JP4658863B2 - Work slice processing method and wire saw - Google Patents

Description

  The present invention relates to a workpiece slicing method and a wire saw for slicing a workpiece made of a hard and brittle material such as a semiconductor material, a magnetic material, and ceramic, and more specifically, the workpiece and the wire can be adjusted in parallel. The present invention relates to a workpiece slicing method and a wire saw.

  In this type of wire saw, a single slicing (processing) wire is usually spirally wound around a plurality of wire guides (including a slicing processing roller) arranged at a predetermined interval.

  The slicing wire is fed from the feeding reel to the wire guide and passes between the slicing rollers and is wound on the winding reel. Meanwhile, a slurry containing abrasive grains is supplied to the traveling slicing wire, and the workpiece is sliced by the lapping action of the abrasive grains by pressing a workpiece (for example, silicon ingot) against the slicing wire. The The tension of the slicing wire is always adjusted to be constant.

Specifically, it will be described as follows.
FIG. 8 is a schematic view of a cutting room viewed from the front and side of a conventional multi-wire saw. FIG. 9 is a schematic perspective view showing the relationship between a conventional work 1, a work mounting base 2, a blue glass 3, and an aluminum plate 4. FIG.
In FIG. 9, the work 1 is bonded to the blue glass 3. The blue plate glass 3 is bonded to the aluminum plate 4. The aluminum plate 4 is fixed to the work mounting base 2 with bolts.

In FIG. 8, in the wire saw S0, a single slicing wire 32 is spirally wound around a plurality of wire guides (including a slicing roller 33) arranged at a predetermined interval.
The slicing wire 32 is fed from the feeding reel to the wire guide 33 and passes between the processing rollers 33 and taken up by the take-up reel.

  However, when the sliced workpiece, that is, the wafer is made thin, there is a possibility that a defect such as a wedge-shaped cross section of the wafer may occur. In order to slice the thickness of the wafer uniformly and accurately, it is not possible to solve the problem simply by keeping the tension of the conventional wire constant.

On the other hand, in order to process a workpiece with high accuracy, it has been proposed to provide tension adjusting means on the wire feeding side and the feeding side during slicing (see Patent Document 1).
However, even if the tension is adjusted in this way, the workpiece and the wire cannot always be maintained in parallel. This is because the tension and the parallelism between the workpiece and the wire are not directly related.
JP 2004-255538 A

  Therefore, the inventors of the present invention can adjust the thickness of the workpiece sliced with the wire, that is, the thickness of the wafer, if the workpiece and the wire can be adjusted in parallel when the wire for slicing is stopped before the workpiece is sliced with the wire. The present inventors have found that this variation can be improved and have completed the present invention.

The present invention is a slicing method for a workpiece in which a workpiece is sliced by pressing and moving the workpiece against the slicing wire while running a slicing wire wound between a plurality of rollers,
When slicing a workpiece , a paralleling step is performed in advance to parallelize the wire travel direction surface and the slice start surface when the slicing wire travel stops. Press the workpiece to the slicing wire and measure the tension in the vicinity of both ends of the slicing wire, and set the workpiece support direction so that the two measured tension values are the same. Provided is a workpiece slicing method, which is a workpiece support direction adjusting step to be adjusted .
According to another aspect of the present invention, when the workpiece is pressed and moved to the slicing wire during traveling of the slicing wire, the conductive film is attached to the slicing start surface of the workpiece in advance so as to be peeled off. Provided is a method for slicing a workpiece, characterized by detecting a current flowing through a conductive film when pressed against a machining wire and measuring a slice start position of the workpiece.

According to another aspect, the present invention includes a plurality of rollers, a slicing wire wound between these rollers, and a workpiece support that supports the workpiece, while the slicing wire is running. A wire saw that moves the workpiece support and presses the workpiece against the slicing wire to slice the workpiece,
When measuring the tension of the slicing wire in the vicinity of both ends of the slicing wire, and slicing the workpiece, the workpiece was previously pressed and moved to the slicing wire when the wire was stopped. In some cases, it is possible to provide a wire saw including a work support direction adjusting unit that adjusts the support direction of the work on the work support so that the magnitudes of the two obtained tension measurement values are the same.

