than the cutting speed in the second stage, and the cutting speed in the second stage is greater than the cutting speed in the third stage. The cutting depth in the first stage is greater than the cutting depth in the second stage, and the cutting depth in the second stage is greater than the cutting depth in the third stage.

[0051] In the specific operation of the above-described silicon wafer dicing method, the worktable first moves the silicon ingot downwards, bringing it into contact with the dicing wire mesh and gradually guiding it into the mesh. The ingot undergoes the first stage of dicing through the initially forward-moving dicing wires. This first stage of dicing is completed when the worktable has moved the ingot downwards a predetermined first distance. The worktable then continues to move the ingot downwards, performing the second stage of dicing through the reverse-moving dicing wires. This second stage of dicing is completed when the worktable has moved the ingot downwards a predetermined second distance. Finally, the worktable continues to move the ingot downwards, performing the third stage of dicing through the again forward-moving dicing wires. This third stage of dicing is completed when the worktable has moved the ingot downwards a predetermined third distance, successfully dicing the silicon ingot into a silicon wafer.

[0052] The aforementioned silicon wafer cutting method utilizes a single cutting wire three times by cyclically performing an initial forward run, a reverse run, and a second forward run during the cutting process. During these three runs, the cutting depth is maximized during the initial forward run with the highest wire speed, and minimized during the second forward run with the lowest wire speed. Specifically, the cutting speed in the first stage is greater than the cutting speed in the second stage, which in turn is greater than the cutting speed in the third stage. Furthermore, a preset first distance is greater than a preset second distance, and a preset second distance is greater than a preset third distance. This effectively controls the cutting speed and depth based on the wear condition of the cutting wire, allowing for greater cutting speeds at greater depths. This ensures that the cutting wire is fully utilized while maintaining proper wire bowing, thus guaranteeing cutting quality and ultimately ensuring silicon wafer quality.

[0053] In one embodiment, the cutting wires in the cutting wire mesh are driven to reciprocate cyclically by a main roller mechanism, including:

[0054] The main roller mechanism drives the cutting line to perform its initial forward operation, cutting the silicon rod to a depth of 140mm. Specifically, the control table moves the silicon rod downwards, while the drive mechanism drives the feed roller, take-up roller, first upper guide roller, and second upper guide roller to rotate forward, so that the cutting line, running forward for the first time, performs the first stage of cutting on the silicon rod. When the silicon rod is cut to a depth of 140mm, the first stage of cutting on the silicon rod is completed.

[0055] The main roller mechanism drives the cutting line to run in reverse, cutting the silicon rod to a depth of 185mm. Specifically, the control table continues to move the silicon rod downwards, while the drive mechanism drives the feed roller, take-up roller, first upper guide roller, and second upper guide roller to rotate in reverse, causing the reverse-running cutting line to perform the second stage of cutting on the silicon rod. When the silicon rod is cut to a depth of 185mm, the second stage of cutting on the silicon rod is completed.

[0056] The main roller mechanism drives the cutting line to run forward again, cutting the silicon rod to a depth of 190mm, thus cutting the silicon rod into silicon wafers. Specifically, the control table continues to move the silicon rod downward, while the drive mechanism drives the feed roller, take-up roller, first upper guide roller, and second upper guide roller to rotate forward, causing the cutting line running forward again to perform the third stage of cutting on the silicon rod. When the silicon rod is cut to a depth of 190mm, the third stage of cutting on the silicon rod is completed, at which point the silicon rod is completely cut off to form silicon wafers.

[0057] More specifically, in order to cut through the silicon ingot, the total cutting depth of the silicon ingot is set to 190mm in this embodiment of the invention. Within the total cutting depth range, different cutting depths are defined as different cutting stages. The cutting depth range of 0mm-140mm is defined as the first stage; the cutting depth range of 140mm-185mm is defined as the second stage; and the cutting depth range of 185mm-190mm is defined as the third stage. It is understood that the total cutting depth is not limited to 190mm; other total cutting depths are also possible, provided that the silicon ingot is cut through.

[0058] In one embodiment, the running length of the cutting line during its initial forward run is the same as its running length during its reverse run, and the running length of the cutting line during its subsequent forward run is less than its running length during its reverse run.

