Control method for reducing wire breakage caused by insufficient cutting force

Abstract

The invention provides a control method for reducing wire breakage caused by insufficient cutting force, which comprises the following steps of: based on the diameter of a crystal bar, dividing the cutting depth into a plurality of equal feeding positions; in the cutting process, the machine speed and / or the wire using amount and / or the tension are / is controlled to be adjusted along with the increase of the cutting feeding position, so that the acting force of the crystal bar on the diamond wire is reduced. According to the control method for reducing wire breakage caused by insufficient cutting force, the cutting process is optimized, the technical problem that the cutting force of a diamond wire is insufficient is solved to the maximum extent, the cutting quality is improved, the wire breakage rate is reduced to 0.75% from 4.28% at present, the cutting efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of slicing processing, and in particular, relates to a control method for reducing wire breakage caused by insufficient cutting force. Background Art

[0002] The size of existing semiconductor silicon substrates has gradually tended to be thinner and larger in diameter, from the earliest 2 inches and 3 inches to today's 8 inches, 12 inches, and 18 inches under development. With the increase in the area of ​​silicon wafers, the risk of wire breakage for silicon wafers of different sizes has become increasingly stringent. In existing slicing processes, the risk of wire breakage is often caused by insufficient cutting force of the diamond wire. Once a wire break occurs, it not only affects the cutting quality of the silicon wafer surface, but also affects the cutting efficiency. It is necessary to stop the machine immediately for inspection and quickly connect the wire break position. At the same time, the silicon wafer at the wire break needs to be cut off, which directly affects the product yield. Summary of the invention

[0003] The present application provides a control method for reducing wire breakage caused by insufficient cutting force, which solves the technical problem that the existing cutting process design is unreasonable, resulting in insufficient cutting force and easy wire breakage.

[0004] In order to solve at least one of the above technical problems, the technical solution adopted in this application is:

[0005] A control method for reducing wire breakage caused by insufficient cutting force, comprising: dividing the cutting depth into a number of equal feed positions based on the diameter of the crystal rod; during the cutting process, controlling the machine speed and / or wire consumption and / or tension to adjust as the cutting feed position increases, so as to reduce the force exerted by the crystal rod on the diamond wire.

[0006] Furthermore, as the cutting feed position increases, the machine speed first gradually decreases, stabilizes, and then gradually increases, wherein the machine speed after the change is equal to the machine speed before the change multiplied by the change coefficient.

[0007] Furthermore, the changed machine speed has the smallest value when the cutting depth is at the middle position.

[0008] Furthermore, the variation coefficient=1-variation amount, and the variation amount is less than 1.

[0009] Furthermore, the change is the chord length divided by the correction coefficient, wherein the chord length is a line segment between the outermost two end points of the cross section where the crystal rod cutting position is located, and is calculated by a formula; the correction coefficient is greater than 1000.

[0010] Furthermore, the chord length formula is:

[0011]

[0012] Wherein, A(x1, y1) and B(x2, y2) are the positions of the two outermost points of the cross section where the crystal rod is cut;

[0013] K is the slope of line AB;

[0014] The correction factor is 4000.

[0015] Furthermore, as the cutting feed position increases, the wire consumption first increases gradually and then decreases gradually, specifically,

[0016] The forward length is the standard length;

[0017] When the cutting feed position is before the middle position, the forward length of the diamond wire is the standard length, and the backward length is 0.6-0.99 times of the standard length, and the wire consumption increases gradually;

[0018] When the cutting feed position is in the middle, the increase in wire consumption reaches the highest value;

[0019] After the cutting feed position is in the middle position, the forward moving length of the diamond wire is the standard length, and the backward moving length is 0.6-0.99 times of the standard length, and the wire consumption is gradually reduced.

[0020] Furthermore, as the cutting feed position increases, the changed tension value is 1-5N smaller than the tension value before the change; and the changed tension value remains unchanged throughout the entire cutting process.

[0021] Furthermore, during the entire cutting process, the flow rate and concentration of the cutting fluid remain constant.

[0022] Furthermore, the cutting fluid flow rate is 10-100 L / min; the cutting fluid temperature is 15-30°C.

