JP2010069607A - Saw wire reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a saw wire reproducing method for regenerating an used saw wire to be reused as a saw wire. <P>SOLUTION: At least one of a cleaning process (E) and a surface polishing process (F) is applied to the used wire 3 which is used for a slice work of a semiconductor ingot by a wire saw. Then, a drawing process (G) is applied to the wire to reduce a diameter of the partially worn wire 3, adjust a sectional form of the partially worn part and regenerate the saw wire. Further, after the drawn wire is thermally treated, a twisting process (I) may be applied to the wire. Thus, the partially worn part is extended spirally in the longitudinal direction of the wire to have a pocket, Thus, abrasive grain slurry is effectively taken in and supplied and chips are efficiently discharged. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for regenerating a wire (saw wire) for a wire saw used for cutting a semiconductor ingot or the like.

  As a device for cutting a thin flat plate material from a semiconductor ingot or the like, a wire (saw wire) such as a thin steel wire is sent from a reel on the feeding side to a reel on the winding side, and for example at a predetermined pitch between three rollers. A flat plate material is wound by spirally wrapping, pressing a semiconductor ingot toward the wound wire, and feeding the abrasive slurry to the contact portion between the wire and the semiconductor ingot while reciprocating or feeding the wire in one direction. Conventionally, a wire saw in which a large number of pieces are cut out simultaneously has been used.

  The wire used in such a wire saw and wound on a reel on the winding side is removed from the wire saw together with the reel, and the wire is peeled off from the reel by, for example, gas melt cutting (melting cutting) or laser cutting (for example, (See Patent Document 1). The stripped wire was discarded and only the reel was reused.

  In addition, in the manufacture of saw wires, copper or copper alloy plating (brass plating) is applied to the surface of the strands in order to increase the drawability when the strands of steel or the like are drawn through the holes of the dies. However, if the plating layer remains on the surface of the product wire, the cut surface of the semiconductor ingot or the like is contaminated by the metal of the plating layer when the semiconductor ingot or the like is cut. For this reason, it is conventionally known that the brass plating layer is removed by chemical, physical or electrolytic polishing after the final finish drawing (see, for example, Patent Document 2).

  In addition, the abrasive grains can be easily held and discharged by the wire saw when cutting with the wire saw, so that new abrasive grains can be reliably supplied to the contact portion between the wire and the object to be cut, and the cutting ability can be improved. Therefore, it is known that the saw wire is made of a strand having a polygonal or elliptical cross-sectional shape, and the polygonal or elliptical strand is twisted in the cross-sectional shape. (For example, refer to Patent Document 3).

Japanese Patent No. 4083649 Japanese Patent No. 3244426 Japanese Patent Laid-Open No. 9-254006

  As described above, conventionally, the used saw wire is removed from the reel by fusing or the like and discarded, and only the reel is reused. Once used, the saw wire had a round cross-sectional shape before use, but the used part was rubbed in one direction, and it was unevenly worn in the cross-sectional shape, and the used part and the unused part And at least a part of the wire axis direction is unevenly worn in the cross section in the radial direction. Since the cross-sectional shape is unstable between the portions, the slice cutting accuracy varies. Therefore, conventionally, the used saw wire must be discarded.

  However, if the saw wire once used is peeled off from the reel by fusing or the like and discarded, the fusing and the like are costly and the disposal cost is also increased.

  An object of the present invention is to provide a saw wire recycling method for reusing a used saw wire so as to be reusable.

  The present invention adjusts the cross-sectional shape of the wire by applying a wire drawing process to a wire in which at least a part of the wire axial direction after the use as a saw wire is unevenly worn in a radial cross section, and reused as a saw wire Provided is a saw wire reproduction method characterized by enabling reproduction.

  According to this method, by drawing the used saw wire, the wire diameter of the unevenly worn wire is reduced, and the cross-sectional shape of the unevenly worn part is brought close to the original round shape, and the unused part is It is possible to adjust so as to reduce the difference between them, and it is possible to recycle a used saw wire as a reusable saw wire.

