Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2000-07-21
2001-07-31
Hail, III, Joseph J. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C451S036000, C451S063000, C451S160000
Reexamination Certificate
active
06267646
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a polishing machine and a polishing method of polishing work pieces such as semiconductor device wafers, or optical parts, functional parts, mechanical parts, etc. that require parallelism and flatness, and particularly to enhancement of the parallelism and flatness of the work piece realized by simultaneously polishing both front and back surfaces of each work piece, and miniaturization of the machine.
As a polishing machine which polishes both surfaces of a disc-like work piece such as a semiconductor device wafer, a batch-type polishing machine
10
for loading a plurality of wafers W at one time as shown in
FIG. 4
is well known. In the polishing machine
10
, an upper surface plate
11
and a lower surface plate
12
are provided to face one another and a plurality of wafers W supported by internal gears
13
are loaded between the upper surface plate
11
and the lower surface plate
12
. The internal gears
13
revolves while rotating around a sun gear
14
provided at the center of the machine. With this structure, both surfaces of each wafer W are uniformly polished by polishing cloths
11
a
and
12
a
provided respectively on the upper surface plate
11
and the lower surface plate
12
.
The above-described conventional batch-type polishing machine
10
has the following problem. A plurality of wafers W are processed simultaneously, and if the thicknesses of the wafers W before polished are not uniform, the upper surface plate
11
or the lower surface plate
12
is inclined, which causes poor accuracy in the parallelism or flatness after the polishing.
Further, it is difficult to uniformly adjust the thicknesses of large wafers W such as Si wafers whose diameter ranges 8 to 12 inches, before polishing.
On the other hand, as such a polishing machine
10
is structurally in a large scale, the upper surface plate
11
and the lower surface plate
12
are larger as the wafers W are larger, which makes high accuracy flattening and management of the surface plates that influence the accuracy in polishing difficult. At the same time, the required installation area of the polishing machine
10
is increased, and installing it in a limited space such as a clean room and the like is limited.
BRIEF SUMMARY OF THE INVENTION
The present invention aims at keeping the parallelism and flatness at high accuracy even when both surfaces of a work piece such as a semiconductor device wafer and the like having a large diameter are polished simultaneously.
The present invention comprises a support unit for horizontally supporting a work piece at an outer peripheral edge thereof, to be freely rotatable with a central axis thereof serving as a center of the rotation; a rotation driving unit for driving rotation of the work piece with the central axis thereof serving as a center of the rotation; a polishing plate provided to be opposite to a surface of the work piece and reciprocate along a direction of a diameter of the work piece, and pressed onto the surface of the work piece at a predetermined force; and polishing cloth provided between the polishing plate and the surface of the work piece.
In the present invention, an outer peripheral edge of a work piece is supported, the work piece is rotated with its central axis serving as the center of rotation, and polishing cloth is reciprocated along the direction of the diameter of the work piece. Thus, the shape of polishing plates formed at high accuracy can be transferred onto the work piece. Therefore, even when a work piece having a large diameter is polished, the parallelism and flatness can be kept at high accuracy. On the other hand, as work pieces can be polished one by one, the machine can be miniaturized.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 4588473 (1986-05-01), Hisatomi et al.
patent: 4821466 (1989-04-01), Kato et al.
patent: 5419735 (1995-05-01), Imahashi et al.
patent: 5575706 (1996-11-01), Tsai et al.
patent: 5624300 (1997-04-01), Kishii et al.
patent: 360186368 (1985-09-01), None
patent: 363127872 (1988-05-01), None
Hail III Joseph J.
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ojini Anthony
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