JP5876388B2 - Workpiece cutting method - Google Patents

Description

  The present invention relates to a workpiece cutting method for manufacturing a substrate from a workpiece by cutting a workpiece made of a semiconductor material or the like using a wire saw device.

  A wire saw apparatus is known as an apparatus for cutting a block-shaped workpiece obtained by cutting an ingot of a semiconductor material or the like into a predetermined dimension to produce a plurality of substrates from the workpiece.

  For example, the wire of the wire saw device is guided from the supply reel to the first main roller via the guide roller, and is wound around the first main roller and the second main roller to form a wire row. Further, the wire extending from the second main roller is guided to the take-up reel through the guide roller, and is taken up by the take-up reel.

  Then, the workpiece can be cut (sliced) into a plurality of substrates by pressing the workpiece fixed to the pedestal via an adhesive at a predetermined speed against a wire train that has been run at high speed.

  The workpiece is cut using a wire saw device by cutting with a cutting fluid containing abrasive grains supplied to the wire array (free abrasive grain type) and using a wire with abrasive grains fixed to the surface. Method (fixed abrasive type). In addition, as a method of traveling the wire, a method of cutting the wire while reciprocating between the first main roller and the second main roller in both directions (bidirectional slicing), and the wire always traveling in one direction. There is a method (one-way slicing) in which a new wire before cutting the workpiece is continuously supplied from the first main roller to the second main roller for cutting.

  In FIG. 10, in the above-described bidirectional slice, the workpiece is arbitrarily moved when moving in a certain direction on the wire side (in FIG. 10, the X-axis direction (for example, the pressing direction of the workpiece)). The relationship between the workpiece position which is a position (a height position etc.) in a location, and the wire travel distance in a fixed direction (Y-axis direction in FIG. 10) is shown. Conventionally, in the bidirectional slice, as shown in FIG. 10, wire supply (for example, a line from coordinates Z0 to Z1) and wire unwinding (for example, a line from coordinates Z1 to Z2) are performed every cycle. The new wire before cutting the workpiece is supplied little by little while repeating the above. That is, as shown in FIG. 10, for example, the maximum distance of the wire travel distance in the first wire supply (Y-axis position of the coordinate Z1) and the maximum distance of the wire travel distance in the next wire supply (the Y-axis position of the coordinate Z3). The difference between this and the new wire supply amount. Thus, the wire supply length for each reciprocating cycle is set to be longer than the wire rewind length, and the difference becomes the new wire supply amount for each cycle.

  The wire is wound from one end side (supply side) to the other end side (winding side) of the main roller. Therefore, as the wire supplied to the main roller moves toward the other end of the main roller, the cutting ability accompanying wear of the wire (or fixed abrasive in the case of a fixed abrasive type wire) decreases, and one end of the workpiece The bending of the wire due to the change in the thickness of the substrate after cutting, the difference in the amount of cutting, and the like from one end to the other end occurs. These are the causes of cracks that occur particularly at the end of slicing the workpiece.

For example, in Patent Document 1 below, regarding a method of cutting a workpiece with a wire saw device, a change in cutting ability on one end side and the other end side of the workpiece is reduced by using a plurality of wires. A method is disclosed.

Japanese Patent Laid-Open No. 9-290417

  However, the apparatus configuration using a plurality of systems of wires is complicated, and there is a problem that a difference in cutting ability occurs in a region shared by each system of wires.

  The present invention has been made in view of the above-described problems. In slicing of a workpiece using a wire saw device, the substrate surface between a plurality of substrates manufactured from the workpiece and one substrate The main object of the present invention is to provide a workpiece cutting method capable of reducing variations in the substrate surface in the process and reducing cracks generated in the workpiece.

