JP5964197B2 - Wire saw - Google Patents

Description

  The present invention relates to a wire saw for processing a wafer by cutting a workpiece such as a semiconductor ingot into slices by a wire that is circulated between a plurality of processing rollers.

  Conventionally, in a wafer used for a solar cell, in order to improve the energy absorption rate of sunlight, a texture structure by chemical treatment for roughening the surface of the wafer or an uneven structure by mechanical treatment is formed. There is. If the texture structure and the concavo-convex structure are formed after the wafer cutting process using a wire saw, it is inevitable that the number of processes and the amount of work increase.

  In order to deal with such a problem, for example, a wafer manufacturing method using a wire saw as disclosed in Patent Document 1 has been proposed. In this conventional method, when the workpiece is cut by the wire of the wire saw to cut and form the wafer, either the wire or the workpiece is finely reciprocated in the longitudinal direction perpendicular to the thickness direction of the workpiece, Fine irregularities are formed on the surface of the wafer. Thereby, it is not necessary to form a texture structure or a concavo-convex structure on the surface of the wafer in a subsequent process of the wafer cutting process, and the manufacturing process and the amount of work can be reduced.

JP 10-44141 A

  However, Patent Document 1 does not disclose any specific configuration for minutely reciprocating either a wire or a workpiece in a longitudinal direction perpendicular to the thickness direction of the workpiece. For this reason, it is practically difficult to cut out and form a wafer having irregularities on the surface in a wire saw.

  The present invention has been made paying attention to such problems existing in the prior art. An object of the present invention is to provide a wire saw capable of easily cutting out and forming a wafer having irregularities on the surface.

In order to achieve the above object, according to the present invention, a wire is wound between a plurality of parallel processing rollers, the wire is circulated along with the rotation of the processing roller, and the workpiece is cut by the wire in the processing portion. In the wire saw, a moving mechanism for reciprocally moving the processing rollers on both sides of the processing portion integrally and periodically in a direction crossing the traveling direction of the wire is provided . The piezoelectric elements are provided at two positions spaced apart in the axial direction of the processing roller, and voltages having different polarities are alternately applied to the piezoelectric elements .

  Therefore, in the wire saw of the present invention, when the workpiece is cut and the wafer is cut out by the wire circulated between the plurality of processing rollers, the processing rollers on both sides of the processing portion are moved by the moving mechanism. It is reciprocated integrally and periodically in a direction crossing the traveling direction. Thereby, unevenness | corrugation is formed in the surface of a wafer and the wafer which has an unevenness | corrugation on the surface can be obtained.

  As described above, according to the wire saw of the present invention, it is possible to easily cut out and form a wafer having irregularities on the surface.

The schematic front view which shows the wire saw of 1st Embodiment. The schematic plan view of the wire saw of FIG. The expanded sectional view in the 3-3 line of FIG. FIG. 4 is a partial sectional view showing a part of FIG. 3 in an enlarged manner. The fragmentary sectional view which shows the wire saw of 2nd Embodiment. The perspective view which shows the state which cut | disconnected the workpiece | work with the wire saw. The perspective view which expands and shows the cut | disconnected wafer.

(First embodiment)
A wire saw according to a first embodiment of the present invention will be described below with reference to FIGS.

  As shown in FIGS. 1 to 3, the device frame 11 is provided with a pair of bearing portions 12 and 13 on two parallel axes. A shaft assembly 14 is fitted and supported on each bearing 12, 13. Each shaft assembly 14 is rotatably supported through a shaft support cylinder 15 fitted and fixed to the bearing sections 12 and 13 and bearings 16 and 17 each including a plurality of ball bearings. The spindles 18 and 19 as shaft portions and an end plate 20 that covers the inner end face of the shaft support cylinder 15 are configured. The bearings 16 and 17 are divided into a plurality of positions at positions corresponding to both ends of the spindles 18 and 19. Trapezoidal engaging convex portions 181 and 191 are formed at the inner end portions of the spindles 18 and 19, respectively. A screw hole 182 is formed at the center of the inner end of one spindle 18. A screw insertion hole 192 is formed at the center of the other spindle 19.

