JP5101340B2 - Wire saw - Google Patents

Description

  The present invention relates to a wire saw that cuts a workpiece by cutting and feeding a workpiece such as a semiconductor ingot to a wire group constituted by cutting wires.

Conventionally, a wire saw is known as means for cutting a workpiece into a wafer shape. As shown in FIG. 6, the wire saw is stretched in a state in which a large number of wires 61 are arranged by winding a cutting wire 61 between a plurality of guide rollers 60A and 60B. A machining fluid (slurry) is supplied to the wire group while being driven at high speed, and in this state, the work 64 held by the work holding unit 63 is directed to the wire group in a direction perpendicular to the axial direction of the cutting wire 61. By cutting and feeding, a large number of workpieces 64 are cut out simultaneously in a wafer shape (Patent Document 1). In addition, nozzles 62 for supplying a machining fluid are disposed on both sides of the cutting position of the workpiece 64 in the wire group, and the machining fluid is supplied from these nozzles 62 to the wire group.
Japanese Patent Laid-Open No. 11-10511

  In the cutting operation by the wire saw, the wafer may be warped due to the expansion and contraction (thermal displacement) of the work due to the processing heat, but when supplying the processing liquid to the wire group driven at a high speed as described above, Since the machining fluid scatters, at the end of cutting, as shown by a one-dot chain line arrow in FIG. 6, the machining fluid supplied to the wire group rises along the workpiece 64 to cool the workpiece holder 63, and as a result In addition to the thermal displacement of the workpiece 64, thermal displacement also occurs in the workpiece holding portion 63, which is one of the causes for promoting warpage of the wear at the end of cutting. Further, the so-called machining liquid that has risen is supplied again to the wire group and enters the cutting groove, which accumulates between the wafers, and similarly causes the above-described warpage.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wire saw that can suppress warping of a wafer cut out from a workpiece.

In order to solve the above problems, engaging Ruwa Iyaso the present invention, the wire group to be formed by the cutting wire wound in a plurality of guide rollers, wire drive for driving the wire group in a wire axis Means, a feed means for cutting and feeding the workpiece held by the holding member relative to the wire group, and a wire shaft more than a region of the wire group where the workpiece is cut and fed. A wire drive control means for periodically reversing a wire drive direction by the wire drive means, in a wire saw provided with a work fluid supply means that is disposed outside in the direction and supplies a work fluid to the wire group; and Feed position detecting means for detecting that the work has reached a predetermined position in the vicinity of the cutting feed end position, which is a work feed position by the feed means. The drive control means controls the wire drive means based on the detection of the predetermined position by the feed position detection means so that the reversal period in the wire drive direction after the detection is shorter than the previous reversal period. It is.

  In this wire saw, while the wire group is driven in the axial direction and the machining fluid is supplied, the workpiece is cut and fed relative to the wire group, and the driving direction of the wire is periodically reversed. The wafer is cut out. At that time, when the work reaches a predetermined position near the cutting and feeding end, the reversal period of the driving direction of the subsequent wire group becomes shorter than the previous reversal period. In other words, the wire group drive direction is frequently reversed to increase the wire group stop time, and the machining fluid is scattered compared to the case where the wire group is continuously driven in one direction for a long time ( (Rolling up) becomes difficult, and the absolute amount of the machining fluid scattered is reduced. Therefore, at the end of cutting, the workpiece holding member is excessively cooled by the processing liquid, or a large amount of the processing liquid enters between the wafers.

  Each of the wire saws described above is provided with a work holding member or a cover member that prevents the work liquid scattered by being supplied to the wire group from the work liquid supply means from diffusing to the work side. Is preferred.

  According to this configuration, it is structurally possible to prevent the machining fluid from splashing onto the workpiece holding member and the workpiece.

  For example, the cover member is interposed between the region of the wire group where the workpiece is cut and fed and a machining fluid supply position by the machining fluid supply means, and integrally with the wire group with respect to the workpiece. It is provided so as to be movable in the cutting and feeding direction, and is a workpiece feeding position by the feeding means, and at least within a range from a predetermined position in the vicinity of the cutting and feeding end to the end position, from the wire cutting position of the workpiece to the workpiece holding member It is comprised so that the part which covers may be covered.

  According to this configuration, it is possible to effectively suppress the scattering of the machining liquid to the workpiece holding member side, which is a problem mainly at the end of cutting, and the penetration of the machining liquid between the wafers.