[0023] A control method designed in this application is used to reduce wire breakage caused by insufficient cutting force, optimize the cutting process, and make appropriate adjustments based on different problems during cutting. By controlling the process conditions such as console speed, wire, tension, etc., the cutting process is more closely matched to the steel wire, and the technical problem of insufficient cutting force of the diamond wire is minimized, the cutting quality is improved, and the wire breakage rate is reduced from the current 4.28% to the current 0.75%, which not only improves the cutting efficiency but also reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of the control method in this application;

[0025] Figure 2 is a schematic diagram of the chord length in this application;

[0026] Figure 3 It is a comparison curve diagram before and after the machine speed changes in this application;

[0027] Figure 4 It is a comparison curve diagram before and after the change of thread usage in this application;

[0028] Figure 5 It is a comparison curve diagram before and after the tension changes in this application.

[0029] In the figure:

[0030] 10, crystal rod 20, diamond wire DETAILED DESCRIPTION

[0031] The present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] This embodiment proposes a control method to reduce the wire breakage caused by insufficient cutting force, such as Figure 1 As shown, including:

[0033] Based on the diameter of the crystal rod 10, the cutting depth is first divided into several equal feed positions. In this embodiment, the diameters of all crystal rods 10 are divided into 22 equal parts, starting from position 0 and ending at the 22nd equal part. In this way, you don't need to consider the actual diameter size of the crystal rod 10, and you can directly know its position based on the equal part where the feed position is located. In the actual slicing system, the cutting depth is also defined by dividing the diameter equally, so as to observe or monitor its feed position. When the feed position is located between the 10th and 11th parts, it is the middle position of the cutting depth. Taking the middle position as the dividing line, the feed position in front of it, that is, the feed position between the 0th-10th equal parts, is the upper half of the cutting depth; the feed position behind it, that is, the feed position between the 11th-22nd equal parts, is the lower half of the cutting depth.

[0034] During the cutting process, the machine speed V (mm / min) and / or the amount of wire used will be adjusted as the cutting feed position increases, that is, as the cutting feed position increases, the machine speed is controlled to first gradually decrease, stabilize, and then gradually increase; and / or, the amount of wire used is controlled to first gradually increase and then gradually decrease; thereby reducing the force exerted by the crystal rod 10 on the diamond wire 20 by adjusting the machine speed and the amount of wire used, thereby reducing the technical problem of wire breakage caused by insufficient cutting force.

[0035] Specifically, as the cutting feed position increases, the machine speed V will first gradually decrease during the 0th-7th feed position; when it is at the 7th-15th feed position, cutting is performed at the stable value; when it is at the 16th-22nd feed position, the machine speed will gradually increase. The law of the machine speed gradually increasing during the 16th-22nd feed position is the same as the law of its gradual decrease during the 0th-7th feed position.

[0036] Furthermore, the machine speed is the smallest at the 7th-15th feed positions, that is, the 7th-15th feed positions are the middle positions of the cutting depth, and the value of the changed machine speed in this middle position interval is at the minimum value. Because this stage is the stable stage in the cutting process of the crystal rod 10, it is in the middle interval of the cutting depth of the crystal rod 10. Not only is the friction of the crystal rod 10 on the diamond wire 20 large, but the cutting force is also very easy to be insufficient, so a lower machine speed is required, that is, it is necessary to cut at a lower feed speed, so as to reduce the force of the crystal rod 10 on the diamond wire 20; after the force is reduced, the diamond wire 20 is not easy to break.

[0037] The machine speed V after the change is equal to the machine speed V0 before the change multiplied by the change coefficient N.

[0038] That is, V=V0×N, wherein the coefficient of change N=1-the amount of change n, and the amount of change n is less than 1.

[0039] Furthermore, the variation n is the chord length divided by the correction coefficient m, wherein the correction coefficient m is greater than 1000. Based on multiple experimental verifications, the correction coefficient m is 4000, and the data of the machine speed V obtained is the best.

[0040] like Figure 2 As shown, during the downward cutting process of the crystal ingot 10, the diamond wire 20 is pressed down by the crystal ingot 10, generating a curved surface that bends downward. Since the crystal ingot 10 presses the diamond wire 20, the bending deformation of the diamond wire 20 is similar to an arc curve. The chord length is the line segment between the two outermost end points of the cross section where the crystal ingot cutting position is located, and it is calculated by the chord length formula.

[0041] The chord length formula is:

[0042]

[0043] Among them, A(x1, y1) and B(x2, y2) are the positions of the two outermost end points of the cross section where the cutting position of the crystal rod 10 is located. Since the straight line AB is always set horizontally, its slope is always 0. Accordingly, the length of the line segment AB is the chord length AB, which is the absolute value of x2-x1.

