JP2020131299A - Workpiece cutting method and workpiece cutting device - Google Patents

Abstract

To provide a workpiece cutting method in which a satisfactory and stable Warp value can be obtained from initial use of a wire guide.SOLUTION: A wire guide 102 comprises: a groove upper part 105 which, on its outer surface, includes a plurality of grooves formed at a prescribed pitch along a rotational direction, and in which an opposing groove wall 107 has a first open angle (θ); a groove lower part 106 which is located below the groove upper part 105, and in which the opposing groove wall 107 has a second open angle (θ); and a groove bottom part 108 located at a lower end of the groove. In a workpiece cutting method, the first open angle (θ) and the second open angle (θ) satisfy a relationship of θ>θ, and a wire 101 is brought into contact with the groove wall 107 of the groove lower part 106 of the wire guide 102 by using the wire 101 and the wire guide 102, and disposes the wire in a state of not contacting the groove bottom part 108, in order to start cutting the workpiece in the state that the wire 101 does not contact the groove bottom part 108.SELECTED DRAWING: Figure 2

Description

The present invention relates to a work cutting method and a work cutting device.

In recent years, an increase in the size (larger diameter) of a wafer has been desired, and with this increase in size, a wire saw is exclusively used for cutting an ingot (for example, Patent Document 1). A wire saw is an ingot made of a brittle material such as silicon, glass, or ceramics while a wire (high-strength steel wire) is run at high speed and a slurry is hung on the wire saw. Hereinafter, the ingot is simply referred to as an ingot. It is a cutting device that cuts a large number of wafers at the same time by pressing it against it.

Here, FIG. 9 shows an outline of a general example of a wire saw. As shown in FIG. 9, the wire saw 100 is mainly formed on a wire 101 and a wire 101 formed by winding a wire 101 for cutting an ingot (work) 104 around a plurality of wire guides 102. It is provided with a tension applying mechanism (not shown) for applying tension, an ingot feeding means (not shown) for feeding the ingot (work) 104 to be cut, and the like.

The wire 101 is unwound from one of the wire reels 103, passes through a tension applying mechanism, and enters the wire guide 102. The wire 101 is wound around the wire guide 102 about 300 to 400 times, and then wound on the wire reel 103'through the other tension applying mechanism.

The wire guide 102 is a roller in which a resin such as polyurethane is press-fitted around a steel cylinder and grooves are cut at a constant pitch on the surface thereof, and the wound wire 101 is predetermined by a drive motor. It can be driven in the reciprocating direction in a cycle. FIG. 10 shows an installation state of the wire 101 in the groove of the wire guide 102.

As one of the important qualities in cutting a semiconductor wafer, evaluation is performed by Warp (or Warp value), which is a parameter related to the work shape. The definition of this Warp is shown in FIG. Warp is a shape parameter related to the deviation of the wafer from the center line surface, and is the maximum in-plane distance between the virtual center surface of the wafer that is not suction-fixed and the reference plane. Bow in the figure is an evaluation similar to Warp, but is a shape parameter of the distance between the center of the wafer and the reference plane. The measuring method is defined by JEIDA-43-1999 and ASTM F1530-94.

As the quality requirements of products increase, it is desired to further reduce the Warp value. It is known that the cause of the deterioration of Warp is the superposition of the effects of thermal expansion of the grooved roller and the work, the straightness of the work feed, and the deflection of the wire during cutting. As a means, a method as described in Patent Document 2 has been adopted.

In Patent Document 2, when the ingot is cut, the displacement amount of the ingot that changes in the axial direction is measured, and the displacement amount in the grooved roller axial direction is controlled correspondingly (cooling water temperature flowing through the grooved roller). A method of cutting while controlling the relative position of the wire with respect to the total length of the ingot that changes in the axial direction by adjusting the flow rate or the like is disclosed.

Japanese Unexamined Patent Publication No. 09-262826 Japanese Unexamined Patent Publication No. 2008-213110

The cross-sectional shape of the groove of the wire guide used in the wire saw is known to be V-shaped, U-shaped, or the like, and various groove opening angles such as 40 degrees to 110 degrees are used. In general, when the opening angle of the groove is large, workability such as wire delivery is excellent, and when it is narrow, the wire holding effect tends to be good. From the viewpoint of stabilizing the Warp value of the work, it is desirable that the opening angle of the guide groove is narrow.

During the period of use of the wire guide, the groove is gradually cut by the wire and deformed while the work is being cut. When the present inventor diligently investigated the transition of the Warp value of the work after cutting in the cutting of the work using the wire saw, the Warp value of the work was found in the cutting at the initial stage of the wire guide life (the initial stage of using the wire guide). , The average value and the variation were found to be large.

