JP6080753B2 - How to resume wire saw operation - Google Patents

Description

  The present invention relates to cutting a workpiece with a wire saw, and relates to a method for resuming the operation of a wire saw when a cutting of a wire is interrupted and then the cutting is resumed after the cutting is temporarily interrupted.

  Conventionally, a wire saw is known as means for cutting a workpiece such as a semiconductor ingot into a wafer shape. In this wire saw, a plurality of cutting wires are wound around a plurality of grooved rollers to form a wire row, the cutting wires are driven at high speed in the axial direction, and slurry is appropriately supplied. When the work is pushed down relative to the wire row, the work is simultaneously cut at each wire position.

Here, FIG. 2 shows an outline of an example of a general wire saw.
As shown in FIG. 2, in the wire saw 1, the wire 2 for cutting the workpiece W is fed from the wire reel 6 on the supply side and enters the roller 3 with the groove. A wire row 7 is formed by winding the wire 2 around the grooved roller 3 about 300 to 500 times. Further, the wire 2 is unwound from the grooved roller 3 and wound on the wire reel 6 'on the collecting side.
When cutting the workpiece W, the wire 2 is reciprocated in the wire axis direction at a predetermined travel distance, and a new wire is gradually supplied from the supply side of the wire row to the recovery side.

Therefore, the amount of wear of the wire is larger on the side of the wire wound around the grooved roller 3 where the new line is supplied, that is, on the side where the wire is collected, that is, on the collection side than on the supply side. Wire diameter is reduced. For this reason, the wafer cut on the collection side tends to be thicker than the wafer cut on the supply side.
In view of this, a structure in which the pitch between the plurality of grooves of the grooved roller is narrower on the collecting side than on the supply side is used (Patent Document 1).

  By the way, the wire of the wire saw is made of a wire material having high wear resistance and tensile resistance and having high hardness such as a piano wire, and the grooved roller is made of a resin having a predetermined hardness in order to prevent the wire from being damaged. Although a roller is used, the wire may break during cutting of the workpiece due to wear or fatigue of the wire over time, and cutting of the wafer may not be continued.

  When a wire is broken on the wire reel side on the new wire supply side or on the grooved roller while the workpiece is being processed by the wire saw, first, the workpiece is avoided and then the broken portion is connected to the new line. Then, after the wire connection part has been sent to the wire reel side on the recovery side, the work is returned to the cutting position at the time of disconnection, the wire is placed at the cutting position of the work, and cutting is resumed.

  In order to solve the problem of wire breakage, a method of improving the strength of the wire (see Patent Document 2) or detecting a sign of breakage with a wire saw and stopping cutting (see Patent Document 3) is known. With such a technique, the frequency of wire breakage can be reduced to some extent.

JP-A-10-249701 JP 2002-256391 A JP 2011-31355 A

Ultra-precise wafer surface control technology, Yoshiaki Matsushita et al. Published February 28, 2000 at Science Forum Inc.

However, with the increase in productivity in recent years, the use load of the wire also increases, and disconnection cannot be avoided completely.
In addition, when wire breakage occurs, the wire that has been worn due to cutting is replaced with a new wire that does not wear, so it becomes difficult to return the workpiece to the cutting position at the time of wire breakage due to the difference in wire diameter. End up. Furthermore, even if the workpiece is returned to the cutting position at the time of disconnection and cutting is resumed, a groove is formed on the cut surface of the workpiece due to the difference in the diameters of the wires. Recently, in order to reduce the manufacturing cost of wafers, the lapping cost at the lapping process in the subsequent process is designed to be small, so the above groove cannot be removed by lapping process, and a lot of defective products are generated. Cause the problem of end.

  Furthermore, in recent years, a wire with a small diameter and a high count abrasive with a small average abrasive grain size are used for resource saving. When such a wire or abrasive grain is used for cutting, the cutting allowance of the workpiece is small, so that when a wire breakage occurs, it becomes even more difficult to pass a new line with a large diameter at the cutting position of the workpiece. .

  Further, in the case of a cutting recipe in which the amount of wear of the wire is large, the diameter of the wire is correspondingly reduced and the cutting allowance is reduced. Grooves are generated in the cut part by increasing the cutting allowance of the workpiece after resuming cutting.

