JP6277924B2 - Ingot cutting method - Google Patents

Description

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

  In recent years, an increase in the size of a wafer has been desired, and with this increase in size, a wire saw apparatus is exclusively used for cutting an ingot.

  The wire saw device runs a wire (high-strength steel wire) at a high speed, and applies a workpiece (for example, a silicon ingot, hereinafter referred to simply as an ingot) while cutting the slurry on the wire. In this apparatus, a large number of wafers are cut out simultaneously (see Patent Document 1).

Here, FIG. 4 shows an outline of an example of a conventional general wire saw device.
As shown in FIG. 4, the wire saw device 101 mainly includes a wire 102 for cutting the ingot W, a wire guide 103 around which the wire 102 is wound, a tension applying mechanism 104 for applying tension to the wire 102, 104 ′, an ingot feeding means 105 for feeding the ingot W to be cut, a nozzle 106 for supplying a slurry in which abrasive grains are dispersed and mixed at the time of cutting, and the like.

  The wire 102 is fed out from one bobbin 107 (wire reel), and passes through a traverser 108 and a tension applying mechanism 104 including a powder clutch (constant torque motor 109), a dancer roller (dead weight) (not shown), etc. It is in the wire guide 103. The wire 102 is wound about 300 to 400 times around the wire guide 103 and then wound around the bobbin 107 ′ through the other tension applying mechanism 104 ′.

  The wire guide 103 is a roller in which polyurethane resin is press-fitted around a steel cylinder and grooves are cut at a constant pitch on the surface thereof. The wound wire 102 is predetermined by a driving motor 110. It can be driven in a reciprocating direction with a period.

  A nozzle 106 is provided in the vicinity of the wire guide 103 and the wound wire 102. When cutting the ingot W, slurry can be supplied from the nozzle 106 to the wire guide 103 and the wire 102. And after cutting, it is discharged as waste slurry.

  Using such a wire saw device 101, an appropriate tension is applied to the wire 102 using the tension applying mechanisms 104 and 104 ′, and the wire 102 is caused to travel in the reciprocating direction by the driving motor 110 to supply the slurry. By slicing the ingot W, a desired slice wafer is obtained.

  At this time, as a quality of the wafer after cutting, a flat wafer having a small warpage and no waviness is desirable.

JP-A-10-86140

  However, when the shape of the wafer obtained by cutting the ingot with a wire saw is confirmed, warping and undulation tend to occur in the region of the ingot starting portion.

  This is because the tension of the wire when cutting the ingot is low, so that the wire is likely to be shaken during the cutting of the ingot, and the warpage of the wafer after cutting is likely to increase.

  One method for reducing such warping and undulation at the beginning of cutting is to increase the tension of the wire. By stretching the wire with high tension, it is considered that the lateral blurring of the wire at the time of cutting is reduced, and warpage and undulation in the wafer surface are reduced.

However, if the tension applied to the wire at the time of cutting the ingot is increased too much, there arises a problem that the wire is easily broken during the ingot cutting.
If the wire breaks during the cutting of the ingot, the cutting of the ingot is interrupted and much time and effort are required for the recovery work. As a result, the production efficiency of the wafer is significantly reduced. Further, when the wire breaks, the wafer quality after cutting is greatly deteriorated. Therefore, it is desirable that the breakage of the wire during ingot cutting should not occur as much as possible.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ingot cutting method capable of cutting a wafer with less warpage from an ingot without deteriorating the rate of occurrence of wire breakage. .

In order to achieve the above object, according to the present invention, a wire fed out from one of a pair of bobbins and wound around the other bobbin is spirally wound between a plurality of wire guides and travels in an axial direction. Tension forming mechanisms respectively arranged on the bobbin side for feeding out the wire and the bobbin side for winding the wire while forming a wire row and supplying a machining fluid to the contact portion between the ingot and the wire By applying the tension to the wire by pressing the ingot against the wire row, the ingot cutting method for cutting the ingot into a wafer shape,
When the tension applied to the wire on the side fed out from the bobbin when cutting the maximum diameter portion of the ingot is a reference tension,
When cutting the cutting start portion of the ingot, the tension applied to the wire on the side fed out from the bobbin is made higher than the reference tension,
A method for cutting an ingot is provided, wherein the ingot is cut with a tension applied to the wire wound on the bobbin being lower than the reference tension.

