JP2011005617A - Wire saw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire saw device for reducing defective slice.SOLUTION: The wire saw device includes a wire having the mean diameter D with abrasive grains fixed to the surface thereof, and a main roller having a plurality of grooves wound with the wire therearound on the surface of the roller. The sectional shape of each groove is trapezoidal, the opening angle A of each groove is 30-38°. B/D satisfies the inequalities (1/cos(A/2)-tan(A/2))<B/D≤0.800, where B is the length of a bottom face of each groove.

Description

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

  For example, when a semiconductor substrate such as a solar cell element is manufactured, an ingot is cut into a predetermined size to form a block, and the block is bonded to a slice base with an adhesive, and then a plurality of wires are used by using a wire saw device or the like. The board is manufactured by cutting into sheets.

  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. Further, 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.

  As a slicing method using a wire saw device, there is a method (fixed abrasive grain type) of cutting with an abrasive fixed wire in which abrasive particles are fixed to the wire from the beginning. For example, in Patent Document 1 below, a plurality of grooves provided in the main roller have an inclined groove bottom surface with a tapered section that contacts and supports the wire at the lower outer periphery, and a partition wall projects between the grooves, It is disclosed that the side surfaces of the inclined grooves are formed on both sides of the partition walls at an opening angle smaller than the bottom surfaces of the inclined grooves facing the both sides of the outer periphery of the wire via a gap.

JP 2001-79748 A

  However, in the above-described wire saw device, if an abrasive wire having a small wire diameter is used, the run-out of the wire increases, so that slice marks and undulations occur on the surface of the manufactured semiconductor substrate and the like, resulting in poor slicing. May occur frequently. Moreover, in the structure described in patent document 1, it is necessary to process a groove | channel in two steps, and a process becomes complicated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly reliable wire saw device in which defective slices are reduced.

  A wire saw device according to an embodiment of the present invention includes a wire having abrasive grains fixed to a surface thereof, and a main roller having a plurality of grooves wound with the wire on a surface thereof, and the cross-sectional shape of the grooves is trapezoidal. And the wire contacts the bottom surface of the groove and each of the two slopes of the groove.

Further, a wire saw device according to an embodiment of the present invention includes a wire having an average diameter D, with abrasive grains fixed to the surface, and a main roller having a plurality of grooves wound with the wire on the surface, When the cross-sectional shape of the groove is a trapezoid, the opening angle A of the groove is 30 degrees or more and 38 degrees or less, and the length of the bottom surface of the groove is B, B / D satisfies the following formula. Features.
(1 / cos (A / 2) -tan (A / 2)) <B / D ≦ 0.800
Here, B / D significant digits are limited to 3 digits after the decimal point.

  With the above-described configuration, the wire saw device according to the present invention can reduce the run-out of a traveling wire even when an abrasive wire having a small wire diameter is used, and a slice of a workpiece surface such as a manufactured semiconductor substrate. It is possible to reduce the occurrence of traces and undulations and reduce slice defects.

It is a schematic perspective view which shows typically one Embodiment of the wire saw apparatus which concerns on this invention. It is a figure which illustrates one Embodiment of the wire saw apparatus which concerns on this invention typically, and is an expanded sectional view which shows the groove shape of the main roller which comprises a wire saw apparatus.

  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 of the present embodiment includes a wire 3 having an average diameter D and a plurality of grooves 5 a around which the wire 3 is wound, and a main roller 5 having a plurality of grooves 5 a around which the wire 3 is wound. .

  As shown in FIG. 2, the cross-sectional shape of the groove 5a is trapezoidal, and the wire 3 is in contact with the bottom surface of the groove 5a and the two inclined surfaces of the groove 5a. Thereby, a wire can be supported stably. Alternatively, when the opening angle A of the groove 5a is not less than 30 degrees and not more than 38 degrees and the width of the bottom surface of the groove 5a is B, (1 / cos (A / 2) -tan (A / 2)) <B / D ≦ 0.800. Here, the average diameter D of the wire 3 is the average value obtained by measuring the diameter including the abrasive grains from three directions at any 10 locations of the wire 3. Here, (1 / cos (A / 2) -tan (A / 2)) = B / D is a condition in which the bottom surface of the wire 3 is in contact with the slope of the wire 3. B / D significant digits are limited to 3 digits after the decimal point.