In order to improve the yield of the cut work, it is necessary to obtain a good and stable work shape (Warp value) from the initial stage of use (immediately after the start of use) of the wire guide. By slowing down the cutting speed at the beginning of use of the wire guide, a stable work shape (Warp value) can be obtained to some extent, but it is still unstable at the very beginning, and if the cutting speed is slowed down, it will be produced. There was a problem that the capacity (throughput) decreased.

The present invention has been made to solve the above problems, and has a good and stable work shape (Warp value) from the initial stage of use (immediately after the start of use) of the wire guide while suppressing a decrease in production capacity (throughput). It is an object of the present invention to provide a work cutting method and a work cutting device capable of obtaining a work quality that does not depend on the life of the wire guide.

The present invention has been made to achieve the above object, and a wire row is formed by spirally winding a wire around a plurality of cylindrical wire guides installed so that their rotation axes are parallel to each other. , The work is pressed against the wire row while the wire is traveling in the axial direction, and the work is cut into a wafer shape at a plurality of places at the same time. The wire guide is predetermined on the outer surface along the rotation direction. The cross-sectional shape of the groove in the unused wire guide having a plurality of grooves formed at the same pitch is at least located on the outer surface side of the wire guide, and the opposing groove walls have a first opening angle (1). A groove upper portion having θ ₁ ), a groove lower portion located below the groove upper portion and having a groove wall facing each other having a _second opening angle (θ ₂ ), and a groove bottom portion located at the lower end of the groove are provided. , The first opening angle (θ ₁ ) and the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ ₂ , and the maximum groove width of the groove lower part of the unused wire guide. The value (W _{0, max} ) is equal to or greater than the wire diameter (φ ₀ ) of the unused wire, and the minimum value (W _{0, min} ) of the groove width at the lower portion of the groove of the unused wire guide is the said. Using the unused wire and the unused wire guide having a relationship of less than the wire diameter (φ ₀ ) of the unused wire, the unused wire is transferred to the lower portion of the groove of the unused wire guide. Provided is a method for cutting a work, which is installed in a state of being in contact with the groove wall and not in contact with the groove bottom, and starts cutting the work in a state where the wire does not contact the groove bottom.

According to such a work cutting method, the Warp value of the work can be stabilized from the initial stage of the wire guide life (initial stage of use of the wire guide) while suppressing a decrease in the cutting speed (production capacity).

At this time, a work cutting method using a wire guide in which the cross-sectional shape of the groove bottom portion is arcuate, V-shaped, or flat can be used.

This makes it possible to prevent the wire from coming into contact with the groove bottom of the wire guide at low cost.

At this time, as the cutting of the work progresses, the wire can be used as a cutting method of the work for cutting the groove wall, and further, as the cutting of the work progresses, the wire comes into contact with the groove bottom portion. However, it can be used as a cutting method for a work that cuts the groove bottom.

As a result, the state in which the lateral vibration of the wire is suppressed can be maintained more stably.

At this time, as the unused wire guide, the maximum value (W _{0, max} ) of the groove width of the lower portion of the groove in the plurality of grooves and / or the second opening angle (θ ₂ ) of the wire is set. It is possible to use a work cutting method that is changed in the direction of travel.

As a result, it is possible to more stably prevent the wire from coming into contact with the groove bottom of the wire guide.

At this time, a plurality of cylindrical wire guides arranged at predetermined intervals so that the directions of rotation axes are parallel to each other and grooves are formed on the outer surface at a predetermined pitch, and the grooves of the wire guides. A wire row formed by wires spirally wound at a predetermined pitch is provided, and the work is pressed against the wire row while the wire is driven in the axial direction by rotating the wire guide. It is a cutting device that cuts into a wafer shape at a plurality of places at the same time, and the cross-sectional shape of the groove in the wire guide is located at least on the outer surface side of the wire guide, and the opposing groove walls have a first opening angle. A groove upper portion having (θ ₁ ), a groove lower portion located below the groove upper portion and having an opposite groove wall having a second opening angle (θ ₂ ), and a groove bottom portion located at the lower end of the groove. The first opening angle (θ ₁ ) and the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ ₂ , and the wire and the wire guide are the wire guides. The maximum value (W _{0, max} ) of the groove width of the lower portion of the groove is equal to or larger than the wire diameter (φ ₀ ) of the wire, and the minimum value (W _{0, min) of the} groove width of the lower portion of the groove of the wire guide. ) Is less than the wire diameter (φ ₀ ) of the wire, and when the wire is installed so as to be in contact with the groove wall at the lower part of the groove, the wire and the groove bottom of the wire guide are connected. A device for cutting a workpiece that does not come into contact can be provided.