  In this way, a wafer with less warpage can be cut out from the ingot without deteriorating the rate of breakage of the wire.

At this time, the tension to be applied to the wire on the side fed out from the bobbin when cutting the cutting start portion of the ingot is 1.1 times or more of the reference tension,
It is preferable that the tension applied to the wire on the side wound around the bobbin is a tension equal to or less than half of the reference tension.
In this way, a wafer with less warpage can be cut out from the ingot without deteriorating the breaking rate of the wire more reliably.

At this time, the reference tension can be set to 20 to 30N.
In this way, it is possible to cut efficiently, and to cut out a wafer with less warpage from the ingot without deteriorating the rate of breakage of the wire.

At this time, when cutting other than the cutting start portion of the ingot, the tension applied to the wire on the side fed out from the bobbin is the same as the reference tension,
The tension applied to the wire wound on the bobbin is preferably constant at a value lower than the reference tension, regardless of the cutting position of the ingot.
In this way, the operation is simple, and a wafer with less warpage can be cut out from the ingot more reliably without deteriorating the breakage occurrence rate of the wire.

  With the ingot cutting method of the present invention, it is possible to cut out a wafer with less warpage from the ingot without deteriorating the rate of breakage of the wire.

It is the schematic which showed an example of the wire saw apparatus which can be used by this invention. In the Example and the comparative example 1, it is the figure which showed the relationship between the cutting position of an ingot, and the tension | tensile_strength added to the wire by the side of feeding. It is the figure which showed the relationship of the tension | tensile_strength added to the cutting position of an ingot and the wire by the side of winding in an Example and the comparative example 1. FIG. It is the schematic which showed an example of the general wire saw apparatus.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
As described above, when the tension applied to the wire is increased in order to reduce warpage or undulation that occurs at the beginning of cutting the ingot, there is a problem that the wire is easily broken during ingot cutting.

  Therefore, the present inventor has intensively studied to solve such problems. As a result, the tension applied to the wire drawn out from the bobbin when cutting the ingot cutting start portion is made higher than the reference tension, and the tension applied to the wire wound on the bobbin is set to the reference It was conceived that by cutting the ingot below the tension, a wafer with less warpage can be cut out from the ingot without deteriorating the rate of breakage of the wire. And the best form for implementing these was scrutinized and the present invention was completed.

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

  As shown in FIG. 1, the wire saw device 1 mainly includes a wire 2 for cutting the ingot W, a wire guide 3 (roller with a groove) wound with the wire 2, and a tension for applying tension to the wire 2. The tension applying mechanisms 4 and 4 ', the ingot feeding means 5 for feeding out the ingot W to be cut, and the nozzle 6 for supplying the machining fluid to the wire 2 at the time of cutting are configured.

  The wire 2 is fed out from one bobbin 7 (wire reel), and passes through a tension applying mechanism 4 including a powder clutch (constant torque motor 9), a dancer roller (dead weight) (not shown) and the like via a traverser 8. It is in the wire guide 3.

  Then, the wire 2 is wound about 300 to 400 times between the plurality of wire guides 3 to run in the axial direction, and after forming a wire row, the other bobbin 7 ′ is passed through the other tension applying mechanism 4 ′. It is wound on.

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

A nozzle 6 is provided in the vicinity of the wire guide 3 and the wound wire 2. When cutting the ingot W, slurry can be supplied from the nozzle 6 to the wire guide 3 and the wire 2. And after cutting, it is discharged as waste slurry.
As described above, the wire saw device used in the method for cutting an ingot according to the present invention can be applied to those conventionally used in general.

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

  In the wire saw device 1, while supplying the processing liquid to the contact portion between the ingot W and the wire 2, the tension applying mechanism 4 disposed on the bobbin 7 side that unwinds the wire 2 and the bobbin 7 ′ side that winds the wire 2 The ingot W is cut into a wafer shape by pressing the ingot W against the traveling wire row while applying tension to the wires 2 by the arranged tension applying mechanism 4 '.