[0044] During the actual cutting process, the system will automatically monitor and identify the positions of point A and point B, calculate their coordinates, and calculate the length of the string length AB directly in real time through the string length formula preset in the system. Then, through the equal division of the crystal rod 10 feeding position, the curve diagram of the machine speed and the coefficient of variation can be directly obtained.

[0045] like Figure 3 As shown, it is a comparison curve chart before and after the machine speed changes at different feed positions. The horizontal axis is the equally divided cutting steps of the crystal rod 10, from 0 to 22, which are the cutting steps obtained by dividing along the cutting depth of the crystal rod 10. The vertical axis represents the change in the machine speed. When the change is 1, it means that the machine speed is the speed before the change; when the change is less than 1, the change at this position multiplied by the speed before the change is the machine speed after the change; because the speed before the change is only related to the speed before the change and the change, the speed before the change is omitted, and the change curve of the machine speed is only presented through the change curve of the change with the cutting depth. Figure 3 In the figure, a is the change in machine speed before the change, and b is the change in machine speed after the change.

[0046] It can be seen from the figure that the machine speed was uniformly decreased before the improvement, and variable speed after the improvement, and it was first decreased in the 0-7 cutting steps, kept stable in the middle 7-15 cutting steps, and gradually increased in the 15-22 cutting steps. This operation not only takes into account the impact of the diamond wire 20 load caused by the change in the diameter of the crystal rod 10, but also reduces the force of the load change on the diamond wire 20, thereby reducing the risk of the diamond wire 20 breaking.

[0047] Furthermore, as the cutting feed position increases, the amount of wire used first gradually increases and then gradually decreases. Specifically, during the slicing process, the diamond wire 20 will reciprocate to cut the crystal rod 10. Among them, the forward and backward lengths of the diamond wire 20 are preset in advance. In principle, they move equally, but generally the forward length is longer and the backward length is shorter. The forward length minus the backward length is the amount of wire used. In this embodiment, the forward length is used as a reference and is called the standard length L.

[0048] Before the cutting feed position is in the middle position, the forward length of the diamond wire 20 remains unchanged, that is, the standard length, and the backward length is 0.6-0.99 times the standard length, and the amount of wire used gradually increases. When the cutting feed position is in the middle position, the increase in the amount of wire used reaches the highest. After the cutting feed position is in the middle position, the forward length of the diamond wire 20 remains unchanged, that is, the standard length, and the backward length is 0.6-0.99 times the standard length, and the amount of wire used gradually decreases. Among them, the gradually increasing amount of the diamond wire 20 and the gradually decreasing amount of the wire used are symmetrical relative to the highest value.

[0049] like Figure 4 As shown, it is a comparison curve before and after the change of wire usage at different feeding positions. In the figure, the horizontal axis is the cutting step of the crystal rod 10 in equal parts during the feeding process of the crystal rod 10, and the vertical axis is the wire usage; c is the wire usage before the change, and d is the wire usage after the change. It can be seen from this figure that the wire usage reaches the maximum in the cutting steps 10-11 in the middle position. In the cutting steps 1-10, the wire usage is gradually increased; in the cutting steps 11-20, the wire usage is gradually reduced. But when it is from cutting step 20 to 21, it suddenly decreases. This position is the knife exit position, and there is no need to use too much wire. Before the change, the wire usage is a fixed value and remains unchanged. But after the change, it changes with the change of the cutting area. This method takes into account the load impact of the diamond wire 20 caused by the diameter change in the off-season, and can compensate for the cutting force loss of the new diamond wire 20 by appropriately increasing or reducing the wire usage, thereby reducing the risk of the diamond wire 20 breaking.

[0050] Furthermore, during the cutting process, as the cutting feed position increases, the tension is controlled to be reduced to reduce the technical problem of wire breakage caused by insufficient cutting force. The changed tension value is 1-5N less than the tension value before the change, and the changed tension value remains unchanged throughout the cutting process.

[0051] like Figure 5 As shown in the figure, it is a comparison curve before and after the tension changes; in the figure, the horizontal axis is the cutting steps in equal parts during the feeding process of the crystal rod 10, and the vertical axis is the tension; e is the tension before the change, and f is the tension after the change. It can be seen from the figure that the tension before the change is too large, and the tension after the change is 1N lower than before the change. Appropriately reducing the cutting tension can reduce the tensile stress of the tension on the diamond wire 20 itself, and reserve a safe space for the wire break caused by the increase of resistance during cutting.