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

  The block 1 is formed by cutting the end portion of the ingot. The ingot is made of, for example, single crystal silicon or polycrystalline silicon. More specifically, when a single crystal silicon ingot is used, the ingot has a cylindrical shape. In addition, a polycrystalline silicon ingot is generally a substantially rectangular parallelepiped, and has a size capable of taking out a plurality of silicon blocks. The silicon block has a rectangular cross section (including a square), For example, it is formed in a rectangular parallelepiped of 156 × 156 × 300 mm.

  The block 1 is bonded to the slice base 2 made of a material such as a carbon material, glass 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. Then, one or a plurality of blocks 1 bonded to the slice base 2 are arranged in the apparatus by the work holder 10.

  The wire 3 is supplied from the supply reel 7 and taken up on the take-up reel 8. The wire 3 is wound around a plurality of main rollers 5 between the supply reel 7 and the take-up reel 8 and is stretched between the main rollers 5. The wire 3 is made of, for example, a piano wire whose main component is iron or an iron alloy, and has a wire diameter of 100 μm to 150 μm, more preferably 100 μm to 130 μm. In the present embodiment, the wire 3 is an abrasive fixed wire in which abrasive grains made of diamond or silicon carbide are fixed around the wire by plating with nickel, copper, or chromium. The average grain size of the abrasive grains is preferably 5 μm or more and 30 μm or less, and D is 110 μm or more and 210 μm or less, and more preferably D is 110 μm or more and 170 μm or less.

  The coolant liquid is supplied to the wire 3 from the plurality of openings of the supply nozzle 4. The coolant liquid is made of a water-soluble solvent such as glycol. The supply flow rate of the coolant liquid supplied to the supply nozzle 4 is appropriately set according to the size and number of blocks. Further, the coolant liquid may be circulated and used, and the abrasive grains and chips contained in the coolant liquid are removed at that time.

  The main roller 5 includes a first main roller 5A and a second main roller 5B disposed below the block 1, and is made of, for example, an ester-based, ether-based or urea-based urethane rubber, or a resin such as neurite. The diameter is about 150 to 500 mm and the length is 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. The shape of the groove of this embodiment will be described later.

  A dip tank 6 is provided below the wire 3 for the purpose of collecting block chips and coolant 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 also 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.

  Further, the wire saw device 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.

  In the wire saw device of the present embodiment, the cross-sectional shape of the groove 5a of the main roller is trapezoidal, the opening angle A of the groove 5a is 30 degrees or more and 38 degrees or less, and the length of the bottom surface of the groove 5a is B. In this case, the ratio B / D with the average diameter D of the wire satisfies the relationship of (1 / cos (A / 2) −tan (A / 2)) <B / D ≦ 0.800. As a result, even if an abrasive wire having a small wire diameter, for example, an average diameter of 170 μm or less is used, it is possible to reduce the runout of the traveling wire and to generate slice marks and waviness on the surface of the manufactured semiconductor substrate. And slice defects can be reduced. This is an abrasive-fixed wire in which the wire 3 has abrasive grains fixed to the surface, and since the size of the abrasive grains varies, the cross-sectional shape of the wire 3 is not a perfect circle. Unnecessary stress is not applied to the wire 3 by making it trapezoidal rather than U-shaped or V-shaped, and by reducing the distance between the wire 3 provided on the groove 5a and the side surface of the groove, the wire It is thought that blurring was reduced.

  The depth C of the groove 5a is such that the ratio C / D to the average diameter D of the wire 3 is 1.5 or more and 1.85 or less, so that the partition wall 5b formed between the grooves It is possible to suppress the wire 3 from rising and derailing while reducing deformation. Furthermore, the deformation of the partition wall 5b can be further reduced by setting the upper surface width E of the partition wall 5b to 0.05 mm or more.

