JP2017121686A - Cutting method of ingot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting method of an ingot by a wire saw capable of restraining the occurrence of disconnection of a wire.SOLUTION: In a cutting method of an ingot for cutting in a wafer shape by pushing the ingot against a wire row while imparting tension to a wire by a tension imparting mechanism respectively arranged on the supply wire reel side and the recovery wire reel side, while reciprocatably traveling by repeating winding by the length smaller than the predetermined length on a supply wire reel, by delivering the wire by the predetermined length from the supply wire reel, by forming the wire row by winding the wire in a spiral shape between a plurality of grooved rollers, the cutting method of the ingot cuts the ingot in the wafer shape by controlling so that a value of A/B×100 becomes 60 or more, assuming winding tension of an undelivered wire wound on the supply wire reel as A and wire winding tension when the supply wire reel winds the wire as B.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for cutting an ingot.

  Conventionally, a wire saw is known as means for cutting a wafer from a silicon ingot, a compound semiconductor ingot, or the like. As disclosed in Patent Document 1, in a wire saw, a wire array is formed by winding a large number of ingot cutting wires around a plurality of grooved rollers, and the wires are driven at high speed in the axial direction. In addition, the ingot is cut and fed to the wire row while the slurry is appropriately supplied, so that the ingot is simultaneously cut at the position of each wire.

  Here, FIG. 3 shows an outline of an example of a general wire saw. As shown in FIG. 3, the wire saw 101 is mainly cut by a wire 102 for cutting the ingot W, a plurality of grooved rollers 103 around which the wire 102 is wound, a mechanism 104 for adjusting the tension of the wire 102, and the wire saw 102. A mechanism 105 for feeding the ingot W downward, and a mechanism 106 for supplying slurry at the time of cutting.

  The wire 102 is fed out from one wire reel 107, passed through a tension applying mechanism 112 including a traverser 108, a pulley 109, and a tension adjusting mechanism 104, and then wound around the grooved roller 103 about 300 to 500 times. It is wound around a wire reel 107 ′ through a tension applying mechanism 112 ′ including one tension adjusting mechanism 104 ′, a pulley 109 ′, and a traverser 108 ′.

  Further, the grooved roller 103 is a roller in which polyurethane resin is press-fitted around a steel cylinder and grooves are cut on the surface thereof at a substantially constant pitch, and the wound wire 102 is driven by the grooved roller drive motor 110. It can be driven in a reciprocating direction at a predetermined cycle.

  Further, the wire reels 107 and 107 ′ are rotationally driven by the wire reel drive motors 111 and 111 ′, and are applied to the wire 102 by controlling the speeds of the grooved roller drive motor 110 and the wire reel drive motors 111 and 111 ′, respectively. The tension can also be adjusted.

  The tension adjusting mechanisms 104 and 104 ′ have a role of adjusting the tension applied to the wire 102 with higher accuracy as disclosed in, for example, Patent Document 2.

  Using such a wire saw 101, an appropriate tension is applied to the wire 102 using the wire tension applying mechanism 104, and the drive motor 110 slices the ingot while the wire 102 travels in the reciprocating direction.

  As disclosed in Patent Document 3, when the wire saw 101 as described above is used, the cutting ability is improved by increasing the traveling speed of the wire 102 operated by the drive motor 110. That is, since the ingot can be efficiently cut, the productivity of the wafer can be improved.

JP-A-9-262826 Japanese Patent Laid-Open No. 9-94755 JP 2000-117726 A JP 2013-27958 A

  However, when the traveling speed of the wire is increased, it is necessary to rotate the grooved roller 103, the wire reel 107 and the like at high speed, and the tension fluctuation of the wire becomes large. Therefore, the wire breakage is likely to occur.

  When the wire breaks, there is a problem that a step is generated on the surface of the wafer cut out from the ingot, or the nanotopography on the surface of the wafer is deteriorated, resulting in a defective product. Therefore, it is an important issue to reduce the occurrence rate of wire breakage.

  On the other hand, for example, Patent Document 4 discloses a technique for reducing fluctuations in wire tension by further disposing a mechanism such as a buffer wire reel between a grooved roller and a wire reel. Yes. However, with this method, the apparatus becomes large and the effect of suppressing disconnection cannot be obtained sufficiently.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method for cutting an ingot with a wire saw capable of suppressing the occurrence of wire breakage.

