JP5806082B2 - Workpiece cutting method - Google Patents

Description

  The present invention relates to a method for cutting a workpiece for performing processing such as cutting and grooving using a wire on a workpiece such as a semiconductor material.

  For example, when manufacturing a semiconductor substrate including a solar cell element or the like, first, the ingot is cut into a predetermined size to form a block. Thereafter, the block as the workpiece is bonded to the slice base with an adhesive, and then cut into a plurality of sheets using a wire saw device or the like to manufacture a substrate.

  The wire of such a wire saw device is guided from a supply reel to a main roller by a guide roller and wound around the main roller to form a wire row. The wire extending from the main roller is guided to the take-up reel by the guide roller and is taken up by the take-up reel.

  In the slicing method using a wire saw device, a cutting fluid containing abrasive grains is used to cut by the lapping action of the wire (free abrasive grain type), and an abrasive fixed wire in which the abrasive grains are fixed to the wire from the beginning. There is a method of cutting (fixed abrasive grain type). When the latter fixed abrasive type wire saw device is used, there is an effect that kerf loss can be reduced, but there is a possibility that minute cracks may occur in the block.

  For example, Patent Document 1 discloses that the surface of a block facing a wire row is sliced at a predetermined angle with respect to the surface having the wire row in a loose abrasive grain type.

JP 2004-82282 A

  However, in the fixed abrasive type wire saw apparatus, even if the block is simply tilted and sliced, the generation of minute cracks cannot be reduced.

  The present invention has been made in view of the above-described problems, and a main object of the present invention is to provide a workpiece cutting method capable of reducing cracks generated in a block which is a 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, the first main roller, and the second main roller. a wire abrasive grains are fixed to the plurality of rows is stretched in a planar shape, the surface between, scan
And a rice-based, the while supplying the wire to the first main roller, using a wire saw device for delivering said wire from said second main roller, the first surface lower surface planar with said A workpiece having a second surface which is located on the opposite side of the first surface and is bonded to the slice base, the wire stretched in a plane between the first main roller and the second main roller; A method of cutting a workpiece, wherein the first surface is disposed so as to face the wire, and the workpiece is cut in a direction from the first surface toward the second surface, At the start of cutting the workpiece, the first end of the first surface located on the first main roller side of the workpiece with respect to a virtual plane including the plurality of rows of wires in an unloaded state is the Move away from the virtual plane With tilting the first surface to the direction, the contacting of the second end portion of the first surface located on the second main roller side of the workpiece first on the wires Rutotomoni, of the workpiece The central position of the second surface is positioned closer to the first main roller than the central position between the first main roller and the second main roller, and the first surface of the workpiece is Cutting is performed by positioning the second end portion closer to the second main roller than the center position.

  According to the workpiece cutting method, the occurrence of cracks in the workpiece can be sufficiently reduced.

It is a schematic perspective view which shows typically one Embodiment of the wire saw apparatus which concerns on the slicing method of this invention. It is a schematic sectional drawing which illustrates typically one Embodiment of the wire saw apparatus which concerns on the slicing method of this invention. It is a figure which illustrates typically one Embodiment of the wire saw apparatus which concerns on the slicing method of this invention, (a) is a schematic sectional drawing, (b) is an enlarged view of the part A of (a). It is a schematic sectional drawing which illustrates typically one Embodiment of the wire saw apparatus which concerns on the slicing method of this invention.

  Hereinafter, an embodiment of a wire saw according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the wire saw device S of the present embodiment has a main roller 5 (first main roller 5a, first wire) having abrasive grains fixed on the surface and a wire 3 having an average diameter D having a plurality of grooves on the surface. 2 main roller 5b and third main roller 5c), and a supply nozzle 4 for supplying a processing liquid is provided above the wire 3.

  In the wire saw device S, 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 plane in a plurality of rows between the main 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, but the wire 3 reciprocates between the main rollers.

