Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
1999-05-21
2001-05-08
Hail, III, Joseph J. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C451S108000
Reexamination Certificate
active
06227945
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for mirror-polishing, for example, the outer periphery of a disc-shaped semiconductor wafer and the chamfered portion of the outer periphery of the wafer.
2. Description of the Related Art
Disc-shaped semiconductor silicon wafers (hereinafter, referred to as semiconductor wafers) having a relatively large diameter are subjected to mirror-polishing not only on the surface of them but also on the outer periphery thereof and on the chamfered portion formed to the outer periphery in a manufacturing process, and the reduction of the yield of the wafers due to powder dust deposited on them is prevented thereby.
The outer periphery of wafers has been mirror-polished by the method disclosed in, for example, Japanese Unexamined Patent Publication No. 64-71656 or Japanese Unexamined Patent Publication No. 64-71657.
That is, the chamfered portion of the outer periphery of a semiconductor wafer is mirror-polished in such a manner that the semiconductor wafer is held with a suction chuck or the like and the chamfered portion is pressed against the outer periphery of a polishing drum having an abrasive cloth wound around the surface thereof while rotating the polishing drum at a prescribed speed.
In the above conventional mirror-polishing method, however, there is a problem that a long time is required for the mirror polishing and working efficiency is low because the chamfered portion of the outer periphery of the semiconductor wafer is in line-contact with the abrasive cloth wound around the polishing drum and it is polished under conditions wherein the contact region of the wafer is very narrow.
Further, when the outer periphery of the semiconductor wafer has chamfered portions on both the sides thereof, it is impossible to polish both sides at once. Therefore, after one of the chamfered portions is polished, the semiconductor wafer must be removed from the suction chuck and the other of the chamfered portions must be polished after the semiconductor wafer is reversed and rechucked, which is a troublesome job and by which productivity is lowered.
An object of the present invention, which was made to solve these problems, is to provide a polishing method and apparatus for polishing the outer periphery of a disc-shaped workpiece in order to increase polishing efficiency and to greatly improve productivity by increasing the region where the outer periphery of the workpiece is in contact with an abrasive cloth as well as by continuously and easily polishing a chamfered portion, even if the workpiece has the chamfered portion on both the sides of it.
SUMMARY OF THE INVENTION
To achieve the above object, a polishing method of the present invention is characterized in that a disc-shaped workpiece supported by a support shaft is accommodated in a cylindrical polishing drum having an abrasive material disposed to the inner periphery of it and the outer periphery of the workpiece is polished by relatively rotating the polishing drum and the workpiece while causing at least a part of the outer periphery of the workpiece to come into contact with the abrasive material.
In the above method, it is preferable that the outer periphery of the workpiece is polished while relatively moving the polishing drum and the workpiece in the axial direction of the polishing drum.
In the above method, it is preferable that any one of the axial line of the polishing drum and the workpiece support shaft is tilted with respect to the other of them a prescribed angle so that the outer periphery of the workpiece alternately comes into contact with both the inner peripheries of the abrasive material which confront each other at approximately 180°.
In the above method, it is preferable that the outer periphery of the workpiece is polished by alternately tilting any one of the axial line of the polishing drum and the workpiece support shaft with respect to the other of them a prescribed angle.
In the above method, it is preferable that the outer periphery of the workpiece is polished by tilting any one of the axial line of the polishing drum and the workpiece support shaft so that a part of the outer periphery of the workpiece is in plane contact with the abrasive material.
To achieve the above object, a polishing apparatus of the present invention for polishing the outer periphery of a disc-shaped workpiece is characterized by comprising a cylindrical polishing drum having an abrasive material disposed to the inner periphery of it, a workpiece holding member attached to support shaft so that it can be inserted into and removed from the polishing drum; and a drive means for relatively rotating any one of at least the polishing drum and the workpiece holding member.
In the above apparatus, it is preferable to provide a moving means for relatively moving any one of the polishing drum and the support shaft in the axial direction of the polishing drum.
In the above apparatus, it is preferable to provide a second moving means for relatively moving any one of the polishing drum and the support shaft in a direction perpendicular to the axis of the polishing drum.
In the above apparatus, it is preferable to provide a rotating means for relatively horizontally rotating any one of the polishing drum and the support shaft.
In the above apparatus, it is preferable that the abrasive material disposed to the inner periphery of the polishing drum has an inner peripheral shape having a small diameter on both the ends of it and a large diameter at the central portion of it.
In the above apparatus, it is preferable that the abrasive material disposed to the inner periphery of the polishing drum has an inner periphery formed to a waveform.
According to the polishing method and apparatus of the present invention, the outer periphery of the workpiece is caused to come into contact with the abrasive material in the cylindrical polishing drum, and the polishing drum and the workpiece are relatively rotated, whereby the region where the outer periphery of the workpiece is in contact with the abrasive cloth is increased and the polishing effect can be increased.
REFERENCES:
patent: 5404678 (1995-04-01), Hasegawa et al.
patent: 5547415 (1996-08-01), Hasegawa et al.
patent: 64-71656 (1989-03-01), None
patent: 64-71657 (1989-03-01), None
patent: 740214 (1995-02-01), None
patent: 7164291 (1995-06-01), None
Hirabayashi Toshihiko
Takahashi Shuzo
Hail III Joseph J.
Hayes, Soloway, Hennessey Grossman & Hage, P.C.
Kyokuei Kenmakako Kabushiki Kaisha
Nguyen George
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