According to another aspect of the present invention, the workpiece support base further includes a horizontal level and a support angle adjusting unit that adjusts a support angle around the axis of the workpiece based on the horizontal level. Can be provided.
According to yet another aspect of the present invention, the work support base includes a set of a plurality of work support bases that movably support a plurality of works, and each work support base is capable of adjusting a descending speed. A wire saw can be provided.

  According to the present invention, when slicing a workpiece by pressing and moving the traveling slicing wire, the wire traveling direction surface and the slicing start surface are parallelized in advance when the slicing wire is stopped traveling. Accordingly, the traveling direction surface of the slicing wire and the slicing start surface of the workpiece can be accurately parallelized before slicing, thereby improving the thickness variation of the sliced workpiece (wafer).

  In the slicing method for a workpiece according to the present invention, when the slicing wire is traveling, the slicing wire is preliminarily stopped when the slicing wire is stopped while the slicing wire is moved by pressing the workpiece against the slicing wire. A parallelizing step for parallelizing the direction surface and the slice start surface is added.

  Here, “perform parallel” means that the traveling direction surface of the slicing wire and the slice start surface of the workpiece are made parallel in advance. The running direction surface of the slicing wire is a surface that connects the peaks of the wire rows that come into contact with the slice start surface of the workpiece during slicing. In addition, this “perform parallel” may be simply used as “perform parallel to wire and workpiece” as a whole.

As a specific paralleling process, (1) the workpiece is pressed and moved to the slicing wire in advance when the slicing wire is stopped, and the tension in the vicinity of both ends of the slicing wire is measured. In addition, there is a work support direction adjusting step of adjusting the support direction of the work so that the two measured tension values are the same.
Here, the tension measurement in the vicinity of the both ends of the slicing wire is performed, for example, by interposing a tension detection sensor in the vicinity of the both ends of the slicing wire. As these tension detection sensors, what are usually called “load cells” can be used. Details of the method for adjusting the support direction of the workpiece will be described later.

Furthermore, as a specific paralleling step, (2) when the pair of auxiliary wires are pressed against the slicing wire between the workpiece and the slicing wire when the slicing wire is stopped in advance, Then, the work is pressed and moved to the auxiliary wire, and the tension in the vicinity of at least one end of each auxiliary wire is measured, so that the two measured tension values are the same. A work support direction adjusting step for adjusting the work support direction is given.
Here, the tension measurement in the vicinity of the one stretched end of each auxiliary wire is performed, for example, by interposing a tension detection sensor in the vicinity of the one stretched end of the auxiliary wire. As this tension detection sensor, a so-called “load cell” can be used. Details of the method for adjusting the support direction of the workpiece will be described later. An example of a wire that can be used as an auxiliary wire is a piano wire.

  In the present invention, when the tension of the auxiliary wire is measured at a position outside the tension width of the slicing wire when slicing the workpiece, the traveling direction surface of the slicing wire is parallel to the slice start surface of the workpiece. This is preferable because the degree can be secured more accurately and the variation in the thickness of the sliced workpiece (wafer) can be further improved.

  In the present invention, when the workpiece is pressed and moved to the slicing wire during the running of the slicing wire, the conductive film is attached in advance to the slicing start surface of the workpiece so as to be peelable, and is pressed against the slicing wire. Sometimes, by detecting the current flowing through the conductive film and measuring the slice start position of the workpiece, the slice of the workpiece can be simultaneously started. Accordingly, it is possible to prevent an uneven load from being applied to the slicing wire, which is more preferable.

