Abrading – Precision device or process - or with condition responsive... – With indicating
Reexamination Certificate
1999-03-26
2001-04-17
Bray, W. Donald (Department: 3725)
Abrading
Precision device or process - or with condition responsive...
With indicating
C451S024000, C451S398000, C451S288000
Reexamination Certificate
active
06217411
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus, in particular, a semiconductor wafer polishing apparatus.
A typical semiconductor wafer polishing apparatus includes, as shown in
FIG. 6
, a polishing pad
3
provided on an upper surface of a turn table (not shown), a wafer carrier
2
for carrying a wafer
1
to be polished and a shaft-like support
4
connected to the carrier
2
at the lower end thereof through a universal joint
5
. The support
4
is adapted to be drivingly rotated around its axis by means of a motor (not shown) connected to the support and the universal joint
5
is adapted to transmit a rotational torque from the support to the carrier
2
to rotate the carrier about its axis while allowing the carrier
2
to pivot about the universal joint
5
.
In operation, the turn table with the polishing pad
3
is drivingly rotated and the support
4
is positioned so that the wafer
1
carried by carrier
2
is brought into contact with a flat polishing surface
3
′ of the polishing pad
3
with a degree of pressure F, with the support
4
being simultaneously drivingly rotated, whereby the surface of the wafer
1
contacting the polishing surface of the polishing pad is polished.
Accordingly, a friction force f between the polishing pad and the wafer causes an angular moment M which acts on the carrier
2
with the wafer
1
about the universal joint
5
or the connecting point between the carrier
2
and the support
4
, whereby the carrier with the wafer tilts about the universal joint
5
thereby causing an unevenness or gradient in a pressure generated between the contacting surfaces of the wafer and the polishing pad. This causes a deterioration in quality of the polishing operation.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a polishing apparatus which solves the problem discussed above.
In accordance with the present invention, a polishing apparatus comprises a polishing member having a polishing surface, a carrier for carrying an article to be polished, a support for supporting the carrier in such a manner that the article carried by the carrier Is engaged with the polishing surface, the carrier and the polishing pad being adapted to be moved relative to each other in such a manner that the article carried by the carrier is moved relative to and on the polishing surface of the polishing pad, a sensor device for sensing a friction force generated between the article and the polishing surface and imposed on the carrier due to the relative movement of the article on the polishing surface, a pressing device operatively associated with the carrier to impose a counter angular moment against a angular moment on the carrier by applying a pressure to at least one point on the carrier towards the polishing surface to generate the counter angular moment, and a control unit for determining a magnitude of the pressure applied to the above-noted at least one point on the carrier on the basis of the friction force sensed by the sensor device so that the angular moment is compensated by the counter angular moment.
The above features and advantages of the present invention will be become apparent from the following description and the appended claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5738568 (1998-04-01), Jurjevic
patent: 5743784 (1998-04-01), Birang et al.
patent: 5916009 (1999-06-01), Izumi et al.
patent: 5938884 (1999-08-01), Hoshizaki et al.
patent: 5975998 (1999-11-01), Olmstead
patent: 6019868 (2000-02-01), Kimura et al.
patent: 6027401 (2000-02-01), Saito et al.
Hirokawa Kazuto
Hiyama Hirokuni
Matsuo Hisanori
Wada Yutaka
Bray W. Donald
Ebara Corporation
Wenderoth , Lind & Ponack, L.L.P.
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