JP2009107050A - Method of cutting workpiece by wire saw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of cutting a workpiece by a wire saw capable of achieving a high cutting rate by improving a working fluid. <P>SOLUTION: In this method of cutting a workpiece by a wire saw while supplying the working fluid to a wire during the working, abrasive grains and micro nano bubble water are contained in the working fluid used for cutting the workpiece. The micro nano bubble water is generated by a micro nano bubble water generator installed on a wire saw device, and mixed in the working fluid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a workpiece cutting method using a wire saw, and more particularly to a workpiece cutting method using a wire saw that achieves a high cutting rate.

  In the cutting process of cutting a silicon wafer from a silicon ingot, high-rate cutting is required from the viewpoint of increasing the diameter of the ingot and reducing the cost. For this reason, in recent years, it has become mainstream to use the wire saw method from the inner peripheral blade method, which has been the mainstream until now (for example, Patent Document 1). In the wire saw method, the processing rate (cutting rate) per silicon wafer can be higher than that of the inner peripheral blade method for single wafer cutting. For this reason, the overall cutting time is much longer than that of the inner peripheral blade method, but it is possible to cut a silicon single crystal ingot with a length of several hundred mm with one cutting, and several hundred silicon wafers can be cut at a time. Can be cut out.

  In cutting with a wire saw, methods for increasing the cutting speed (cutting rate) of a silicon single crystal ingot include a method of cutting using a large abrasive grain, a method of increasing the pressing pressure of a silicon single crystal ingot on a wire, and running Each method of increasing the speed of the wire to be used is effective.

However, the method using a large abrasive grain has a problem that the kerf loss at the time of cutting becomes large and the surface roughness after cutting deteriorates. Further, in the method of increasing the pressing pressure, the deflection of the wire being cut increases, and the waviness and surface roughness after cutting deteriorate. In addition, the method for increasing the wire speed has limitations on the apparatus.
JP 2001-328057 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a work cutting method using a wire saw that achieves a high cutting rate by improving the machining fluid.

  A workpiece cutting method using a wire saw according to one aspect of the present invention is a workpiece cutting method using a wire saw for cutting a workpiece by supplying a machining fluid, wherein the machining fluid includes abrasive grains and micro-nano bubble water. .

  Here, it is desirable that the micro / nano bubble density in the micro / nano bubble water is 1000 / ml or more.

  Here, the micro-nano bubble water is preferably micro-nano bubble water within 10 hours after the generation of micro-nano bubbles.

  Here, it is desirable that the ratio of micro / nano bubble water in the processing liquid is 6.25 wt% or more.

  Here, the workpiece is preferably a silicon single crystal.

  According to the present invention, it is possible to provide a work cutting method using a wire saw that achieves a high cutting rate by improving the machining fluid.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a workpiece cutting method using a wire saw according to the present invention will be described with reference to the accompanying drawings. Here, a case where a silicon single crystal is a target as a workpiece (or an object to be cut) to be cut with a wire saw will be described as an example. In the present specification, micro-nano bubbles are defined as bubbles having a diameter of 1 nm or more and less than 100 μm. And micro nano bubble water shall refer to the pure water containing this micro nano bubble.

  The workpiece cutting method using the wire saw according to the present embodiment is a workpiece cutting method using a wire saw that supplies a machining liquid (or slurry) to cut the workpiece, and that the machining liquid contains abrasive grains and micro / nano bubble water. Features.

  FIG. 2 is a schematic view of a wire saw device used in the method of the present embodiment. The wire saw device 10 includes a wire bobbin 12 and a pulley 14, and a wire 16 stretched between the wire bobbin 12 and the pulley 14 so as to be able to reciprocate. For example, a work attachment jig 20 for attaching a work 18 such as a silicon single crystal is provided. The mounting jig 20 is incorporated in the balance weight mechanism 22, and the balance weight mechanism 22 can adjust the load applied to the wire 16 of the workpiece 18. Further, the wire saw device 10 is provided with a machining liquid supply unit 24 that supplies a machining liquid to the wire 16 during workpiece cutting.

  Furthermore, a micro / nano bubble water generating device 26 is attached to the wire saw device 10. The machining liquid supply system is configured such that the micro / nano bubble water generated by the micro / nano bubble water generation device 26 can be mixed with abrasive grains and supplied to the wire 16 from the machining liquid supply unit 24. For example, air, oxygen, or the like can be used as the gas in the micro / nano bubbles, but the gas is not particularly limited.

  The micro-nano bubble water generator 26 is designed to generate micro-nano bubbles having a density of 1,000 to several million / ml using, for example, a swirling flow type micro-nano bubble generating mechanism.

  Next, a work cutting method using the wire saw device 10 and the micro / nano bubble water generating device 26 will be described.

  First, the tension of the wire 16 stretched between the wire bobbin 12 and the pulley 14 is adjusted to a predetermined tension. Next, for example, the workpiece 18 that is a silicon single crystal is fixed to the workpiece mounting jig 20. And the balance weight mechanism 22 is adjusted so that the weight with respect to the wire 16 at the time of the cutting | disconnection of the fixed workpiece | work 18 may become predetermined | prescribed weight.