  To achieve the above object, according to the present invention, a wire array is formed by spirally winding a wire supplied from a supply wire reel and recovered on a recovery wire reel between a plurality of grooved rollers, The supply wire reel and the collection wire reel while the wire is reciprocated by repeating a predetermined length from the supply wire reel and winding the supply wire reel to a length less than the predetermined length. An ingot cutting method for cutting the ingot into a wafer by pressing an ingot against the wire row while applying tension to the wire by a tension applying mechanism arranged on each of the wire reels, The winding tension of the unwound wire wound around the supply wire reel is A, and the supply wire reel is A method for cutting an ingot, characterized by controlling the value of A / B × 100 to be 60 or more when the wire winding tension when winding the wire is B, and cutting the ingot into a wafer shape I will provide a.

  With such an ingot cutting method, it is possible to suppress the occurrence of wire breakage during cutting without requiring a large-scale device.

  At this time, the maximum traveling speed of the wire can be set to 900 m / min or more.

  According to the ingot cutting method of the present invention, even when the maximum traveling speed of the wire is set to 900 m / min or more, the occurrence rate of the wire breakage can be reduced. That is, according to the ingot cutting method of the present invention, even if the traveling speed of the wire is increased in order to improve the cutting efficiency, the wire is hardly broken.

  With the ingot cutting method of the present invention, it is possible to suppress the occurrence of wire breakage during cutting without requiring a large-scale device.

It is the schematic which shows an example of the wire saw which can be used for the cutting method of the ingot of this invention. It is the graph which put together the incidence rate of the break of the wire in an Example and a comparative example. It is the schematic which shows an example of a common wire saw.

  Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.

  As described above, in the conventional method, the wire breakage is likely to occur as the traveling speed of the wire increases. Moreover, the wire breakage suppressing method in the prior art is likely to be a large-scale device, and the effect of suppressing the wire breakage has not been sufficiently obtained.

  Therefore, the present inventors have investigated the cause of wire breakage in order to solve such problems. As a result, in particular, there is a large tension fluctuation at the timing when an unused wire (a wire that has been wound around the supply wire reel and is not fed) is fed from the supply wire reel, and this tension fluctuation causes a break in the wire. I understood that.

  The winding tension of the unwinded wire wound around the supply wire reel is usually a low value (for example, 1/3 or less) of the tension of the wire at the time of cutting. In the reciprocating movement of the wire, when the supply wire reel is on the winding side of the wire, the wire is usually wound with a cutting tension. Therefore, it has been found that a large tension fluctuation occurs at the moment when the unused wire is fed out when the supply wire reel is changed from the wire winding side to the feeding side. And it became clear that the tension adjusting mechanism 104 (see FIG. 3) could not control the fluctuation of the tension as the wire traveling speed increased, and the disconnection occurred. Based on such knowledge, the present inventors have completed the ingot cutting method of the present invention.

  First, an example of a wire saw that can be used in the ingot cutting method of the present invention will be described.

  As shown in FIG. 1, the wire saw 1 mainly includes a wire 2 for cutting the ingot W, a plurality of grooved rollers 3 in which the wire 2 is spirally wound, and a wire wound around the grooved roller 3. 2, a tension applying mechanism 12, 12 ′ for applying tension to the wire 2, a feed mechanism 5 for sending the ingot W to be cut downward, a slurry supply mechanism 6 for supplying slurry at the time of cutting, and the like.

  The wire 2 is supplied from a supply wire reel 7, passed through a tension applying mechanism 12 including a traverser 8, a pulley 9, and a tension adjusting mechanism 4, and then wound around the grooved roller 3 about 300 to 500 times. The tension adjusting mechanism 4 ', the pulley 9', and the traverser 8 'including the traverser 8' are collected on the collecting wire reel 7 '.

  The grooved roller 3 is a roller in which polyurethane resin is press-fitted around a steel cylinder and grooves are cut on the surface thereof at a substantially constant pitch. The wound wire 2 is moved by the grooved roller drive motor 10. It can be driven in a reciprocating direction at a predetermined cycle.

  Further, the supply wire reel 7 and the recovery wire reel 7 ′ are rotationally driven by wire reel drive motors 11 and 11 ′, and control the speeds of the grooved roller drive motor 10 and the wire reel drive motors 11 and 11 ′, respectively. The tension applied to the wire 2 can also be adjusted.

  Next, the ingot cutting method of the present invention when this wire saw 1 is used will be described.

  First, the wire 2 supplied from the supply wire reel 7 and collected on the collection wire reel 7 ′ is spirally wound between the plurality of grooved rollers 3 to form a wire row 13. Then, the wire 2 is reciprocated by repeatedly feeding the wire 2 from the supply wire reel 7 to a predetermined length and winding the supply wire reel 7 to a length less than the predetermined length. At this time, tension is applied to the wire 2 by the tension applying mechanisms 12 and 12 ′ disposed on the supply wire reel 7 side and the recovery wire reel 7 ′ side, respectively. Then, the ingot W is cut into a wafer shape by reciprocating the wire 2 and pressing the ingot W against the wire row 13 while applying tension to the wire 2. At this time, the ingot W can be cut while supplying the slurry from the slurry supply mechanism 6.

