JP2002011648A - Wire saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire saw to increase machining precision of an ingot by the wire saw and to extend the life of a lining material. SOLUTION: During cutting of an ingot, a force to press an ingot 1 against a wire 11a under reciprocating running is applied mainly on groove rollers 12A and 12B for a wire saw arranged on both sides of an ingot cutting position (a) of the wire 11a. In that case, since hardness of the lining materials 12a and 12b is higher than that of a lining material 12c of a group roller 12C for other wire saw, the damage of the forming part of a wire groove 12d is suppressed, machining precision of the ingot 1 is improved, wharve of a wafer is decreased, and flatness is improved. Further, the two lining materials 12a and 12b and in its turn, the lives of the two lining materials 12a and 12b are elongated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire saw, and more particularly, to a wire saw in which the hardness of a lining material of a groove roller is made different between the rollers to increase the working accuracy of an ingot and prolong the life of the lining material.

[0002]

2. Description of the Related Art In a wire saw, an ingot cutting wire derived from a wire feeding reel (or bobbin) of a feeding device is transferred to a plurality of wire saw groove rollers (hereinafter, may be simply referred to as groove rollers). On the other hand, the device is wound in a coil shape and then wound around a wire winding reel (or bobbin) of a winding device. The basic structure of these groove rollers is such that an outer peripheral surface of a cylindrical base metal is coated with a lining material (urethane rubber) having a predetermined thickness, and a wire groove is formed on the outer peripheral surface of the lining material. The hardness of each lining material is set to the same value in all groove rollers. When cutting a single-crystal silicon ingot with a wire saw, the ingot is moved relative to the wire row while reciprocating while supplying a slurry-like abrasive liquid containing free abrasive grains (hereinafter sometimes referred to as abrasive grains) to wrapping oil. Forcefully. Thereby, the ingot is cut into many wafers by the grinding action of the abrasive grains.

[0003]

However, the groove rollers to which the pressing force at the time of cutting the ingot directly acts are always disposed on both sides of the ingot cutting position regardless of the number of groove rollers incorporated in the wire saw. There are two groove rollers. Therefore, for example, in the case of a triangular group of groove rollers arranged in a triangular shape, the lining material of both groove rollers which receives this pressing force at the time of cutting the ingot has a larger wire groove formation than the lining material of the remaining one groove roller. Damage due to wear of the part was severe. For this reason, the wire groove is deepened in a relatively short time, and the wire tension is reduced, thereby reducing the processing accuracy of the ingot. As a result, the obtained wafer has an increased warp (warp) and a TT
The wafer flatness such as V was also reduced. In addition, since the wear rate of the wire groove forming portion during the cutting of the ingot is increased, the time required for the depth of the wire groove to reach the depth at which the lining material has to be replaced is shortened, and thus the lining material is reduced. Had a shortened lifespan.

Therefore, it is conceivable to increase the hardness of the lining material of the three groove rollers evenly by the same value. However, in this case, since the wire is wound between the three hard lining materials, there is a concern that the wire may be easily cut during cutting of the ingot. Moreover, when the three lining materials are hardened equally, the lining material of the pair of groove rollers arranged on both sides of the ingot cutting position of the wire is also higher than the lining materials of the other groove rollers. The wear rate is also faster. Therefore, there is a concern that the life of the lining material will vary, and it will not be possible to replace three lining materials at the same time, thus lowering the maintenance work efficiency.

The inventor of the present invention has conducted extensive studies over a long period of time and found that among the plurality of groove rollers, the hardness of the lining material of the groove roller, which affects the processing accuracy of the ingot, was higher than the lining material of the other groove rollers. For example, during the cutting of the ingot, the wear speed of the wire groove forming portions of the groove rollers arranged on both sides of the ingot cutting position decreases, thereby reducing the wire tension or reducing the wire tension in the width direction of the wire row. Variations are less likely to occur and the accuracy of processing the ingot with the wire saw increases, and the time required for the depth of the wire grooves of the groove rollers arranged on both sides of the ingot cutting position to reach the depth where the lining material needs to be replaced is required. And the life of the lining material of the groove rollers on both sides is prolonged. It found that, to complete the present invention.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the possibility of breaking a wire during cutting of an ingot, to efficiently perform maintenance of a lining material incorporated in a wire saw, and to improve the processing accuracy of the ingot by the wire saw. It is an object of the present invention to provide a wire saw capable of extending the life of a lining material of groove rollers disposed on both sides of an ingot cutting position.