According to such a work cutting device, it is possible to stabilize the Warp value of the work from the initial stage of the wire guide life (initial stage of use of the wire guide) while suppressing a decrease in the cutting speed (production capacity). ..

At this time, the work cutting device may have a cross-sectional shape of the groove bottom portion of the wire guide, which is arcuate, V-shaped, or flat.

This makes it possible to prevent the wire from coming into contact with the groove bottom of the wire guide at low cost.

At this time, in the wire guide, the maximum value (W _{0, max} ) of the groove width of the lower portion of the groove in the plurality of grooves and / or the second opening angle (θ ₂ ) is set in the traveling direction of the wire. It can be a cutting device for a workpiece that has been changed toward it.

As a result, the contact between the wire and the groove bottom of the wire guide can be prevented more stably.

As described above, according to the work cutting method of the present invention, the Warp value of the work is good from the initial stage of the wire guide life (initial stage of use of the wire guide) while suppressing the decrease in the cutting speed (production capacity). And it is possible to stabilize it. Further, according to the work cutting device of the present invention, the Warp value of the work is made good from the initial stage of the wire guide life (initial stage of use of the wire guide) while suppressing the decrease in the cutting speed (production capacity). , It becomes possible to stabilize.

It is explanatory drawing of the cross-sectional structure of the groove of a wire guide. An example of the installation state of the wire in the wire guide groove in the work cutting device according to the present invention is shown. Another example of the installation state in the wire guide groove of the wire which concerns on this invention is shown. Another example of the installation state of the wire according to the present invention in the wire guide groove is shown. The installation state of the wire in the wire guide groove in Comparative Example 1 is shown. The installation state of the wire in the wire guide groove in Comparative Example 2 is shown. The transition of the Warp value of the wafer is shown. An enlarged view of the initial stage of the wire guide life in FIG. 7 is shown. An outline of a general example of a wire saw is shown. A conventional example of the installation state of the wire in the groove of the wire guide is shown. It is a drawing which shows the definition of Warp.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

As described above, it is possible to obtain a good and stable work shape (Warp value) from the initial stage of use (immediately after the start of use) of the wire guide while suppressing a decrease in production capacity (throughput). There has been a demand for a work cutting method and a work cutting device capable of obtaining life-independent work quality.

As a result of diligent studies on the above problems, the present inventors spirally wound wires around a plurality of cylindrical wire guides installed so that their rotation axes are parallel to each other to form a wire row. A method in which a work is pressed against the wire row while the wire is traveling in the axial direction and cut into a wafer shape at a plurality of points at the same time. The wire guide is provided on an outer surface in a predetermined direction along a rotation direction. The cross-sectional shape of the groove in the unused wire guide having a plurality of grooves formed at a pitch is located at least on the outer surface side of the wire guide, and the opposing groove walls have a first opening angle (θ). A groove upper portion having ₁ ), a groove lower portion located below the groove upper portion and having a groove wall facing each other having a _second opening angle (θ ₂ ), and a groove bottom portion located at the lower end of the groove are provided. The first opening angle (θ ₁ ) and the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ ₂ , and the maximum value of the groove width at the lower portion of the groove of the unused wire guide. (W _{0, max} ) is equal to or larger than the wire diameter (φ ₀ ) of the unused wire, and the minimum value (W _{0, min} ) of the groove width at the lower portion of the groove of the unused wire guide is not. Using the unused wire and the unused wire guide having a relationship of less than the wire diameter (φ ₀ ) of the used wire, the unused wire is transferred to the lower portion of the groove of the unused wire guide. The cutting speed (production capacity) is determined by the cutting method of the work, which is installed in contact with the groove wall and not in contact with the groove bottom, and starts cutting the work in a state where the wire does not contact the groove bottom. The present invention has been completed by finding that the Warp value of the work can be made good and stable from the initial stage of the wire guide life (initial stage of use of the wire guide) while suppressing the decrease.

