Abrading – Machine – Endless band tool
Reexamination Certificate
2001-05-07
2002-04-09
Hail, III, Joseph J. (Department: 3723)
Abrading
Machine
Endless band tool
C451S041000, C451S299000, C451S307000, C451S312000, C451S324000, C451S443000
Reexamination Certificate
active
06368197
ABSTRACT:
TECHNICAL FIELD
The present invention is directed toward methods and apparatuses for supporting, cleaning and/or drying a polishing pad used for mechanical and/or chemical-mechanical planarization.
BACKGROUND OF THE INVENTION
Mechanical and chemical-mechanical planarizing processes (collectively “CMP”) are used in the manufacturing process of microelectronic devices to form 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
11
is attached to the platen
20
to provide a flat, solid workstation for supporting a portion of a web-format polishing pad
16
in a planarizing zone “A” during planarization. The polishing pad
16
has a rear surface
19
that engages the sub-pad
11
and a planarizing surface
18
facing opposite the rear surface
19
to planarize a substrate
12
.
The planarizing machine
10
also has a pad-advancing mechanism, including a plurality of rollers, to guide, position and hold the polishing pad
16
over the sub-pad
11
. 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
and the supply roller
24
to advance and retract the polishing pad
16
over the sub-pad
11
along a travel path T—T. The first idler roller
21
a
and the first guide roller
22
a
press an operative portion of the polishing pad
16
against the sub-pad
11
to hold the polishing pad
16
stationary during operation.
The planarizing machine
10
further includes a carrier assembly
30
to translate the substrate
12
over the polishing pad
16
. 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
32
and a drive assembly
33
that can move along the gantry
32
. The drive assembly
33
has an actuator
34
, a drive shaft
35
coupled to the actuator
34
, and an arm
36
projecting from the drive shaft
35
. The arm
36
carries the head
31
via a terminal shaft
37
. The actuator
34
orbits the head
31
about an axis B—B (as indicated by arrow R
1
) and can rotate the head
31
about an axis C—C (as indicated by arrow R
2
) to move the substrate
12
over the polishing pad
16
while a planarizing fluid
17
flows from a plurality of nozzles
38
in the bead
31
. The planarizing fluid
17
may be a conventional CMP slurry with abrasive particles and chemicals that etch and/or oxidize the surface of the substrate
12
, or the planarizing fluid
17
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 carrier assembly
30
presses the substrate
12
against the planarizing surface
18
of the polishing pad
16
as the carrier head
31
moves the substrate
12
over the planarizing surface
18
. The polishing pad
16
moves across the sub-pad
11
along the pad travel path T—T either during or between planarizing cycles to change the particular portion of the polishing pad
16
in the planarizing zone A. For example, the supply and take-up rollers
24
,
23
can drive the polishing pad
16
between planarizing cycles such that a point P moves incrementally across the sub-pad
11
to a number of intermediate locations I
1
, I
2
), etc. Alternatively, the rollers
24
,
23
may drive the polishing pad
16
between planarizing cycles such that the point P moves all the way across the sub-pad
11
toward the take-up roller
23
to completely remove a used or postoperative portion of the polishing pad
16
from the planarizing zone A. The rollers
24
,
23
may also continuously drive the polishing pad
16
at a slow rate during a planarizing cycle such that the point P moves continuously across the sub-pad
11
during planarization.
The planarizing machine
10
can also include a planarizing surface cleaner
40
(shown schematically in
FIG. 1
) positioned between the platen
20
and the take-up roller
23
to clean the post-operative portion of the polishing pad
16
. The planarizing surface cleaner
40
can include a brush
41
having bristles that contact the planarizing surface
18
of the polishing pad
16
and a liquid dispenser
42
positioned proximate to the brush
41
to dispense a cleaning liquid on the planarizing surface
18
. Accordingly, the planarizing surface cleaner
40
can clean the post-operative portion of the polishing pad
16
as it moves off the platen
20
along the travel path T—T. Once the post-operative portion of the polishing pad
16
has been cleaned, it can be translated back onto the platen
20
along the travel path T—T and into the planarizing zone A for another planarizing cycle.
One drawback with the apparatus
10
shown in
FIG. 1
is that the rear surface
19
of the polishing pad
16
can become contaminated with debris (such as liquid and/or particulate matter) during the planarizing process and/or the cleaning process. The debris can become trapped between the polishing pad
16
and the sub-pad
11
, causing a local bump or other non-uniformity to form in the planarizing surface
18
. The non-uniformity in the planarizing surface
18
can create a non-uniformity in the substrate
12
and/or can cause the polishing pad
16
to wear in a non-uniform manner.
A further drawback is that liquid on the rear surface
19
of the polishing pad
16
can form an adhesive bond between the polishing pad
16
and the sub-pad
11
. The adhesive bond can inhibit relative movement between the polishing pad
16
and the sub-pad
11
when the polishing pad
16
moves along the travel path T—T. In one conventional method, the idler rollers
21
a
,
21
b
and/or the guide roller
22
a
move the polishing pad
16
normal to the upper surface of the sub-pad
11
to break the adhesive bond. However, the action of the rollers against the polishing pad
16
may not be effective to separate the polishing pad
16
from the sub-pad
11
. Furthermore, if the polishing pad
16
is dragged over the sub-pad
11
, the frictional contact between the two can abrade particulate matter from the polishing pad
16
and/or the sub-pad
11
, which can cause a bump or other nonuniformity to form in the planarizing surface
18
, as discussed above.
SUMMARY OF THE INVENTION
The present invention is directed toward methods and apparatuses for supporting, cleaning and/or drying a polishing pad used for mechanical and/or chemical planarization of microelectronic substrates and substrate assemblies. In one aspect of the invention, a cleaning head is positioned proximate to a postoperative portion of the polishing pad to remove material from a rear surface of the polishing pad that faces opposite a planarizing surface of the polishing pad. The cleaning head can have a cleaning device operable to remove liquid and/or particulate material from the rear surface. For example, the cleaning device can include a contact element such as an absorbent brush or an impermeable blade positionable to contact the rear surface of the post-operative portion of the polishing pad, an orifice facing toward the rear surface of the polishing pad to provide gas or liquid to the rear surface, and/or a heat source to dry the rear surface of the polishing pad. Alternatively, the cleaning head can include a vessel proximate to the post-operative portion of the polishing pad. The vessel can have an opening configured to receive the post-operative portion and an interior volume in fluid communication with the opening and configured to contain a quantity of cleaning liquid
Dorsey & Whitney LLP
Hail III Joseph J.
McDonald Shantese
LandOfFree
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