According to the present invention, when the workpiece reaches a predetermined position in the vicinity of the cutting feed end, the subsequent reversal cycle in the wire driving direction is shorter than the previous reversal cycle, that is, the operation in which the machining liquid is not easily scattered (rolled up). Switch to state. Therefore, the absolute amount of the machining fluid scattered at the end of cutting is reduced, and at the end of cutting, the workpiece holding member is excessively cooled by the machining fluid, or the wafer warp due to a large amount of machining fluid entering between the wafers. As a result, the wafer can be cut out with less warpage.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows the overall configuration of a wire saw according to the present invention. The wire saw shown in this figure includes a pair of wire feeding / winding devices 10A and 10B, guide pulleys 12A and 12B, guide pulleys 14A and 14B, guide pulleys 16A and 16B, wire tension adjusting devices 18A and 18B, guide pulleys 22A and 22B. , And four guide rollers 24A, 24B, 26A, 26B.

  The guide rollers 24A and 24B are arranged at the same height position, and the guide rollers 26A and 26B are arranged at positions below the guide rollers 24A and 24B, respectively, so that the guide roller 26A is rotationally driven by the drive motor 25. It has become.

  Each of the wire feeding / winding devices 10A and 10B includes bobbins 9A and 9B around which a wire W for cutting is wound, and bobbin driving motors 11A and 11B that rotationally drive the bobbins. The wire W fed from the bobbin 9A of one wire feeding / winding device 10A is hung in the order of the guide pulleys 12A, 14A, 16A, the pulley 20A of the wire tension adjusting device 18A, and the guide pulley 22A, and further the guide roller 24A. 24B, 26B, 26A, guide pulley 22B, wire tension adjustment after being wound (wound) around the guide rollers a number of times while being fitted into guide grooves (not shown) on the outer peripheral surfaces of guide rollers 22B, 26B, 26A The pulley 20B of the device 18B and the guide pulleys 16B, 14B, and 12B are hung in this order, and are wound around the bobbin 9B of the other wire feeding / winding device 10B, and are appropriately applied to the wire W by the both wire tension adjusting devices 18A and 18B. Tension is applied. Then, the rotation driving direction of the guide roller 26A by the drive motor 25 and the rotation driving direction of the bobbins 9A and 9B by the bobbin driving motors 11A and 11B are switched between forward and reverse, so that the wire W is fed out from the bobbin 9A and bobbins. The driving direction of the wire W can be reversed between a state wound around 9B (referred to as a forward drive state) and a state where the wire W is fed from the bobbin 9B and wound around the bobbin 9A (referred to as a backward drive state). .

  That is, in this wire saw, a wire group in which a large number of wires W are stretched in parallel with each other is formed between the guide rollers 24A and 24B, and these wire groups can be driven back and forth in the axial direction. Yes. In this embodiment, the wire feeding / winding devices 10A, 10B and the like correspond to the wire driving means of the present invention.

  FIG. 2 illustrates the portion between the guide rollers 24A and 24B in some detail. As shown in this figure, the wire group is located on both outer sides of the wire group in the drive direction (left-right direction in the figure) of the wire W from the region where the workpiece 28 is cut and fed, and above the wire group. A pair of slurry supply devices 36 and 37 for supplying slurry (a working fluid containing loose abrasive grains) is provided.

  Each of these slurry supply devices 36 and 37 includes a pair of nozzle members 36a and 36b (37a and 37b). These nozzle members 36a, 36b, 37a, 37b have, for example, slit-like liquid discharge ports extending in the front-rear direction (a direction orthogonal to the paper surface in FIG. 2), and by discharging slurry from the liquid discharge ports. The slurry is supplied over the entire wire group, that is, the entire arrangement direction of the wires W.

  The nozzle members 36a, 36b and 37a, 37b are arranged at regular intervals in the driving direction of the wire W, respectively, so that two nozzles 36a, 36b and 37a, 37b are arranged on both sides of the working area, that is, upstream and downstream in the driving direction of the wire W, respectively. Slurry is supplied to the wire group at the location. Particularly, among the nozzle members 36a, 36b, 37a, and 37b of each set, the nozzle members 36a and 37a on the side away from the work area are disposed directly above the guide rollers 24A and 24B, and guide together with the wire group. By supplying slurry to the rollers 24A and 24B, the rollers 24A and 24B can be cooled.