Further, as a result of diligent studies on the above-mentioned problems, the present inventors have arranged them at predetermined intervals so that their rotation axis directions are parallel to each other, and grooves are formed on the outer surface at a predetermined pitch. A plurality of cylindrical wire guides and a wire row formed by wires spirally wound around the grooves of the wire guides at a predetermined pitch are provided, and the wires are formed by rotating the wire guides. A cutting device that presses a work against the wire row while traveling in the axial direction and cuts the work into a wafer shape at a plurality of points at the same time. The cross-sectional shape of the groove in the wire guide is at least the outer surface of the wire guide. A groove upper portion located on the side and facing the groove wall having a first opening angle (θ ₁ ) and a groove upper portion located below the groove upper portion and facing the groove wall having a second opening angle (θ ₂ ). A groove bottom portion and a groove bottom portion located at the lower end of the groove are provided, and the first opening angle (θ ₁ ) and the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ _2. In the wire guide and the wire guide, the maximum value (W _{0, max} ) of the groove width at the lower portion of the groove of the wire guide is equal to or larger than the wire diameter (φ ₀ ) of the wire, and the wire guide The minimum value (W _{0, min} ) of the groove width of the groove lower part is less than the wire diameter (φ ₀ ) of the wire, and the wire is installed so as to be in contact with the groove wall of the groove lower part. Occasionally, the wire guide life initial stage (initial stage of use of the wire guide) while suppressing a decrease in cutting speed (production capacity) by a work cutting device in which the wire and the groove bottom portion of the wire guide do not come into contact with each other. Therefore, it was found that the Warp value of the work can be made good and stable, and the present invention has been completed.

Hereinafter, description will be made with reference to the drawings.

As a result of diligent investigation by the present inventor, the cause that the Warp value of the work becomes large in both the average value and the variation at the initial stage of the wire guide life (a certain period from the start of cutting the work) during the wire saw operation (cutting the work). It was presumed that this was due to the wire vibrating due to the play in the lateral direction of the wire. Therefore, we investigated the structure of a work cutting device that can prevent the wire from vibrating due to play in the lateral direction of the wire. As a result, the reduction in cutting speed (production capacity) is suppressed by installing the wire in the groove of the wire guide so that the groove of the wire and the wire guide have a certain relationship, and then starting the operation of the wire saw. While doing so, he found that the Warp value became stable from the initial stage of the wire guide life (the initial stage of use of the wire guide) to the final stage, and completed the present invention.

First, a wire saw which is a work cutting device according to the present invention will be described. The wire saws are arranged at predetermined intervals so that their rotation axes are parallel to each other, and a plurality of cylindrical wire guides having grooves formed on the outer surface at a predetermined pitch and the grooves of the wire guides. It is provided with a wire row formed by wires spirally wound at a predetermined pitch. During operation (cutting the work), the work is pressed against the wire row while the wire is driven in the axial direction by rotating the wire guide, and the work is cut into a wafer shape at a plurality of places at the same time.

First, the cross-sectional structure of the groove of the wire guide will be described with reference to FIG. 1 while defining the terms used in the present specification. The wire guide shown in FIG. 1 is also a typical example of the work cutting method of the present invention and the wire guide used in the work cutting device in an unused state.

As shown in FIG. 1, the cross-sectional shape of the groove of the wire guide is located at least on the outer surface side of the wire guide, and the groove wall facing the groove has a first opening angle (θ ₁ ) and the groove upper portion thereof. It includes a groove lower portion located below the groove upper portion and having a _second opening angle (θ ₂ ) on the opposing groove wall, and a groove bottom portion located at the lower end of the groove. That is, it is a structure having two or more stages having two or more opening angles in a cross-sectional view (cross section). For example, in the case of a two-stage structure, the upper portion of the groove is the first-stage groove and the lower portion of the groove is the second-stage groove, and the shape changes in the depth direction of the groove.

Here, the first opening angle (θ ₁ ) of the upper portion of the groove and the lower portion of the groove having the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ ₂ . By using a wire guide having such a relationship, it is possible to achieve both an improvement in workability such as wire delivery and a wire holding effect.

Further, in the work cutting device according to the present invention, as shown in FIGS. 1 and 2, the wire 101 and the wire guide 102 have the maximum groove width of the groove frontage of the groove of the wire guide 102, that is, the groove width of the lower portion of the groove. The value (W _{0, max} ) is equal to or greater than the wire diameter (φ ₀ ) of the wire 101, and the minimum value (W _{0, min} ) of the groove width at the bottom of the wire guide groove is the wire diameter (φ ₀ ) of the wire. When the wire is installed so as to be in contact with the groove wall 107 of the groove lower portion 106 located below the groove upper portion 105, for example, as shown in FIG. 2, the wire 101 is attached to the groove upper portion 105. It is in contact with the side wall 107 of the groove lower portion 106 located below, and the wire 101 and the groove bottom portion 108 of the wire guide 102 do not come into contact with each other. That is, when the unused wire 101 is installed in the groove of the unused wire guide 102, the wire 101 is in a state of being fitted in the groove lower portion 106 and floating without contacting the groove bottom portion 108 of the wire guide 102. It is in.