A workpiece cutting method according to the present invention includes a first main roller, a second main roller disposed at a predetermined distance from the first main roller, and the rollers of the first main roller and the second main roller. Using a wire saw device provided with a wire stretched in between, the work piece is disposed so as to face the wire between the rollers, and the wire is run between the rollers. A workpiece cutting method for cutting the workpiece with the wire while pressing the workpiece against the wire at a predetermined pressing speed,
A step P1 of cutting the workpiece while supplying the wire by a length L1 in the first direction from the first main roller to the second main roller is performed, and after the step P1, the workpiece The step P1 and the step of performing the step P2 of cutting the workpiece while returning the wire used for cutting by a length L2 shorter than the length L1 in a second direction opposite to the first direction. the P2 series of steps have a one or more rows, and then A1 cutting step to finish by performing the step P1,
After the A1 cutting step, a step P3 of cutting the workpiece while returning the wire used for cutting the workpiece between the rollers by the length L3 in the second direction is performed. And performing the step P4 of cutting the workpiece while supplying the wire used for cutting the workpiece in the first direction by a length L4 shorter than the length L3, and A2 cutting step of performing the series of steps of the step P4 one or more times;
After the A2 cutting step, the old wire supply for supplying the wire in the first direction until the wire not used for cutting the workpiece comes out following the wire used for cutting the workpiece. A process,
Thereafter, the series of steps of the A1 cutting step, the A2 cutting step, and the old wire supplying step is performed once or more .

  According to the workpiece cutting method described above, it is possible to reduce inter-plane and in-plane variations in the thickness of a substrate manufactured from the workpiece, and to reduce cracks generated in the workpiece.

FIG. 1 is a schematic perspective view schematically showing an example of a wire saw device used in a workpiece cutting method according to the present invention. FIG. 2 is a perspective view schematically showing an example of a workpiece used in the workpiece cutting method according to the present invention. FIG. 3 is a block diagram showing an example of a control system of the wire saw apparatus used in the workpiece cutting method according to the present invention. FIG. 4 is a graph showing the relationship between the wire travel distance and the workpiece position for explaining an embodiment of the workpiece cutting method according to the present invention. FIG. 5 is a graph showing the E portion of FIG. 4 in an enlarged manner. FIG. 6 is a graph showing the F portion of FIG. 4 in an enlarged manner. FIG. 7 is a graph showing the relationship between the wire travel distance and the workpiece position for explaining an embodiment of the workpiece cutting method according to the present invention, which is different from FIG. FIG. 8 is a perspective view schematically showing the state of the workpiece after the A1 cutting step or the B1 cutting step. FIG. 9 is a perspective view schematically showing the state of the workpiece after the A2 cutting step or the B2 cutting step. FIG. 10 is a graph showing the relationship between the wire travel distance and the workpiece position for explaining a conventional workpiece cutting method.

  Hereinafter, an embodiment of a workpiece cutting method according to the present invention will be described with reference to the drawings. In the drawings schematically shown, the dimensional ratios and positional relationships of the components are not necessarily accurate.

<Basic configuration of wire saw device and basic cutting method of workpiece using wire saw device>
The wire saw device of the present embodiment has a configuration as shown below, for example. As shown in FIG. 1, the wire saw device S includes a main roller 5 (a first main roller 5a, a second main roller 5b, a first main roller 5a having a plurality of grooves on the surface of a single wire 3 having abrasive grains fixed on the surface. 3, a supply nozzle 4 for supplying a processing liquid is provided around a region where the workpiece is disposed above the wire 3.

  The first main roller 5a and the second main roller 5b are arranged at a predetermined distance, and the wire 3 is stretched in a plurality of rows between these rollers. The wire saw device S sends the wire 3 from the second main roller 5b while supplying the wire 3 to the first main roller 5a, and the wire 3 reciprocates between the rollers.

  Next, the workpiece 1 will be described by taking as an example the case where the workpiece 1 has a rectangular parallelepiped shape. The rectangular parallelepiped workpiece 1 is fixed to the pedestal 2 so that its first main surface faces the wire 3 stretched in a plane between the first main roller 5a and the second main roller 5b. In order to facilitate the following explanation, as shown in FIG. 2, when the workpiece 1 is regarded as a complete rectangular parallelepiped, the main surface (the lower surface in the case of the present embodiment) facing the wire 3 is formed. The first surface 1a is a main surface opposite to the first surface 1a (the upper surface in this embodiment), and the main surface facing the pedestal 2 is a second surface 1b. The main surface (one long side surface in FIG. 2) located on the supply side (first main roller 5a side) of the wire 3 is defined as a third surface 1c, and the winding side of the wire 3 (opposite to the supply side). The main surface (the other long side surface in FIG. 2) located on the side) is defined as a fourth surface 1d. The third surface 1c and the fourth surface 1d are each perpendicular to the traveling direction of the wire. Further, the main surface (one short side surface in FIG. 2) to which a new wire (cutting the workpiece 1) is supplied through the first main roller 5a is defined as the fifth surface 1e, and the old surface is transmitted through the second main roller 5b. The main surface (the other short side surface in FIG. 2) on the side where the wire is wound is defined as a sixth surface 1f.