  As shown in FIGS. 1 to 3, between the spindles 18 and 19 of the shaft assembly 14 in both the bearing portions 12 and 13, engaging recesses 211 formed on both end surfaces of the processing roller 21 are respectively provided to the spindle 18. , 19 are engaged and supported by the spindles 18 and 19 so as to rotate together with the engaging projections 181 and 191. A screw rod 22 is screwed into the screw hole 182 of one spindle 18 through the center of the processing roller 21 from the screw insertion hole 192 of the other spindle 19. A nut 23 is screwed to the screw portion 221 on the outer periphery of the base end of the screw rod 22. The processing roller 21 is clamped and fixed between the spindles 18 and 19 by tightening the nut 23.

  A plurality of annular grooves 212 are formed on the outer peripheral surface of each processing roller 21 at intervals. Between the annular grooves 212 of both the processing rollers 21, a single wire 24 is wound many times so as to be installed. Both ends of the wire 24 are wound on a winding reel or a feeding reel (not shown). Then, when the processing roller 21 is rotated by a motor (not shown), the wire 24 travels between the processing rollers 21.

  As shown in FIGS. 1 and 2, the workpiece 41 such as a semiconductor ingot is supported on a support base 26 at a position above the processing portion 25 between the processing rollers 21 and can be moved up and down by a lifting mechanism (not shown). Is arranged. Then, as the processing roller 21 rotates, the wire 24 is circulated and the work 41 is lowered from the upper position indicated by the solid line to the lower position indicated by the chain line in FIG. Is cut into slices. Thereby, as shown in FIGS. 6 and 7, the wafer 42 is cut out and formed.

  As shown in FIGS. 3 and 4, the bearings 16 and 17 side of the apparatus frame 11 and the processing rollers 21 are disposed in the bearing portions 12 and 13 of the pair of processing rollers 21 located on both sides of the processing portion 25. A moving mechanism 27 for reciprocating the processing roller 21 integrally and periodically in a direction intersecting the traveling direction of the wire 24 is provided between the spindles 18 and 19 as the shaft portion. Yes.

  The moving mechanism 27 is composed of a pair of annular piezoelectric elements 28 and 29 that form a ring shape and are arranged at two positions spaced apart in the axial direction of the processing roller 21. Then, voltages having different polarities are alternately applied to these piezoelectric elements 28 and 29 from a drive circuit (not shown).

Next, the operation of the wire saw configured as described above will be described.
During the operation of the wire saw, the pair of processing rollers 21 are rotated by a motor (not shown), and the wire 24 travels between the processing rollers 21. At the same time, the work 41 is lowered toward the wire 24 of the processing section 25 by an elevating mechanism (not shown). As a result, the workpiece 41 is cut into slices by the wire 24, and the wafer 42 is cut out and formed.

  At this time, in the respective bearing portions 12 and 13 of both the processing rollers 21, voltages having different polarities are alternately applied from the drive circuit (not shown) to the two piezoelectric elements 28 and 29 of the moving mechanism 27. 29 are alternately expanded and contracted. That is, in FIG. 3, when a voltage having a plus or minus polarity is applied to the piezoelectric element 28 on the right side of the bearing portions 12 and 13, a voltage having an opposite characteristic is applied to the left piezoelectric element 29. The application of this voltage is alternately switched at a predetermined cycle. As a result, as indicated by arrows in FIGS. 2 and 3, a reciprocating force in the axial direction is applied to the spindles 18 and 19 via the bearings 16 so that the pair of processing rollers 21 rotate, that is, the wires. While the wire 24 travels, the wire 24 is reciprocated integrally and periodically with a minute stroke (about 5 to 20 μm) in a direction intersecting the traveling direction. As a result, as shown in FIGS. 6 and 7, fine irregularities 421 are formed on the surface of the wafer 42 cut out from the workpiece 41. Note that when the reciprocating stroke of the processing roller 21 is increased in order to increase the height difference of the unevenness 421, a stacked type may be used as the piezoelectric element 29.

Therefore, according to this embodiment, the following effects can be obtained.
(1) In this wire saw, a moving mechanism 27 is provided for reciprocally moving the processing roller 21 integrally and periodically in a direction intersecting the traveling direction of the wire 24.

