JPH06315830A - Beveling method for cut-resistant material - Google Patents

Abstract

(57) [Summary] [Construction] The main electrode 2 is opposed to the outer peripheral edge B of the silicon wafer A, and the electrolytic solution D in the container 4 is supplied to the main electrode 2 and the auxiliary electrode arranged in the container 4. When a voltage is applied to the outer peripheral edge portion B by the discharge heat generated at the tip portion of the main electrode 2, the grindstone 3 is arranged at the lower side position of the main electrode 2 and This is a beveling method in which the electrolytic solution D is supplied to the grindstone 3 side. [Effect] Since the electrolytic solution is supplied to the grindstone side for polishing the outer peripheral edge portion, it is possible to prevent the surface other than the outer peripheral edge portion from being electrolytically polished, and at the same time as the electrolytic polishing, mechanical polishing by the grindstone is performed. Since it is also performed, even if there is a deep scratch on the wafer, it can be reliably removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beveling method for polishing an outer peripheral edge portion of a disc-shaped difficult-to-cut material by an electrolytic polishing method.

[0002]

2. Description of the Related Art Heretofore, as insulating difficult-to-cut materials, there are ceramic materials formed by processing alumina, zirconia, silicon carbide, etc., and also glass, silicon wafers cut out from silicon ingots, etc.

By the way, such a difficult-to-cut material has properties of being hard and brittle, and in order to be used for mechanical parts and semiconductor parts, it must be mechanically processed, and such processing is carried out. Therefore, it is necessary to use, for example, a diamond tool, which has a drawback that the processing cost is high.

Therefore, recently, there has been proposed a method for electrically processing the above-mentioned difficult-to-cut material, that is, a processing method by electrolytic polishing, utilizing an electrolytic discharge action generated in an electrochemical solution, that is, an electrolytic solution.

This electrolytic polishing method is a method of processing a difficult-to-cut material by a thermochemical action associated with an electrolytic discharge action, and can process the difficult-to-cut material at a lower cost than that using a diamond tool, for example. It is a product.

By the way, as shown in FIG. 2, for example, when drilling a difficult-to-cut material by this electrolytic polishing method, first, in an electrolytic solution D obtained by dissolving an electrolyte in water,
The workpiece F, which is a difficult-to-cut material, is dipped, and the rod-shaped main electrode 31 is formed so that its tip end contacts the processing position of the workpiece F, and the plate-shaped auxiliary electrode 32 is formed on the workpiece F. It is placed in the electrolytic solution D at a position slightly away from.

Next, a power source 33 is connected between the electrodes 31 and 32 to apply a DC or AC voltage V having a predetermined value, and the tip of the main electrode 31 is pressed against the workpiece F side.
At this time, the electrolytic strength E in the vicinity of the main electrode 31 increases as the voltage increases, and as the electrolytic strength E increases, the current I flowing in the electrolytic solution D is increased as indicated by the solid line f in FIG.
Is increased and the electrolytic action proceeds.

By the way, as shown in FIG. 3A, no change occurs in the vicinity of the main electrode 31 when the current I does not flow and when the current I is small, but the current I does not flow. When the electrolysis is increased and starts, as shown in FIG. 3B, minute bubbles such as hydrogen H ₂ , oxygen O ₂ and air are generated in the vicinity of the main electrode 31 so as to surround the main electrode 31. start.

Then, as the current I increases, as shown in FIG.
As shown in FIG. 3C, when the bubble gradually becomes larger and starts to float and the current I further increases, as shown in FIG. The amount of air bubbles that float around the surface increases with the surrounding area.

Further, when the current I increases more than in the case of FIG. 3 (d), if the electrolytic strength E near the main electrode 31 exceeds the dielectric breakdown strength of the bubbles, so-called dielectric breakdown occurs, and FIG. 3 (e). As shown in, a large number of fine bubbles are generated due to the dielectric breakdown, and at this time, the current I sharply decreases and
Discharge light emission and heat generation occur.

Due to the heat generation, the thermochemical action on the workpiece F becomes remarkable, and this action causes the workpiece F to be perforated. The removal amount W of the workpiece F at this time is as shown by the solid line g in FIG.

In FIG. 2, reference numeral 41 is a floating fine bubble, and 42 is a fine bubble generated by dielectric breakdown.
When the edge portion of the outer peripheral portion of the silicon wafer is polished as a workpiece by such an electrolytic polishing method,
As shown in FIG. 4, a silicon wafer in which an auxiliary electrode 53 is inserted and arranged in a container 51 in which an electrolytic solution D is placed and which is supported by a rotation support shaft 54 side (hereinafter, simply referred to as wafer A)
By immersing a part of A in the electrolytic solution D and bringing the tip of the main electrode 52 into contact with the outer peripheral edge portion B of the wafer A to cause discharge between the main electrode 52 and the electrolytic solution D, The peripheral edge B was polished.