  For example, the wire saw device S cuts the workpiece 1 in a direction from the first surface 1a toward the second surface 1b. In the present embodiment, the workpiece 1 is disposed opposite to the wire 3 stretched between the first main roller 5a and the second main roller 5b, and the wire 3 travels between the rollers. The workpiece 1 is cut with the wire 3 while pressing the workpiece 1 against the traveling wire 3 at a predetermined pressing speed.

  Here, the mechanism for pressing the workpiece 1 against the wire 3 is not shown, but for example, the base plate 10 bonded to the workpiece 1 and the base 2 is moved up and down by rotation of a ball screw (not shown). The fixed part 11 is fixed to the movable fixing part 11 using a clamp (not shown) and the fixing part 11 is moved up and down by converting the rotational movement of a motor (not shown) connected to the ball screw into vertical movement by the ball screw. By moving the workpiece 1, the workpiece 1 is pressed against the wire 3, and the pressing speed or the like is controlled.

  In this embodiment, as shown in FIGS. 1, 4 and 5, the workpiece 1 is supplied while supplying the wire 3 by a length L1 in the first direction H1 from the first main roller 5a toward the second main roller 5b. And after this step P1, the wire 3 used for cutting the workpiece 1 is returned to the second direction H2 opposite to the first direction H1 by a length L2 shorter than the length L1. However, there is an A1 cutting step in which a series of steps P2 of cutting the workpiece 1 is performed once or more.

  Furthermore, in this embodiment, after the A1 cutting step, as shown in FIGS. 1, 4 and 6, the wire 3 used for cutting the workpiece 1 between the rollers is returned to the second direction H2 while being returned. A process P3 for cutting the workpiece 1 and a series of processes P4 for cutting the workpiece 1 while supplying the wire 3 used for cutting the workpiece 1 in the first direction H1 after the process P3. It has A2 cutting process performed once or more. In addition, it is desirable that the A1 cutting process before the start of the A2 cutting process is ended in the process P1.

  Since cutting is performed without using a new wire in the A2 cutting process, the cutting force of the wire 3 is inferior to that in the A1 cutting process. Therefore, the wire travel distance L3 in the process P3 of the A2 cutting process is the process P1 of the A1 cutting process. It is preferable that the wire travel distance L1 is larger than the wire travel distance L1 of the process P4 of the A2 cutting step, and it is preferable that the wire travel distance L2 of the process P2 of the A1 cutting step is larger. Specifically, the average value of the length L3 and the length L4 in the A2 cutting process may be larger than the average value of the length L1 and the length L2 in the immediately preceding A1 cutting process. Thereby, even if it cuts the to-be-processed object 1 using the wire 3 with which cutting force fell, the disconnection rate of the wire 3 and the incidence rate of a defective board | substrate can be reduced.

  For the same reason, the old line supply amount (length L3−length L4) when the process P3 and the process P4 are each performed once in the A2 cutting process is the same as the process P1 and the process in the immediately preceding A1 cutting process. It is desirable that the new line supply amount (length L1−length L2) when P2 is performed once is larger.

  Here, as shown in FIG. 4, after the A2 cutting step, the wire 3 is used for cutting the workpiece 1 following the wire (old wire) used for cutting the workpiece in the first direction H1. The old wire supply process is performed until no wire (new wire) comes out. That is, in FIG. 1, the wire 3 that enters the workpiece 1 first is used for cutting the workpiece 1 at the position W1 immediately before the tip of the third surface 1c of the workpiece 1 on the fifth surface 1e side. Feed wire 3 until no new wire comes out.

Moreover, as shown in FIG. 4, after performing an old wire supply process, you may make it perform a series of processes of an A1 cutting process, an A2 cutting process, and an old wire supply process once or more.