FIG. 4 is a diagram for explaining a change in the work cutting allowance from the supply side to the recovery side of the wire row in a general wire saw.
In general, it is known that the workpiece cutting allowance is a value obtained by adding three times the average abrasive grain size of the abrasive grains in the slurry to the diameter of the wire (Non-Patent Document 1). Here, d is the average abrasive grain size of the abrasive grains contained in the slurry, R ₁ is the diameter (new wire diameter) of the wire on the supply side of the wire array, R ₂ is the diameter (wear diameter) of the wire on the recovery side, and the wire It represented the amount of wear When _{ΔR (= R 1 -R 2)} , a cutting margin of the supply side as in the work is _R 1 + 3d, a cutting margin of the recovery side of the workpiece and the _{R 2 + 3d = R 1 -ΔR} + 3d . If cutting margin of the recovery side of the wire row workpiece is less than Shinsen径R _1, when cutting resumed, it is impossible to return the new line to cut position of the workpiece. Therefore, to return to cut the work position, a cutting margin of the recovery side should there be Shinsen径R ₁ or more. That is, the wear amount ΔR needs to satisfy the following formula.
R ₁ −ΔR + 3d−R ₁ ≧ 0 ⇔ 3d ≧ ΔR (1)

  Therefore, conventionally, the wire wear amount is limited to a range within a certain limit that satisfies the above formula (1), so that the wire can be used only with a limited cutting recipe, and the wire cannot be effectively used.

  The present invention has been made in view of the above-described problems. In the cutting of a workpiece such as a semiconductor ingot using a wire saw, even when the cutting of the workpiece is interrupted due to the disconnection of the wire, the wire is not affected by the amount of wear of the wire. A wire saw operation resumption method that can return the workpiece to the workpiece cutting position, suppress the occurrence of grooves in the cut wafer after restarting operation, and suppress the occurrence of abnormal shapes due to disconnection in the wafer in a later process .

  In order to achieve the above object, according to the present invention, a wire array is formed by winding a wire around a plurality of grooved rollers, the wire is reciprocated in a predetermined cycle in the axial direction, and the wire is cut. In the operation of a wire saw that cuts the workpiece into a wafer shape by relatively pushing down the workpiece and pressing the workpiece against the wire row while supplying a slurry for use, the cutting of the workpiece is caused by the occurrence of the breakage of the wire An operation resumption method in the case where the cutting is resumed after being temporarily interrupted in the middle, wherein the wire has a length capable of cutting at least one or more of the workpieces, and at least the wire row can be formed from the tip. A step of preparing a worn wire that has been worn down, and after the wire is broken, the broken wire is replaced with the worn wire to form a wire row again. And a step of resuming cutting after moving the wear wire so that the worn wire in the re-formed wire row is the cut position of the workpiece. A method for resuming the operation of a wire saw is provided.

  In this way, the replaced wire is worn in advance and has a small diameter, so that the wire can be returned to the cut position of the workpiece. Therefore, it can suppress that a groove | channel generate | occur | produces in the wafer cut | disconnected after restarting operation | movement, and can suppress that the defect resulting from a disconnection generate | occur | produces in a wafer. Furthermore, the cutting recipe at the time of workpiece | work cutting | disconnection is hardly restrict | limited, A wire can be used effectively without depending on the amount of wear of a wire.

At this time, the Shinsen径R ₁ is the diameter of the wire in the new line supply side of the wire array of wires and the broken, measuring the wear diameter R ₂ is the diameter of the wire at the recovery side of the wire array of wires and the broken Then, in the step of restarting the cutting, the diameters of the wires on the new wire supply side and the recovery side of the wire array formed again with the wear wires are the same as the new wire diameter R ₁ and the wear diameter R ₂ , respectively. Thus, it is preferable to resume cutting after moving the wear wire.

  In this way, a wear wire having a diameter that is smaller than the workpiece cutting margin and approximately the same diameter as the broken wire can be reliably returned to the workpiece cutting position, so that a groove is generated in the cut wafer after the operation is resumed. Can be suppressed more reliably.