[0052] The above analysis only includes three situations of adjusting the machine speed, thread amount, or tension separately. Of course, the three factors that affect thread breakage, namely machine speed, thread amount, and tension, can be controlled not only separately but also in combination. Among them, the combination method includes synchronously adjusting the machine speed and thread amount, or synchronously adjusting the machine speed and tension, or synchronously adjusting the thread amount and tension, or synchronously adjusting the machine speed, thread amount, and tension. Regardless of the combination method, the control method of the machine speed, thread amount, and tension must comply with the above description.

[0053] Furthermore, during the entire cutting process, the flow rate and concentration of the cutting fluid remain unchanged, and the flow rate of the cutting fluid is 10-100 L / min, while the temperature of the cutting fluid is 15-30°C.

[0054] A control method designed in this application is used to reduce wire breakage caused by insufficient cutting force, optimize the cutting process, and make appropriate adjustments based on different problems during cutting. By controlling the process conditions such as console speed, wire, tension, etc., the cutting process is more closely matched to the steel wire, and the technical problem of insufficient cutting force of the diamond wire is minimized, the cutting quality is improved, and the wire breakage rate is reduced from the current 4.28% to the current 0.75%, which not only improves the cutting efficiency but also reduces the production cost.

[0055] The above detailed description of the embodiments of the present application is only a preferred embodiment of the present application and cannot be considered to limit the scope of implementation of the present application. All equivalent changes and improvements made within the scope of the present application should still fall within the scope of the patent coverage of the present application.

Claims

1. A control method for reducing wire breakage caused by insufficient cutting force, characterized in that: include: Based on the ingot diameter, the cutting depth is divided into several equal feed positions; During the cutting process, the machine speed and / or wire amount and / or tension are controlled to be adjusted as the cutting feed position increases, so as to reduce the force exerted by the crystal rod on the diamond wire.

2. A control method for reducing wire breakage caused by insufficient cutting force according to claim 1, characterized in that: As the cutting feed position increases, the machine speed first gradually decreases, stabilizes, and then gradually increases, wherein the machine speed after the change is equal to the machine speed before the change multiplied by the change coefficient.

3. A control method for reducing wire breakage caused by insufficient cutting force according to claim 2, characterized in that: The changed machine speed is the smallest when the cutting depth is in the middle.

4. A control method for reducing wire breakage caused by insufficient cutting force according to claim 2 or 3, characterized in that: The variation coefficient=1-variation amount, and the variation amount is less than 1.

5. A control method for reducing wire breakage caused by insufficient cutting force according to claim 4, characterized in that: The variation is the chord length divided by the correction coefficient, wherein the chord length is the line segment between the two outermost end points of the cross section where the crystal rod cutting position is located, and is calculated by the formula; the correction coefficient is greater than 1000.

6. A control method for reducing wire breakage caused by insufficient cutting force according to claim 5, characterized in that: The chord length formula is: Wherein, A(x1, y1) and B(x2, y2) are the positions of the two outermost points of the cross section where the crystal rod is cut; K is the slope of line AB; The correction factor is 4000.

7. A control method for reducing wire breakage caused by insufficient cutting force according to any one of claims 1-3, 5-6, characterized in that: As the cutting feed position increases, the wire consumption first increases gradually and then decreases gradually. Specifically, The forward length is the standard length; When the cutting feed position is before the middle position, the forward length of the diamond wire is the standard length, and the backward length is 0.6-0.99 times of the standard length, and the wire consumption increases gradually; When the cutting feed position is in the middle position, the increase in wire consumption reaches the highest value; After the cutting feed position is in the middle position, the forward moving length of the diamond wire is the standard length, and the backward moving length is 0.6-0.99 times of the standard length, and the wire consumption is gradually reduced.

8. A control method for reducing wire breakage caused by insufficient cutting force according to claim 1, characterized in that: As the cutting feed position increases, the changed tension value is 1-5N smaller than the tension value before the change; and the changed tension value remains unchanged throughout the entire cutting process.

9. A control method for reducing wire breakage caused by insufficient cutting force according to claim 8, characterized in that: During the entire cutting process, the flow rate and concentration of the cutting fluid remain unchanged.

10. A control method for reducing wire breakage caused by insufficient cutting force according to claim 9, characterized in that: The cutting fluid flow rate is 10-100 L / min; the cutting fluid temperature is 15-30°C.

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