  Further, instead of the above cutting method, the following cutting method may be employed. That is, in the same manner as the cutting method described above, the first main roller 5a, the second main roller 5b arranged at a predetermined distance from the first main roller 5a, the first main roller 5a and the second main roller 5b. Using the wire saw device S provided with the wire 3 stretched between the rollers, the workpiece 1 is disposed so as to oppose the wire 3 between the rollers, and the wire 3 runs between the rollers, In the workpiece cutting method in which the workpiece 1 is cut with the wire 3 while pressing the workpiece 1 against the traveling wire 3 at a predetermined pressing speed, as shown in FIGS. A B1 cutting step of cutting the workpiece 1 while supplying a length L1 of a new wire not used for cutting the workpiece 1 in the first direction H1 from the main roller 5a toward the second main roller 5b; After the B1 cutting step, the workpiece 1 is cut while returning the old wire used for cutting the workpiece 1 to a second direction H2 opposite to the first direction H1 by a length L2 shorter than the length L1. B2 cutting step to be performed.

  In such a cutting method, as shown in FIG. 7, after the B2 cutting step, an old wire supplying step for supplying the wire 3 in the first direction H1 until the new wire comes out following the old wire is performed. May be.

  Moreover, as shown in FIG. 7, after performing an old wire supply process, you may make it perform a series of processes of a B1 cutting process, a B2 cutting process, and an old wire supply process once or more.

  In the two cutting methods described above, after the A1 cutting step or the B1 cutting step, the pressing speed of the workpiece 1 to the wire 3 in the A2 cutting step or the B2 cutting step is set to the pressing speed in the A1 cutting step or the B1 cutting step. A slow period that is slower than the speed may be provided.

  Further, during this slow period, the pressing speed may be decreased stepwise.

  Similarly, in the old wire supply process, the pressing speed of the workpiece 1 to the wire 3 may be slower than the pressing speed in the A1 cutting process or the B1 cutting process.

  By these things, even if it is the process using the wire 3 with which cutting ability fell, the disconnection rate of the wire 3 and the incidence rate of a defective board | substrate can be reduced.

<Specific configuration of workpiece and wire saw device>
Below, the component of the to-be-processed object 1 and the wire saw apparatus S is demonstrated concretely. The workpiece 1 is, for example, an ingot made of single crystal silicon or polycrystalline silicon, or a block formed by cutting the ingot. Single crystal silicon ingots can be manufactured by the Czochralski method or the like, and the outer shape thereof is generally cylindrical. A polycrystalline silicon ingot can be manufactured by a casting method or the like, and its outer shape is generally a rectangular parallelepiped. A block having a desired cross-sectional shape and size is obtained by cutting the end portion of such an ingot or dividing the ingot into a plurality of blocks. Hereinafter, description will be made assuming that the workpiece 1 is the above-described rectangular parallelepiped block.

The workpiece 1 is fixed on a base 2 made of a material such as a carbon material, glass, silicon, or resin by an adhesive or the like. When an adhesive is used for fixing the workpiece 1, the adhesive is made of a thermosetting two-component epoxy resin, an acrylic resin, a reacrate resin, a wax, or the like. In order to make it easy to peel the obtained substrate from the pedestal 2 after the slicing of the object 1, a material whose adhesive force is lowered by raising the temperature is used.

  The base 2 and the base plate 10 are held by bonding or clamping. The base plate 10 is fixed to the fixing portion 11 by screws or clamps, and one or a plurality of workpieces 1 are arranged in the wire saw device S. The base 2 has a thickness of 10 to 30 mm, for example, and the base plate 10 has a thickness of 10 to 30 mm, for example. As described above, the second surface 1b facing the workpiece 1 is fixed to the pedestal 2 so that the first surface 1a faces the wire 3.

  The wire 3 is supplied from the supply reel 7 and is taken up by the take-up reel 8. The wire 3 includes a plurality of main rollers 5 disposed at least at both ends between the supply reel 7 and the take-up reel 8 (in this embodiment, a first main roller 5a, a second main roller 5b, a third main roller). 5c) and stretched between these rollers to form a plurality of rows. The wire 3 is made of, for example, a piano wire mainly composed of iron or an iron alloy, and has a wire diameter of 60 μm or more and 150 μm or less.