  Here, in the ingot cutting method of the present invention, A is the winding tension of the unwound wire wound around the supply wire reel 7, and B is the wire winding tension when the supply wire reel 7 winds the wire. Then, the ingot W is cut into a wafer shape by controlling so that the value of A / B × 100 is 60 or more.

  In this way, in the reciprocating travel of the wire 2, it is possible to reduce the tension fluctuation at the moment when the wire 2 is fed when the supply wire reel 7 is on the feeding side of the wire 2. Therefore, if it is the ingot cutting method of this invention, since this tension fluctuation | variation can be restrained small, generation | occurrence | production of the disconnection of a wire can be suppressed. Moreover, it is not necessary to make the device large. The upper limit value of A / B × 100 is preferably 90.

  At this time, in the ingot cutting method of the present invention, the maximum traveling speed of the wire 2 can be set to 900 m / min or more. By setting the maximum traveling speed of the wire in this way, the cutting efficiency of the ingot can be improved. Further, with the ingot cutting method of the present invention, even when the wire is run at a high speed as described above, the wire is hardly broken. A higher traveling speed is preferable from the viewpoint of cutting efficiency, but as an upper limit of the maximum traveling speed, for example, 1500 m / min is sufficient for cutting using slurry (free abrasive grains).

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention, but the present invention is not limited to these examples.

(Example)
Using a wire saw 1 as shown in FIG. 1, a silicon ingot having a diameter of 300 mm was cut by the ingot cutting method of the present invention. That is, in the cutting of the silicon ingot, the winding tension A of the unwinded wire wound around the supply wire reel and the wire winding tension B when the supply wire reel winds the wire are A / B × 100 ≧ 60. It was carried out to satisfy.

  Further, the silicon ingot was cut a plurality of times by changing the cutting conditions within the range of Table 1 below, with the value of A or the maximum traveling speed of the wire. Further, the wire winding tension B when the supply wire reel winds the wire was fixed at 23 (N). The wire tension in the grooved roller 3 in FIG. 1 when the ingot was cut was the same value as B.

  Table 1 summarizes the cutting conditions in the examples.

(Comparative example)
The silicon ingot was cut in the same manner as in the example except that the value of A was changed so that A / B × 100 <60. The silicon ingot was cut a plurality of times, and each time, the value of A or the maximum traveling speed of the wire was changed within the range shown in Table 2 below.

  Table 2 summarizes the cutting conditions in the comparative example.

  Table 3 and FIG. 2 show the results of summarizing the occurrence rate (disconnection rate) of the wire breakage for each of the values of A / B × 100 and the maximum traveling speed of the wire in cutting the ingots of the above examples and comparative examples. .

  As can be seen from Table 3 and FIG. 2, if the value of A / B × 100 is controlled to 60 or more as in the embodiment, the disconnection rate is suppressed to 0% or extremely low regardless of the wire traveling speed. It was confirmed that In particular, when the maximum traveling speed of the wire is as high as 900 m / min or more, in the comparative example, the higher the maximum traveling speed of the wire, the higher the probability of disconnection. However, in the example of the present invention, it was confirmed that the wire breakage hardly occurred even at such a high speed, and the breakage rate was suppressed to be considerably lower than that of the comparative example. Thus, it was confirmed that the present invention is particularly effective when the maximum traveling speed of the wire is high.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

1 ... wire saw, 2 ... wire, 3 ... grooved roller,
4, 4 '... tension adjustment mechanism, 5 ... feed mechanism, 6 ... slurry supply mechanism,
7 ... Supply wire reel, 7 '... Recovery wire reel, 8, 8' ... Traverser,
9, 9 '... pulley, 10 ... grooved roller drive motor,
11, 11 '... wire reel drive motor, 12, 12' ... tension applying mechanism,
13 ... Wire row, W ... Ingot.

Claims (2)

The wire supplied from the supply wire reel and collected on the collection wire reel is spirally wound between a plurality of grooved rollers to form a wire row, and the wire is fed out from the supply wire reel by a predetermined length, Tension applying mechanisms respectively arranged on the supply wire reel side and the recovery wire reel side while reciprocating the wire by repeatedly winding the supply wire reel less than the predetermined length. The ingot cutting method of cutting the ingot into a wafer by pressing the ingot against the wire row while applying tension to the wire by:
The value of A / B × 100, where A is the winding tension of the unwinded wire wound around the supply wire reel, and B is the wire winding tension when the supply wire reel winds the wire. Is controlled to be 60 or more, and the ingot is cut into a wafer shape.   The ingot cutting method according to claim 1, wherein the maximum traveling speed of the wire is set to 900 m / min or more.

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