  As shown in FIG. 2 and the like, the workpiece 1 has a first surface 1a having a flat bottom surface and a second surface 1b located on the opposite side of the surface. The workpiece 1 is arranged on the wire 3 stretched between the first main roller 5 a and the second main roller 5 b so that the first surface 1 a faces the wire 3.

  In this way, the wire saw device S cuts the workpiece 1 in the direction from the first surface 1a toward the second surface 1b. In this embodiment, as shown in FIG. 2 and FIG. 3 (b), when the workpiece 1 is started to be cut, the workpiece 1 is compared with the virtual plane 12 including a plurality of rows of wires 3 in an unloaded state. The first end 21 of the first surface 1a located on the first main roller 5a side inclines the first surface 1a in a direction away from the virtual plane 12, and on the second main roller 5b side of the workpiece 1 Cutting is performed by first bringing the second end 22 of the first surface 1a positioned into contact with the wire 3.

  Further, before the end of cutting the workpiece 1, as shown in FIGS. 3A and 4, the first end 23 of the second surface 1b located on the first main roller 5a side of the workpiece 1 is used. Instead, the second end 24 of the second surface 1b located on the second main roller 5b side of the workpiece 1 is brought into contact with the wire 3 first to perform cutting.

  Here, when the workpiece 1 is cut, the center position of the second surface 1b of the workpiece 1 is set to be greater than the center position between the first main roller 5a and the second main roller 5b. The cutting may be performed by being positioned on the roller 5a side.

  Further, the second end 22 of the first surface 1a of the workpiece 1 is positioned closer to the second main roller 5b than the center position between the first main roller 5a and the second main roller 5b, and cutting is performed. You should do it.

  By such a wire saw device S, the substrate 1 is manufactured by pressing and cutting the workpiece 1 to be cut against the wire 3 traveling between the plurality of main rollers 5.

  Below, the component of the to-be-processed object 1 and the wire saw apparatus S is demonstrated concretely. As the workpiece 1, for example, an ingot made of single crystal silicon or polycrystalline silicon, or a block formed by cutting an end of the ingot or the like is used. More specifically, when a single crystal silicon ingot is used, the ingot is generally cylindrical. In addition, a polycrystalline silicon ingot is generally a rectangular parallelepiped, and has a size that allows a plurality of silicon blocks to be taken out. The silicon block has a rectangular cross section (including a square shape). For example, it is formed in a rectangular parallelepiped of 156 mm × 156 mm × 300 mm.

  The workpiece 1 is bonded to the slice base 2 made of a material such as carbon material, glass, silicon, or resin by an adhesive or the like. This adhesive consists of a thermosetting two-part adhesive such as epoxy, acrylic, reacrate, or wax. After slicing, the temperature is raised to make it easier to peel off the substrate from the slice base 2. An adhesive whose adhesive strength is reduced is used.

The slice base 2 and the base plate 10 are held by bonding or clamping. The base plate 10 is fixed to the apparatus fixing portion 11 by screws or clamps, and the workpiece 1 is arranged in the wire saw apparatus S or a plurality of workpieces 1 so as to be elongated in the direction perpendicular to the traveling direction of the wire. Generally, the slice base 2 has a thickness of 10 to 30 mm, and the base plate 10 has a thickness of 10 to 30 mm. In the following description, for ease of explanation, when the workpiece 1 is regarded as a complete rectangular parallelepiped, a surface facing the wire 3 is defined as a first surface 1a and a surface facing the slice base 2 is bonded. The second surface 1b, the surface located on the wire 3 supply side (first main roller 5a side) and connecting the first surface 1a and the second surface 1b is the third surface 1c, opposite to the wire 3 supply side A surface that is located at and is connected to the first surface 1a and the second surface 1b is referred to as a fourth surface 1d. Further, the wire 3 reciprocates. Hereinafter, the side to which the new line is supplied will be referred to as the wire supply side.