  In the present embodiment, the wire 3 is fixed to abrasive grains in which abrasive grains made of diamond or silicon carbide are fixed around the wire by plating with nickel, copper, or chromium, or a resin such as an epoxy resin, a phenol resin, or a polyurethane resin. Use wires. In this case, the average grain size of the abrasive grains is preferably 5 μm or more and 30 μm or less, and the average diameter D of the entire wire including the fixed abrasive grains is 70 μm or more and 210 μm or less.

  The wire 3 is supplied with a machining fluid serving as a coolant fluid for cooling the wire 3 and the workpiece 1 from the plurality of openings of the supply nozzle 4. The processing liquid is composed of, for example, a water-soluble solvent such as glycol or an oily solvent, and these solvents may be diluted with water. The supply flow rate of the processing liquid supplied to the supply nozzle 4 is appropriately set according to the size of the workpiece. Moreover, you may circulate and use a processing liquid, and in that case, it is good to remove and use the abrasive grain and chips which fell from the wire 3 contained in a processing liquid. The machining fluid supplied from the supply nozzle 4 is supplied to the cut portion of the workpiece 1 and the vicinity thereof.

  The main roller 5 is made of, for example, urethane resin or polyethylene resin, and has a diameter of 150 mm to 500 mm and a length in the longitudinal direction of about 200 mm to 1000 mm. A plurality of grooves for arranging the wires 3 supplied from the supply reel 7 at predetermined intervals are provided on the surface of the main roller 5. The thickness of the substrate is determined by the relationship between the groove interval and the diameter of the wire 3, and the thickness of the substrate is 250 μm or less.

  Below the wire 3, a dip tank 6 is provided for the purpose of collecting chips and machining fluid of the workpiece 1 generated during cutting.

  The supply reel 7 and the take-up reel 8 have a wire 3 wound around a bobbin-shaped surface made of steel or the like. The wire saw device S includes a motor (not shown) for rotating the supply reel 7 and the take-up reel 8 at a predetermined speed, and a traverser (not shown) for guiding the wire 3 to wind it at a predetermined position. .

  The plurality of guide rollers 9 have a role of guiding the wire 3 from the supply reel 7 to the main roller 5 and from the main roller 5 to the take-up reel 8. Each guide roller 9 has a groove in which the wire 3 travels. Such a guide roller 9 is made of, for example, urethane resin or polyethylene resin.

  In addition, the wire saw device S includes means for adjusting the tension of the wire 3 wound around the supply reel 7 and the take-up reel 8 and a sensor for detecting the tension applied to the wire 3.

  Further, the wire saw device S includes a control system as shown in FIG. 3, for example. The wire saw device S includes, for example, a control unit configured by a wire travel condition control unit, a workpiece position control unit, a machining liquid supply condition control unit, and the like. By this control unit, a wire supply unit (wire 3, The main roller 5, the supply reel 7, the take-up reel 8, the guide roller 9, etc.) can be controlled so that the wire 3 has a predetermined tension, travel speed, travel direction, travel distance, and the like. In addition, the control unit can control the workpiece 1 so as to have a predetermined pressing speed and position with respect to the workpiece holding unit (the base plate 10 and the fixing unit 11 and the like). Further, the control unit can control the supply amount of the processing liquid, the liquid temperature, the viscosity, and the like with respect to the processing liquid supply unit (the supply tank (not shown), the supply nozzle 4 and the liquid recovery mechanism (not shown)). .

<Specific cutting method of workpiece>
Below, the slice method using the wire saw apparatus S of this embodiment is demonstrated concretely. The wire 3 is supplied from the supply reel 7 and guided to the main roller 5 by the guide roller 9. The wires 3 are wound around the main roller 5 and arranged at predetermined intervals. By rotating the main roller 5 at a predetermined rotational speed, the wire 3 can travel in the longitudinal direction of the wire 3. The wire 3 traveling at high speed cuts the workpiece 1 and is wound around the take-up reel 8. Further, by changing the rotation direction of the main roller 5, the wire 3 is reciprocated as shown by arrows in FIG.