  The slurry supply / discharge system has, for example, a tank (not shown) equipped with a feed pump, and the slurry stored in the tank is led out from the tank by driving the pump, and the common pipe 40 and the branch pipes 41 to 44. Through the nozzle members 36a, 36b, 37a, 37b to be supplied to the wire group, and after the supply, the slurry is extracted from the slurry pans arranged below the guide rollers 24A, 24B, 26A, 26B. The liquid is returned to the tank through the liquid recovery pipe. The branch pipes 41 to 44 are provided with electromagnetic bubbles 41a to 44a, respectively, and according to the operation of the electromagnetic bubbles 41a to 44a, the slurry discharge amount (supply) by the nozzle members 36a, 36b, 37a, 37b is supplied. Amount) is controlled.

  Further, drip-proof covers 38 and 38 (corresponding to a cover member according to the present invention) are respectively arranged on both sides of the work area in the vicinity of the wire group. These drip-proof covers 38, 38 prevent the slurry supplied and scattered to the wire W from diffusing to the working area side, and the nozzle members 36b, 37b, It is provided so as to block the work area. These drip-proof covers 38 and 38 are respectively vertically movable so as to cover the portion extending from the wire cutting position to the workpiece 28 to the workpiece holding portion 32, which will be described later, within a range from a predetermined position near the cutting feed terminal of the workpiece 28 to the terminal position. The dimension of the direction (the cutting feed direction described later) is set (see FIG. 3).

  Above the group of wires stretched between the guide rollers 24A and 24B, a work feeding device 30 for moving a cylindrical work (ingot) 28 is provided. The workpiece feeding device 30 corresponds to the feeding means according to the present invention, and includes a workpiece holding portion 32 (work holding member) and a workpiece feeding motor 34.

  The work holding unit 32 holds the work 28 in an orientation in which a desired crystal orientation can be obtained based on the crystal axis via the slice base 33, and the work feed motor 34 is combined with a ball screw (not shown). Thus, the workpiece holding portion 32 and the workpiece 28 are moved up and down integrally (that is, cut and fed). Therefore, in this wire saw, the wire group stretched between the guide rollers 24A and 24B is simultaneously driven at a high speed in the longitudinal direction, and the machining fluid is supplied to the wire group from the nozzle members 36a, 36b, 37a and 37b. In this state, the workpiece 28 is cut and fed downward with respect to the wire group, whereby a large number of wafers (thin pieces) are simultaneously cut out from the workpiece 28 at the same time.

  As shown in FIG. 1, the wire saw has an NC device 50 for controlling the workpiece cutting operation. During the cutting operation, the wire W is driven and the slurry is supplied according to predetermined conditions. The bobbin drive motors 11A and 11B, the drive motor 25, the work feed motor 34, and the electromagnetic bubbles 41a to 44a are based on output signals from encoders (not shown) incorporated in the work feed motor 34. Are controlled by the NC device 50 in an integrated manner. That is, in this embodiment, the NC device 50 corresponds to the liquid amount control means, the speed control means, and the wafer drive control means according to the present invention, and the encoder of the work feed motor 34 and the NC device 50 according to the present invention. It corresponds to the feed position detecting means.

  Next, control of the cutting operation of the workpiece 28 by the NC device 50 will be described with reference to the flowchart of FIG.

  When the workpiece 28 is held by the workpiece holding unit 32, the NC device 50 drives the workpiece feed motor 34 to set the workpiece 28 at an initial position spaced above the wire group by a predetermined dimension. At this time, the electromagnetic bubbles 41a to 44a are closed, and accordingly, the supply of slurry to the wire group is stopped.

  When the workpiece 28 is set at the initial position, the NC device 50 controls the drive motor 25 and the bobbin drive motors 11A and 11B, and controls the electromagnetic bubbles 41a to 44a, so that the wire feed / While the wire W is being unwound from the winding device 10A, the wire W is wound by the other wire unwinding / winding device 10B, and the wire W is wound at a predetermined speed V1 (600 m / min in this example) as shown by a solid line arrow in FIG. While driving forward, supply of slurry (predetermined flow rate Q1) from both slurry supply devices 36 and 37 to the wire group is started (step S1).

  Further, the NC device 50 starts the cutting and feeding of the workpiece 28 at a constant speed by controlling the workpiece feeding motor 34 and operates the reverse timer (steps S3 and S5). In this way, cutting and feeding of the workpiece 28 is started, and when the wire W cuts into the workpiece 28, slurry containing loose abrasive particles attached to the wire W is moved into the workpiece 28 (cutting groove) as the wire W moves. It is brought in, and the workpiece 28 is cut by this. The inversion timer measures the time for switching the driving state of the wire W (switching time between the forward driving state and the backward driving state), and measures a predetermined set time T1 (60 seconds in this example).