  The wire saw according to the present invention includes a slice measuring wire tension measuring unit for measuring the tension in the vicinity of both ends of the slicing wire, and slicing the workpiece in advance when the wire travel is stopped when slicing the workpiece. And a workpiece support direction adjustment section that adjusts the workpiece support direction on the workpiece support base so that the magnitudes of the two measured tension values are the same when the wire is pressed and moved. And

  Furthermore, the wire saw according to the present invention has a pair of auxiliary wires, and these auxiliary wires are stretched between the workpiece and the slicing wire so as to be releasably opposed when pressing the workpiece against the slicing wire. The supporting struts, the tension measuring part of the auxiliary wire that measures the tension of each auxiliary wire, and the two tension measurement values obtained when the workpiece is pressed and moved in advance when slicing the workpiece. And a workpiece support direction adjusting section for adjusting a workpiece support direction on the workpiece support base so that the sizes are the same.

  These work support direction adjustment parts can adjust the work support direction on the work support base, specifically, both ends or one end of the work can be slightly moved up and down relative to the work support base. Examples include a configuration in which a bolt and nut are fastened through a long hole, a combination configuration of a rack and a pinion that uses screws, and the support direction (axial direction) of a columnar workpiece is slightly upward or downward. Can be adjusted. The work support direction adjusting unit can be configured so that the support direction of the work on the work support can be adjusted manually or automatically.

  In the present invention, when the work support is further provided with a horizontal level and a support angle adjusting unit that adjusts a support angle around the axis of the work based on the horizontal level, not only the support direction of the work. It is preferable because the support angle around the workpiece axis can be adjusted, and the traveling direction surface of the slicing wire and the slicing start surface of the workpiece can be paralleled more accurately.

  In the present invention, the work support base is composed of a set of a plurality of work support bases that movably support a plurality of works (such a wire saw is referred to as a multi-wire saw), and the descending speed of each work support base is adjusted. It may be possible. This adjustment of the descending speed is preferable because even if the workpieces have different shapes, slicing can be started simultaneously with the slicing wire, and fluctuations in the load can be prevented.

Hereinafter, embodiments of a wire saw according to the present invention will be described with reference to the drawings, and a workpiece slicing method according to the present invention will be described.
[Embodiment 1]
FIG. 1 is a schematic view of a cutting room as viewed from the front and side of a multi-wire saw as Embodiment 1 of the wire saw according to the present invention. 2 to 5 are equivalent views of FIG. 1 showing a state different from FIG.

  In FIG. 1, a multi-wire saw S1 includes four rollers 13, a slicing wire (piano wire) 12 wound between these rollers, and four work mounting bases (inserts) as work support bases. In addition, parallel wires (piano wires) 9 as auxiliary wires are provided in a total of four (two pairs) on the upper stage and two (pairs) on the lower stage. Further, the parallel wire 9 is supported by a front column 10 and a back column 11.

Reference numeral 19 denotes a workpiece holding unit that holds the workpiece support 2. The work holding unit 19 has a configuration in which a bolt 20 and a nut 21 are fastened through a long hole 22, holds the work 1 through the support base 2, and can adjust the support direction of the work 1. It becomes a support direction adjustment part.
Reference numerals 23 and 24 are tension detection sensors for detecting the tension of the pair of auxiliary wires 9, and 25 is a monitor for comparing and displaying the measured values of both tensions based on detection signals from the two tension detection sensors. Configure the measurement unit. The tension detection sensors 23 and 24 are usually referred to as “load cells”.

  As shown in FIG. 2, the parallel wires 9 and 9 of the support column 10 and the support column 11 of FIG. FIG. 3 shows a state in which the slicing wire 12 and the workpiece 1 are not yet parallel. FIG. 4 shows the completion of parallel feeding of the workpiece 1. FIG. 5 shows a state where it has been moved to the original location.

Next, a procedure for creating a workpiece will be described.
The Si ingot is square-processed into Si blocks. The angular dimensions of the Si block are 155 mm to 156 mm, and the length is 200 mm to 250 mm.
Si ingots are usually rounded with a band saw and an outer peripheral blade.
Remove processing damage on Si block surface.
A Si block is stuck on a blue plate glass (scrap plate) with an adhesive.
Two Si blocks of 200 mm to 250 mm are bonded to the blue plate glass. The total length of the two Si blocks is within 400 mm to 500 mm.
In addition, an aluminum plate is bonded under the blue plate glass. This completes the work preparation.