  Here, when the portion with the maximum diameter of the ingot W is cut, the tension applied by the tension applying mechanism 4 to the wire 2 fed out from the bobbin 7 is set as a reference tension.

  At this time, the reference tension is not particularly limited, but can be generally 20 to 30 N. Thereby, an ingot can be cut | disconnected as usual.

  And the tension | tensile_strength provided with the tension | tensile_strength provision mechanism 4 to the wire of the side drawn out from the bobbin 7 at the time of cut | disconnecting the cutting start part of the ingot W is set so that it may become higher than a reference | standard tension | tensile_strength. On the other hand, the tension applied by the tension applying mechanism 4 'to the wire wound on the bobbin 7' is set to be lower than the reference tension.

  That is, it is possible to reduce warpage and undulation generated at the cutting start portion of the wafer to be cut out by increasing the tension on the drawing side in cutting the cutting start portion. At this time, if the tension on the winding side is lowered, it is possible to suppress the breakage of the wire.

It should be noted that the cutting start portion of the ingot W includes a portion where the ingot W first contacts the wire 2.
For example, specifically, it may be a section cut to 10 mm in the ingot feeding direction from the position where the ingot W first contacts the wire 2.

  By cutting the ingot W in this manner, a wafer with less warpage can be cut out from the ingot without deteriorating the rate of occurrence of wire breakage.

  Further, the tension applied by the tension applying mechanism 4 to the wire 2 on the side fed out from the bobbin 7 when cutting the cutting start portion of the ingot W is set to 1.1 times or more of the reference tension, and too much. If high tension is applied, the rate of occurrence of wire breakage may increase again, so it is preferable to make it within 2 times.

  Further, the tension applied by the tension applying mechanism 4 ′ to the wire 2 on the side wound around the bobbin 7 ′ is preferably set to a tension equal to or less than half of the reference tension. In addition, if the tension of the wire 2 on the winding side is excessively lowered, the wound wire 2 is easily unwound from the bobbin 7 ′, and therefore a winding tension of a certain size or more (for example, 0.1 times or more) is necessary. Become.

  Further, when cutting the portion other than the cutting start portion of the ingot W, the tension applied by the tension applying mechanism 4 to the wire 2 on the side fed out from the bobbin 7 is the same as the reference tension, and is wound on the bobbin 7 ′. The tension applied to the wire 2 by the tension applying mechanism 4 ′ is preferably constant at a value lower than the reference tension regardless of the cutting position of the ingot W.

  By doing so, the cutting operation can be simplified, and a wafer with less warpage can be cut out from the ingot more reliably without deteriorating the rate of breakage of the wire.

  In the above description, the case where the wire is sent out from the bobbin 7 and wound around the bobbin 7 ′ (forward rotation direction) has been described as an example, but the present invention is not limited to this.

  That is, when the wire 2 travels in the forward rotation direction, as described above, the tension is applied to the wire 2 with a tension higher than the reference tension according to the cutting position of the ingot W as described above. On the other hand, the tension applying mechanism 4 ′ applies a tension lower than the reference tension to the wire 2.

  Conversely, when the wire 2 travels in the reverse direction, which is opposite to the forward direction, a tension higher than the reference tension is applied to the wire 2 by the tension applying mechanism 4 ′ according to the cutting position of the ingot W as described above. On the other hand, the tension applying mechanism 4 applies a tension lower than the reference tension to the wire 2. In this way, if the above operation is repeated alternately, a plurality of ingots can be cut continuously.

  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.

(Example)
An ingot W having a diameter of 300 mm was cut using a wire saw device 1 as shown in FIG.
When cutting the maximum diameter portion of the ingot W, the tension applied by the tension applying mechanism to the wire 2 on the side fed out from the bobbin was set to 23 N, and this was used as the reference tension.