When the wire 101 is installed in the groove of the wire guide 102 in this way, the lateral play of the wire in the groove lower part of the wire guide 102 is reduced, and as a result, the lateral vibration of the wire 101 can be suppressed. This is a cutting device that can stably lower the Warp value immediately after the start of use of the work cutting device (from the beginning of the use period) without lowering the cutting speed.

When the wire 101 is installed in the groove of the wire guide 102 as described above and the operation of the wire saw is started, the wire 101 becomes the wire guide 102 as the work is cut (the operation of the wire saw). While scraping the side wall 107 of the groove, it approaches the bottom 108 of the groove. Then, when a certain time has elapsed from the start of cutting the work (operation of the wire saw), the wire 101 comes into contact with the groove bottom 108 of the wire guide 102, and the groove bottom 108 is scraped. In this case, since the groove bottom 108 with the side wall 107 of the groove is shaved and the groove shape that matches the wire shape is formed by itself, the state in which the lateral vibration of the wire 101 is suppressed is maintained more stably. Therefore, the deterioration of the Warp value does not occur.

However, it goes without saying that the effect of the present invention can be exhibited by designing the structure so that the wire 101 does not come into contact with the groove bottom of the wire guide 102 until the end of the wire guide life. According to the investigation by the present inventor, the wire diameter of the wire 101 tends to be reduced by about 10% with use, although it depends on the material used. Taking this into consideration, it is possible to set the relationship between the groove shape and the wire diameter (φ ₀ ).

Here, the cross-sectional shape of the groove bottom 108 of the wire guide 102 is not particularly limited, and may be an arc shape, a V shape, or a flat shape. An example in which the wire 101 is installed on such a wire guide 102 is shown in FIG. 2-4. The matters described in FIG. 2 will be omitted as appropriate in the following description of FIG. 3-6. Further, in FIG. 3-6, only one groove is shown.

The groove having the above-mentioned shape can be produced relatively easily (low cost) and with high accuracy, and the contact between the wire 101 and the groove bottom of the wire guide 102 can be prevented at low cost. In particular, the cross-sectional shape of the groove bottom 108 is arcuate as shown in FIG. 3, and the radius of curvature R thereof is less than the radius of the wire, or the cross-sectional shape of the groove bottom 108 is V-shaped (that is, as shown in FIG. 2). , R = 0), which is preferable because the contact between the wire 101 and the groove bottom 108 of the wire guide 102 can be more reliably prevented from the time of installation to the initial stage of the wire guide life. Further, as shown in FIG. 4, the groove bottom 108 may be flat as long as the minimum value of the groove width of the groove bottom 106 is less than the wire diameter and the wire is not brought into contact with the groove bottom 108.

Further, the wire guide is obtained by changing the maximum value (W _{0, max} ) and / or the second opening angle (θ ₂ ) of the groove width at the lower portion of the groove in a plurality of grooves in the traveling direction of the wire. Can be. As described above, the wire width tends to be reduced by about 10% due to use. For this reason, the portion of the wire having a long cutting processing history is thinner than the unused portion or the portion having a short cutting processing history. In this way, the line width of the wire in use may differ depending on the part of the wire. Therefore, assuming that the shape of the plurality of grooves is changed in the direction of travel of the wire as described above. , The non-contact state between the wire and the groove bottom of the wire guide at the initial stage of the wire guide life can be stably realized.

The first opening angle (θ ₁ ) of the upper portion of the groove of the wire guide 102 is preferably 60 to 110 °. If it is set in such a range, the cutting device has more excellent workability in the wire delivery work. Further, the second opening angle (θ ₂ ) of the lower part of the groove is preferably 20 to 60 °. If it is set in such a range, the cutting device can hold the wire more stably and manufacture a device having a low Warp value.

When installing the wire in the groove of the wire guide 102, shape the wire and the groove so that the upper part of the wire is located above the upper end (groove frontage) of the lower part of the groove at the start of use. It is preferable to set. In this way, the life of the wire guide 102 can be extended.

Further, the groove width of the groove frontage (the boundary between the groove upper part and the groove lower part) and the wire diameter (φ ₀ ), which are the maximum value of the groove width of the groove lower part (W _{0, max} ), are W _{0. , Max} / φ ₀ = 1.01 to 1.30. With such a relationship, the wire can be installed in the lower portion of the groove more reliably, and the lateral vibration of the wire can be prevented more reliably.

Further, the radius of curvature R at the bottom of the groove and the wire diameter (φ ₀ ) are preferably set so that R / φ ₀ is in the range of less than 0.5. With such a relationship, the non-contact state between the wire and the groove bottom 108 of the wire guide 102 can be more stably and surely realized at the initial stage of cutting.