[0059] Specifically, the cutting line runs for 16 km during its initial forward run, 16 km during its reverse run, and 6 km during its second forward run. More specifically, the cutting line runs for 16 km during the first stage of the cutting process, 16 km during the second stage of the cutting process, and 6 km during the third stage of the cutting process.

[0060] Existing methods involve first running the dicing wire in the forward direction, then running it in the reverse direction to cut the silicon rod into silicon wafers. Experiments have shown that this method is less effective than the method described in this application in ensuring both normal bow and dicing wire operation. Specific experimental data can be found in Tables 1, 2, 3, and 4 below.

[0061]

[0062] Table 1

[0063]

[0064] Table 2

[0065]

[0066] Table 3

[0067]

[0068] Table 4

[0069] Table 1 shows the bow values ​​for the cutting method where the dicing wire is first moved forward for 16 km to cut the silicon ingot to a depth of 185 mm, and then moved backward for 6 km to cut the silicon ingot to a depth of 190 mm. Table 2 shows the bow values ​​for the cutting method where the dicing wire is first moved forward for 16 km to cut the silicon ingot to a depth of 120 mm, and then moved backward for 16 km to cut the silicon ingot to a depth of 190 mm. Table 3 shows the bow values ​​for the cutting method where the dicing wire is first moved forward for 16 km to cut the silicon ingot to a depth of 140 mm, and then moved backward for 16 km to cut the silicon ingot to a depth of 190 mm. Table 4 shows the bow values ​​of the cutting method used in this application, in which the cutting line is first run forward for 16km to cut the silicon rod to a depth of 140mm, then run in reverse for 16km to cut the silicon rod to a depth of 185mm, and then run forward for 6km to cut the silicon rod to a depth of 190mm to complete the cutting.

[0070] Comparing Tables 1, 2, 3, and 4, it can be seen that the bow values ​​in Tables 2 and 3 are all less than 6. Therefore, compared with the method corresponding to Table 1, the methods corresponding to Tables 2 and 3, and the method of this application corresponding to Table 4, can achieve the effect of reducing the bow size when used.

[0071] However, during the experiment, it was found that the method corresponding to Table 2 had poor cutting force when the cutting line was running in reverse for 16km, resulting in cutting abnormalities and even line breakage. Therefore, by increasing the cutting depth of the first forward run to 140mm, the probability of cutting abnormalities and line breakage during subsequent reverse runs of the cutting line was reduced.

[0072] After increasing the initial forward cut depth to 140mm, when operating using the method corresponding to Table 3, it was found that the wire bow was large during the 16km reverse run, and there were still 10% of cutting anomalies or even wire breaks. However, when operating using the method of this application corresponding to Table 4, the wire bow was smaller during both the 16km reverse run and the 6km forward run, and there were no cutting anomalies or wire breaks.

[0073] Therefore, compared with the cutting method of first running the cutting line in the forward direction and then running the cutting line in the reverse direction, this application can achieve the effect of making full use of the cutting line and ensuring the cutting quality while ensuring the normal operation of the wire bow, thereby ensuring the quality of the silicon wafer.

[0074] Besides linear speed, the table feed rate is also a crucial factor affecting the wire bow and cutting quality. In the silicon wafer cutting industry, TTV (Total Thickness Variation) refers to the deviation between the thickest and thinnest points on the same silicon wafer. It is typically measured at four symmetrical points on the circumference, 6mm from the wafer's edge and at the center. The difference between the maximum and minimum thickness measurements is called the total thickness variation. Abnormal TTV results in persistent thin and thick wafers. For silicon wafers, thin and thick wafers are a very important indicator of wafer quality, and their presence affects the wafer yield.

[0075] Most existing silicon wafer cutting methods are unable to adapt to the cutting of large-size silicon wafers. The feed speed of the worktable cannot be combined with the cutting capability of the cutting line, resulting in a decrease in the cutting capability of the cutting line when the feed speed of the worktable is high, which leads to excessive wire bowing during cutting and abnormal TTV index of silicon wafer.

[0076] To avoid excessively large wire bowing during the cutting process and to reduce wire breakage and TTV abnormalities, in one embodiment, the silicon rod to be cut is fed to the cutting wire mesh via a worktable. The total cutting depth of the silicon rod is 190mm, and the feed speed of the worktable in the cutting depth range of 20mm-80mm is greater than the feed speed in other cutting depth ranges.