  In this method, the wire drawing process may be a drawing process using a die.

  The wire drawing is ideally performed by a method capable of minimizing variation in the processing degree, and as a method, a general method capable of reducing the diameter of the wire material such as rolling with a roller die or a roller can be used, and the method is particularly limited. Although not intended, die drawing is most desirable in view of the fact that the wire diameter of the object to be processed is thin and that accuracy is required for adjustment of the cross-sectional shape.

  Also, the saw wire redrawn by drawing with die drawing has the plating layer (brass plating layer) peeled off when the original saw wire is used, so the metal of the plating layer cuts the semiconductor ingot etc. when cutting There is little risk of contaminating the surface.

  In this case, the area reduction rate by the die (the reduction rate of the wire cross-sectional area after passing through the die relative to the wire cross-sectional area before passing through the die) is preferably 15% or less.

  In the new state of the saw wire, a plating layer for lubrication or the like at the time of wire drawing remains on the wire surface, but the plating layer is peeled off after being used once with the wire saw. Therefore, although a lubricating action by a plating layer such as brass plating cannot be expected, disconnection and the like can be suppressed by performing die drawing with a surface reduction rate of 15% or less.

  In addition, the die used for wire drawing is preferably a deformed die having a deformed die hole close to the shape of the radial cross section of the part of the wire that has been partially worn.

  The used wire wears unevenly in the used portion, and remains in a round shape in the unused portion. In such a case, for example, if the die hole is a perfect circle, there is a large difference in the degree of processing between the used part with uneven wear and the unused part with a round cross section. For this reason, it is recommended to use a deformed die having a deformed die hole close to the radial cross-sectional shape of the unevenly worn part of the wire. (Difference from the diameter of the partial wear direction of the part) or the amount of wear of the used part was measured, and a die having a die hole with an intermediate shape between the original round cross-sectional shape and the irregular cross-sectional shape of the unevenly worn used part It is better to use and draw.

  In the wire drawing process using the deformed die as described above, it is preferable to adjust the position in the wire radial direction cross section of the uneven wear of the wire fed to the deformed die so as to match the shape of the die hole of the deformed die.

  In this way, by adjusting the position of the uneven wear of the wire in the wire radial cross section to match the shape of the die hole of the irregular die, the degree of processing of the unevenly worn portion is stabilized, and the cross-sectional shape of the unevenly worn portion is not changed. A regenerated saw wire having a stable shape with a small difference from the cross-sectional shape of the used portion can be obtained.

  In addition, the present invention may be applied by performing a twisting process after performing a wire drawing process on a wire in which at least a part in the wire axial direction after being used as a saw wire is unevenly worn in a radial cross section, or further Thereafter, by performing a wire drawing process, the cross-sectional shape of the wire is adjusted so that the uneven wear portion remains and the uneven wear portion extends spirally in the wire axis direction, and is regenerated to be reusable as a saw wire. A saw wire recycling method is provided.

  According to this method, the wire diameter of the unevenly worn wire is reduced by performing a twisting process after performing a wire drawing process on a used saw wire, or further performing a wire drawing process thereafter, In addition, the cross-sectional shape of the unevenly worn part is brought close to the original round shape to reduce the difference from the unused part, while the cross-sectional shape of the wire remains in the unevenly worn part and the unevenly worn part spirals in the wire axis direction. And can be regenerated as a reusable saw wire.

  The regenerated saw wire has a partial wear portion extending spirally in the wire axis direction, which forms a spiral pocket with the cut surface when cutting (slicing) a semiconductor ingot or the like. As a result, the carrying and feeding of the abrasive slurry are improved, and the cutting chips are efficiently discharged, thereby improving the slicing processability. In addition, the used saw wire is not straight as it is, but it is not straight, but when it is regenerated by this method, it becomes a straight saw wire by being twisted.