[0007]

According to a first aspect of the present invention, there are provided three or more wire saw groove rollers each having a lining material having a wire groove engraved on an outer peripheral surface thereof. In a wire saw that cuts an ingot by pressing the wire relatively to the wire by reciprocating the wire wound around the wire, a lining material for a pair of wire saw groove rollers disposed on both sides of the ingot cutting position of the wire. Is a wire saw whose hardness is higher than the hardness of the lining material of other wire saw groove rollers.

[0008] The type of wire saw to which the present invention is applied is not limited. For example, the ingot may be moved to press and contact the wire row to cut it, or conversely, the wire row may be moved to press and contact the ingot to cut it. Further, the lower surface of the ingot may be in contact with the upper portion of the wire array, and the upper surface of the ingot may be pressed against the lower portion of the wire array. Examples of the ingot cut by the wire saw include a silicon single crystal, a compound semiconductor single crystal, a magnetic material, quartz, and ceramics. As the abrasive liquid used for cutting, for example, a well-known abrasive liquid containing abrasive grains such as SiC having an average particle diameter of 5 to 50 μm can be used.

The number of groove rollers for the wire saw to be assembled and arranged on the wire saw may be three or more. For example, the number may be four. The structure of the groove roller for a wire saw is not limited. Usually, the outer peripheral surface of a cylindrical base metal is coated with a lining material (urethane rubber) having a predetermined thickness, and a wire groove is formed on the outer peripheral surface of the lining material. The hardness of the lining material of the pair of groove rollers arranged on both sides of the ingot cutting position of the wire is not limited as long as the hardness of the lining material of the other groove rollers is higher. The hardness of the other groove rollers is not limited. In this hardness measurement, Asker hardness meter J
IS6301 (A type) is used.

According to a second aspect of the present invention, the hardness of the lining material of each wire saw groove roller disposed on both sides of the ingot cutting position is measured by an Asker hardness tester in a range of 95 to 1.
2. The wire saw according to claim 1, wherein the hardness of the lining material of the other wire saw groove roller is 87 to 93 degrees by an Asker hardness meter. If the hardness of the lining material is less than 95 degrees as measured by an Asker hardness tester, the cutting precision of the ingot decreases. Further, when the hardness of the lining material exceeds 100 degrees by the Asker hardness meter, a deep groove is liable to occur due to uneven wear of the wire groove forming portion of the lining material.

[0011]

According to the present invention, when the ingot is cut, the pressing force acting relatively between the reciprocating wire and the ingot is mainly caused by the pair of wire saws disposed on both sides of the ingot cutting position of the wire. On the groove roller. At this time, since the hardness of the lining material of the pair of wire saw groove rollers is higher than the hardness of the lining material of the other wire saw groove rollers, the wear rate of the wire groove forming portion of these hard lining materials decreases. Thus, damage to the groove forming portion is suppressed. This makes it difficult for the wire tension to decrease, and as a result, the ingot can be cut with high accuracy. as a result,
The warp (warpage) of the cut wafer is reduced, and the TT
The flatness such as V also increases. Since the wear rate of the formation portion of the wire groove of the hard lining material is reduced in this manner, the pair of wire saw groove rollers disposed on both sides of the ingot cutting position has a depth that requires replacement of the lining material. The time until the depth of the wire groove reaches is increased, and the life of each lining material is extended.