[0077] For example, in an embodiment of the present invention, the total cutting depth of the silicon rod is set to 190mm. Within the total cutting depth range, different cutting depths are defined as different cutting stages. Specifically, the cutting depth range of 0mm-20mm is defined as the early cutting stage; the cutting depth range of 20mm-80mm is defined as the middle cutting stage; and the cutting depth range of 80mm-190mm is defined as the late cutting stage. It can be understood that the total cutting depth is not limited to 190mm; other total cutting depths are also possible, provided that the silicon rod can be cut through.

[0078] The feed rate during the middle stage of the cutting process is higher than the feed rate during the early stage of cutting. This facilitates the cutting wire's entry into the silicon ingot and prevents the cutting wire from accidentally jumping out. Specifically, before the silicon ingot contacts the cutting wire, the table feed rate is lower than the table feed rate within the 0mm-20mm cutting depth range. This ensures the cutting wire enters the silicon ingot and prevents uneven thickness of the silicon wafers at the entry point. After the cutting wire enters the silicon ingot, the table feed rate is slightly increased, but still lower than the feed rate within the 20mm-80mm cutting depth range to prevent the cutting wire from accidentally jumping out.

[0079] The feed rate during the middle stage of cutting is higher than that during the later stage. This allows the cutting wire to work in conjunction with the higher feed rate of the table while maintaining strong cutting power, thus ensuring cutting efficiency and minimizing wire bowing. Specifically, when the cutting depth of the cutting wire into the silicon ingot is within the range of 20mm-80mm, the feed rate is increased to improve cutting efficiency. When the cutting depth of the cutting wire into the silicon ingot is within the range of 80mm-190mm, the feed rate is decreased to prevent cutting wire breakage.

[0080] Experiments have confirmed that the above speed distribution achieves good results. Specific experimental data can be found below.

[0081] Tables 5, 6, and 7.

[0082]

[0083] Table 5

[0084]

[0085] Table 6

[0086]

[0087] Table 7

[0088] Table 1 shows the bow values ​​when the table feed rate in the 20mm-40mm cutting depth range is greater than the feed rate in other cutting depth ranges. Table 6 shows the bow values ​​when the table feed rate in the 20mm-80mm cutting depth range is greater than the feed rate in other cutting depth ranges. Table 7 shows the bow values ​​when the table feed rate in the 20mm-60mm cutting depth range is greater than the feed rate in other cutting depth ranges.

[0089] Comparing Tables 5 and 6, it can be seen that when the cutting depth is in the range of 80mm-100mm, if the table continues to feed at a speed of 2.8mm / min, the arc value of the cutting line will increase significantly, and the cutting line is prone to cutting abnormalities and breakage.

[0090] Comparing Tables 6 and 7, it can be seen that when the cutting depth is in the range of 60mm-100mm, if the worktable starts to slow down, the bow value of the cutting line will decrease accordingly, but the total cutting time will increase, thus affecting the production capacity.

[0091] Therefore, it can be seen that the speed allocation of the workbench in this embodiment can simultaneously ensure the normal operation of the pantograph and the production capacity requirements.

[0092] In one embodiment, the table feed rate is 2.3 mm / min in the 0 mm-20 mm cutting depth range, 2.8 mm / min in the 20 mm-80 mm cutting depth range, and gradually decreases in the 80 mm-190 mm cutting depth range.

[0093] In practice, before the silicon ingot contacts the dicing wire, the table feed rate is less than 2.3 mm / min to facilitate the dicing wire's entry into the silicon ingot and prevent uneven thickness of the silicon wafers at the entry point. After the dicing wire enters the silicon ingot, the table feed rate is increased to 2.3 mm / min, but still below 2.8 mm / min to prevent the dicing wire from accidentally jumping out. When the dicing depth of the silicon ingot is within the range of 20 mm to 80 mm, the table feed rate is increased to 2.8 mm / min to improve cutting efficiency. When the dicing depth of the silicon ingot is within the range of 80 mm to 190 mm, the table feed rate is gradually reduced to prevent the dicing wire from breaking.