  In this method, it is preferable to use a deformed die having a deformed die hole that is close to the shape of the radial cross section of the part of the wire that has been partially worn in the wire drawing process before the twisting process. By using such a deformed die and adjusting the position of the uneven wear of the wire in the wire radial direction cross section to match the shape of the die hole of the deformed die, the cross-sectional shape of the unevenly worn portion and the unused portion are used. It becomes a wire with a stable shape with a small difference from the cross-sectional shape of the part, and by twisting this wire, the shape is stabilized, the uneven wear part is extended in a spiral shape, and the abrasive slurry is brought in and A recycled saw wire with good feed and chip discharge is obtained. For wire drawing performed after the twisting process, it is preferable to use a die having a perfect circular die hole.

  Further, the present invention provides a wire that is subjected to a wire drawing process after a twisting process is applied to a wire that has been unevenly worn in an irregular shape in a radial cross section after being used as a saw wire. A saw wire recycling method is provided in which the uneven wear portion remains and the uneven wear portion extends spirally in the wire axis direction and is reusably regenerated as a saw wire.

  According to this method, the wire diameter of the partially worn wire is reduced by twisting the used saw wire and then drawing, and the cross-sectional shape of the unevenly worn portion is reduced to the original. A reusable saw wire that adjusts the cross-sectional shape of the wire so that the uneven wear portion remains and the uneven wear portion extends spirally in the wire axis direction while reducing the difference from the unused portion by approaching the round shape. Can be played as.

  The regenerated saw wire has a partial wear portion extending spirally in the wire axis direction, which forms a spiral pocket with the cut surface when cutting (slicing) a semiconductor ingot, etc. As a result, the carrying and feeding of the abrasive slurry are improved, and the cutting chips are efficiently discharged, thereby improving the slicing processability. In addition, the used saw wire is not straight as it is, but it is not straight. However, when it is regenerated by this method, it becomes a saw wire with good straightness by being twisted.

  In this method, the wire drawing process is preferably performed using a die having a perfect circular die hole. In this method, the used unevenly worn wire is first twisted, whereby the shape seen from the wire axis direction (apparent cross-sectional shape) is rounded, and thus a die having a perfect circular die hole is used. As a result, the die wear is made uniform.

  In these saw wire recycling methods, it is preferable to perform at least one of a cleaning process and a polishing process on the wire prior to all the processes of wire drawing and twisting.

  Saw wire sprays an abrasive slurry (for example, a slurry mixed with GC abrasive grains) and cuts the ingot while being sandwiched between the saw wire and the ingot. Therefore, abrasive particles adhere to the used saw wire. This hinders wire drawing and twisting. Therefore, prior to the process such as wire drawing, a cleaning or polishing process is performed to remove the abrasive grains.

  Further, in these saw wire recycling methods, it is preferable to heat-treat the wire at a heating temperature of 700 to 800 ° C., for example, before the wire drawing process.

  By performing the heat treatment in this way, the physical properties of the work-hardened wire can be adjusted.

  Thus, according to the saw wire recycling method of the present invention, a used saw wire can be recycled as a saw wire so that it can be reused. Therefore, it is not necessary to peel off the used saw wire from the reel by fusing, etc. as before, and to reduce the cost of fusing and disposal, and to save resources and reduce industrial waste through recycling (reuse). Can contribute.

  And since the saw wire regenerated by this method becomes plating-free, there is little possibility that the metal of the plating layer contaminates the cut surface of the semiconductor ingot or the like at the time of cutting.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 7 show an embodiment of the present invention. 1 is an overall explanatory view of the embodiment, FIG. 2 is an explanatory view of an electrolytic pickling process using ultrasonic vibration, FIG. 3 is an explanatory view of a mechanical polishing process using a polishing wheel, and FIG. 4 is an explanatory view of a wire drawing process. FIG. 5, FIG. 5 is a state explanatory view of a used wire, FIG. 6 is a shape explanatory view of a die hole of a deformed die, and FIG. 7 is an explanatory view of a twisting process.

  In this embodiment, a used saw wire is subjected to a drawing process and a twisting process to be recycled so as to be reusable, and the entire process including the regeneration process is as shown in FIG. .