  Further, at this time, the worn wire to be replaced can be exchanged for the wire worn by cutting the workpiece with the same cutting recipe as that for cutting the workpiece in which the disconnection has occurred.

  In this way, since the worn wire to be replaced with the broken wire is used in the same cutting recipe, the diameter and the method of changing the diameter can be made the same. Accordingly, the diameter of each wire at the cutting position of the workpiece at the time of disconnection can be easily reproduced when cutting is resumed. As a result, it is possible to suppress the generation of grooves in the further cut wafer.

  At this time, after the cutting of the workpiece is resumed and the cutting of the workpiece is completed, the wear wire can be replaced with the disconnected wire, and then the next workpiece can be cut.

  If it does in this way, since the new line which remained in the disconnected wire can be used for cutting again, the cost concerning a wire can be reduced.

  At this time, when the wire breakage occurs in the wire supply side or in the wire row, the wire saw operation resuming method described above can be implemented.

  The method for resuming the operation of the wire saw of the present invention is particularly suitable when a disconnection occurs on the wire supply side or in the wire row.

  According to the wire saw operation resumption method of the present invention, it is possible to suppress the generation of grooves in the wafer cut after the operation is restarted, and to suppress the occurrence of defects due to disconnection in the wafer. In addition, the wire can be returned to the cutting position of the workpiece without depending on the amount of wear of the wire at the time of cutting, and the operation can be resumed with almost no restrictions on the fine wire, abrasive grain size, or cutting recipe. Can be used effectively.

It is the flowchart which showed an example of the operation resumption method of the wire saw of this invention. It is the schematic which shows an example of a common wire saw. It is a figure which shows the result of an Example and a comparative example. It is a figure explaining the cutting margin of the workpiece | work in a general wire saw.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
As described above, if the wire breaks while the workpiece is being cut by the wire saw, when the workpiece is resumed, the diameter of the new line is larger than the cutting margin of the workpiece on the collection side of the wire row, and the wire is broken. It becomes impossible to return to the cutting position at the time. Even if the workpiece can be returned to the cutting position at the time of disconnection and cutting can be resumed, there is a problem that the diameter of the new line is large, there is a difference in the diameter of the wire, and a groove is generated on the cut surface of the workpiece. .

  The inventor has intensively studied to solve such problems. As a result, the wire that has broken is replaced with a wear wire that has been worn for a certain length from the tip prepared in advance, and the diameter of the replaced wire at the workpiece cutting position is made approximately equal to the diameter of the wire just before the break. As a result, it was found that the cutting can be resumed without problems and the generation of the groove can be suppressed, and the present invention has been completed.

First, the operation of a wire saw that cuts a workpiece into a wafer will be described.
As shown in FIG. 2, the wire saw 1 includes a wire 2 for cutting the workpiece W, a plurality of grooved rollers 3 around which the wire 2 is wound, and a workpiece feeding mechanism 4 for feeding the workpiece W to be cut relatively downward. In addition, it has a slurry supply means 5 for supplying slurry to the wire 2 at the time of cutting.
The wire 2 is fed out from the wire reel 6 on the supply side and enters the grooved roller 3. A wire row 7 is formed by winding the wire 2 around the grooved roller 3 about 300 to 500 times. Further, the wire 2 is unwound from the grooved roller 3 and wound around the collecting-side wire reel 6 ′.

A wire tension applying mechanism (not shown) for applying tension to the wire 2 is provided between the grooved roller 3 and the wire reels 6 and 6 '.
When cutting the workpiece W, the wire 2 is reciprocated in the wire axis direction at a predetermined travel distance. At this time, the traveling distances of the reciprocating wires in the respective directions are not the same, and the traveling distance in one direction is longer. As a result, the new wire is gradually supplied from the supply side to the collection side as shown in FIG.

  The workpiece W is held by the workpiece feeding mechanism 4 and fed to the wire 2 positioned relatively below. The workpiece feeding mechanism 4 presses the workpiece W against the wire row 7 and cuts the workpiece W relatively downward until the wire 2 reaches the contact plate. Then, after the cutting of the workpiece W is completed, the cut workpiece W is pulled out from the wire row by reversing the feeding direction of the workpiece W.