  The wire 3 is supplied from the supply reel 7 and is taken up by the take-up reel 8. The wire 3 is wound around a plurality of main rollers 5 (first main roller 5a, second main roller 5b, and third main roller 5c) installed at least at both ends between the supply reel 7 and the take-up reel 8. A plurality of rows are formed between the main 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 to 150 μm, more preferably 80 μm to 130 μm.

  In the present embodiment, the wire 3 has abrasive grains made of diamond or silicon carbide 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. It is a fixed wire. In this case, the average particle diameter of the abrasive grains is preferably 5 μm or more and 30 μm or less, and the average diameter D is 70 μm or more and 210 μm or less, and more preferably the average diameter D is 90 μm or more and 170 μm or less.

  The wire 3 is supplied with a machining fluid serving as a coolant fluid that cools the wire 3 and the workpiece 1 from a plurality of openings of the supply nozzle 4. The processing liquid is composed of a water-soluble solvent such as glycol or an oily solvent, for example, and the solvent 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, At that time, it removes and removes the abrasive grain, chips, etc. 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, an ester-based, ether-based, or urea-based urethane rubber, or a resin such as neurite, and has a diameter of 150 to 500 mm and a length 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 formed to 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 generated during cutting.

  The supply reel 7 and the take-up reel 8 have an abrasive grain fixing wire 3 wound around a bobbin-shaped surface made of steel or the like. The wire saw device S includes a motor for rotating the supply reel 7 and the take-up reel 8 at a predetermined speed, and a traverser 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, an ester-based, ether-based, or urea-based urethane rubber. In particular, by using an ether-based urethane rubber, the guide roller 9 has a guide roller 9 having a similar hardness than the ester-based one. Wear can be reduced.

  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.

Below, the slicing method using the wire saw apparatus S of this embodiment is demonstrated concretely. The wire 3 is supplied from the supply reel 7 and is guided to the main roller 5 by the guide roller 9. The wire 3 is wound around the main roller 5 and arranged at a predetermined interval. 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 running at high speed cuts the workpiece 1 and is wound around the take-up reel 8. Further, the wire 3 is reciprocated by changing the rotation direction of the main roller 5. At this time, the length for supplying the wire 3 from the supply reel 7 is made longer than the length for supplying the wire 3 from the take-up reel 8, and the new line is supplied to the first main roller 5a.

  As shown in FIG. 2, the first surface 1 a of the workpiece 1 has the first surface 1 a of the workpiece 1 so that the fourth surface 1 d side (second end portion 22) comes into contact with the wire 3 first. It is made to incline with respect to the virtual plane 12 mentioned above (refer FIG.3 (b)). The virtual plane 12 may be a plane including a line connecting the upper edge portion of the first main roller 5a and the upper edge portion of the second main roller 5b. For cutting the workpiece 1, the workpiece 1 is lowered while supplying the machining liquid from the supply nozzle 4 toward the wire 3 that is traveling at a high speed, and the workpiece 1 is relatively pressed against the wire 3. It is done by doing. The workpiece 1 is divided into a plurality of substrates having a thickness of 200 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 (feed 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 feed speed is set to 350 μm / min or more and 1100 μm / min or less. At this time, when the wire 3 reciprocates, the feed speed also changes as the traveling speed of the wire changes.