  Thus, after adjusting the tension of the wire 16 and the pressing load of the work 18 against the wire 16, the work 18 is pressed against the wire 16 and a motor (not shown) connected to the wire bobbin 12 is driven to drive the wire 16. Is reciprocatingly moved to cut the workpiece 18. When the workpiece 18 is cut, the machining liquid containing abrasive grains and micro / nano bubble water generated by the micro / nano bubble water generator 26 is supplied from the machining liquid supply unit 24 to the wire 16. This machining fluid may contain a known wire saw machining fluid.

  As in the present embodiment, it is possible to achieve a high cutting rate for a workpiece by adding micro / nano bubble water to the working fluid in addition to the abrasive grains. At the same time, the wear of the wire is reduced, and the life of the wire can be improved.

  As described above, in the present embodiment, the reason why a high cutting rate for the workpiece can be realized is considered as follows. FIG. 3 is a diagram illustrating the action of micro / nano bubble water. FIG. 3A shows a case where a conventional machining fluid is used, and FIG. 3B shows a case where a machining fluid containing micro / nano bubble water according to the present embodiment is used.

  As shown in FIG. 3B, the wettability between the machining liquid 30 and the wire 16 is improved by adding the micro-nano bubble water to the machining liquid 30 containing the abrasive grains 28. Therefore, it adheres more smoothly than in the case of FIG. This is considered to be due to the surface active effect of the micro / nano bubbles.

  FIG. 4 is also a diagram illustrating the action of micro / nano bubble water. The processed portion where the wire 16 and the workpiece 18 come into contact has a thin slit shape as shown in FIG. For this reason, the higher the wettability of the processing liquid, the easier it is to enter the slit-shaped gap, and as a result, more abrasive grains are supplied to the processed portion, and a high cutting rate can be realized. In addition, since the micro / nano bubbles have a large zeta potential, the adhesion of abrasive grains to the wire 16 also contributes to the realization of a high cutting rate.

  And since the adhesion of the abrasive grains 28 to the wire 16 becomes strong, the slip between the abrasive grains 28 and the wire 16 is reduced. For this reason, the abrasion by the friction with the abrasive grain 28 of the wire 16 reduces. Therefore, the wire life can be improved.

  In the present embodiment, it is desirable that the micro / nano bubble density of the micro / nano bubble water is 1000 / ml or more. This is because if the density is higher than this density, a high cutting rate realization effect and a wire life improvement effect can be obtained sufficiently in practical use. Furthermore, it is desirable that the micro / nano bubble density of the micro / nano bubble water is 500,000 / ml or more. This is because when the density is equal to or higher than this density, a high cutting rate realization effect and a wire life improvement effect are remarkably obtained.

  The micro / nano bubble water is preferably micro / nano bubble water within 10 hours after the generation of micro / nano bubbles. This is because the micro-nano bubble density and the zeta potential in the micro-nano bubble water decrease with time, and if it is within 10 hours after the generation of the micro-nano bubble, the same effect is obtained immediately after the generation of the micro-nano bubble.

  Moreover, it is desirable that the ratio of the micro / nano bubble water in the working fluid is 6.25% by weight or more. This is because, at this ratio, a high cutting rate, a realization effect, and a wire life improvement effect can be obtained sufficiently in practical use.

  The embodiments of the present invention have been described above with reference to specific examples. In the description of the embodiment, the description of the parts that are not directly necessary for the description of the present invention is omitted in the wire saw device, the work cutting method using the wire saw, etc. However, the required wire saw device and the work cutting method using the wire saw are omitted. It is possible to appropriately select and use elements related to the above.

  For example, in the above-described embodiment, the wire saw device has been described by taking a device that targets a relatively small work as an example, but the application of the present invention is not limited to such a device, but a silicon single crystal ingot or the like. It is also possible to apply to a wire saw device that cuts a large workpiece. In addition, the silicon single crystal has been described as an example of the workpiece. However, the work is not necessarily limited to the silicon single crystal, and may be a single crystal other than silicon, such as a GaAs single crystal or InP single crystal, as long as it is a solid to be cut with a wire saw It can also be applied to glass, ceramics and the like.

  In addition, any work cutting method using a wire saw that includes the elements of the present invention and can be appropriately modified by those skilled in the art is included in the scope of the present invention.

Examples of the present invention will be described below.

(Example 1)
A 20 mm × 20 mm × 20 mm silicon single crystal workpiece was cut using a wire saw device (model number 3032-4 / S) manufactured by Meiwa Forsys, Ltd., which is a wire saw device as shown in FIG. The cut surface was a Si (100) surface. As the wire, SRM 0.14 mm made by Japan Fine Steel having a wire diameter of 0.14 mm was used. Further, as processing conditions, the wire tension (tension) was 1.0005 kgf and the wire traveling speed was 170 m / min. Moreover, the weight with respect to the wire of a workpiece | work was cut | disconnected by the balance weight mechanism as a fixed load of 0.2N.