Recently, in order to shorten the slicing time, a multi-wire saw equipped with four workpieces is often used.
The work and the wire must be parallel, but in reality, the adhesive 1 is not parallel because of the uneven thickness of the adhesive when the work 1 and the blue plate glass 3 are bonded and the blue plate glass 3 and the aluminum plate 4 are bonded.

The features of the multi-wire saw S0 as the first embodiment of the present invention shown in FIGS.
In order to make the workpiece and the wire for slicing parallel, the four workpiece mounting base insertion ports 5 to 8 in FIG. 1 can be moved up and down separately by changing the angle (work supporting direction adjusting section).
The paralleling wire 9 is movable only up and down, in front, and in the back.
The parallel wire 9 does not travel like the slicing wire 12.
It is fixed to the columns 10 and 11 except when a predetermined tension is set.
The struts 10 and 11 can move individually.

Next, a paralleling method will be described.
[Example 1]
In the conventional mirch wire saw of FIG. 8, a total of four workpiece mounting base insertion ports, two at the upper stage and two at the lower stage, are all moved simultaneously.
The multi-wire saw of the present invention shown in FIG. 1 performs parallel workpieces individually (each workpiece). That is, it is necessary to carry out the workpiece parallel four times. This is because if parallelism is performed simultaneously, individual workpieces cannot be parallelized due to the influence of the tension of the adjacent workpiece.

After the four workpieces are mounted, as shown in FIG. 2, the support 10 of FIG. 1 and the parallel wire 9 of the support 11 are moved to a parallel place 16 under the work 1.
The paralleling wire 9 before paralleling is pulled within a range of 20 to 25N.
FIG. 3 shows a state where the slicing wire 12 and the workpiece 1 are not yet parallel.
As shown in FIG. 3, the workpiece 1 is paralleled and lowered until a sufficient tension is applied to the wire 9.
The weight applied to the parallel wire by the work needs to be such that the parallel wire is bent. Specifically, a weight of about 20N is required.

  The tension of the parallel wire 9 between the front column 10 and the back column 11 is measured. For example, when the tension of the parallel wire 9 of the support column 10 at the front is high and the tension of the wire 9 of the support column 11 at the back is low, the bolt 20 is lowered via the elongated hole 22 by loosening the nut 21. By retightening the nut 21), the depth of the work mounting base 6 is lowered. In addition, if the back side of the workpiece mounting base insertion port 6 is lowered too much, the tension of the parallel wire 9 of the back column 11 becomes high.

By changing the holding direction (angle) of the work mount insertion port 6, the tension of the support wire 10 and the wire 9 for paralleling the support column 11 is made the same.
When the tension of the support wire 10 and the wire 9 for paralleling the support column 11 are the same, the parallelism of the workpiece 1 is completed.

The manual paralleling method has been described above, but the tension of the support wire 10 and the wire 9 for paralleling the support column 11 can be automatically made the same.
FIG. 4 shows a state in which the parallel projection of the workpiece 1 is completed.
The workpiece 1 that has been parallelized is moved upward. The next workpiece is placed in parallel. When the paralleling is finished four times, the paralleling wire 9 is moved from the bottom of the workpiece to the original position 15 as shown in FIG.

At this time, the parallel wire 9 needs to be sufficiently separated from the wire guide 13.
This is because if the paralleling wire 9 and the wire guide 13 are close to each other, slicing is started and there is a possibility that the paralleling wire 9 may come into contact with the workpiece when the workpiece is lowered. When the workpiece comes into contact with the parallel wire 9, the workpiece cannot reach the slicing wire 12 and cannot be sliced.