  Then, as shown in Condition 1 in Table 1 below, the tension applied by the tension applying mechanism to the wire 2 on the side fed out from the bobbin when the cutting start portion of the ingot W is cut is 1.. It was set to 27N, which is 17 times, so as to be 1.1 times or more of the reference tension.

  On the other hand, the tension applied to the wire 2 wound around the bobbin by the tension applying mechanism is set to 10 N, which is a value equivalent to 43% of the reference tension, so that the tension is less than half of the reference tension. did.

  In addition, the section cut to 10 mm in the feeding direction of the ingot W from the position where the ingot W and the wire 2 first contact each other was used as a start portion.

  Then, as shown in FIG. 2, after the cutting position 10 mm of the ingot W, the tension applied by the tension applying mechanism to the wire 2 that is fed out from the bobbin is linearly lowered, and at the cutting position 50 mm of the ingot W. The tension was the same as the standard tension.

  Moreover, as shown in FIG. 3, the tension | tensile_strength provided with the tension | tensile_strength provision mechanism to the wire 2 of the side wound up by the bobbin was made into the constant value with the low value irrespective of the cutting position of the ingot W. 2 and 3 also show Comparative Example 1 described later.

  Twenty-five ingots W were cut with the same single wire saw device 1 under the cutting conditions as described above (condition 1 in Table 1). And when each ingot W was cut | disconnected, the frequency | count that the fracture | rupture of the wire 2 generate | occur | produced was counted, and the value divided by the number of cutting | disconnection was made into the wire breakage incidence rate.

  And it represented with the relative value which set the value of the wire fracture occurrence rate at the time of cutting | disconnection by the conditions 2 of the comparative example 1 (conventional conditions) mentioned later as 1, and described in Table 1.

  Further, the wafer after cutting was measured with an electrostatic capacitance type SBW330 manufactured by Kobelco Research Institute, the amount of warped displacement was calculated, and the warpage of the wafer was measured. And it represented by the relative value which set the value of the curvature of the wafer at the time of cut | disconnecting on the conditions 2 of the comparative example 1 mentioned later as 1, and described in Table 1.

  As described above, when the breakage of the wire occurs, there is a great disadvantage in terms of productivity and wafer quality after cutting. Therefore, it is preferable not to deteriorate the wire breakage occurrence rate, and a smaller value is desirable. It is desirable that the wafer warp has a small value.

  As a result, as shown in Table 1, the rate of occurrence of wire breakage was the same level as in Comparative Example 1 under the conventional conditions. Further, the wafer warpage was 0.92 times that of Comparative Example 1 under the conventional conditions, indicating an improvement in wafer quality.

  As described above, in the example, a wafer with less warpage could be cut out from the ingot without deteriorating the breakage occurrence rate of the wire.

(Comparative Example 1)
As shown in FIGS. 2 and 3, both the tension applied to the wire drawn out from the bobbin by the tension applying mechanism and the tension applied to the wire wound around the bobbin by the tension applying mechanism are both at the cutting position of the ingot. Regardless, the ingot was cut in the same manner as in Example except that it was set to 23.0 N which is the same value as the reference tension (Condition 2).

  And the measurement about the wire breakage incidence at this time and the curvature of the obtained wafer was performed like the Example. In addition, on the basis of the measurement results of the wire breakage incidence and wafer warpage in Comparative Example 1, the values of the above Examples and Comparative Examples 2 to 4 described later are shown in Table 1 as relative values. It was.

(Comparative Example 2)
When cutting the starting part of the ingot, both the tension applied to the wire that is fed out from the bobbin by the tension applying mechanism and the tension applied to the wire wound around the bobbin by the tension applying mechanism are both set to the standard tension. On the other hand, the ingot was cut in the same manner as in the example except that it was set to 27.0 N which is 1.17 times the value (Condition 3).

  And the measurement about the wire breakage incidence at this time and the curvature of the obtained wafer was performed like the Example, and was shown in Table 1.

  As a result, as shown in Table 1, the warpage of the wafer was improved by 0.92 times that of Comparative Example 1 under the conventional conditions. However, the rate of wire breakage deteriorated to 1.4 times. As described above, the wire breakage has a large demerit, and the breakage occurrence rate is not an acceptable level.