As the wire guide 102, one in which a resin such as polyurethane (ester type, ether type) is press-fitted around a steel cylinder can be preferably used. Further, as the work cutting device, any device of free abrasive grain type and fixed abrasive grain type can be applied.

As an example of the groove shape of the wire guide groove described above, the shape having an apex is shown at the connection portion between the groove upper portion and the groove lower portion, but the connection portion may be smoothly connected.

Next, a method of cutting the work according to the present invention will be described. By cutting the work using the above-mentioned work cutting device, the work shape (Warp) is good and stable from the initial stage of use of the wire guide (immediately after the start of use) while suppressing a decrease in production capacity (throughput). Value) can be obtained, and the quality of the work that does not depend on the life of the wire guide can be obtained.

First, the cutting device is set before the start of cutting the work. Wires are spirally wound around a plurality of cylindrical wire guides installed so that their rotation axes are parallel to each other to form a wire row.

As described above, the cross-sectional shape of the groove in the unused wire guide 102 is at least located on the outer surface side of the wire guide, and the groove wall 107 facing the groove wall 107 has a first opening angle (θ ₁ ). A first groove portion 106, which is located below the groove upper portion 105 and whose opposite groove wall 107 has a second opening angle (θ ₂ ), and a groove bottom portion 108 located at the lower end of the groove. The opening angle (θ ₁ ) and the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ ₂ . Further, the maximum value (W _{0, max} ) of the groove width of the groove lower portion 106 of the unused wire guide is equal to or larger than the wire diameter (φ ₀ ) of the unused wire 101, and the groove lower portion of the unused wire guide 102. The minimum value (W _{0, min} ) of the groove width of 106 is less than the wire diameter (φ ₀ ) of the unused wire 101 (W _{0, min} <φ ₀ ≦ W _{0, max} ). The unused wire 101 and the unused wire guide 102 having such a relationship are used, and the unused wire 101 is in contact with the groove wall 107 of the groove lower portion 106 of the unused wire guide 102, and By installing the wire guide 102 in a state where it does not contact the groove bottom portion 108 and starting cutting the work in a state where the wire does not contact the groove bottom portion 108, the initial use of the wire guide 102 (throughput) is suppressed. A good and stable work shape (Warp value) can be obtained immediately after the start of use), and the life-independent work quality of the wire guide 102 can be obtained.

When the wire is installed in the wire guide groove as described above and the operation of the wire saw is started, immediately after the operation is started, the wire is in a state of being supported (held) by the side wall at the lower part of the groove, and the work is cut (wire). As the saw operation progresses, the wire approaches the groove bottom while scraping the side surface of the wire guide groove, and the cutting proceeds while forming the optimum groove shape according to the wire diameter. Then, when a certain time elapses from the start of cutting the work (operation of the wire saw), the wire contacts the groove bottom of the wire guide and scrapes the groove bottom. Even when the wire comes into contact with the groove bottom of the wire guide in this way, the lateral vibration of the wire remains suppressed because the wire advances while shaving the groove, and therefore the Warp value does not deteriorate. ..

Further, as described for the device, if the work is cut using a wire guide in which the shapes of a plurality of grooves are changed in the traveling direction of the wire as described above, the wire guide life is set in the early stage. A non-contact state between the wire and the groove bottom of the wire guide can be stably realized. Moreover, since it is not necessary to reduce the cutting speed, it is possible to suppress a decrease in production capacity.

Hereinafter, the present invention will be described in detail with reference to examples, but this does not limit the present invention.

(Example)
As an unused (new) wire guide, the first opening angle (θ ₁ ) of the upper part of the groove is 90 degrees, the second opening angle (θ ₂ ) of the lower part of the groove is 40 degrees, the depth of the lower part of the groove is 130 μm, and the lower part of the groove. The groove width (W _{0, max} ) of the groove frontage was 140 μm, the radius of curvature R of the groove bottom was 0.030 mm, and each groove shape parameter was used. When an unused (new) wire having a wire diameter (φ ₀ ) of 0.13 mm is installed in such a wire guide, the wire contacts the groove wall at the bottom of the groove of the wire guide and also contacts the bottom of the groove. It was installed without it (see Fig. 3).

Next, a silicon single crystal ingot having a diameter of 200 mm was used as a work to be cut, cutting was performed using a wire saw device, the shape of the silicon wafer obtained by cutting was measured, and the Warp value was calculated.

(Comparative Example 1)
As an unused (new) wire guide, use one with a groove cross-sectional shape of one V-groove, a groove opening angle of 90 degrees, and a groove width of 0.6 mm (600 μm) on the outer surface of the wire guide. Except for the above points, cutting was performed under the same conditions as in Example 1, and the shape of the silicon wafer obtained by cutting was measured. When the wire was installed on the wire guide used in Comparative Example 1, the state as shown in FIG. 5 was obtained. When the wire was installed in the groove, the wire had lateral play in the groove.