  In this embodiment, as shown in FIG. 1, the saw wire (SW) is delivered to the user in a state where a new product is reel-wound by a manufacturer (A). Then, it is used by a user for cutting (slicing) a semiconductor ingot by a wire saw (B).

  The wire saw, for example, feeds a wire (saw wire) 3 such as a thin steel wire from a reel 1 on the feeding side to a reel 2 on the winding side, and at a predetermined pitch between the three rollers 4, 5, 6. Winding in a spiral shape, pressing the semiconductor ingot 7 toward the wound wire 3, feeding abrasive slurry to the contact portion between the wire 3 and the semiconductor ingot 7, reciprocating the wire 3, or feeding in one direction By doing so, a large number of flat plate materials (wafers) are cut out simultaneously.

  The used wire 3 is wound around the take-up reel 2 that was an empty reel (C). Then, the reel is removed from the wire saw and returned to the manufacturer (D).

  Such a returned wire 3 is remanufactured as a saw wire by a manufacturer. The reproduction method is as follows.

  First, the wire 3 is subjected to at least one of cleaning (E) and surface polishing (F) to remove surface abrasive grains and slurry.

  Cleaning (E) is performed by immersion cleaning, ultrasonic cleaning, water jet spray cleaning, or the like. The surface polishing (F) is performed by chemical polishing, mechanical polishing, or the like. A method of performing cleaning (E) and surface polishing (F) at the same time may be used.

  In the immersion cleaning, the wire is immersed in an acid (for example, sulfuric acid) solution, and the surface brass and the surface layer of the high-carbon steel as a base material are dissolved by the acid to remove dirt and abrasive grains.

  In ultrasonic cleaning, a wire is run in an acid (for example, sulfuric acid) solution, and ultrasonic vibrations are generated in the solution to dissolve the surface brass and the surface layer of the high-carbon steel of the base material with the acid. In this case, the eroded abrasive grains are dropped from the wire by a physical action. In this case, the cleaning capability is enhanced by ultrasonic vibration.

  In the water jet spray cleaning, a high-pressure water stream is sprayed at 1 MPa, for example, to blow away dirt on the wire surface layer or bite abrasive grains. In this case, the blown abrasive grains can be collected. Also, the water used is water, which can be recycled and is good for the environment.

  In the chemical polishing, for example, the wire surface is polished by electrolytic pickling using an acid (for example, sulfuric acid).

  In mechanical polishing, for example, a wire surface is polished using a polishing wheel.

  FIG. 2 shows the treatment of the electrolytic pickling process using ultrasonic vibration together. In this process, ultrasonic cleaning and chemical (electrolytic) polishing are simultaneously performed. As shown in FIG. 2, an oscillator 12 and an electrode (minus) are contained in an acid (for example, sulfuric acid) solution 11 stored in a solution tank 10. 13 is arranged, the vibrator 12 is connected to the oscillator 14, and the electrode 13 is connected to the power source 15. Then, the wire 3 is passed through the solution 11 and connected to the power source 15 so that the wire 3 is the other electrode (plus). Then, while running the wire 3 in the solution 11 of acid (for example, sulfuric acid), ultrasonic vibration is generated by the vibrator 12 to dissolve the surface brass and the surface layer portion of the high-carbon steel of the base material with the acid, The abrasive grains, etc. that have digged in are dropped from the wire by physical action, and the effect is further enhanced by electrolytic pickling. At that time, if oxygen generated by electrolysis of water adheres to the surface of the wire, the electrolytic pickling ability may be hindered. However, since ultrasonic vibration is also used, bubbles (oxygen) on the surface of the wire are removed. Therefore, the electrolytic pickling ability is maintained well.

  FIG. 3 shows the processing of a mechanical polishing process using a polishing wheel. In this process, the entire circumference 360 ° of the wire 3 is polished using the polishing wheel 21. The polishing depth is several μm. If the material of the polishing wheel 21 is a nonwoven fabric, it is suitable for polishing the surface layer. In this case, since the surface layer of the wire 3 is all polished, a cleaning process is not necessarily required.