(Comparative Example 3)
When cutting the starting part of the ingot, the tension applied to the wire that is fed out from the bobbin by the tension applying mechanism is 23.0 N, which is the same size as the reference tension, and the tension is applied to the wire that is wound around the bobbin. The ingot was cut in the same manner as in Example except that the tension applied by the applying mechanism was set to 17.3 N, which is 75% of the reference tension (Condition 4).

  And the measurement about the wire breakage incidence at this time and the curvature of the obtained wafer was performed like the Example, and was shown in Table 1.

  As a result, as shown in Table 1, both the wire breakage rate and wafer warpage were the same as in Comparative Example 1, and no improvement was observed.

  From this result, in order to contribute to the improvement of the wire breakage occurrence rate, the tension applied to the wire wound on the bobbin by the tension applying mechanism is less than half of the reference tension as in the condition 1 of the embodiment. It is considered effective to reduce it.

(Comparative Example 4)
When cutting the starting part of the ingot, both the tension applied to the wire drawn out from the bobbin by the tension applying mechanism and the tension applied to the wire wound around the bobbin by the tension applying mechanism are both The ingot was cut in the same manner as in Example except that the condition was set to 17.3 N which is 75% (Condition 5) to obtain a wafer.

  And the measurement about the wire breakage incidence at this time and the curvature of the obtained wafer was performed like the Example, and was shown in Table 1.

  As a result, as shown in Table 1, the wire breakage incidence was the same level as in Comparative Example 1. On the other hand, the warpage of the wafer was 1.2 times that of Comparative Example 1 and worsened.

  From this result, it was found that when the ingot cutting start portion is cut, the warp of the wafer is likely to deteriorate if the tension applied by the tension applying mechanism to the wire on the side fed from the bobbin is too low.

  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, 101 ... wire saw device, 2, 102 ... wire,
3, 103 ... wire guide, 4, 4 ', 104, 104' ... tension applying mechanism,
5, 105 ... Ingot feeding means, 6, 106 ... Nozzle,
7, 7 ', 107, 107' ... bobbins, 8, 108 ... traversers,
9, 109 ... constant torque motor, 10, 110 ... drive motor,
W ... Ingot.

Claims (5)

A wire that is drawn out from one of the pair of bobbins and wound around the other bobbin is spirally wound between a plurality of wire guides to run in the axial direction, forming a wire row, and between the ingot and the wire While supplying the working fluid to the contact part, while applying tension to the wire by the tension applying mechanism respectively arranged on the bobbin side for feeding out the wire and on the bobbin side for winding the wire, A method of cutting an ingot by pressing the ingot to cut the ingot into a wafer shape,
When the tension applied to the wire on the side fed out from the bobbin when cutting the maximum diameter portion of the ingot is a reference tension,
When cutting the cutting start portion of the ingot, the tension applied to the wire on the side fed out from the bobbin is made higher than the reference tension,
A method for cutting an ingot, wherein the ingot is cut with a tension applied to the wire on the side wound around the bobbin being lower than the reference tension. When the cutting start portion of the ingot is cut, the tension applied to the wire on the side fed out from the bobbin is a tension that is 1.1 times or more of the reference tension,
The method for cutting an ingot according to claim 1, wherein a tension applied to the wire on the side wound around the bobbin is set to a tension equal to or less than half of the reference tension.   The ingot cutting method according to claim 1 or 2, wherein the reference tension is 20 to 30N. When cutting other than the cutting start portion of the ingot, the tension applied to the wire on the side fed out from the bobbin is the same as the reference tension,
The tension applied to the wire on the side wound around the bobbin is made constant at a value lower than the reference tension regardless of the cutting position of the ingot. The ingot cutting method according to claim 1. From the position where the ingot and the wire first contact each other, when the section cut to 10 mm in the feeding direction of the ingot is the cutting start portion,
The tension applied to the wire on the side fed out from the bobbin is linearly lowered after the cutting start portion, and is equal to the reference tension. The ingot cutting method according to one item .

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