Abrading – Machine – Rotary tool
Reexamination Certificate
1997-04-25
2001-05-08
Morgan, Eileen P. (Department: 3723)
Abrading
Machine
Rotary tool
C451S288000, C451S443000, C451S451000, C451S287000
Reexamination Certificate
active
06227954
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polishing apparatus for polishing a workpiece such as a semiconductor wafer to a flat mirror finish, and more particularly to a polishing apparatus having an easy maintenance characteristic.
2. Description of the Related Art
Recent rapid progress in semiconductor device integration demands smaller and smaller wiring patterns or interconnections and also narrower spaces between interconnections which connect active areas. One of the processes available for forming such interconnections is photolithography. Though the photolithographic process can form interconnections that are at most 0.5 &mgr;m wide, it requires that surfaces on which pattern images are to be focused by a stepper be as flat as possible because the depth of focus of the optical system is relatively small.
It is therefore necessary to make the surfaces of semiconductor wafers flat for photolithography. One customary way of flattening the surfaces of semiconductor wafers is to polish them with a polishing apparatus, and such a process is called Chemical Mechanical polishing.
FIG. 7
shows one conventional polishing apparatus having a polishing section
100
for polishing semiconductor wafers. The polishing section
100
comprises a turntable
110
having a polishing surface
111
and rotatable about its own axis at a predetermined speed, a top ring
120
for holding a semiconductor wafer to rotate the semiconductor wafer at a predetermined speed and pressing the semiconductor wafer against the polishing surface
111
of the turntable
110
for thereby polishing a surface of the semiconductor wafer, and a dressing tool
130
for dressing the polishing surface
111
to regenerate the polishing surface in contact therewith. The turntable
110
, the top ring
120
, and the dressing tool
130
are housed in a single chamber
101
.
The polishing apparatus also has a cleaning section
140
for conveying the semiconductor wafers and cleaning the semiconductor wafers. The cleaning section
140
comprises two workpiece conveying robots
151
,
153
for taking a semiconductor wafer out of a cassette and delivering the semiconductor wafer to the polishing section
100
, primary and secondary cleaning devices
161
,
163
for cleaning the semiconductor wafer which has been polished, a drying device
170
for drying the semiconductor wafer which has been cleaned, and two workpiece reversing devices
181
,
183
for reversing the semiconductor wafer upside down. The workpiece conveying robots
151
,
153
, the primary and secondary cleaning devices
161
,
163
, the drying device
170
, and the workpiece reversing devices
181
,
183
are housed in a single chamber
141
.
Certain parts of the top ring
120
, a polishing cloth which provides the polishing surface
111
of the turntable
110
, and a dressing element such as a dresser brush or a diamond grain layer on the dressing tool
130
are expendable articles or parts that should be replaced with new ones periodically by maintenance operations.
The cleaning devices
161
,
163
also have expendable articles including cleaning brushes and sponge elements which are also required to be replaced with new ones periodically by maintenance operations.
The above maintenance operations are not and do not signify service repair activities for repairing the polishing section
100
and the cleaning section
140
in the event of malfunctions or failures, but periodical replacement routines for replacing expendable articles or parts.
Heretofore, the maintenance operations or activities which involve parts replacement have been carried out at three different side faces of the apparatus, i.e., a side face “a” for maintenance such as replacement of the parts of the top ring
120
, a side face “b” for maintenance such as replacement of the polishing cloth constituting the polishing surface
111
, and a side face “c” for maintenance such as replacement of the dresser brush of the dressing tool
130
and the cleaning brushes of the cleaning devices
161
,
163
.
Because of these three side faces “a”, “b” and “c” involved, it has been necessary to provide respective empty spaces in front of the side faces “a”, “b” and “c” to allow approach and access to the side faces “a”, “b” and “c” for maintenance such as the replacement of parts. Consequently, any one of these side faces “a”, “b” and “c” cannot be positioned closely to other hindering objects such as walls or pillars, with the result that a large installation space has been required for the installation of the polishing apparatus.
When the polishing apparatus is to be maintained or serviced successively at the side faces “a”, “b” and “c”, the maintenance operator has to move from one side face to another while carrying tools and parts. Therefore, maintenance of the polishing apparatus has been troublesome and time-consuming.
FIG. 8
is a perspective view showing an outer appearance of the conventional polishing apparatus shown in FIG.
7
. As shown in
FIG. 8
, the polishing section
100
and the cleaning section
140
are housed in respective chambers in the form of rectangular parallelepipeds.
The polishing section
100
and the cleaning section
140
have a number of pipes
171
,
181
extending from side walls of the chambers for supplying liquid to and discharging liquid from the various units and machines in the polishing section
100
and the cleaning section
140
. The pipes
171
,
181
extend vertically through a floor
180
into a machinery room (not shown) below the floor
180
, and are connected to various devices in the machinery room.
Heretofore, the pipes
171
,
181
projecting out of the chambers are randomly located, and cause various problems described below.
Since the pipes
171
,
181
project from the side walls of the chambers, they present obstacles when the polishing section
100
and the cleaning section
140
are maintained, or transported for installation thereof. When the pipes
171
,
181
are damaged or broken by collision with operators or other objects, they give rise to safety problems.
The operation of installation of the polishing apparatus on the floor
180
is troublesome and time-consuming because the floor
180
has to be drilled to make holes for insertion of the pipes
171
,
181
.
The pipes
171
,
181
project from the side walls of the chambers into passages around the chambers and tend to obstruct operators walking along the passages. Therefore, the pipes
171
,
181
cause the polishing apparatus to take up a greater installation space than would be required by their physical size. In addition, the pipes
171
,
181
are not sightly to external view.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a polishing apparatus which allows a maintenance operator to easily perform maintenance activities such as replacement of various expendable articles or parts, and which can be installed in a relatively small installation space.
Another object of the present invention is to provide a polishing apparatus which can be easily maintained, transported and installed, does not obstruct operators walking along passages therearound, and is sightly to external view.
According to one aspect of the present invention, there is provided a polishing apparatus for polishing a surface of a workpiece comprising: a turntable having a polishing surface; a top ring for holding a workpiece and pressing the workpiece against the polishing surface of the turntable to polish the workpiece, the top ring being movable to a first maintenance position therefor; and a dressing tool for dressing the polishing surface of the turntable, the dressing tool being movable to a second maintenance position therefor. The top ring, the polishing surface of the turntable, and the dressing tool are housed in a first chamber having a plurality of side faces, and the polishing surface, the first maintenance position and the second maintenance position are positioned closely to one of the side faces. The one of the side
Sakurai Kunihiko
Togawa Tetsuji
Yajima Hiromi
Yamaguchi Kuniaki
Ebara Corporation
Morgan Eileen P.
Wenderoth , Lind & Ponack, L.L.P.
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