As a micro nano bubble water production | generation apparatus, it produced | generated using the Kyowa machine establishment nano bubble production | generation apparatus BUVITAS (form: HYK-25). The gas in the micro / nano bubble was air. The micro-nano bubble water produced | generated by operating a micro-nano bubble water production | generation apparatus for 30 minutes with respect to 18L pure water was made to contain in a processing liquid. The nanobubble water used this time was subjected to particle size distribution measurement by laser diffraction method after 40 minutes had elapsed after the formation of relatively stable bubbles. As a result, the bubble density was 2.7 to 7.4 × 10 ⁶ particles / ml, the bubble particle size was Median of 0.593 to 0.596 μm, and histogram peaks were observed in the vicinity of 0.1 μm, 0.3 μm, and 0.5 μm, respectively. The processing liquid used is a mixture of the above micro-nano bubble water, Yushiro Chemical Co., Ltd. wire saw processing liquid (Yushiro Tech WL665) and Riken Corundum GC abrasive grains (GCR # 1500) in a weight ratio of 25: 175: 200. It was.

  Cutting was performed while changing the time from micro-nano bubble water generation to cutting (time after generation), and the processing rate (cutting rate) was calculated from the workpiece cutting time. The results are shown in FIG. Moreover, the tensile strength of the wire after cutting was measured for the case immediately after the generation (Example 1-1) and the case after the generation 5 days (120 hours) (Example 1-2). The tensile strength was measured with a tensile tester (Olintec UCT). The results are shown in FIG. Moreover, about Example 1-1, the wire surface after a cutting | disconnection was performed by SEM (1500 times). The results are shown in FIG.

(Comparative Example 1)
The workpiece was cut under the same conditions as in Example 1 except that the micronano bubble water was not included in the processing liquid.

  The processing rate result is shown in FIG. 1, the tensile strength result is shown in FIG. 5, and the wire surface observation result is shown in FIG. 6 (a).

(Comparative Example 2)
The workpiece was cut under the same conditions as in Example 1 except that pure water not containing micro / nano bubbles was used instead of micro / nano bubble water.

  The result of the tensile strength is shown in FIG.

(Comparative Example 3)
The wire before use was designated as Comparative Example 3.

  The result of the tensile strength is shown in FIG. The wire surface observation results are shown in FIG.

  As shown in FIG. 1, when a processing liquid containing micro / nano bubble water is used, the processing rate is improved as compared to a processing liquid not containing micro / nano bubble water (Comparative Example 1). Moreover, about the processing liquid containing micro nano bubble water, a correlation is seen by the time after production | generation, and a processing rate, and the improvement effect of a processing rate is remarkable especially in the case of less than 10 hours after production | generation.

  Further, as shown in FIG. 5, the tensile strength of the wire after cutting is such that when the processing liquid containing micro-nano bubble water (Example 1-1, Example 1-2) is used, the processing liquid does not include micro-nano bubble water. Compared with (Comparative Examples 1 and 2), deterioration of the tensile strength when compared with before use (Comparative Example 3) is suppressed.

  And as shown in FIG. 6, the surface (FIG.6 (b)) at the time of using the process liquid (Example 1-1) containing micro nano bubble water is the process liquid (Comparative Example 1) which does not contain micro nano bubble water. ), No streak-like scratches due to friction between the abrasive grains and the wire as seen on the surface (FIG. 6A) are observed.

  As mentioned above, the effect | action and effect of this invention were confirmed by the present Example.

The figure which shows the processing rate calculation result of an Example. The schematic of the wire saw apparatus of embodiment. Explanatory drawing of an effect | action of embodiment. Explanatory drawing of an effect | action of embodiment. The figure which shows the measurement result of the tensile strength of an Example. The figure which shows the wire surface observation result of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wire saw apparatus 12 Wire bobbin 14 Pulley 16 Wire 18 Workpiece 20 Work attachment jig 22 Balance weight mechanism 24 Processing liquid supply part 26 Micro nano bubble water production | generation apparatus 28 Abrasive grain 30 Processing liquid

Claims (5)

A workpiece cutting method using a wire saw that supplies a machining fluid to cut a workpiece,
A workpiece cutting method using a wire saw, wherein the machining liquid contains abrasive grains and micro / nano bubble water.   2. The work cutting method using a wire saw according to claim 1, wherein a density of micro / nano bubbles in the micro / nano bubble water is 1000 / ml or more.   The said micro nano bubble water is the micro nano bubble water within 10 hours after micro nano bubble production | generation, The workpiece cutting method by the wire saw of Claim 1 or Claim 2 characterized by the above-mentioned.   The work cutting method using a wire saw according to any one of claims 1 to 3, wherein a ratio of micro / nano bubble water in the working fluid is 6.25% by weight or more. The work cutting method using a wire saw according to any one of claims 1 to 4, wherein the work is a silicon single crystal.