[0094] In one embodiment, the table feed rate is 2.6 mm / min within the 80mm-100mm cutting depth range, 2.3 mm / min within the 100mm-120mm cutting depth range, 2 mm / min within the 120mm-140mm cutting depth range, 1.7 mm / min within the 140mm-160mm cutting depth range, 1.4 mm / min within the 160mm-180mm cutting depth range, and 1 mm / min within the 180mm-190mm cutting depth range. By gradually reducing the table feed rate, breakage of the cutting line in the later stages of cutting is avoided.

[0095] In one embodiment, when setting the new cutting lines on the main roller mechanism to form a cutting wire mesh, the method further includes:

[0096] Adjust the height of the first and second upper guide rollers of the main roller mechanism so that the height difference between the first and second upper guide rollers is greater than 0.3 mm and less than 0.7 mm.

[0097] Specifically, the main roller mechanism includes an adjustment mechanism, a first upper guide wheel, and a second upper guide wheel. The adjustment mechanism is connected to the first upper guide wheel and the second upper guide wheel to adjust the distance between the first upper guide wheel and the worktable and the distance between the second upper guide wheel and the worktable, so that the difference between the distance between the first upper guide wheel and the worktable and the distance between the second upper guide wheel and the worktable is greater than 0.3 mm and less than 0.7 mm.

[0098] Adjust the position of the lower guide wheel of the main roller mechanism so that the axis of the lower guide wheel intersects the perpendicular bisector of the line connecting the first upper guide wheel and the second upper guide wheel.

[0099] Specifically, the main roller mechanism also includes a lower guide wheel, which is located below the first and second upper guide wheels and is connected to the adjustment mechanism. The adjustment mechanism can adjust the position of the lower guide wheel so that the axis of the lower guide wheel intersects the perpendicular bisector of the line connecting the first and second upper guide wheels.

[0100] The cutting wire is wound around the first upper guide wheel, the second upper guide wheel and the lower guide wheel, and the cutting wire mesh is formed between the first upper guide wheel and the second upper guide wheel.

[0101] In one embodiment, when adjusting the height of the first upper guide wheel and the second upper guide wheel of the main roller mechanism, the height difference between the first upper guide wheel and the second upper guide wheel is 0.5 mm.

[0102] Specifically, the control and adjustment mechanism adjusts the distance between the first upper guide wheel and the worktable and the distance between the second upper guide wheel and the worktable, so that the difference between the distance between the first upper guide wheel and the worktable and the distance between the second upper guide wheel and the worktable is 0.5mm.

[0103] Experiments have confirmed that the above positional allocation can result in a smaller bowing of the cutting line during the cutting process. Specific experimental data can be found in Table 8 below.

[0104] Lower guide wheel The difference is 0.3. Difference 0.5 Difference 0.7 flush with the first upper guide wheel 5.5 5.9 6.5 flush with the second upper guide wheel 5.4 6 6.7 Centered on the two upper guide wheels 5.2 5.5 6.3 Remark 0.3 exists in TTV

[0105] Table 8

[0106] Table 8 shows the pantograph values ​​when the height difference between the first and second upper guide rollers is 0.3 mm, 0.5 mm, and 0.7 mm, respectively.

[0107] The comparison shows that when the height difference between the first and second upper guide rollers is 0.3mm, the wire bow value of the cutting line is the smallest. However, the cut silicon wafers generally exhibit TTV (Total Thickness Variation), thus affecting the wafer yield. When the height difference between the first and second upper guide rollers is 0.5mm and 0.7mm, the cut silicon wafers do not exhibit TTV. However, the wire bow value is larger when the height difference between the first and second upper guide rollers is 0.7mm, making the cutting line more prone to cutting abnormalities and wire breaks.

[0108] In summary, when the height difference between the first and second upper guide rollers is 0.5mm, it can ensure that the cut silicon wafer does not have TTV (Total Thickness Variation) and that the cutting wire has a small wire bow during cutting, making it less likely to have cutting abnormalities and wire breakage.

[0109] In addition, Table 8 also shows the line bow values ​​when the axis of the lower guide wheel intersects the perpendicular bisector of the first upper guide wheel, the line bow values ​​when the axis of the lower guide wheel intersects the perpendicular bisector of the line connecting the first and second upper guide wheels, and the line bow values ​​when the axis of the lower guide wheel intersects the perpendicular bisector of the second upper guide wheel.

