Abrading – Flexible-member tool – per se
Reexamination Certificate
1999-04-02
2001-10-02
Banks, Derris H. (Department: 3723)
Abrading
Flexible-member tool, per se
C451S539000, C451S490000
Reexamination Certificate
active
06296557
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods and devices for releasably coupling a polishing pad to a support surface of a planarizing machine used in mechanical and/or chemical-mechanical planarization of microelectronic-device substrate assemblies.
BACKGROUND OF THE INVENTION
Mechanical and chemical-mechanical planarizing processes (collectively “CMP”) are used in the manufacturing of electronic devices for forming a flat surface on semiconductor wafers, field emission displays and many other microelectronic-device substrate assemblies. CMP processes generally remove material from a substrate assembly to create a highly planar surface at a precise elevation in the layers of material on the substrate assembly.
FIG. 1
is a schematic isometric view of a web-format planarizing machine
100
that has a support table
102
with a support surface
110
at a workstation defining a planarizing zone. The support surface
110
is generally a rigid panel or plate attached to the table
102
to provide a flat, solid surface to which a portion of a web-format planarizing pad
140
is supported during planarization. The planarizing machine
100
also has a plurality of rollers to guide, position, and hold the web-format pad
140
over the support surface
110
. The rollers generally include a supply roller
120
, first and second idler rollers
121
a
and
121
b
, first and second guide rollers
122
a
and
122
b
, and a take-up roller
123
. As explained below, a motor (not shown) drives the take-up roller
123
, and possibly the supply roller
120
, to advance the pad
140
across the support surface
110
along a travel axis T—T. The first idler roller
12
la and the first guide roller
122
a
also stretch the pad
140
over the support surface
110
to hold the pad
140
during operation.
The planarizing machine
100
also has a carrier assembly
130
to translate a substrate assembly
12
across the pad
140
. In one embodiment, the carrier assembly
130
has a substrate assembly holder
132
to pick up, hold and release the substrate assembly
12
at appropriate stages of the planarizing process. The carrier assembly
130
also has a support gantry
134
and a drive assembly
135
that can move along the gantry
134
. The drive assembly
135
has an actuator
136
, a drive shaft
137
coupled to the actuator
136
, and an arm
138
projecting from the drive shaft
137
. The aim
138
carries the substrate assembly holder
132
via another shaft
139
. The actuator
136
orbits the substrate assembly holder
132
about an axis B—B to move the substrate assembly
12
across the pad
140
.
The polishing pad
140
may be a non-abrasive polymeric web (e.g., a polyurethane sheet), or it may be a fixed abrasive polishing pad having abrasive particles fixedly dispersed in a suspension medium. During planarization of the substrate assembly
12
, a planarizing fluid
144
flows from a plurality of nozzles
145
. The planarizing fluid
144
may be a conventional CMP slurry with abrasive particles and chemicals that etch and/or oxidize the substrate assembly
12
, or the planarizing fluid
144
may be a nonabrasive planarizing( solution without abrasive particles. In most CMP applications, abrasive slurries are used on non-abrasive polishing pads, and non-abrasive planarizing solutions are used on fixed abrasive polishing pads.
The planarizing machine
100
incrementally moves the pad
140
across the support surface
110
either during or between planarizing cycles to change the particular portion of the polishing pad
140
in the planarizing zone. For example, the supply and take-up rollers
120
and
123
can drive the polishing pad
140
such that a point P moves incrementally across the support surface
110
to a number of intermediate locations I
1
, I
2
, etc. Alternatively, the rollers
120
and
123
may drive the polishing pad
140
such that the point P moves all the way across the support surface
110
to completely remove a used portion of the pad
140
from the planarizing zone on the support surface
110
. The rollers may also continuously drive the polishing pad at a slow rate such that the point P moves continuously across the support surface
110
. Thus, the polishing pad
140
should be free to move axially over the length of the support surface
110
along the travel axis T—T.
CMP processes should consistently and accurately produce a uniform, planar surface on the substrate assembly to enable circuit and device patterns to be formed with photolithography techniques. As the density of integrated circuits increases, it is often necessary to accurately focus the critical dimensions of the photo-patterns to within a tolerance of approximately 0.1 &mgr;m. Focusing photo-patterns to such small tolerances, however, is difficult when the planarized surface of the wafer is not uniformly planar. Thus, CMP processes should create a highly uniform, planar surface to be effective.
One processing concern associated with web-format planarizing machines is that the polishing pad
140
may move transversely to the travel axis T—T during a planarizing cycle of the substrate assembly
12
. For example, although the first idler roller
121
a
and the first guide roller
122
a
stretch the pad
140
over the support surface
110
, the orbital motion of the substrate assembly
12
and the friction between the substrate assembly
12
and the pad
140
may cause the pad
140
to move transverse to the travel axis T—T. Such transverse movement of the polishing pad
140
can produce inconsistent planarizing results because it stretches and/or damages the polishing pad
140
. The transverse movement of the polishing pad
140
may also allow the slurry to seep underneath the polishing pad
140
, which causes uneven wear of the pad
140
and contamination of the planarizing machine
200
. Moreover, if the pad wears unevenly, the topography of the pad may cause vibrations in the CMP machine that further affect the planarity of the finished surface and the consistency of the CMP process.
SUMMARY OF THE INVENTION
The present invention is directed toward methods and apparatuses for releasably securing a polishing pad to a support surface in mechanical and/or chemical-mechanical planarization of microelectronic-device substrate assemblies. In one embodiment of the invention, a polishing pad for planarizing microelectronic-device substrate assemblies has a first surface configured to engage a substrate assembly and a second surface configured to releasably engage the support surface of a planarizing machine. The second surface of the polishing pad, for example, can have an interlocking element configured to engage a corresponding retaining member on the support surface to inhibit relative movement between the polishing pad and the support surface. In a particular embodiment of the invention, the interlocking element and the retaining member are configured so that the pad can move over the support surface along a travel path or axis, but relative movement between the pad and the support surface transverse to the travel axis is at least substantially inhibited.
The interlocking element and the retaining member can have several embodiments. For example, the interlocking element can be an elongated tongue on the second surface of the polishing pad extending along the travel axis and the retaining member can be an elongated groove in the support surface. The interlocking element and the retaining member can alternatively be another type of a protuberance and a reciprocal depression combination, such as elongated ridges or teeth extending along the travel axis. In the above embodiments, the support surface can further include one or more apertures coupled with a fluid pump to draw together or blow apart the interlocking elements and the retaining members.
REFERENCES:
patent: 3695131 (1972-10-01), Zimmermann
patent: 3918220 (1975-11-01), Jury et al.
patent: 4617767 (1986-10-01), Ali
patent: 5201785 (1993-04-01), Nagano
patent: 5876268 (1999-03-01), Lamphere et al.
patent: 5958794 (1999-09-01), Bruxv
Banks Derris H.
Dorsey & Whitney LLP
Micro)n Technology, Inc.
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