  In the A1 cutting step shown in FIGS. 4 and 5, first, the workpiece 1 is cut while supplying the wire 3 by the length L1 from the supply side (step P1). At this time, the travel distance and workpiece position of the wire 3 are on the line from the coordinates C0 to C1 shown in FIG.

  Thereafter, as shown in FIGS. 4 and 5, the workpiece 1 is cut while rewinding the wire 3 by a length L2 shorter than the length L1 from the winding side (step P2). At this time, the travel distance and workpiece position of the wire 3 are on the line from the coordinates C1 to C2 shown in FIG.

  And a series of processes of process P1 and process P2 are repeated once or more.

  In the A2 cutting step, as shown in FIGS. 4 and 6, following the A1 cutting step, the workpiece 1 is cut while rewinding the wire 3 from the winding side by a length L3 (step P3). . At this time, the travel distance and workpiece position of the wire 3 are on the line from the coordinates C5 to C6 shown in FIG.

  Next, the workpiece 1 is cut while supplying the wire 3 from the supply side by a length L4 shorter than the length L3 (step P4). At this time, the travel distance and the workpiece position of the wire 3 in the workpiece 1 are on the line from the coordinates C6 to C7 shown in FIG.

  And a series of processes of process P3 and process P4 are repeated once or more.

  Instead of the above cutting method, a cutting method as shown in FIG. 7 may be adopted. As shown in FIG. 7, first, in the B1 cutting step, a new wire that is not used for cutting the workpiece 1 in the first direction H1 from the first main roller 5a toward the second main roller 5b has a length L1. The workpiece 1 is cut while feeding only. At this time, the travel distance and workpiece position of the wire 3 are on the line from the coordinates D0 to D1 shown in FIG.

  Next, in the B2 cutting step, after the B1 cutting step, the old wire used for cutting the workpiece 1 is moved in the second direction H2 opposite to the first direction H1 by a length L2 shorter than the length L1. The workpiece 1 is cut while returning.

  In such a cutting method, as shown in FIG. 7, after the B2 cutting step, an old wire supplying step for supplying the wire 3 in the first direction H1 until the new wire comes out following the old wire is performed. May be.

  Moreover, as shown in FIG. 7, after performing an old wire supply process, you may make it perform a series of processes of a B1 cutting process, a B2 cutting process, and an old wire supply process once or more.

  In the two cutting methods described above, after the A1 cutting step or the B1 cutting step, the pressing speed of the workpiece 1 to the wire 3 in the A2 cutting step or the B2 cutting step is set to the pressing speed in the A1 cutting step or the B1 cutting step. A slow period that is slower than the speed may be provided.

  Further, during this slow period, the pressing speed may be decreased stepwise.

  As described above, in the A1 cutting process or the B1 cutting process, the workpiece 1 is cut while supplying a new wire as usual, and in the A2 cutting process or the B2 cutting process, the workpiece is rewound while the old wire is rewound. 1 is cut. The supply length of the wire in each process may be constant or may be changed continuously or stepwise as long as the length relationship in the preceding and following processes is maintained.

  For cutting the workpiece 1, the workpiece 1 is lowered while supplying the machining liquid from the supply nozzle 4 toward the wire 3 running at a high speed, and the workpiece 1 is pressed against the wire 3 relatively. Is made by The workpiece 1 is divided into a plurality of substrates having a thickness of 250 μm or less, for example. At this time, the tension of the wire 3, the speed at which the wire 3 travels (travel speed), and the speed at which the workpiece is lowered (pressing speed) are appropriately controlled. For example, the maximum traveling speed of the wire 3 is set to 500 m / min or more and 1500 m / min or less, and the maximum pressing speed is set to 350 μm / min or more and 1100 μm / min or less. At this time, when the wire 3 reciprocates, the pressing speed also changes as the traveling speed of the wire changes.

  FIG. 8 shows a cutting state of the workpiece 1 in the A1 cutting step or the B1 cutting step. In the A1 cutting process or the B1 cutting process, the workpiece 1 is cut while supplying a new wire from the supply side. Therefore, from the one end (fifth surface 1e) side of the workpiece 1 on the wire supply side to the wire winding side. Due to the deterioration of the cutting performance accompanying the deterioration of the abrasive grains fixed to the surface of the wire 3 toward the other end (sixth surface 1f) side, a difference occurs in the progress of the cutting. Such a difference in the cutting performance from one end side to the other end side of the workpiece 1 causes the occurrence of defects such as bending of the wire 3, a difference in substrate thickness, chipping and cracking.

