JP2005276851A - Wire saw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire saw which can cut a workpiece into wafers of a uniform thickness, by suppressing warpages, waviness, and variations in the thicknesses of cut wafers. <P>SOLUTION: The wire saw has a work plate 6 for holding the workpiece via a slice base 10; a working fluid supplier 8a for supplying a working fluid onto the upper surface of the work plate 6; a working fluid supplying port 6b formed in the upper surface 6a, through passages 6c which communicate with the working fluid supplying port 6b and are extended through the work plate 6 to supply the working fluid to the workpiece W; and straightening vane 9 for supplying the working fluid supplied from the through passages 6c evenly onto the workpiece W. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wire saw, and more particularly, to a wire saw provided with a current plate for rectifying a machining fluid at a machining fluid supply port above a workpiece.

  In recent years, wire saws are generally used for cutting single crystal ingots with the increase in diameter and flattening of wafers. This wire saw is a device that presses a workpiece against a wire array having a predetermined pitch, moves a wire and the workpiece relative to each other while pouring a machining liquid containing abrasive grains, and simultaneously cuts a large number of wafers by a grinding action.

  The advantage of the wire saw is that a large number of wafers can be cut simultaneously from the ingot, so that the productivity is high, and the wafers after cutting can be manufactured into almost the same shape by simultaneous cutting. On the other hand, the problem of using this wire saw is that the wafer warps after cutting. In a wire saw, the temperature rises due to the influence of frictional heat generated in the bearing portion of the grooved roller around which the wire is wound and frictional heat generated when the ingot is pressed against the wire. Due to this temperature rise, the ingot and each part of the apparatus are thermally expanded, the work plate is bent and an angle error occurs in the cut surface of the work piece, or the work plate is extended and the work piece is wavy or warped.

  As a method for indirectly preventing thermal deformation of the workpiece, a method of directly pouring a temperature control medium on the workpiece and performing temperature control is proposed in Patent Document 1, and Patent Document 2 has a full width. The machining fluid is supplied to the outer periphery of the workpiece by the machining fluid supply means having the machining fluid supply port opened across, and the machining fluid is supplied to the press contact portion between the workpiece and the wire via the outer periphery of the workpiece. Wire saws have been proposed.

However, in the method of Patent Document 1, irregularities in the flow of the machining fluid give an irregular force other than the traveling direction to the wire that cuts the workpiece, so that when the machining fluid is supplied to the workpiece, There is a problem that liquid flow unevenness occurs, and extreme thickness unevenness occurs in the cut wafer. Further, since the apparatus of Patent Document 2 supplies the machining liquid from the machining liquid supply port that is opened over the entire width, similarly to Patent Document 1, the uneven flow of the machining liquid is applied to the wire that cuts the workpiece. Therefore, there is a problem that extreme thickness variations occur in the cut wafer.
WO00 / 43162 JP-A-11-277395

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a wire saw capable of cutting a wafer having a uniform thickness while suppressing warpage undulation and thickness variation of the cut wafer.

  In order to achieve the above object, according to one aspect of the present invention, a workpiece is pressed while supplying a machining liquid to a wire array formed by winding a traveling wire around a plurality of grooved rollers. In a wire saw that cuts a workpiece into a plurality of wafers by a workpiece plate, a workpiece plate that holds the workpiece via a slice base, a machining fluid supply unit that supplies a machining fluid to the upper surface of the workpiece plate, and the upper A machining fluid supply port provided on the surface, a through channel that communicates with the machining fluid supply port and passes through the work plate and supplies the machining fluid to the workpiece, and a machining fluid supplied from the through channel There is provided a wire saw having a current plate for evenly supplying to a workpiece. As a result, a wire saw that can cut a wafer having a uniform thickness while suppressing warpage and thickness variation of the cut wafer is realized.

  According to the wire saw according to the present invention, it is possible to provide a wire saw capable of cutting a wafer having a uniform thickness while suppressing warpage undulation and thickness variation of the cut wafer.

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

  FIG. 1 is a conceptual diagram showing a front state of an embodiment of a wire saw according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing the vicinity of a supply port on the workpiece of the wire saw according to the present invention.

