Abrading – Tool support for flexible-member tool
Reexamination Certificate
2001-02-27
2001-12-18
Hail, III, Joseph J. (Department: 3723)
Abrading
Tool support for flexible-member tool
C451S041000, C451S059000, C451S288000, C451S296000, C451S299000, C451S303000
Reexamination Certificate
active
06331139
ABSTRACT:
TECHNICAL FIELD
The present invention is directed toward methods and apparatuses for supporting a polishing pad relative to a microelectronic substrate during mechanical and/or chemical-mechanical planarization.
BACKGROUND OF THE INVENTION
Mechanical and chemical-mechanical planarizing processes (collectively “CMP”) are used in the manufacturing of microelectronic devices for forming a flat surface on semiconductor wafers, field emission displays, and many other microelectronic-device substrates and substrate assemblies.
FIG. 1
is a partially schematic isometric view of a conventional web-format planarizing machine
10
that has a platen
20
. A sub-pad
50
is attached to the platen
20
to provide a flat, solid workstation for supporting a portion of a web-format planarizing pad
40
in a planarizing zone “A” during planarization. The planarizing machine
10
also has a pad-advancing mechanism, including a plurality of rollers, to guide, position, and hold the web-format pad
40
over the sub-pad
50
. The pad-advancing mechanism generally includes a supply roller
24
, first and second idler rollers
21
a
and
21
b
, first and second guide rollers
22
a
and
22
b
, and a take-up roller
23
. As explained below, a motor (not shown) drives the take-up roller
23
to advance the pad
40
across the sub-pad
50
along a travel path T—T. The motor can also drive the supply roller
24
. The first idler roller
21
a
and the first guide roller
22
a
press an operative portion of the pad
40
against the sub-pad
50
to hold the pad
40
stationary during operation.
The planarizing machine
10
also has a carrier assembly
30
to translate a substrate
12
over the polishing pad
40
. In one embodiment, the carrier assembly
30
has a head
31
to pick up, hold and release the substrate
12
at appropriate stages of the planarizing process. The carrier assembly
30
also has a support gantry
34
and a drive assembly
35
that can move along the gantry
34
. The drive assembly
35
has an actuator
36
, a driveshaft
37
coupled to the actuator
36
, and an arm
38
projecting from the driveshaft
37
. The arm
38
carries the head
31
via a terminal shaft
39
. The actuator
36
orbits the head
31
about an axis B—B (as indicated by arrow R
1
) and can rotate the head
31
(as indicated by arrow R
2
) to move the substrate
12
over the polishing pad
40
while a planarizing fluid
43
flows from a plurality of nozzles
45
in the head
31
. The planarizing fluid
43
may be a conventional CMP slurry with abrasive particles and chemicals that etch and/or oxidize the substrate
12
, or the planarizing fluid
43
may be a non-abrasive planarizing solution without abrasive particles. In most CMP applications, conventional CMP slurries are used on conventional polishing pads, and planarizing solutions without abrasive particles are used on fixed-abrasive polishing pads.
In the operation of the planarizing machine
10
, the polishing pad
40
moves across the sub-pad
50
along the travel path T—T either during or between planarizing cycles to change the particular portion of the polishing pad
40
in the planarizing zone A. For example, the supply and take-up rollers
24
,
23
can drive the polishing pad
40
between planarizing cycles such that a point P moves incrementally across the sub-pad
50
to a number of intermediate locations I
1
, I
2
, etc. Alternatively, the rollers
24
,
23
may drive the polishing pad
40
between planarizing cycles such that the point P moves all the way across the sub-pad
50
to completely remove a used portion of the polishing pad
40
from the planarizing zone A. The rollers
24
,
23
may also continuously drive the polishing pad
40
at a slow rate during a planarizing cycle such that the point P moves continuously across the sub-pad
50
during planarization. In any case, the motion of the polishing pad
40
is generally relatively slow when the substrate
12
engages the polishing pad
40
and the relative motion between the substrate
12
and the polishing pad
40
is primarily due to the motion of the head
31
.
One drawback with the apparatus shown in
FIG. 1
is that debris can become caught between the polishing pad
40
and the sub-pad
50
. The debris can cause a local bump or other non-uniformity in the polishing pad
40
which can create a corresponding non-uniformity in the substrate
12
and/or can cause the polishing pad
40
to wear in a non-uniform manner.
A further drawback is that the polishing pad
40
can adhere to the sub-pad
50
during planarization. This adhesive bond must be broken in order to advance the polishing pad
40
. In one conventional method, the idler rollers
21
a
,
21
b
and/or the guide roller
22
a
are actuated to move the polishing pad
40
normal to the upper surface of the sub-pad
50
and break the adhesive bond. However, moving the polishing pad
40
normal to the sub-pad
50
can flex the polishing pad
40
and cause cracks, pits, and other defects to form in the polishing pad
40
, which can in turn create non-uniformities in the planarized surface of the substrate
12
.
Another drawback is that the polishing pad
40
and the sub-pad
50
can wear or abrade as they rub against each other. Accordingly, the polishing pad
40
and the sub-pad
50
may need to be replaced on a frequent basis and/or the polishing pad
40
may develop non-uniformities.
One conventional CMP apparatus which may address some of the foregoing drawbacks includes a polishing pad that forms a continuous loop and that moves a high speed relative to the substrate, in the manner of a belt sander.
FIG. 2
is a partially schematic side elevation view of one such conventional CMP apparatus
10
a
having a continuous polishing pad
40
a
extending around two rollers
25
. The polishing pad
40
a
can be supported by a continuous support band
41
, formed from a flexible material, such as a thin sheet of stainless steel. A pair of platens
20
a
provide additional support for the polishing pad
40
a
at two opposing planarizing stations. Two carriers
30
a
, each aligned with one of the platens
20
a
can each bias a substrate
12
against opposing outwardly-facing portions of a planarizing surface
42
a
of the polishing pad
40
a
. Devices such as the apparatus
10
a
shown in FIG.
2
and having vertically oriented planarizing stations are available from Aplex, Inc. of Sunnyvale, Calif. under the name AVERA™. Generally similar devices having a horizontally-oriented polishing pad
40
a
and a single carrier
30
a
are available from Lam Research Corporation of Fremont, Calif.
During operation, the continuous polishing pad
40
a
moves at a relatively high speed around the rollers
25
while the carriers
30
a
press the substrates
12
against the polishing pad
40
a
. An abrasive slurry is introduced to the planarizing surface
42
a
of the polishing pad
40
a
so that the slurry, in combination with the motion of the polishing pad
40
a
relative to the substrates
12
, mechanically removes material from the substrates
12
.
One drawback with the apparatus
10
a
shown in
FIG. 2
is that the polishing pad
40
a
must move at a high speed to effectively planarize the substrates
12
. The high-speed polishing pad
40
a
can present a safety hazard to personnel positioned nearby, for example, if the polishing pad
40
a
should break, loosen, or otherwise malfunction during operation.
Another drawback is that the combination of the polishing pad
40
a
and the support band
41
may also wear more quickly than other polishing pads because both the planarizing surface
42
a
of the polishing pad
40
a
and a rear surface
44
of the support band
41
rub against relatively hard surfaces (i.e., the polishing pad
40
a
rubs against the substrate
12
and the support band
41
rubs against the platen
20
a
). This drawback can be serious because, once a defect forms in the polishing pad
40
a
, it can affect each subsequent substrate
12
.
Still another drawback is that the interface between the support band
41
and the platen
Robinson Karl M.
Walker Michael A.
Dorsey & Whitney LLP
Hail III Joseph J.
McDonald Shantese
Micro)n Technology, Inc.
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