Perform slicing.
A single slicing wire 12 is spirally wound around a plurality of wire guides 13 arranged at a predetermined interval.
The slicing wire 12 is fed from the feeding reel to the wire guide 13, and the slicing wire 12 that has passed between the wire guides 13 is taken up by the take-up reel.
Then, slurry containing abrasive grains is supplied to the traveling slicing wire 12 from the slurry nozzle 14, and the workpiece is pressed against the slicing wire 12, whereby the workpiece is sliced by the lapping action of the abrasive grains.

[Example 2]
The multi-wire saw of the present invention can individually set the descending speed of the workpiece mounting base insertion port.
Therefore, the workpiece mounting base insertion port can be lowered individually, and workpieces of different sizes can be sliced simultaneously. It is necessary to determine the descending speed of the workpiece mounting base so that the workpieces of different sizes can be sliced simultaneously.

For example, a 156 mm square Si ingot is attached to the workpiece mounting base insertion port 5 in FIG. 3, and a 126 mm square Si ingot is attached to the workpiece mounting base insertion port 6 in FIG. 3.
The processing speed of the work mount insertion slot 5 is set to 200 μm / min. Processing time is 720 minutes. If the processing speed of the workpiece mount 6 is 175 μm / min, the processing time is 720 minutes.

[Example 3]
The slicing method when the Si ingot is different by 1 to 2 mm due to variations in the accuracy of corner processing will be described below. Paralleling is the same as in Example 1.
Affix aluminum foil to the workpiece. Since it is necessary to peel off the aluminum foil later, the adhesive strength is sufficient if it can be peeled off. Moreover, it is not limited to aluminum foil, and any conductive material may be used.
The non-standard workpiece mounting base insertion port and the standard workpiece mounting base insertion port corresponding to any of the workpiece mounting base insertion ports 5, 6, 7, and 8 are individually lowered onto the slicing wire.

The workpiece contacts the slicing wire.
When the contact is made, the current flowing through the slicing wire 12 and the aluminum foil attached to the workpiece are electrically connected to electrically detect the position of the slicing wire 12. When detected, the descent of the work mount insertion slot stops.
The contact position is stored as the position at which to start slicing. Lift up the mounting base once again and peel off the aluminum foil.
Set the position to start slicing the corresponding workpiece.
After completion, slices can be simultaneously sliced from the positions stored by the workpieces that are not defined and within defined specifications.

  Previously, non-standard and non-standard workpieces were sliced at the same time. However, when the slicing start position is aligned with the specified workpiece, the non-specified workpiece does not contact the slicing wire 12 or contacts the slicing wire 12 before the specified workpiece. A sudden load is applied. For this reason, the tension of the slicing wire 12 is reduced, and the slicing wire 12 jumps out of the groove of the wire guide 13, and the slicing wire 12 cannot maintain a predetermined interval, which causes variations in wafer thickness.

[Embodiment 2]
FIG. 6 is a schematic view showing the workpiece and the periphery of the support stand as viewed from the front, showing Embodiment 2 of the wire saw according to the present invention, and FIG. 7 is a view corresponding to FIG.
In FIG. 6, the wire saw S <b> 2 includes a work support base 25 that supports the work 22, a roller 33, and a slicing wire 32 wound around the roller. Reference numeral 37 denotes a support portion of the work support base 25, and 38 denotes a horizontal level.

[Example 4]
A method of adjusting the support angle of the support portion 37 when the slice start surface of the workpiece 22 is not parallel to the slicing wire 32 when the workpiece 22 is viewed from the front will be described.
6 shows a state before adjusting the support angle of the support part 37 when the work 22 is viewed from the front, and FIG. 7 shows a state after adjusting the support angle of the support part 37 when the work is viewed from the front. .

The support portion 37 for adjusting the support angle in FIG. 6 is rotated around the axis. A horizontal level 18 is provided on the support portion 37 for angle adjustment. The angle adjusting support portion 37 is rotated until it becomes horizontal.
The reason for adjusting the front angle is that when the workpiece corner comes into contact with the slicing wire 32 at the start of slicing, a rapid load is applied to the slicing wire 32 as in the third embodiment due to the resistance of the workpiece corner. is there.