[0110] The comparison shows that the bow value is small when the axis of the lower guide wheel intersects the perpendicular bisector of the line connecting the first and second upper guide wheels. Therefore, when the axis of the lower guide wheel intersects the perpendicular bisector of the line connecting the first and second upper guide wheels, the cutting line can be guaranteed to have a small bow during cutting, and there is less chance of cutting abnormalities and line breakage.

[0111] See Figure 2The embodiments of this application also provide a silicon wafer cutting apparatus for implementing the silicon wafer cutting method in any of the above embodiments, including a worktable 1 and a main roller mechanism 2 arranged vertically. The worktable 1 is used to fix the silicon rod to be cut, and the main roller mechanism 2 is used to install cutting wires to form a cutting wire mesh.

[0112] Specifically, the main roller mechanism 2 is located below the worktable 1 and includes a first upper guide roller 21, a second upper guide roller 22 and a lower guide roller 23. The difference between the distance between the first upper guide roller 21 and the worktable 1 and the distance between the second upper guide roller 22 and the worktable 1 is greater than 0.3 mm and less than 0.7 mm. The lower guide roller 23 is located below the first upper guide roller 21 and the second upper guide roller 22, and the axis of the lower guide roller 23 intersects the perpendicular bisector of the line connecting the first upper guide roller 21 and the second upper guide roller 22.

[0113] More specifically, the main roller mechanism 2 includes an adjustment mechanism, a first upper guide wheel 21, a second upper guide wheel 22, and a lower guide wheel 23. The adjustment mechanism is pulsatorically connected to the first upper guide wheel 21, the second upper guide wheel 22, and the lower guide wheel 23 to adjust their positions. The difference between the distance between the first upper guide wheel 21 and the worktable 1 and the distance between the second upper guide wheel 22 and the worktable 1 is 0.5 mm, and the axis of the lower guide wheel 23 intersects the perpendicular bisector of the line connecting the first upper guide wheel 21 and the second upper guide wheel 22. The adjustment mechanism may include a first cylinder, a second cylinder, and a third cylinder, which are pulsatorically connected to the first upper guide wheel 21, the second upper guide wheel 22, and the lower guide wheel 23, respectively.

[0114] In use, the silicon wafer cutting device described above fixes the silicon rod to be cut on the worktable 1 and fixes the cutting line on the main roller mechanism 2, forming a cutting wire mesh between the first upper guide roller 21 and the second upper guide roller 22. The worktable 1 then moves the silicon rod downwards, bringing it into contact with the cutting wire mesh and gradually guiding it into the mesh. The first stage of cutting is performed by the initially forward-moving cutting wire. This first stage of cutting is completed when the worktable 1 moves the silicon rod downwards a predetermined first distance. The worktable 1 then continues to move the silicon rod downwards, performing a second stage of cutting by the reverse-moving cutting wire. This second stage of cutting is completed when the worktable 1 moves the silicon rod downwards a predetermined second distance. Finally, the worktable 1 continues to move the silicon rod downwards, performing a third stage of cutting by the again forward-moving cutting wire. This third stage of cutting is completed when the worktable 1 moves the silicon rod downwards a predetermined third distance, and the silicon rod is successfully cut into silicon wafers.

[0115] The aforementioned silicon wafer cutting device uses a main roller mechanism 2 to mount a cutting wire to cut silicon rods. During the cutting process, the silicon wafer cutting method described in this embodiment maximizes the cutting depth during the initial forward run with the highest wire speed and minimizes the cutting depth during the subsequent forward run with the lowest wire speed. Specifically, the cutting speed in the first stage is greater than the cutting speed in the second stage, the cutting speed in the second stage is greater than the cutting speed in the third stage, the preset first distance is greater than the preset second distance, and the preset second distance is greater than the preset third distance. This effectively controls the cutting wire speed and cutting depth based on the wear condition of the cutting wire, allowing the cutting wire to have a correspondingly higher cutting speed at greater cutting depths. This ensures that the cutting wire is fully utilized while maintaining proper wire bow operation, thus guaranteeing cutting quality and ultimately ensuring silicon wafer quality.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method of cutting a silicon wafer, characterized by, The method comprises the following steps: providing a cutting wire net; providing a silicon rod and moving the silicon rod towards the cutting wire net; driving the cutting wire in the cutting wire net to perform a reciprocating operation to cut the silicon rod into silicon wafers; wherein the reciprocating operation comprises a first forward operation, a reverse operation and a second forward operation, the wire speed of the first forward operation is greater than the wire speed of the reverse operation, the wire speed of the reverse operation is greater than the wire speed of the second forward operation, the cutting depth of the first forward operation is greater than the cutting depth of the reverse operation, and the cutting depth of the reverse operation is greater than the cutting depth of the second forward operation.