  By inclining the workpiece 1, the distance of the workpiece 1 through which the wire 3 passes in the initial stage of cutting is shortened, so that occurrence of chipping and cracking at the beginning of cutting can be reduced. Thereby, the feed speed in the initial stage of cutting can be increased as compared with the conventional one. For example, conventionally, when the feed speed at the initial stage of cutting is slower than the feed speed at the middle stage of cutting, the feed speed at the initial stage of cutting can be made equal to the feed speed at the middle stage of cutting by inclining the workpiece 1. In addition, even when slicing a new workpiece 1 using the wire 3 that has been used once, even if the abrasive grains are worn and the cutting force is reduced, it is possible to slice without reducing the feed rate. . Furthermore, when slicing the 1st surface 1a of the to-be-processed object 1, the wire 3 is supplied toward the 4th surface from the 3rd surface 1c, and the 4th surface 1d side is made to contact the wire 3 previously. . That is, when the third surface side 1c (first end portion 21) of the first surface 1a is separated upward from the wire 3, the machining liquid is easily supplied between the first surface 1a and the wire 3 and is worn. Even the wire 3 having abrasive grains can be sliced in a state containing a large amount of processing liquid, so that the abrasive grains can be reduced in wear and sliced, and the generation of chips and cracks can be reduced. . As a method of inclining the workpiece 1, for example, by making the fourth surface 1 d side larger than the third surface 1 c side in the thickness of the base plate 10, the slice base 2 to which the workpiece 1 is bonded is used as the base plate 10. When attached to the workpiece 1, the workpiece 1 is installed with an inclination.

Further, as shown in FIG. 3, the second surface 1b of the workpiece 1 is such that the fourth surface 1d side (second end 24) is the wire 3 before the third surface 1c side (first end 23). You may make it incline at an angle which contacts. That is, the contact between the wire 3 and the slice base 2 is performed on the fourth surface 1d side before the third surface 1c side. Then, the workpiece 1 is continuously sliced on the third surface 1c side of the workpiece 1, and the slice base 2 is sliced as needed from the fourth surface 1d side to the third surface 1c side. Usually, when the wire 3 bends at the time of slicing, the wire 3 slices the slice base 2 on the third surface 1c side and the fourth surface 1d side, and the wire 3 slices the workpiece 1 in the central portion. Become. At this time, since the hardness of the workpiece 1 and the slice base 2 are different, the wire 3 is shaken due to the delay in cutting on the workpiece 1 side, and a minute crack is generated on the second surface 1b of the workpiece 1. there's a possibility that. Therefore, the wire 3 slices the slice base 2 on the fourth surface 1d side, and the wire 3 slices the workpiece 1 on the other third surface 1c side and the center portion, thereby reducing the occurrence of minute cracks. can do. When the wire 3 is supplied from the wire supply side, the wire 3 having abrasive grains that are not worn or less worn enters the workpiece 1 first. At the time of slicing the slice base 2, the wire 3 has passed through the workpiece 1, so that the abrasive grains are worn and the cutting ability is reduced, so that the wire 3 is less likely to be shaken and cracks are generated. It is thought that it was able to reduce. Furthermore, when the wire 3 is supplied from the opposite side of the wire supply side by the reciprocating travel of the wire 3, the cutting ability is reduced by the wire 3 having the worn abrasive grains, so that the workpiece 1 and the slice base 2 It is considered that the difference in the cutting ability is reduced and the wire 3 is less likely to be shaken. The angle B with the virtual plane 12 shown in FIG. 3B is formed to be 0.3 to 2.5 degrees.

  Further, as shown in FIG. 4, the center position 1e of the second surface 1b of the workpiece 1 is on the wire 3 supply side (first side) than the center position 5d between the first main roller 5a and the second main roller 5b. By being positioned on the main roller 5a), that is, on the third surface 1c side, the distance between the first main roller 5a and the workpiece 1 is shortened, and the bending amount of the wire 3 can be reduced. Thereby, it can reduce more that the wire 3 slices the slice base 2 in the 3rd surface 1c side and the 4th surface 1d side. As a result, the generation of minute cracks on the second surface 1b of the workpiece 1 can be reduced.

  Further, the fourth surface 1d side (second end portion 22) of the first surface 1a of the workpiece 1 is closer to the wire 3 supply side than the center position 5d between the first main roller 5a and the second main roller 5b. Since the distance between the first main roller 5a and the second main roller 5b can be shortened by being positioned on the opposite side (second main roller 5b side), that is, on the fourth surface 1d side, The distance is also shortened and the amount of deflection can be reduced.