  Below, the slicing method using the wire saw apparatus of this embodiment is demonstrated. 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 traveling at high speed cuts the block 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 15. At this time, the length for supplying the wire 3 from the supply reel 7 is longer than the length for supplying the wire 3 from the take-up reel 8, and the new line is supplied to the main roller 5.

  The block 1 is cut by lowering the block 1 while supplying the coolant liquid toward the wire 3 running at a high speed and relatively pressing the block 1 against the wire 3. The block 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 block 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 1000 m / min or less, and the maximum feed speed is set to 350 μm / min or more and 1100 μm / min or less.

  At the same time as slicing the block 1, the slice base 2 is also cut to about 2 mm or more and 5 mm or less, and the 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 a cleaning liquid, and water-soluble coolant and dirt adhering to the substrate are cleaned, 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, the slicing process may be performed as it is without cutting the ingot. The workpiece is not limited to a semiconductor material such as a solar cell element, and may be other metal or ceramics, for example.

<Example 1>
Hereinafter, more specific examples will be described. First, an epoxy adhesive was applied to a slice base made of a glass plate, and a rectangular parallelepiped polycrystalline silicon block of 156 mm × 156 mm × 300 mm was placed on the slice base to cure the adhesive.

  Next, the silicon block adhered to the two slice bases was installed in a wire saw device. Then, while the wire (wire diameter = 130 μm, abrasive grain size = 15 μm, average diameter D = 160 μm) in which diamond abrasive grains are fixed by Ni plating is run in both directions, the block adhered to the slice base is sliced. A silicon substrate having an average thickness of 200 μm was produced.

  Here, the cross-sectional shape of the groove of the main roller was a trapezoid, and the groove depth was 0.26 mm. When the groove opening angle A and the length of the bottom surface of the groove are B, the ratio B / D of the average diameter D of the wire is evaluated under various conditions shown in Table 1 to evaluate the defective rate of the slice when sliced. did. The defective items are the presence or absence of slicing marks, the presence or absence of undulations, and the presence or absence of waviness. The defect rate (%) was calculated from the number of sheets. The results are shown in Table 1. Note that (1 / cos (A / 2) -tan (A / 2)) at each opening angle A is 0.767 at 30 degrees, 0.733 at 35 degrees, 0.713 at 38 degrees, and 0 at 40 degrees. 700.

  As shown in Table 1, no. From the results of 1 to 26, when the opening angle A of the groove of the main roller is 30 degrees or more and 38 degrees or less and the length of the bottom surface of the groove is B, the ratio B / D to the average diameter D of the wire is ( By satisfying the relationship of 1 / cos (A / 2) -tan (A / 2)) <B / D ≦ 0.800, it was confirmed that the slice defect rate was reduced to less than 5%.

  When a main roller having an opening angle A of less than 30 degrees, for example, 25 degrees, was used, the wire could not be wound in the groove and could not be sliced.

1: Block 3: Wire 5: Main roller 7: Supply reel 8: Take-up reel

Claims (4)

A wire with abrasive grains fixed on its surface;
A main roller having a plurality of grooves wound with the wire on its surface,
The wire saw device, wherein the cross-sectional shape of the groove is trapezoidal, and the wire is in contact with the bottom surface of the groove and the two inclined surfaces of the groove. Abrasive grains fixed to the surface, and a wire with an average diameter D,
A main roller having a plurality of grooves wound with the wire on its surface,
When the cross-sectional shape of the groove is a trapezoid, the opening angle A of the groove is 30 degrees or more and 38 degrees or less, and the length of the bottom surface of the groove is B, B / D satisfies the following formula. A featured wire saw device.
(1 / cos (A / 2) -tan (A / 2)) <B / D ≦ 0.800   The wire saw device according to claim 2, wherein when the depth of the groove is C, C / D is 1.5 or more and 1.85 or less.   The wire saw device according to any one of claims 1 to 3, wherein an upper surface width of the partition wall formed between the grooves is 0.05 mm or more.

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