  As described above, when the multi-wire saw of the present invention is used, the wafer thickness can correspond to 100 μm to 120 μm. Also, the wire and the Si ingot can be made vertical, and the variation in wafer thickness can be improved.

It is the schematic of the cutting room seen from the front and side of a multi-wire saw as Embodiment 1 of the wire saw which concerns on this invention. FIG. 2 is a view corresponding to FIG. 1 illustrating a state in which a parallel wire moves below a workpiece along with a support. FIG. 2 is a view corresponding to FIG. 1 showing a state in which the parallel wire moves under the workpiece. FIG. 2 is a view corresponding to FIG. 1 and illustrating a state in which the parallel alignment of workpieces is completed. FIG. 2 is a view corresponding to FIG. 1 showing a state in which the parallel wire is returned to its original state along with the support. It is the schematic seen from the front of one work support stand of a multi-wire saw as Embodiment 2 of the wire saw concerning the present invention, and shows the state before adjusting the support angle around a work axis. FIG. 7 is a view corresponding to FIG. 6 showing different states, and shows a state after adjusting a support angle around the workpiece axis. It is the schematic of the cutting room seen from the front and side of the conventional multi-wire saw. It is a schematic perspective view which shows the relationship between the conventional workpiece | work 1, the workpiece mounting base 2, the blue plate glass 3, and the aluminum plate 4. FIG.

Explanation of symbols

1 Work 2 Work mounting base (Work support base)
3 Blue plate glass 4 Aluminum plate 5 Insert 6 Insert 7 Insert 8 Insert 9 Parallel wire (auxiliary wire)
10 Prop 11 Prop 12 Cutting wire (Slicing wire)
13 Wire guide (roller)
14 Slurry nozzle 15 Original location 16 Parallel projection location 17 Support portion 18 for angle adjustment Horizontal level 19 Work holding portion 20 Bolt 21 Nut 22 Long hole 23 Tension detection sensor 24 Tension detection sensor 25 Monitor

Claims (5)

A slicing method for a workpiece in which a workpiece is sliced by moving the workpiece against the slicing wire while running a slicing wire wound between a plurality of rollers,
When slicing the workpiece, add a paralleling step to parallelize the wire traveling direction surface and the slice starting surface in advance when the slicing wire travel stops ,
Two parallel tensioning values are obtained by measuring the tension in the vicinity of both ends of the slicing wire by pressing and moving the workpiece to the slicing wire in advance when the slicing wire stops running. A workpiece slicing method, which is a workpiece support direction adjusting step of adjusting a workpiece support direction so that the sizes of the workpieces are the same . When the workpiece is pressed and moved to the slicing wire during travel of the slicing wire, the conductive film is detachably pasted to the slicing start surface of the workpiece in advance, and the conductive film is attached to the slicing wire when pressed. The workpiece slicing method according to claim 1, wherein the slice start position of the workpiece is measured by detecting a current flowing through the workpiece. A plurality of rollers, a wire for slicing wound between these rollers, and a work support for supporting the work, and moving the work support while moving the slicing wire for slicing A wire saw that presses a workpiece against a wire and slices the workpiece,
When measuring the tension of the slicing wire in the vicinity of both ends of the slicing wire, and slicing the workpiece, the workpiece was previously pressed and moved to the slicing wire when the wire was stopped. A wire saw comprising: a work support direction adjusting unit that adjusts a support direction of a work on a work support so that two magnitudes of obtained tension measurement values are the same. The wire saw according to claim 3, wherein the work support further includes a horizontal level and a support angle adjusting unit that adjusts a support angle around the axis of the work based on the level. The wire saw according to claim 3 or 4 , wherein the work support base is composed of a set of a plurality of work support bases that respectively support a plurality of works so as to be movable, and each work support base is capable of adjusting a descending speed.