The wire saw operation resuming method of the present invention is a method of resuming operation when the wire 2 is disconnected and the cutting of the workpiece W is temporarily interrupted in the middle of the operation, and then the cutting is resumed. Hereinafter, it will be described in detail with reference to FIGS.
First, when the wire 2 is disconnected, the cutting of the workpiece W is interrupted and the position of the disconnection is confirmed (S101 in FIG. 1).

At this time, it is effective to implement the wire saw operation resuming method of the present invention, particularly when the wire 2 is disconnected in the wire 2 supply side or in the wire row 7.
When the wire breakage occurs at a position on the collection side with respect to the grooved roller 3, the wire breakage portions may be connected to each other at a position not directly involved in cutting, so that a small amount of the wire 2 is supplied from the wire reel 6 on the supply side. It is only necessary to unwind, and the worn part of the wire can be pressed against the workpiece again to resume cutting.

  However, if the wire breakage occurs within the length of reciprocal movement of the wire from the grooved roller 3 to the supply side, the wire row 7, or from the wire row 7 to the collection side, the connection portion is not involved in cutting. Therefore, it is necessary to unwind the wire from the wire reel 6 on the supply side, and the wire used directly for cutting becomes a new line. The wire saw operation resumption method of the present invention is particularly effective when such wire breakage occurs on the wire supply side or in the wire row.

  After confirming the broken position of the wire, the work is temporarily retracted from the wire row (S102 in FIG. 1), and an operation for removing the broken wire is performed (S103 in FIG. 1).

  At this time, in the present invention, a wear wire is prepared in advance that has a length capable of cutting at least one workpiece and is worn from the tip to a length at which at least the wire row 7 can be formed. The length that can be formed by the wire row 7 is the product NL of the number N of grooves of the grooved roller 3 and the length L necessary for winding the wire around the plurality of grooved rollers. Can be easily calculated as long as the wire row 7 can be formed.

  Then, after removing the broken wire, the wire reel 6 on the supply side around which the broken wire is wound is replaced with a wire reel around which the wear wire is wound, and the wire row 7 is formed again (FIG. 1). S104). At this time, the collection-side reel 6 ′ can be used as it is without replacement, and a wear wire is connected to the disconnected wire of the collection-side reel 6 ′ to form the wire row 7 again.

  At this time, the wear wire can be exchanged for a broken wire as a wire worn by cutting the workpiece with the same cutting recipe as that for cutting the workpiece in which the disconnection has occurred.

  In this way, if the wire used in the same cutting recipe as the cutting in which the disconnection occurred is prepared as a wear wire for replacement, the wire diameter and the method of changing the diameter are almost the same as the state immediately after the disconnection. The diameter of the wire at the cutting position of the workpiece at the time of disconnection can be easily reproduced when cutting is resumed.

  For example, in the normal work cutting, the wear wire leaves a new line on the supply-side wire reel 6 that can cut at least one work, and is at least as long as the wire row 7 can be formed. By winding the worn wire back onto the wire reel 6 on the supply side, a wire reel wound with the worn wire can be prepared.

  Next, after the wear wire is moved so that the wear wire in the re-formed wire row becomes the work cutting position (S105 in FIG. 1), cutting is resumed (S106 in FIG. 1). ). At this time, the position of the wire can be aligned while measuring the diameter of the wire with a measuring machine such as a laser displacement meter.

  In this way, the replaced wire is worn in advance and has a small diameter, so that the wire can be easily returned to the work cutting position. Therefore, it is possible to suppress the generation of grooves in the wafer cut after the restart of operation. Moreover, it can suppress that the defect resulting from a disconnection generate | occur | produces on a wafer. Furthermore, since cutting is resumed with a worn wire, the cutting recipe is hardly limited, and the wire can be used effectively without depending on the amount of wear of the wire during cutting.

In addition, when moving the wear wire so that it is at the cutting position of the workpiece immediately after the disconnection occurs and restarting the cutting, the new wire diameter that is the diameter of the wire on the new line supply side of the wire array of the disconnected wire R ₁ and the wear diameter R ₂ , which is the diameter of the wire on the collection side of the wire row of the broken wire, are measured, and the diameters of the wire on the new line supply side and the collection side of the wire row 7 re-formed with the wear wire are It is preferable to resume cutting after moving the wear wire so that the new wire diameter R ₁ and the wear diameter R ₂ are the same. In this way, the wire diameter at the time of resuming cutting can be more accurately reproduced as before disconnection. Also in this case, the position of the wire can be aligned while measuring the diameter of the wire with a measuring machine such as a laser displacement meter.