  As shown in FIGS. 1 and 2, a wire saw 1 according to the present invention is stretched between three grooved rollers 2 (2 a, 2 b, 2 b) that are rotatably provided and these grooved rollers 2. A roller mechanism portion 4 having a wire row 3 made of wires 3a, a work holding mechanism portion 5 for holding a workpiece (for example, a single crystal ingot) W pressed by the wire 3a and cut, and a work plate 6 are attached. The workpiece holding mechanism unit 5 is movably attached to the workpiece feeding mechanism unit, and the roller mechanism unit 4 and the workpiece feeding mechanism unit are mounted on an apparatus stand (not shown). ).

  Of the three grooved rollers 2 (2a, 2b, 2b), the grooved roller 2a is a drive roller driven by a roller drive motor (not shown), and the other grooved rollers 2b, 2b are driven rollers. The wire 3a of the wire row 3 is reciprocated by driving a grooved roller 2a that is a drive roller.

  Further, when the single crystal ingot W is cut, the grooved rollers 2b and 2b and the machining liquid supply device 7 for supplying the machining liquid to the upper part of the workpiece W are provided. The machining liquid supply device 7 is provided with roller side machining liquid supply ports 7b and 7b for supplying the machining liquid to the grooved rollers 2b and 2b via the machining liquid supply pipe 7p. A workpiece-side machining fluid supply port 7a for supplying a machining fluid to the upper portion of the workpiece W is provided.

  The machining liquid supply flow path 8 is opened to face the machining liquid supply pipe 8p and the upper surface 6a of the work plate 6, and the branched pipe body 8a as the machining liquid supply unit for supplying the machining liquid to the upper surface 6a, the upper surface 6 a, an upper part of the work plate 6, for example, a plate-side machining liquid supply port 6 b provided on the upper surface 6 a, and a plurality of through-flow passages 6 c provided through the work plate 6. Is provided with the workpiece side machining fluid supply port 7a.

  The workpiece side machining liquid supply port 7a is provided with a rectifying plate 9 extending in the longitudinal direction of the workpiece W and having an L-shaped cross section. The horizontal surface portion 9a of the rectifying plate 9 includes Along the longitudinal direction of the workpiece W, there is provided a machining fluid outflow slit 9b formed between the slice bases 10 to which the workpiece W is attached.

  The slit may be a slit whose long side is opened as in the present embodiment and is closed by a slice base, or may be a completely rectangular slit provided in a horizontal plane part. The slits may be disposed between the side edges and the slice base simply so as to be separated from the rectifying plate. Further, in the present embodiment, an example using a rectifying plate having three flat sides will be described. Alternatively, a rectifying plate provided with rises on both short sides of the horizontal plane portion may be used, and a slit may be formed in the rectifying plate that prevents the machining fluid from flowing from both short sides.

  Since the wire saw device of the present embodiment has the above-described structure, as shown in FIGS. 2 and 3, during the cutting process of the workpiece W, the machining fluid is supplied from the machining fluid supply device 7 through the machining fluid supply pipe 7p. Are supplied to the grooved rollers 2b and 2b from the roller side machining liquid supply ports 7b and 7b, and further, a machining liquid supply pipe 8p, a branch pipe body 8a, and an upper surface 6a of the work plate 6 which form the machining liquid supply flow path 8. Then, the workpiece is supplied from the workpiece side machining liquid supply port 7a to the upper portion of the workpiece W through the plate side machining liquid supply port 6b and the through flow path 6c. Accordingly, the temperature of the workpiece plate 6 is controlled by the machining fluid, and the machining fluid supplied to the upper portion of the workpiece W from the workpiece-side machining fluid supply port 7a is once stored in the current plate 9 and then from the slit 9b. Supplied in curtain form. For this reason, the processing liquid is supplied uniformly to the workpiece W, the temperature of the workpiece W is uniformly controlled, and the wafer is cut evenly without warping and uneven thickness.