Further, since a relatively low hardness lining material is also left in a part of the lining material, it is possible to prevent the wire from being broken at the time of cutting the ingot, which is a concern when all the lining materials are hardened. That is, since a high tension is applied to the wire, if all the lining material around which the wire is wound is hardened, the wire is easily cut. Moreover, by adjusting the hardness of the high-hardness lining material and the low-hardness lining material, it is possible to make the wear rates of all the lining materials during ingot cutting substantially the same. Thereby, all the lining materials can be replaced at the same time, and as a result, the lining materials incorporated in the wire saw can be efficiently maintained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic view of a main part of a wire saw according to one embodiment of the present invention. FIG. 1B is a partially enlarged view of a groove roller for a wire saw incorporated in the wire saw according to one embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a wire saw according to an embodiment of the present invention. The wire saw 10 is a device for cutting a single crystal silicon ingot I pulled up by the CZ method into a large number of wafers. The wire saw 10 has three groove rollers 1 arranged in an inverted triangle shape when viewed from the front.
2A, 12B, and 12C. A single wire 1 is provided between the groove rollers 12A, 12B, and 12C.
1a are wound parallel to each other at a constant pitch. Thereby, the groove rollers 12A, 12B, 1
The wire array 11 appears between 2C. The wire row 11 is
The three groove rollers 12A, 12B, and 12C are reciprocated by a drive motor. The middle between the two groove rollers 12A and 12B arranged on the upper side is the ingot I.
At the ingot cutting position a of the wire row 11 for cutting the wire. Above both sides of the ingot cutting position a, for example, a pair of abrasive liquid supply units (not shown) for continuously supplying the abrasive liquid onto the wire row 11 are provided.

These three groove rollers 12A, 1
The outer peripheral surfaces of 2B and 12C are covered with lining materials 12a, 12b and 12c of urethane rubber having a predetermined thickness. Among them, the hardness of the lining material 12a of the groove roller 12A and the lining material 12 of the groove roller 12B arranged on both sides of the ingot cutting position a
The hardness of b is a relatively high hardness of 96 degrees by an Asker hardness tester. On the other hand, the lining material 12 of the groove roller 12C
The hardness of c is a relatively low hardness of 89 degrees by an Asker hardness tester. Wire grooves 12d are engraved on the outer peripheral surfaces of the lining members 12a, 12b, and 12c, respectively (FIG. 1).
(B)).

The wire 11a is led out of the bobbin 20 of the feeding device 13, and is supplied with a guide roller (not shown) on the supply side.
Through these groove rollers 12A, 12B, 1
After being wound around 2C, it is wound on the bobbin 21 of the winding device 15 via a guide roller (not shown) on the outlet side. The rotating shafts of the feeding device 13 and the winding device 15 are connected to output shafts of drive motors 16 and 17, respectively. When the drive motors 16 and 17 are periodically driven, the bobbins 20 and 21 supported by the pair of bearings 18 are used.
However, the wire 11a rotates in the clockwise direction or the counterclockwise direction in FIG. 1 around the axis, and the wire 11a reciprocates. In FIG. 1, reference numeral 19 denotes a lift for raising and lowering the ingot I, and 19 a denotes a carbon bed for fixing the ingot I to the lift 19.

Next, a method of cutting the ingot I by the wire saw 10 will be described. As shown in FIG. 1, a wire saw 10 supplies an abrasive fluid from an unillustrated abrasive fluid supply unit to a wire row 11.
And the drive motor 16 rotates the bobbin 20 of the feeding device 13 so that the wire 11a passes through the supply-side guide roller and the groove rollers 12A, 12B,
Supply 12C. On the other hand, the bobbin 21 of the winding device 15 is rotated by the drive motor 17 to rotate the groove roller 1.
The wire 11a is wound up via 2A, 12B, 12C and a guide roller on the outlet side. And, as appropriate, each bobbin 20,
The wire 11a is reciprocated by changing the rotation direction of the wire 21. Accordingly, the other two groove rollers 12
As A and 12B rotate, both guide rollers also rotate. At this time, a groove motor 12C is rotated by a rotation motor (not shown) to assist the reciprocating movement of the wire array 11.

During the reciprocation of the wire row 11, the ingot I is pressed against the wire row 11 from above. Thereby, the ingot I is cut into a number of wafers. That is, during the reciprocation of the wire array 11, the loose abrasive grains in the abrasive liquid are rubbed against the bottom of the cutting groove by the wire 11a of the wire array 11, so that the bottom is gradually scraped off, and finally a large number of Cut into thin wafers. At the time of cutting the ingot, the pressing force of the ingot I directly acting on the reciprocating wire row 11 is mainly applied to the two groove rollers 12A and 12B arranged on both sides of the ingot cutting position a. Therefore, the lining members 12a and 12b of the two groove rollers 12A and 12B which receive this pressing force usually have the remaining groove rollers 1a and 12b.
The formation of the wire groove 12d is more severely damaged by abrasion than the 2C lining material 12c.