  In this way, the wear wire having a diameter equal to or smaller than the workpiece cutting allowance can be reliably returned to the workpiece cutting position, so that it is possible to more reliably suppress the generation of a groove in the wafer cut after the restart of operation. Moreover, in the present invention, even if the wire used is a thin wire or the abrasive used is a fine particle size, even if the cutting allowance was originally small. The cutting can be restarted with certainty and no step is generated on the wafer.

And the cutting | disconnection of the workpiece | work W cut | disconnected when the disconnection generate | occur | produced is completed (S107 of FIG. 1).
After the work W has been cut, the wire reel around which the wear wire is wound is removed from the wire saw 1, and the wire reel 6 in which the wire breakage has occurred is installed again. The next workpiece is preferably cut (S108 and S109 in FIG. 1).

  In this way, since the new line remaining on the wire reel 6 where the disconnection has occurred can be used for cutting the next workpiece, an unused wire is not wasted.

  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.

In the following examples and comparative examples, d is the average abrasive grain size (μm), ΔR is the difference (R ₁ −R ₂ ) between the new wire diameter (μm) and the wear diameter (μm), that is, the amount of wire wear. For example, d = 0.30 × ΔR indicates that the wire was cut under the wear condition of the wire where d is 0.3 times ΔR.

Example 1
Using a wire saw as shown in FIG. 2, a silicon ingot having a diameter of 200 mm was cut by a cutting recipe under wear conditions where d = 0.30 × ΔR. Then, during cutting at a cutting position of 100 mm from the lower end of the workpiece, a break was generated at a position closer to the supply side than the grooved roller. And the cutting | disconnection of a workpiece | work was restarted with the operation resumption method of the wire saw of this invention as shown in FIG. At this time, by replacing the wire reel on the supply side with a wire reel around which a wear wire prepared in advance is wound, the broken wire is d / 0 from the tip to at least the length that can form the wire row. Replaced with a worn wire worn by .30 = ΔR. Then, the wear wire was unwound from the wire reel, the wire row was formed again, and the cutting was resumed after moving the wear wire so that the worn wire was at the cut position of the workpiece. Then, after the cutting was completed, the surface shape of the wafer was measured. The result is shown in FIG.
As a result, it is possible to cut by inserting a wire row at the work cutting position. As shown in FIG. 3, no groove is formed on the wafer surface, and a defect occurs due to subsequent processing after cutting. There wasn't. The amount of wear at this time was a value in the range of ΔR> 3d, but cutting could be resumed by fitting the wire row at the workpiece cutting position without any problem. As described above, it was confirmed that the cutting can be resumed by fitting the wire row at the cutting position of the work without using a cutting recipe in which the wear amount is limited as in the prior art, and no step is generated on the wafer.

(Example 2)
Using a wire saw as shown in FIG. 2, a silicon ingot having a diameter of 200 mm was cut by a cutting recipe under wear conditions where d = 0.40 × ΔR. Then, during cutting at a cutting position of 100 mm from the lower end of the workpiece, a break was generated at a position closer to the supply side than the grooved roller. And the cutting | disconnection of a workpiece | work was restarted with the operation resumption method of the wire saw of this invention as shown in FIG. At this time, by replacing the wire reel on the supply side with a wire reel around which a wear wire prepared in advance is wound, the broken wire is d / 0 from the tip to at least the length that can form the wire row. Replaced with a worn wire worn by .40 = ΔR. Then, the wear wire was unwound from the wire reel, the wire row was formed again, and the cutting was resumed after moving the wear wire so that the worn wire was at the cut position of the workpiece. Then, after the cutting was completed, the surface shape of the wafer was measured. The result is shown in FIG.
As a result, it is possible to cut by inserting a wire row at the work cutting position. As shown in FIG. 3, no groove is formed on the wafer surface, and a defect occurs due to subsequent processing after cutting. There wasn't.