  Therefore, in this wire saw, when the workpiece 41 is cut and the wafer 42 is cut out by the wire 24 circulated between the plurality of processing rollers 21, the processing on both sides of the processing portion 25 is performed by the moving mechanism 27. The roller 21 is reciprocated integrally and periodically in a direction intersecting the traveling direction of the wire 24. Thereby, the unevenness | corrugation 421 is formed in the surface of the wafer 42, and the wafer 42 which has the unevenness | corrugation 421 on the surface can be obtained.

  (2) In this wire saw, the moving mechanism 27 is provided between the apparatus frame 11 and spindles 18 and 19 as shaft portions of the processing roller 21. For this reason, the moving mechanism 27 can be incorporated in the apparatus frame 11 without being bulky, and the structure can be simplified.

  (3) In this wire saw, the moving mechanism 27 is constituted by piezoelectric elements 28 and 29. For this reason, the moving mechanism 27 can be simply and easily downsized, and the processing roller 21 can be reciprocated minutely by the contracting action of the piezoelectric elements 28 and 29. Moreover, since there are no movable parts in the moving mechanism 27, there is almost no risk of failure.

  (4) In this wire saw, the piezoelectric elements 28 and 29 are provided at two locations separated in the axial direction of the processing roller 21. For this reason, the processing roller 21 can be reciprocated stably with a strong torque.

(Second Embodiment)
Next, a second embodiment of the wire saw embodying the present invention will be described focusing on the differences from the first embodiment.

  In the second embodiment, as shown in FIG. 5, in one bearing portion 12 of the apparatus frame 11 that supports one end portion of the pair of processing rollers 21, the end surface of the bearing portion 12 and the end plate of the shaft assembly 14 are used. 20, one annular piezoelectric element 31 constituting the moving mechanism 27 is sandwiched and disposed. When the workpiece 41 is cut, voltages having different polarities are periodically and repeatedly applied to the piezoelectric element 31.

  Therefore, during operation of the wire saw, the piezoelectric element 31 constituting the moving mechanism 27 is repeatedly expanded and contracted, so that the pair of processing rollers 21 are minutely integrated and periodically in a direction intersecting the traveling direction of the wire 24. It is reciprocated with a stroke. As a result, as in the case of the first embodiment, fine irregularities 421 are formed on the surface of the wafer 42 cut out from the workpiece 41.

Therefore, according to the second embodiment, in addition to the effects described in (1) to (3) in the first embodiment, the following effects can be obtained.
(5) In the wire saw of this embodiment, since the moving mechanism 27 is composed of one piezoelectric element 31, the structure of the moving mechanism 27 can be further simplified.

(Example of change)
In addition, this embodiment can also be changed and embodied as follows.
The present invention is embodied in a wire saw having three or more processing rollers 21.

  The piezoelectric elements 28, 29, and 31 that constitute the moving mechanism 27 are arranged at locations different from the configurations of the respective embodiments. For example, it is provided on both sides of the bearing 17 outside the shaft support cylinder 15.

One piezoelectric element of the moving mechanism 27 is provided for each bearing portion 12 and 13.
The moving mechanism 27 is not a piezoelectric element, such as an electrically driven vibrator.

  DESCRIPTION OF SYMBOLS 11 ... Apparatus frame, 12, 13 ... Bearing part, 14 ... Shaft part assembly, 15 ... Shaft support cylinder, 16, 17 ... Bearing, 18, 19 ... Spindle as a shaft part, 20 ... End plate, 21 ... Processing roller , 24 ... wire, 25 ... processing part, 27 ... moving mechanism, 28, 29, 31 ... piezoelectric element, 41 ... work, 42 ... wafer, 421 ... unevenness.

Claims (2)

In a wire saw in which a wire is wound between a plurality of parallel processing rollers, and the workpiece is cut by the wire in the processing portion by rotating the wire as the processing roller rotates.
Provided with a moving mechanism for reciprocating the processing rollers on both sides of the processing unit integrally and periodically in a direction intersecting the traveling direction of the wire ,
The moving mechanism is constituted by a piezoelectric element,
A wire saw characterized in that the piezoelectric elements are provided at two positions spaced apart in the axial direction of the processing roller, and voltages having different polarities are alternately applied to the piezoelectric elements . The wire saw according to claim 1, wherein the moving mechanism is provided between the apparatus frame and a shaft portion of the processing roller.