  Next, the NC device 50 determines whether or not the workpiece 28 has been cut and fed to the cutting end position with respect to the wire group. This determination is made based on the detected position by detecting the feed position of the work 28 by the work feed device 30 based on the output signal from the encoder built in the work feed motor 34. As a result, when it is determined that the terminal position has not been reached (NO in step S7), the NC device 50 further determines whether the set time T1 has elapsed, and if it has determined that it has elapsed ( In step S9, the drive state of the wire W is reversed from the forward drive state to the reverse drive state by controlling the rotation direction of the drive motor 25 and the bobbin drive motors 11A and 11B (step S11). Specifically, after the drive speed of the wire W is decelerated and temporarily stopped, the wire W is fed out from the wire feeding / winding device 10B on the other side. The wire W is wound up by the take-up device 10A, whereby the drive of the wire W is switched to the backward drive as shown by the broken line arrow in FIG.

  Next, the NC device 50 determines whether or not the workpiece 28 has arrived at a predetermined feeding position in the vicinity of the cutting and feeding end, which is the feeding position of the workpiece 28 by the workpiece feeding device 30 (step S13). Specifically, as shown in FIG. 3, it is determined whether the workpiece 28 has been cut and fed to a position where the wire W is cut to a position that is approximately two-thirds of the total cutting dimension L. This determination is made based on the detection of the feed position of the workpiece 28 as in step S7. If NO is determined in step S9, the NC device 50 skips the process of step S11.

  If the NC device 50 determines in step S13 that the workpiece 28 has not reached the predetermined feed position, the NC device 50 proceeds to step S7. On the other hand, when it is determined that the workpiece 28 has reached the predetermined feed position (YES in step S13), the NC device 50 switches the timer value of the reversing timer, the driving speed of the wire W, and the slurry supply amount, respectively. Control (step S15). Specifically, the NC device 50 switches the timer value of the inversion timer from the set time T1 to a predetermined set time T2 (45 seconds in this example) shorter than the set time. Further, the driving speed of the wire W is switched from the speed V1 to a predetermined set speed V2 (300 m / min in this example) lower than the speed. Further, the amount of slurry supplied by the slurry supply devices 36, 37 is switched from the flow rate Q1 to a predetermined set flow rate Q2 smaller than the flow rate. Then, after the switching, the process proceeds to step S5, and the inversion timer is operated at the set time T2 after the switching.

  In this way, the processing of steps S7 to S13 is repeated along with the cutting of the work 28, and when it is finally determined that the work 28 has been cut and sent to the cutting end position with respect to the wire group (YES in step S7), the NC device 50 By controlling the drive motor 25, the bobbin drive motors 11A and 11B, and the electromagnetic bubbles 41a to 44a, the drive of the wire W is stopped and the supply of the slurry by the slurry supply devices 36 and 37 is stopped, thereby a series of cuttings. Finish the work.

  According to the wire saw according to the present invention as described above, when the workpiece 28 reaches a predetermined position near the cutting and feeding end (YES in step S13), the amount of slurry supplied by the slurry supply devices 36 and 37 is reduced from Q1 to Q2. At the same time, the driving speed of the wire W is reduced from the speed V1 to the speed V2, and the inversion cycle in the wire driving direction is shortened from the time T1 to T2, and the subsequent cutting operation is advanced. For this reason, at the end of cutting, it is alleviated that the workpiece holding portion 32 is overcooled by the scattered slurry or a large amount of slurry enters between the wafers. That is, when the slurry supply amount is reduced from Q1 to Q2 as described above, the absolute amount of slurry scattered at the end of cutting is reduced due to the reduction of the slurry itself, and the driving speed of the wire W is increased from the speed V1. When the speed is reduced to V2, the slurry is difficult to roll up, and the absolute amount of slurry that is scattered is reduced accordingly. Furthermore, when the inversion cycle of the wire driving direction is shortened, the driving direction of the wire group is frequently switched. As a result, the wire stop time increases, and the wire group is continuously driven in one direction for a long time. As a result, the slurry is less likely to roll up, and as a result, the absolute amount of slurry that is scattered is reduced.

  Therefore, according to the wire saw, it is possible to suppress the warp of the wafer due to the workpiece holding portion 32 being excessively cooled by the slurry at the end of cutting or the slurry entering between the wafers. The wafer can be cut out in a small state.