(Comparative Example 1)
Similarly to Example 1, a wire saw as shown in FIG. 2 was used to cut a silicon ingot having a diameter of 200 mm using a cutting recipe under wear conditions where d = 0.30 × ΔR. Then, during cutting at a cutting position of 100 mm from the lower end of the workpiece, a break was generated at a position closer to the supply side than the grooved roller. Then, the broken wire was not replaced with a worn wire, and the broken portion was connected as it was to form a wire row again. At this time, since the wire was unwound from the supply-side wire reel and the connection portion was moved to a position on the collection side with respect to the grooved roller, the wire in the part involved in cutting the workpiece in the wire row was a new line. .
After that, it tried to fit the re-formed wire row at the work incision position, but because the wire diameter was larger than the work cutting allowance especially in the second half of the work, the wire row could not be fitted and cutting could not be resumed. .

(Comparative Example 2)
Similarly to Example 1, a wire saw as shown in FIG. 2 was used to cut a silicon ingot having a diameter of 200 mm with a cutting recipe under wear conditions where d = 0.40 × ΔR. Then, during cutting at a cutting position of 100 mm from the lower end of the workpiece, a break was generated at a position closer to the supply side than the grooved roller. Then, the broken wire was not replaced with the worn wire, and the broken portion was connected as it was, and the wire row was formed again. At this time, since the wire was unwound from the supply-side wire reel and the connection portion was moved to a position on the collection side with respect to the grooved roller, the wire in the part involved in cutting the workpiece in the wire row was a new line. .
After that, it was difficult to fit the re-formed wire row at the work cutting position, but the wire row was fitted and cutting was resumed.
Then, after the cutting was completed, the surface shape of the wafer was measured. The result is shown in FIG. In Comparative Example 2, the wire row was fitted again at the workpiece cutting position and cutting was resumed, but as shown in FIG. 3, a deep groove was formed at the cutting position of 100 mm where cutting of the wafer surface was resumed. A defect occurred in a later process.

  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 ... Work feeding mechanism, 5 ... Slurry supply means, 6, 6 '... Wire reel,
7 ... Wire row, W ... Workpiece.

Claims (5)

A wire row is formed by winding a wire on a plurality of grooved rollers, the wire is reciprocated in a predetermined cycle in the axial direction, and a cutting slurry is supplied to the wire while the workpiece is relatively pushed down. In the operation of the wire saw that cuts the workpiece into a wafer shape by pressing against the wire row, the cutting of the workpiece is temporarily interrupted in the middle due to the occurrence of the disconnection of the wire, and then the cutting is resumed. A method for restarting operation,
A wire having a length capable of cutting at least one or more of the workpieces, and preparing a wear wire that is worn from a tip to a length at which the wire row can be formed; and
After disconnecting the wire, replacing the disconnected wire with the wear wire to form a wire row again;
An operation of a wire saw, comprising: a step of resuming cutting after moving the wear wire so that a portion where the wear wire is worn in the re-formed wire row is a cut position of the workpiece. How to resume. And Shinsen径R ₁ is the diameter of the wire in the new line supply side of the wire array of wires and the wire breakage, by measuring the wear diameter R ₂ is the diameter of the wire at the recovery side of the wire array of wires and the wire breakage,
In the step of resuming the cutting, the diameters of the wires on the new wire supply side and the recovery side of the wire array formed again with the wear wires are the same as the new wire diameter R ₁ and the wear diameter R ₂ , respectively. The method of resuming the operation of the wire saw according to claim 1, wherein the cutting is resumed after the wear wire is moved. Wear wire the exchange to claim 1 or claim 2, wherein to Rukoto to that is wear by the cutting of the workpiece in the same cutting recipes cleavage and the work which the disconnection has occurred A method for resuming the operation of the described wire saw.   The cutting of the workpiece is resumed, and after the cutting of the workpiece is completed, the wear wire is replaced with the broken wire again, and then the next workpiece is cut. 4. The wire saw operation restarting method according to any one of items 3 to 3.   The wire saw operation resuming method according to any one of claims 1 to 4, wherein the wire saw operation is resumed when the wire breakage occurs in the wire supply side or in the wire train. How to resume operation.

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