[0013]

By the way, according to the electrolytic polishing method as described above, since the wafer A is immersed in the electrolytic solution D and rotated, as shown in FIG. The electrolytic solution D also adheres to the peripheral portion C, and a thermochemical reaction also occurs in the peripheral portion C due to discharge heat, which causes a problem that the surface of the peripheral portion C is roughened.

As a method for solving such a problem, it is conceivable to cover a portion other than the outer peripheral edge portion B with a coating material such as insulating paint, but in the case of processing a large amount,
This is not practical because the coating material must be coated on each sheet.

Therefore, an object of the present invention is to provide a method for beveling a difficult-to-cut material which can solve the above problems.

[0016]

In order to solve the above problems, a method of beveling a difficult-to-cut material according to the present invention includes a main electrode at the outer peripheral edge of a disc-like hard-to-cut material that is rotatably supported. Discharge generated at the tip of the main electrode by facing and supplying the electrolytic solution filled in the container and applying a voltage between the main electrode and the auxiliary electrode in contact with the electrolytic solution in the container. When polishing the outer peripheral edge of the difficult-to-cut material by heat, a polishing member is integrally arranged at the lower side position of the main electrode, and the electrolytic solution in the container is supplied to the polishing member side. Is the way.

[0017]

[Operation] According to the above beveling method for difficult-to-cut materials,
When a voltage is applied between the main electrode and the auxiliary electrode via an electrolytic solution to perform electropolishing, a polishing member is arranged at the lower side position of the main electrode and the electrolytic solution is supplied to this polishing member side. Since this is done, it is possible to prevent the electrolytic solution from adhering to the extra portion.

Further, since the polishing member is arranged at the position on the lower side of the main electrode, the difficult-to-cut material can be subjected to electrolytic polishing and mechanical polishing at the same time.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the embodiments described below, the case of polishing a silicon wafer (an example of a difficult-to-cut material, which may be applied to a material made of, for example, a ceramic material or a glass material) will be described.

In FIG. 1, reference numeral 1 denotes a disk-shaped silicon wafer (hereinafter simply referred to as a wafer) which is rotated in the direction of arrow a.
This is a polishing apparatus for beveling the outer peripheral edge portion B of A, which uses both electrolytic polishing with an electrolytic solution and mechanical polishing with a grindstone.

That is, the polishing apparatus 1 includes a blade-shaped main electrode (for example, a blade of a cutter knife is used) 2 arranged to face the outer peripheral edge B of the wafer A, and the main electrode 2. Immediately on the lower side (the lower side with respect to the rotation direction a of the wafer A), the through holes (for example, a hole having a diameter of about 1 mm) 3a are integrally connected and arranged, for example, via bolts.
A grindstone (an example of a polishing member, which is made of a ceramic material such as SiNx) 3 in which is formed, a container 4 in which the electrolytic solution D is stored, and a plate-like member arranged at the bottom of the container 4. An auxiliary electrode 5, an electrolyte supply pump 6 provided in the middle thereof, and an electrolyte solution supply pipe 7 for supplying the electrolyte solution D in the container 4 into the through hole 3a of the grindstone 3, the main electrode 2 and the auxiliary electrode 5. It is connected to the electrode 5 and is composed of a power supply 8 for applying a predetermined voltage (DC voltage, AC voltage, pulse voltage or the like) between the electrodes 2 and 5. The electrolyte supply pipe 7 is a pipe body 7a connected to the container 4 side.
And an introducing pipe portion 7b connected to the through hole 3a side of the grindstone 3.

The wafer A is rotated in the direction of arrow a by a rotation driving device (not shown). Therefore, in the above structure, when polishing the outer peripheral edge portion B of the wafer A, first, the wafer A is held on the rotary shaft portion on the side of the rotary drive device via a chuck device or the like.

Next, the liquid supply pump 6 is driven to drive the container 4
The electrolytic solution D therein is guided to the through hole 3a of the grindstone 3, and the electrolytic solution (acid, alkali, neutral liquid, etc.) D is supplied to the portion facing the outer peripheral edge portion B of the grindstone 3 and the main electrode 2.

Next, the wafer A is rotated in the direction of arrow a,
A predetermined voltage is applied between the electrodes 2 and 5, and the main electrode 2 and the grindstone 3 are pressed against the outer peripheral edge portion B with a predetermined pressing force.