However, in this embodiment, since both lining members 12a and 12b are designed to have a high hardness of 96 degrees by an Asker hardness tester, wear of the lining members 12a and 12b in the portions where the wire grooves 12d are formed is reduced. Speed is reduced and its damage is suppressed. Thereby, the high-hardness lining materials 12a and 12b during the cutting of the ingot
The wear rate of the portion where the wire groove 12d is formed decreases. As a result, a decrease in the tension of the entire wire 11a is less likely to occur, and the ingot I can be cut with high accuracy. As a result, the warp (warpage) of the cut wafer is reduced, and the flatness such as TTV is also increased. In addition, since the wear rate of the formation portion of the wire grooves 12d of the lining materials 12a and 12b having high hardness is reduced, the lining materials 12 are formed in the groove rollers 12A and 12B.
The time required for the depth of the wire groove 12d to reach the groove depth at which the a and 12b need to be changed becomes longer than before. Therefore, the life of the pair of lining members 12a and 12b is extended.

Further, the groove rollers 12A, 1
A wire 11a is wound between 2B and 12C with high tension. Therefore, if all the lining materials 12
When a, 12b, and 12c are hardened, there is a concern that the wire 11a may break during cutting of the ingot. However, since the relatively soft lining material 12c remains on a part of the wire, the wire hardly breaks during cutting of the ingot. Moreover, the high hardness lining materials 12a and 12b and the low hardness lining material 1
By adjusting the hardness to 2c, it is possible to set the wear rates of all the lining materials 12a, 12b, 12c during ingot cutting to be substantially the same. As a result, the three lining members 12a, 12b, and 12c can be replaced at the same time. Therefore, the lining materials 12a, 12b, and 12c incorporated in the wire saw 10 can be efficiently maintained. Further, since the lining material 12c of the driving groove roller 12C has lower hardness than the other lining materials 12a and 12b, a relatively large frictional force is obtained between the groove forming portion of the lining material 12c and the wire row 11. Can be Therefore, when the groove roller 12C is rotated by a drive motor (not shown), especially at the start of rotation, the wire 11a is less likely to slip in the wire groove 12d. As a result, smooth reciprocation of the wire array 11 can be obtained.

[0020]

According to the present invention, the hardness of the lining material of the pair of groove rollers arranged on both sides of the ingot cutting position of the wire is made higher than the hardness of the lining material of the other groove rollers. The wire inside is less likely to break, and the lining material incorporated in the wire saw can be efficiently maintained, the working accuracy of the ingot by the wire saw can be increased, and the lining material for a pair of groove rollers Life can be extended.

[Brief description of the drawings]

FIG. 1A is a schematic diagram of a main part of a wire saw according to one embodiment of the present invention. (B) is a partially enlarged view of a groove roller for a wire saw incorporated in the wire saw according to one embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 wire saw, 11a wire, 12A, 12B, 12C groove roller for wire saw, 12a, 12b, 12c lining material, 12d wire groove, I ingot.

Claims (2)

[Claims] 1. An ingot comprising: three or more wire saw groove rollers each having a lining material in which a wire groove is engraved on an outer peripheral surface; and a wire bridged between the wire saw groove rollers is reciprocally moved to form an ingot. To
In a wire saw that is cut by being pressed relatively to this wire, the hardness of the lining material of the pair of wire saw groove rollers arranged on both sides of the ingot cutting position of the wire is set to the hardness of the lining material of another wire saw groove roller. Higher wire saw. 2. The hardness of the lining material of each wire saw groove roller disposed on both sides of the ingot cutting position is 95 to 100 degrees by an Asker hardness meter, and the hardness of the other wire saw groove roller is the Asker hardness. The wire saw according to claim 1, wherein the total is 87 to 93 degrees.