(Comparative Example 2)
As an unused (new) wire guide, the first opening angle (θ ₁ ) of the upper part of the groove is 90 degrees, the second opening angle (θ ₂ ) of the lower part of the groove is 40 degrees, the depth of the lower part of the groove is 130 μm, and the lower part of the groove. The groove width (W _{0, max} ) of the groove frontage was 190 μm, the radius of curvature R at the bottom of the groove was 0.065 mm, and each groove shape parameter was used. When a new wire having a wire diameter (φ ₀ ) of 0.13 mm was installed on such a wire guide, the wire and the groove bottom of the wire guide were in contact with each other (see FIG. 6). When the wire was installed in the groove, the wire had lateral play in the groove. Except for this, cutting processing was performed under the same conditions as in Example 1, and the shape of the silicon wafer obtained by cutting was measured.

For reference, Table 1 shows typical values of cutting processing conditions (including the above-mentioned conditions).

FIG. 7 shows the transition of the Warp value of the wafer. On the horizontal axis, processing batches for a certain period from the beginning of the life of the wire guide were extracted. The vertical axis shows the Warp value. For the plot, the average value of the Warp values for every 10 batches was taken as one plot. Further, in order to compare Examples and Comparative Examples 1 and 2, relative values were compared using the average value of 30 batches from the initial stage of cutting of Comparative Example 1 as a reference 1. As shown in FIG. 7, in Comparative Example 1, it can be seen that the number of cutting processing batches until the Warp value is low and stable is the largest.

FIG. 8 is an enlarged view of the range of 3 plots (30 batches) at the initial stage of the wire guide life in FIG. 7. As shown in FIG. 8, in the examples, the Warp value was low and stable from the very beginning. Further, in Comparative Example 2, as shown in FIG. 7, the Warp value was stabilized at an earlier stage than in Comparative Example 1, but as shown in FIG. 8, the Warp value was high and varied at the very initial stage. When the initial stage of wire guide life (30 batches) was compared based on the data for the very initial 30 batches shown in FIG. 8, in the examples, both the Warp value and the variation were compared with those of Comparative Examples 1 and 2. A stable and high quality product was obtained.

Table 2 summarizes the conditions of Examples and Comparative Examples 1 and 2 described above and the evaluation results.

As shown in FIG. 7, in the embodiment, it is considered that the Warp value is stable from the beginning because the wire is properly fitted in the lower portion of the groove of the wire guide and the play of the wire is eliminated from the start of use. Be done. On the other hand, in all of Examples and Comparative Examples 1 and 2, the Warp value between lots and within lots is finally low and stable. This is because the side surface (side wall) and bottom surface of the wire guide groove are gradually ground toward the bottom of the groove as the wire runs, and the side surface (side wall) and bottom surface of the groove become familiar with the wire shape. It is believed that there is. In Comparative Example 2, although the wire is provided in the lower portion of the groove of the wire guide, since it is installed so as to be in contact with the lower portion of the groove, the play of the wire cannot be eliminated, and compared to the Example, the initial several tens. It seems that the Warp value was disturbed in the batch.

As described above, since the wire wears and becomes thinner with use, the ratio of the groove width (W _{0, max} ) of the groove frontage to the wire diameter (φ) changes depending on the usage condition. When installing the wire in the wire guide groove, in order to maintain the non-contact state between the groove bottom and the wire at the very beginning of the wire life more stably, the fluctuation of the wire diameter (φ) is taken into consideration and it is not yet done. It is preferable to set the relationship with the groove width (W _{0, max} ) of the groove frontage of the wire guide groove used. Therefore, for Example and Comparative Example 2, the ratio of the groove width (W _{0, max} ) of the groove frontage of the unused wire guide to the wire diameter (φ) (groove frontage / wire diameter = W _{0, max} /). φ) and the ratio of the radius of curvature (R) to the wire diameter (φ) at the bottom of the groove of the unused wire guide (groove frontage / wire diameter = R / φ) were investigated. The results are shown in Table 3.

As shown in Table 3, the groove width (W _{0, max} ) of the groove frontage of the wire guide groove is set in the range of 1.01 to 1.30 when the wire diameter (φ ₀ ) is used as a reference. It was found that the radius of curvature R at the bottom of the groove is preferably set in the range of less than 0.5.

For example, as described above, as a wire guide, the shape of a plurality of grooves is gradually changed in the traveling direction of the wire so that the groove width (W _{0, max} ) of the groove frontage of the groove is gradually narrowed. In some cases, it is effective to set within the above range.