Then, a current flows between the main electrode 2 and the auxiliary electrode 5 through the electrolytic solution D, and a discharge is generated at the contact portion with the main electrode 2, and this discharge heat causes the outer peripheral edge of the wafer A. The portion B is subjected to thermal processing (processing by thermal melting or thermochemical reaction), and at the same time, mechanical polishing is performed by the rubbing action of the grindstone 3 arranged on the lower side of the main electrode 2.

As described above, since the electrolytic solution D is supplied only to the outer peripheral edge portion B, which is the polished portion of the wafer A, through the through hole 3a of the grindstone 3, as in the conventional case, a part of the difficult-to-cut material is used. As compared with the case of immersing the electrolyte in the electrolytic solution, the electrolytic solution is prevented from adhering to an excessive portion, and therefore it is possible to prevent the surface other than the outer peripheral edge portion from being roughened.

Further, since mechanical polishing is performed simultaneously with electrolytic polishing with a grindstone, the polishing thickness can be made sufficiently thick, unlike the case of only electrolytic polishing. For example, the thickness of 3 to 5 μm generated in the pretreatment step can be obtained. It is possible to surely remove the depth machining streaks.

The degree of processing can be controlled by adjusting the applied voltage, the rotation speed of the wafer, and the pressing force of the main electrode and the grindstone. Here, a specific processing example will be described.

A silicon wafer having a diameter of 4 inches was used as a difficult-to-cut material which is a work piece. Further, a blade of a cutter knife was used as a main electrode, ceramic (SiNx) was used as a grindstone, an electrolytic solution of 10% neutral salt was used as a processing condition, and the rotation speed of the wafer was set to 1 to 100 rpm.

When the beveling process, that is, the chamfering process was carried out for about 1 minute under the above-mentioned conditions, no corrosion was observed in the parts other than the outer peripheral edge part, and sufficient polishing to remove the processing scratches was confirmed. It was

By the way, in the above embodiment, the electrolytic solution is passed through the through holes formed in the grindstone, and the main electrode and the wafer A
However, it is also possible to dispose the tip of the electrolytic solution supply pipe on the outer surface of the grindstone and to supply from the outer side of the grindstone.

Further, in the above-mentioned embodiment, the blade-shaped electrode is shown as the main electrode, but a rod-shaped electrode or a linear electrode may be used, for example.

[0033]

As described above, according to the beveling processing method of the present invention, when electropolishing is performed by applying a voltage between the main electrode and the auxiliary electrode through the electrolytic solution, the position of the lower side of the main electrode is lowered. Since the polishing member is arranged on the polishing member and the electrolytic solution is supplied to the polishing member side, the electrolytic solution should be attached to an extra portion as compared with the case where a part of the difficult-to-cut material is immersed in the electrolytic solution. Therefore, it is possible to prevent the surface other than the outer peripheral edge portion from being roughened.

Further, since the polishing member is arranged at the position on the lower side of the main electrode, the difficult-to-cut material can be electrolytically polished and mechanically polished at the same time. Therefore, even if the surface of the difficult-to-cut material has deep scratches. , Can be reliably removed.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part for explaining a method of beveling a difficult-to-cut material according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts for explaining the principle of electrolytic polishing in a conventional example.

FIG. 3 is a graph showing the relationship between the current and electrolytic strength and the removal amount of the workpiece for explaining the principle of the same electrolytic polishing.

FIG. 4 is a partially cutaway perspective view illustrating a method of beveling a difficult-to-cut material in a conventional example.

FIG. 5 is a side view illustrating a polished state of a silicon wafer polished by a conventional beveling method.

[Explanation of symbols]

 A Wafer B Outer peripheral edge D Electrolyte 1 Polishing device 2 Main electrode 3 Grinding stone 3a Through hole 4 Container 5 Auxiliary electrode 7 Electrolyte supply pipe 8 Power supply

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masanori Tsukahara, 5-3-8 Nishikujo, Konohana-ku, Osaka-shi, Osaka Prefecture (72) Hitachi Shipbuilding Co., Ltd. (72) Akio Komura 5--9, Nishikujo, Konohana-ku, Osaka No. 28 in Hitachi Shipbuilding Co., Ltd.

Claims (1)

[Claims] 1. A main electrode is made to face an outer peripheral edge of a disc-shaped difficult-to-cut material which is rotatably supported, and an electrolytic solution filled in a container is supplied to the main electrode and the inside of the container. By applying a voltage between the auxiliary electrode that is in contact with the electrolyte,
When the outer peripheral edge of the difficult-to-cut material is polished by the discharge heat generated at the tip of the main electrode, the polishing member is integrally arranged at the lower side position of the main electrode, and the polishing member side has the above-mentioned structure. A method of beveling a difficult-to-cut material, which comprises supplying an electrolytic solution in a container.