2. The method of dicing a silicon wafer of claim 1 wherein, The driving the cutting wire in the cutting wire net to perform a reciprocating operation comprises: driving the cutting wire to perform a first forward operation, so that the ratio of the cutting depth of the cutting wire on the silicon rod to the total cutting depth of the silicon rod is 14:19; driving the cutting wire to perform a reverse operation, so that the ratio of the cutting depth of the cutting wire on the silicon rod to the total cutting depth of the silicon rod is 37:38; driving the cutting wire to perform a second forward operation to cut the silicon rod into silicon wafers.

3. The method of dicing a silicon wafer of claim 1 wherein, The running length of the cutting wire when performing the first forward operation is consistent with the running length of the cutting wire when performing the reverse operation, and the running length of the cutting wire when performing the second forward operation is less than the running length of the cutting wire when performing the reverse operation.

4. The method of dicing a silicon wafer of claim 3 wherein, The running length of the cutting wire when performing the first forward operation is 16 km, the running length of the cutting wire when performing the reverse operation is 16 km, and the running length of the cutting wire when performing the second forward operation is 6 km.

5. The method of dicing a silicon wafer of claim 1 wherein, The providing a silicon rod and moving the silicon rod towards the cutting wire net comprises: when the cutting depth of the cutting wire on the silicon rod is less than 20 mm, the moving speed of the silicon rod towards the cutting wire net is a first speed; when the cutting depth of the cutting wire on the silicon rod is 20 mm-80 mm, the moving speed of the silicon rod towards the cutting wire net is a second speed; when the cutting depth of the cutting wire on the silicon rod is greater than 80 mm, the moving speed of the silicon rod towards the cutting wire net is a third speed; the second speed is greater than the first speed and the third speed.

6. The method of dicing a silicon wafer of claim 5 wherein, The first speed is 2.3 mm / min, the second speed is 2.8 mm / min, and the third speed gradually decreases as the cutting depth of the cutting wire on the silicon rod gradually increases.

7. The method of dicing a silicon wafer of claim 6 wherein, The third speed gradually decreases as the cutting depth of the cutting wire on the silicon rod gradually increases, comprising: In the case that the cutting depth of the cutting line on the silicon rod is 80mm-100mm, the moving speed of the silicon rod and the cutting line net is 2.6mm / min; in the case that the cutting depth of the cutting line on the silicon rod is 100mm-120mm, the moving speed of the silicon rod and the cutting line net is 2.3mm / min; in the case that the cutting depth of the cutting line on the silicon rod is 120mm-140mm, the moving speed of the silicon rod and the cutting line net is 2mm / min; in the case that the cutting depth of the cutting line on the silicon rod is 140mm-160mm, the moving speed of the silicon rod and the cutting line net is 1.7mm / min; in the case that the cutting depth of the cutting line on the silicon rod is 160mm-180mm, the moving speed of the silicon rod and the cutting line net is 1.4mm / min; in the case that the cutting depth of the cutting line on the silicon rod is 180mm-190mm, the moving speed of the silicon rod and the cutting line net is 1mm / min.

8. The method of dicing a silicon wafer of claim 1 wherein, The providing cutting line net comprises: winding the cutting line on the first upper guide wheel, the second upper guide wheel and the lower guide wheel, and the cutting line net is formed between the first upper guide wheel and the second upper guide wheel; adjusting the height of the first upper guide wheel and the second upper guide wheel, so that the height difference between the first upper guide wheel and the second upper guide wheel is greater than 0.3mm and less than 0.7mm; adjusting the position of the lower guide wheel, so that the axis of the lower guide wheel intersects with the perpendicular bisector of the connecting line between the first upper guide wheel and the second upper guide wheel.

9. The method of dicing a silicon wafer of claim 8 wherein, The adjusting the height of the first upper guide wheel and the second upper guide wheel comprises: making the height difference between the first upper guide wheel and the second upper guide wheel be 0.5mm.

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