As described above, according to the embodiment of the present invention, the Warp can be stably set to a good level immediately after the start of use of the wire guide, the work shape quality independent of the wire guide life can be obtained, and the cutting speed can be obtained. It was found that the work shape quality can be maintained without reducing (production capacity).

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any object having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same action and effect is the present invention. Is included in the technical scope of.

100 ... wire saw, 101 ... wire, 102 ... wire guide,
103, 103'... wire reel, 104 ... ingot (work),
105 ... groove upper part, 106 ... groove lower part, 107 ... side wall, 108 ... groove bottom part,
111 ... Wire row.

Claims (8)

A wire is spirally wound around a plurality of cylindrical wire guides installed so that their rotation axes are parallel to each other to form a wire row, and the workpiece is placed on the wire row while the wire is running in the axial direction. It is a method of pressing and cutting into a wafer shape at multiple points at the same time.
The wire guide has a plurality of grooves formed on the outer surface at a predetermined pitch along the rotation direction.
The cross-sectional shape of the groove in the unused wire guide is at least located on the outer surface side of the wire guide, and the groove upper part having a _first opening angle (θ ₁ ) and the groove upper part having the opposite groove walls. It has a groove bottom that is located below and has a _second opening angle (θ ₂ ) on the opposite groove wall, and a groove bottom that is located at the bottom of the groove.
The first opening angle (θ ₁ ) and the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ ₂ .
The maximum value (W _{0, max} ) of the groove width of the groove lower part of the unused wire guide is equal to or larger than the wire diameter (φ ₀ ) of the unused wire, and the groove lower part of the unused wire guide Using the unused wire and the unused wire guide having a relationship in which the minimum value of the groove width (W _{0, min} ) is less than the wire diameter (φ ₀ ) of the unused wire,
The unused wire is installed in a state where it is in contact with the groove wall at the lower portion of the groove of the unused wire guide and not at the bottom of the groove.
A method for cutting a work, characterized in that cutting of the work is started in a state where the wire does not come into contact with the bottom of the groove. The method for cutting a work according to claim 1, wherein a wire guide having a groove bottom having an arc-shaped, V-shaped or flat cross-sectional shape is used. The method for cutting a work according to claim 1 or 2, wherein the wire cuts the groove wall as the cutting of the work progresses. The method for cutting a work according to any one of claims 1 to 3, wherein the wire comes into contact with the groove bottom portion and cuts the groove bottom as the cutting of the work progresses. As the unused wire guide, the maximum value (W _{0, max} ) and / or the second opening angle (θ ₂ ) of the groove width of the lower portion of the groove in the plurality of grooves is set in the traveling direction of the wire. The method for cutting a work according to any one of claims 1 to 4, wherein the work is changed so as to be used. A plurality of cylindrical wire guides arranged at predetermined intervals so that their rotation axes are parallel to each other, and grooves are formed on the outer surface at a predetermined pitch, respectively.
A wire row formed by wires spirally wound around the groove of the wire guide at a predetermined pitch,
Equipped with
It is a cutting device that pushes a work against the wire row while traveling the wire in the axial direction by rotating the wire guide, and simultaneously cuts the work into a wafer shape at a plurality of places.
The cross-sectional shape of the groove in the wire guide is located at least on the outer surface side of the wire guide, the upper portion of the groove having the opposite groove wall having the first opening angle (θ ₁ ), and the lower portion of the upper portion of the groove. A groove bottom having a _second opening angle (θ ₂ ) and a groove bottom located at the lower end of the groove are provided.
The first opening angle (θ ₁ ) and the second opening angle (θ ₂ ) have a relationship of θ ₁ > θ ₂ .
In the wire and the wire guide, the maximum value (W _{0, max} ) of the groove width of the groove lower portion of the wire guide is equal to or larger than the wire diameter (φ ₀ ) of the wire, and the groove lower portion of the wire guide The minimum value of the groove width (W _{0, min} ) is less than the wire diameter (φ ₀ ) of the wire.
A work cutting device, characterized in that, when the wire is installed so as to be in contact with the groove wall at the lower portion of the groove, the wire and the groove bottom portion of the wire guide do not come into contact with each other. The work cutting device according to claim 6, wherein the cross-sectional shape of the groove bottom portion of the wire guide is arcuate, V-shaped, or flat. In the wire guide, the maximum value (W _{0, max} ) and / or the second opening angle (θ ₂ ) of the groove width of the lower portion of the groove in the plurality of grooves changes in the traveling direction of the wire. The work cutting device according to any one of claims 6 and 7, wherein the work is cut.

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