  In addition, this wire saw is structurally provided with drip-proof covers 38, 38 between the nozzle members 36b, 37b of the slurry supply devices 36, 37 and the work area so that the slurry that is supplied to the wire W and scattered is scattered. In particular, the drip-proof covers 38 and 38 are configured to prevent the workpiece holding portion from the wire group within a predetermined range in the vicinity of the cutting feed end, as shown in FIG. Since the portion covering 32 is covered, there is an advantage that it is possible to effectively suppress overcooling of the work holding portion 32 due to scattering of slurry at the end of cutting and unnecessary penetration of slurry between wafers. is there.

  In addition, there is a concern that the switching of the operating conditions as described above (step S15 in FIG. 4) may adversely affect the subsequent cutting of the workpiece 28. However, in the case of the cylindrical workpiece 28 as in the embodiment, In the vicinity of the cutting feed end, the cutting length by the wire W gradually decreases, so that there is almost no influence on the cut surface due to switching of operating conditions.

  By the way, the wire saw demonstrated above is an example of preferable embodiment of the wire saw which concerns on this invention, The concrete structure can be suitably changed in the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, when the workpiece 28 reaches a predetermined position in the vicinity of the cutting feed end, all the operating conditions of the timer value of the reversing timer, the driving speed of the wire W, and the slurry supply amount are switched. (Step S15 in FIG. 4), as described above, since switching of these operating conditions is effective in alleviating the scattering of slurry at the end of cutting, only one or two operating conditions are switched. It may be.

  Further, the switching of the operating state may be performed by switching into a plurality of stages in addition to the switching of one stage as in the embodiment, or may be gradually changed. For example, if the driving speed of the wire W is used, the speed may be reduced stepwise or gradually.

  Further, in the wire saw of the embodiment, the drip-proof covers 38 and 38 are provided so as to suppress the scattering of the slurry to the working area side, but the drip-proof covers 38 and 38 may be omitted. . Further, the shape and arrangement of the drip-proof covers 38 and 38 are not limited to those in the embodiment, and various shapes and arrangements can be used as long as the slurry supplied to the wire group and scattered can be prevented from diffusing to the working area side. Things can be applied. For example, as shown in FIG. 5, in order to mainly prevent overcooling of the work holding part 32, drip-proof covers 38 ′ and 38 ′ are assembled to the work holding part 32, so that the work holding part 32 is mainly attached. Thus, the slurry may be prevented from diffusing.

1 is an overall configuration diagram of a wire saw according to the present invention. It is the schematic which showed the part between the guide rollers of a wire saw. It is the schematic which shows the state which the workpiece | work reached | attained the predetermined position of the cutting | disconnection feed end vicinity. It is a flowchart which shows an example of cutting operation control by NC unit. It is the schematic which shows the principal part of the workpiece feeding apparatus which shows the modification of a drip-proof cover. It is the schematic explaining the problem of the conventional wire saw.

Explanation of symbols

10A, 10B Wire feeding / winding device 11A, 11B Bobbin drive motor 24A, 24B, 26A, 26B Guide roller 25 Drive motor 28 Work 30 Work feed device 34 Work feed motor 36, 37 Slurry supply device 50 NC device W Wire

Claims (3)

A wire group formed by a cutting wire wound around a plurality of guide rollers, a wire driving means for driving the wire group in the wire axial direction, and a work holding member for holding a work, the work holding member A feed means for cutting and feeding the workpiece held by the wire group relative to the wire group, and being arranged outside the region of the wire group where the workpiece is cut and fed, in the wire axial direction, and processing the wire group In a wire saw provided with a processing liquid supply means for supplying a liquid,
Wire drive control means for periodically reversing the wire drive direction by the wire drive means ;
A feed position detecting means for detecting that the work has reached a predetermined position in the vicinity of a cutting feed end, which is a work feed position by the feed means,
The wire drive control means controls the wire drive means based on the detection of the predetermined position by the feed position detection means so that the reversal period in the wire drive direction after the detection is shorter than the previous reversal period. A wire saw characterized by The wire saw according to claim 1, wherein
The machining fluid processing liquid scattered by being supplied from the supply means to the wire group, characterized that you have the cover member is provided to prevent the diffusion of the work holding member, or the working side wire saw. The wire saw according to claim 2,
The cover member includes the region where the workpiece is cut and fed in the wire group, and a machining fluid supply.
And a feed position of the workpiece by the feed means, provided so as to be movable in the cutting and feeding direction integrally with the wire group with respect to the workpiece. A wire saw covering a portion extending from a wire cutting position of the workpiece to a workpiece holding member within a range from a predetermined position near the cutting feed end to the end position .

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