  FIG. 9 shows a cutting state of the workpiece 1 in the A2 cutting step or the B2 cutting step. In the A2 cutting process or the B2 cutting process, the old wire is supplied from the winding side. Therefore, contrary to the first cutting process, the end of the workpiece on the wire winding side end (sixth surface 1f) side. The cutting process proceeds with higher cutting performance. Therefore, contrary to the time of the A1 cutting step or the B1 cutting step, the wire 3 extends from the other end (sixth surface 1f) side to the one end (fifth surface 1e) side of the workpiece on the wire supply side on the wire supply side. The cutting performance is lowered due to the deterioration of the abrasive grains fixed to the surface of the steel, and the progress of the cutting is different in the opposite direction to the A1 cutting process or the B1 cutting process. For this reason, when viewed in total, the difference in cutting progress generated in the A1 cutting process or the B1 cutting process is canceled out in the A2 cutting process or the B2 cutting process, enabling uniform cutting, bending of the wire 3, and substrate It is possible to reduce the occurrence of defects such as thickness difference, chipping and cracking.

  Here, after the A2 cutting step or the B2 cutting step, the old wire is continuously supplied from the supply side so that the workpiece 1 can be cut while supplying the new wire at the start of the next A1 cutting step or B1 cutting step. Thus, it is preferable to perform the A1 cutting step or the B1 cutting step after performing the old wire supplying step of supplying a new wire. Thereby, since it becomes possible to supply a new wire from the beginning of the next A1 cutting process or B1 cutting process, it is possible to reduce wire breakage, bending, and the occurrence of defects due to these.

  Further, in the A2 cutting step or the B2 cutting step, only the old wire is used for cutting the workpiece 1, so that there is a risk that the wire breakage or a defect associated therewith is likely to occur compared to the A1 cutting step or the B1 cutting step. is there. Therefore, it is preferable to provide a period in which the traveling speed of the wire 3 and the pressing speed of the workpiece are lower than those in the A1 cutting process or the B1 cutting process. Thereby, generation | occurrence | production of wire disconnection can be reduced. In the period in which the pressing speed of the workpiece 1 is reduced, it is better to decrease the pressing speed stepwise.

  While slicing the workpiece 1 to the second surface 1b, the pedestal 2 is also cut by 2 mm or more and 5 mm or less, and the cut substrate is bonded to the pedestal 2 and put into the next peeling process and cleaning process. The In the peeling process, the substrate after slicing is heated together with the pedestal 2 to reduce the adhesive strength of the adhesive and separate the substrates one by one. In the cleaning step, the water-soluble coolant and dirt adhering to the substrate are cleaned using the cleaning liquid, and then the cleaning liquid is washed away with water. Then, the surface of the substrate is completely dried by room temperature, heated air, nitrogen gas or the like.

<Modification>
In addition, this invention is not limited to the said embodiment, Many corrections and changes can be added within the scope of the present invention.

  For example, the shape of the workpiece 1 is not limited to a rectangular parallelepiped shape. Moreover, you may perform a slicing process as it is by using the ingot as the workpiece 1 without cutting the ingot into blocks.

  Further, the workpiece 1 is not limited to a semiconductor material such as a solar cell element, and may be, for example, ceramics, a magnetic material, or other metals.

  In addition to a fixed-abrasive wire saw device that cuts using a wire with abrasive grains fixed on the surface, a free-abrasive wire saw device that cuts while supplying a cutting fluid containing abrasive grains to a wire array Moreover, since the change of the cutting performance accompanying the deterioration of the wire from one end of the workpiece 1 to the other end can be improved, the present invention can be suitably applied.

  Hereinafter, more specific examples will be described. First, a rectangular parallelepiped polycrystalline silicon block having a size of 156 mm × 156 mm × 300 mm was prepared as the workpiece 1. And the epoxy-type adhesive agent was apply | coated to the base 2 made from graphite of thickness 15mm, and the to-be-processed object 1 was mounted and pressed on the base, and the adhesive agent was hardened.