  At the same time as the workpiece 1 is sliced, the slice base 2 is also cut to about 2 mm or more and 5 mm or less, and the cut substrate is put into the next cleaning process while being bonded to the slice base 2.

  In the cleaning process, an alkaline liquid or a neutral liquid is used as the cleaning liquid to clean the water-soluble coolant and dirt adhering to the substrate, and then the detergent is washed away with water. Then, the surface of the substrate is completely dried by hot air or air and peeled off from the slice base 2 to complete the substrate.

  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, without slicing the ingot into blocks, the slicing step may be performed as it is using the ingot as a workpiece. Further, the workpiece is not limited to a semiconductor material such as a solar cell element, and may be other metals or ceramics, for example.

  Hereinafter, more specific examples will be described. First, as shown in FIG. 1 and the like, an epoxy adhesive is applied to a slice base made of carbon, and a work piece made of polycrystalline silicon having a size of 156 mm × 156 mm × 300 mm is placed on the slice base and bonded. The agent was cured.

  Next, a silicon block bonded to one slice base was placed on the apparatus fixing portion via a base plate. Then, the silicon block adhered to the slice base is sliced while a wire (wire diameter = 100 μm, abrasive grain size = 15 μm, average diameter D = 130 μm) in which diamond abrasive grains are fixed with acrylic resin is run in both directions. Thus, a silicon substrate having an average thickness of 200 μm was produced.

Here, condition 1 in which the first surface of the silicon block is inclined by 0.7 degrees with respect to the virtual plane 12 so that the fourth surface side of the silicon block comes into contact with the wire first, the third of the wire in the silicon block Condition 2 in which the surface side is in contact with the wire first and is inclined by 0.7 degrees with respect to the virtual plane 12 shown in FIG. 3B, condition 3 in which the silicon block is not inclined
The crack generation rate of the obtained silicon substrate was evaluated.

  As shown in Table 1, from the results of Conditions 1 to 3, the crack occurrence rate in Condition 1 was greatly improved compared to Conditions 2 and 3 which are comparative examples.

  In condition 1, the second surface of the silicon block comes into contact with the wire 3 on the fourth surface side first than the third surface side, and continues to slice from the fourth surface side to the third surface side at any time. The contact was confirmed.

1: Workpiece 2: Slice base 3: Wire 5: Main roller 5a: First main roller 5b: Second main roller 5c: Third main roller 4: Supply nozzle 10: Base plate 11: Device fixing part 12: Processing liquid Receiving member S: wire saw device

Claims (2)

The first main roller, the second main roller disposed at a predetermined distance from the first main roller, and the first main roller and the second main roller are stretched in a plurality of rows in a plane. A wire saw device comprising a wire having abrasive grains fixed to the surface and a slice base, and feeding the wire from the second main roller while supplying the wire to the first main roller A workpiece having a first surface having a flat bottom surface and a second surface to be bonded to the slice base on the opposite side of the first surface, the first main roller and the second main roller On the wire stretched flat between the first surface and the wire so as to face the wire, and the workpiece is directed from the first surface toward the second surface. Of the workpiece to be cut A cross-sectional method,
At the start of cutting of the workpiece, a first end portion of the first surface located on the first main roller side of the workpiece with respect to a virtual plane including the plurality of rows of wires in an unloaded state with tilting the first surface in a direction away from the imaginary plane upward, Ru contacted first the second end of the first surface located on the second main roller side of the workpiece to the wire With
The center position of the second surface of the workpiece is positioned closer to the first main roller than the center position between the first main roller and the second main roller,
A method for cutting a workpiece, wherein the second end of the first surface of the workpiece is positioned closer to the second main roller than the center position .   Prior to the end of cutting the workpiece, the workpiece is located closer to the second main roller than the first end of the second surface located on the first main roller side of the workpiece. The method for cutting a workpiece according to claim 1, wherein the second end of the second surface is brought into contact with the wire first to perform cutting.

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