  If the contact surface of the polishing wheel 21 is the same, the wear proceeds locally, and there is a possibility that the wire 3 having several hundred km cannot be polished over the entire length. For this reason, it is preferable to provide a mechanism for imparting a traverse function to the grinding wheel 21 so that the grinding wheel 21 is worn evenly.

  After performing at least one of cleaning (E) and surface polishing (F) in this way, the wire 3 is drawn in the wire drawing step (G) to adjust the cross-sectional shape of the unevenly worn wire 3. That is, by performing the wire drawing process, the wire diameter of the unevenly worn wire 3 is reduced, and the cross-sectional shape of the unevenly worn portion is adjusted to be close to the original round shape so as to reduce the difference from the unused portion. .

  FIG. 4 shows the wire drawing (G) process. This process is an enlargement process using the die 31. The die 31 is a deformed die having a deformed die hole that is close to the shape of the radial cross section of the part of the wire that has been partially worn.

  The used wire 3 is, for example, in a state where a used portion and an unused portion are repeatedly connected in the wire axis direction as shown in FIG. As shown in a), the cross-sectional shape is rounded, but the used portion is rubbed in one direction, resulting in uneven wear in the cross-sectional shape as shown in FIG. 6 (c). Yes.

  In this case, for example, if the die hole is a perfect circle, a large difference in the degree of processing occurs between the used part that is unevenly worn and the unused part having a round cross section. Therefore, it is preferable to use a deformed die having a deformed die hole close to the shape of the radial cross section of the unevenly worn portion of the wire 3, and in particular, the wire diameter and the used portion of the unused portion of the used wire 3. After measuring the difference in diameter in the direction of uneven wear (referred to as “deviation from the difference in diameter”) or the amount of wear in the used part, the original round cross-sectional shape (FIG. 6 (a)) and uneven wear Drawing is performed by using a deformed die having a die hole having a deformed cross-sectional shape (a shape intermediate between (c) in FIG. 5 (FIG. 6 (b))). The maximum diameter of the hole, which corresponds to the wire diameter of the unused portion, and b is the minimum diameter of the die hole, which is larger than the diameter of the used portion in the direction of uneven wear. The difference (ab) is smaller than the difference in diameter of the used wire 3.

  During the wire drawing process, the azimuth adjusting roller 32 adjusts the position of the radial wear of the wire 3 fed into the die 31 (unshaped die) in the radial section so as to match the shape of the die hole of the die 31 (unshaped die).

  Further, the area reduction rate by the die 31 (deformed die) (the reduction rate of the wire cross-sectional area after passing through the die relative to the wire cross-sectional area before passing through the die, basically the reduction rate of the cross-sectional area of the unused portion) Means 15% or less.

  The wire drawing is ideally performed by a method capable of minimizing the variation in the degree of processing. As a method, the wire diameter of the object to be processed is thin, and accuracy is required for adjusting the cross-sectional shape. In view of this, die drawing is most desirable, but other general methods that can reduce the diameter of the wire, such as rolling with a roller die or a roller, can also be used.

  Before wire drawing (G), for example, the wire is subjected to heat treatment (H) at a heating temperature of 700 to 800 ° C. to adjust the physical properties (tensile strength, etc.) of the work-hardened wire. In addition, when wire drawing (G) is performed in steps, heat treatment (H) is performed each time, and physical properties are adjusted so as to be suitable for wire drawing.

  The wire thus drawn becomes a regenerated saw wire (J) having a stable shape in which the degree of processing of the unevenly worn portion is stable, and the difference between the cross-sectional shape of the unevenly worn portion and the cross-sectional shape of the unused portion is small.

  Moreover, in this method, after heat-treating the drawn wire, you may provide the process (I) which performs a twist process further. For the twisting process, a conventional stranded wire machine (buncher machine, tubular machine) or the like can be used.