Next, the pedestal 2 to which the silicon block was bonded was placed on the fixed portion 11 via the aluminum base plate 10. Then, using a fixed abrasive wire 3 (average diameter = 130 μm) obtained by fixing diamond abrasive grains (average particle diameter = 15 μm) to a stainless steel wire (wire diameter = 100 μm) with an acrylic resin, each of the A2 cutting steps is 1, A silicon block having an average thickness of 200 μm was manufactured by slicing the silicon block under three kinds of processing conditions (respectively, Examples 1, 2, and 3) having two or three times.

  Moreover, the silicon substrate was produced from the silicon block on the processing conditions which have only an A1 cutting process as a comparative example, and the crack generation rate of the silicon substrate obtained by both methods was compared. Here, the crack occurrence rate is the ratio of the number of substrates on which cracks occur to the total number of substrates obtained.

  In the comparative example, the incidence of cracks was 21.3%, whereas in Example 1, it was 12.5%, in Example 2, 7.6%, and in Example 3, 1.1%, It was confirmed that the crack generation rate was greatly improved. In particular, in Example 3, the degree of improvement was significant.

  Moreover, as a result of evaluating and observing the surface of the produced silicon substrate, there is a difference in the surface roughness and reflectance of the substrate between the region cut in the A2 cutting step and the region cut in the A1 cutting step. The progress of cutting in each step in the plane could be confirmed.

  Furthermore, with respect to the silicon block (workpiece 1) and the pedestal 2 at the end of cutting, a position close to the fifth main surface 1e, which is one end on the wire supply side of the silicon block, and the other end on the wire winding side. As a result of comparison with the position close to the sixth main surface 1f, there was a difference of 20.0 mm at the maximum in the cutting position at the end of cutting in the comparative example, whereas in Examples 1 to 3, all were A2 cutting steps An improvement in the difference in the cutting position was observed, and the difference in the cutting position at the end of cutting was 2.5 mm at the maximum in Example 3.

1: Workpiece 2: Base 3: Wire 4: Supply nozzle 5: Main roller 5a: 1st main roller 5b: 2nd main roller 5c: 3rd main roller 7: Supply reel 8: Take-up reel 9: Guide roller 10: Base plate 11: Fixed portion S: Wire saw device

Claims (3)

A wire saw comprising: a first main roller; a second main roller disposed at a predetermined distance from the first main roller; and a wire stretched between the first main roller and the second main roller. An apparatus is used to dispose the work piece so as to face the wire between the rollers, and the wire is caused to travel between the rollers, and the work piece is placed on the running wire in a predetermined manner. A workpiece cutting method for cutting the workpiece with the wire while pressing at a pressing speed,
A step P1 of cutting the workpiece while supplying the wire by a length L1 in the first direction from the first main roller to the second main roller is performed, and after the step P1, the workpiece The step P1 and the step of performing the step P2 of cutting the workpiece while returning the wire used for cutting by a length L2 shorter than the length L1 in a second direction opposite to the first direction. the P2 series of steps have a one or more rows, and then A1 cutting step to finish by performing the step P1,
After the A1 cutting step, a step P3 of cutting the workpiece while returning the wire used for cutting the workpiece between the rollers by the length L3 in the second direction is performed. And performing the step P4 of cutting the workpiece while supplying the wire used for cutting the workpiece in the first direction by a length L4 shorter than the length L3, and A2 cutting step of performing the series of steps of the step P4 one or more times;
After the A2 cutting step, the old wire supply for supplying the wire in the first direction until the wire not used for cutting the workpiece comes out following the wire used for cutting the workpiece. A process,
Thereafter, a workpiece cutting method in which a series of steps of the A1 cutting step, the A2 cutting step, and the old wire supplying step is performed once or more . After said as A1 cutting engineering, the A2 and the pressing speed as the definitive cutting Engineering, workpiece cutting method according to claim 1 to provide a slow period for slower than the pressing speed definitive enough to the A1 cutting Engineering. The workpiece cutting method according to claim 2 , wherein the pressing speed is decreased stepwise in the slow period.

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