  Using a wire saw according to the present invention as shown in FIG. 1, a silicon ingot having a length of about 500 mm is cut into a cutting time of about 10 hours, a water-soluble machining fluid (# 800 abrasive grains), a machining fluid supply rate of 80 to 100 L / min, Cutting is performed under the processing conditions of a wire diameter of 0.14 mm and a wire speed of 750 m / min. At the time of this cutting process, a temperature probe is attached to the work plate, and the temperature of the work plate and the thickness of the workpiece after cutting are cut. Was measured. Specifically, in the temperature control, the center thickness of the work plate 6 and the thickness of the workpiece were measured for the center thickness of the workpiece after cutting (Example).

  Further, in the case where the machining liquid is not supplied to the work plate (Comparative Example 1), the case where the machining liquid is supplied to the work plate but the rectifying plate is not used (Comparative Example 2), the same processing conditions as in the tests in Examples Was cut to measure the temperature of the work plate (Comparative Example 1) and the thickness variation after cutting (Comparative Example 2). The measurement place is the same as in the example.

  FIG. 4 shows temperature changes depending on the machining time at the center of the work plate in (a) the example and (b) comparative example 1.

  FIG. 5 shows variations in the center thickness of the workpiece after cutting between (a) the example and (b) comparative example 2. The horizontal axis in FIG. 5 indicates the distance from the head of the wafer manufactured by cutting the ingot in order from the head to the tail, and the vertical axis indicates the center thickness of the wafer.

  Result: As can be seen from FIG. 4, it was confirmed that the temperature did not rise over time in the example, but the temperature changed over time in Comparative Example 1.

  As can be seen from FIG. 5, in the example, the thickness variation after cutting was relatively small, and it was confirmed that the ingot could be cut without thickness variation as a whole. On the other hand, in the case of the comparative example 2 in which the current plate is not present, it was confirmed that a large thickness variation occurred in the vicinity of the central portion of the ingot (near the central portion of the wire saw). This is because the machining fluid supplied to the work plate flows in a state where it is not firmly rectified, and therefore, an irregular force other than the traveling direction is applied to the wire for cutting the workpiece, and as a result, Comparative Example 2 The thickness variation as shown in FIG.

  As described above, the wire saw of the present invention can suppress the undulation after cutting by suppressing the shape change during processing due to the temperature change of the work plate, and can provide the thickness after cutting by providing the rectifying plate. It was confirmed that the variation can be greatly suppressed.

The conceptual diagram which shows the front state of one Embodiment of the wire saw of this invention. Sectional drawing which expands and shows the supply port vicinity of the workpiece upper part of the wire saw of this invention. The perspective view which shows the attachment state of the baffle plate used for the wire saw of this invention. (A) is an Example, (b) is a time-dependent change figure of the temperature of the workplate center part at the time of the cutting | disconnection of the comparative example 1. FIG. (A) is an Example, (b) is the thickness distribution figure of the center part of the wafer in each cutting position of the ingot of the comparative example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire saw 2 Roller 2a Drive roller 2b Driven roller 3 Wire row | line | wire 3a Wire 4 Roller mechanism part 5 Work holding mechanism part 6 Work plate 6a Upper surface 6b Plate side process liquid supply port 6c Through-flow path 7 Process liquid supply apparatus 7a Work side process Liquid supply port 7b Roller side processing liquid supply port 8 Processing liquid supply flow path 8a Branch pipe 8p Processing liquid supply pipe 9 Current plate 9a Horizontal plane portion 9b Processing liquid outflow slit 10 Slice base W Workpiece

Claims (1)

In a wire saw that cuts a workpiece into a plurality of wafers by pressing the workpiece while supplying a processing liquid to a wire array formed by winding a traveling wire around a plurality of grooved rollers, the workpiece A workpiece plate for holding an object via a slice base, a machining fluid supply unit for supplying a machining fluid to the upper surface of the workpiece plate, a machining fluid supply port provided on the upper surface, and a machining fluid supply port A through-flow path that communicates and penetrates the work plate and supplies the machining fluid to the workpiece, and a current plate for uniformly supplying the machining fluid supplied from the through-flow channel to the workpiece. Wire saw.

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