  By further twisting the drawn wire, the uneven wear portion reduced by drawing is phase (position in the wire radial cross section) in the longitudinal direction (wire axial direction) of the wire 3 as shown in FIG. ) Changes to a spiral shape, which forms a spiral pocket with the cut surface when slicing a semiconductor ingot or the like. Therefore, the carrying and feeding of the abrasive slurry are improved, and the cutting chips are efficiently discharged, thereby improving the workability of slice cutting. Moreover, it becomes a saw wire with good straightness by being twisted.

  In this method, the twisting process may be performed after the wire drawing process, and then the wire drawing process may be performed. For wire drawing performed after the twisting process, a die having a perfect circular die hole is used. Then, before the wire drawing treatment, the wire is heat-treated at a heating temperature of 700 to 800 ° C., for example.

  Further, the wire drawing process may be performed after the used wire is twisted. At this time, a die having a perfect circular die hole is used for the wire drawing process. In this case, the used unevenly worn wire is first twisted, thereby rounding the shape seen from the wire axis direction (apparent cross-sectional shape), so use a die with a perfect circular die hole. Thus, the die wear is made uniform. Also in this case, the wire is heat-treated at a heating temperature of 700 to 800 ° C., for example, before the wire drawing treatment.

  In addition, as a method for reclaiming the used wire, it is not always necessary to draw the wire, and the twist may be applied only by a twisting process. Used wire with irregularly shaped cross-section that has been worn out by twisting will cause the unevenly worn part to extend in a spiral shape, bringing in and feeding the abrasive slurry well, and cutting chips from cutting efficiently. As a result, the workability of slice cutting is improved.

1 is an overall explanatory diagram of an embodiment of the present invention. It is explanatory drawing of the electrolytic pickling process which used together the ultrasonic vibration which concerns on embodiment of this invention. It is explanatory drawing of the mechanical grinding | polishing process using the grinding | polishing wheel which concerns on embodiment of this invention. It is explanatory drawing of the wire drawing process which concerns on embodiment of this invention. It is a state explanatory view of a used wire concerning an embodiment of the present invention. It is shape explanatory drawing of the die hole of the deformed die which concerns on embodiment of this invention. It is explanatory drawing of the twisting process which concerns on embodiment of this invention.

Explanation of symbols

3 wire (saw wire)
31 dies (various dies)
32 Orientation adjustment roller

Claims (8)

After the wire is used as a saw wire, at least a part of the wire in the axial direction is subjected to a wire drawing process on the wire that is irregularly worn in the radial cross section, thereby adjusting the cross-sectional shape of the wire and regenerating it as a saw wire. A saw wire recycling method characterized by the above. The saw wire regeneration method according to claim 1, wherein the wire drawing process is a drawing process using a die. The saw wire recycling method according to claim 2, wherein the area reduction rate by the die is 15% or less. The saw wire recycling method according to claim 2 or 3, wherein the die is a deformed die having a deformed die hole close to a shape of a radial cross section of a part of the wire that has been partially worn. The saw wire regeneration method according to claim 4, wherein, in the wire drawing process, the position of the uneven wear of the wire fed into the deformed die is adjusted to match the shape of the die hole of the deformed die. After using the wire as a saw wire, at least a part of the wire axial direction is irregularly worn in the radial cross section, and after performing the wire drawing process, the wire is subjected to a twisting process, or further after that, the wire drawing process is performed. By performing the adjustment, the cross-sectional shape of the wire is adjusted so that the uneven wear portion remains and the uneven wear portion extends spirally in the wire axial direction, and is regenerated so as to be reusable as a saw wire. After the wire is used as a saw wire, at least a part of the wire axial direction is irregularly worn in the radial cross section, the wire is twisted and then drawn, and then the wire is subjected to uneven wear. A saw wire reclaiming method comprising adjusting a part of the uneven wear part to spirally extend in the wire axis direction and reusable as a saw wire. The saw wire regeneration method according to any one of claims 1 to 7, wherein at least one of a cleaning process and a polishing process is performed on the wire prior to all of the processes.

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