Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
2000-11-02
2002-06-11
Utech, Benjamin L. (Department: 1765)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
Reexamination Certificate
active
06402884
ABSTRACT:
TECHNICAL FIELD
The present invention relates to planarizing solutions, planarizing machines and methods for planarizing microelectronic-device substrate assemblies using mechanical and/or chemical-mechanical planarization processes.
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 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
schematically illustrates an existing web-format planarizing machine
10
for planarizing a substrate assembly
12
. The planarizing machine
10
has a support table
14
with a top panel
16
at a workstation where an operative portion (A) of a polishing pad
40
is positioned. The top panel
16
is generally a rigid plate to provide a flat, solid surface to support the operative section of the polishing pad
40
during planarization.
The planarizing machine
10
also has a plurality of rollers to guide, position and hold the polishing pad
40
over the top panel
16
. The rollers include a supply roller
20
, 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
. The supply roller
20
carries an unused or preoperative portion of the polishing pad
40
, and the take-up roller
23
carries a used or post-operative portion of the polishing pad
40
. Additionally, the first idler roller
21
a
and the first guide roller
22
a
stretch the polishing pad
40
over the top panel
16
to hold the polishing pad
40
stationary during operation. A drive motor (not shown) drives at least one of the supply roller
20
and the take-up roller
23
to sequentially advance the polishing pad
40
across the top panel
16
. As such, clean preoperative sections of the polishing pad
40
may be quickly substituted for used sections to provide a consistent surface for planarizing the substrate assembly
12
.
The web-format planarizing machine
10
also has a carrier assembly
30
that controls and protects the substrate assembly
12
during planarization. The carrier assembly
30
generally has a carrier head
31
with a plurality of vacuum holes
32
to pick up and release the substrate assembly
12
at appropriate stages of the planarizing cycle. A plurality of nozzles
41
attached to the carrier head
31
dispense a planarizing solution
42
onto a planarizing surface
43
of the polishing pad
40
. The carrier assembly
30
also generally has a support gantry
34
carrying a drive assembly
35
that translates along the gantry
34
. The drive assembly
35
generally has actuator
36
, a drive shaft
37
coupled to the actuator
36
, and an arm
38
projecting from the drive shaft
37
. The arm
38
carries the carrier head
31
via another shaft
39
such that the drive assembly
35
orbits the carrier head
31
about an axis B-B offset from a center point C-C of the substrate assembly
12
.
The polishing pad
40
and the planarizing solution
42
define a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the substrate assembly
12
. The web-format planarizing machine
10
typically uses a fixed-abrasive polishing pad having a plurality of abrasive particles fixedly bonded to a suspension material. The planarizing solutions
42
used with fixed-abrasive pads are generally “clean solutions” without abrasive particles because the abrasive particles in conventional abrasive CMP slurries may ruin the abrasive surface of fixed-abrasive pads. In other applications, the polishing pad
40
may be a nonabrasive pad composed of a polymeric material (e.g., polyurethane), a resin, or other suitable materials without abrasive particles. The plananizing solutions
42
used with nonabrasive polishing pads are typically “abrasive” CMP slurries with abrasive particles.
To planarize the substrate assembly
12
with the planarizing machine
10
, the carrier assembly
30
presses the substrate assembly
12
against the planarizing surface
43
of the polishing pad
40
in the presence of the planarizing solution
42
. The drive assembly
35
then orbits the carrier head
31
about the offset axis B-B to translate the substrate assembly
12
across the planarizing surface
43
. As a result, the abrasive particles and/or the chemicals in the planarizing medium remove material from the surface of the substrate assembly
12
.
CMP processes should consistently and accurately produce a uniformly planar surface on the substrate assembly
12
to enable precise fabrication of circuits and photo-patterns. During the fabrication of transistors, contacts, interconnects and other components, many substrate assemblies develop large “step heights” that create a “topographical” surface across the substrate assembly
12
. For the purposes of the present application, a “topographical” surface is a non-planar surface having high and low regions. To enable the fabrication of integrated circuits with high densities of components, it is necessary to produce a highly planar surface at several stages of processing the substrate assembly
12
because even slightly topographical surfaces significantly increase the difficulty of forming submicron features. For example, it is difficult to accurately focus photo-patterns to within tolerances of 0.1 &mgr;m on topographical surfaces because submicron photolithographic equipment generally has a very limited depth of field. Thus, CMP processes are often used to transform a topographical surface into a highly uniform, planar surface.
In the competitive semiconductor industry, it is also highly desirable to produce such a uniformly planar surface at a desired endpoint on a substrate assembly. For example, when a conductive layer on the substrate assembly
12
is under-planarized in the formation of contacts or interconnects, many of these components may not be electrically isolated from one another because undesirable portions of the conductive layer may remain on the substrate assembly
12
. Additionally, when a substrate assembly
12
is over-planarized, components below the desired endpoint may be damaged or completely destroyed. Thus, to provide a high yield of operable microelectronic devices, CMP processing should remove material until the desired endpoint is reached.
To accurately create highly planar substrate surfaces at the desired endpoint, many CMP applications should initially remove material from high regions on topographical surfaces faster than low regions to change the topographical surface to a planar “blanket” surface. After creating a blanket surface on the substrate assembly, CMP applications should remove material from the blanket surface as quickly as possible without adversely affecting its planarity. The CMP processes should then stop removing material at the desired endpoint on the substrate assembly.
One problem with existing CMP techniques, however, is that it is difficult to selectively remove material from high regions on topographical surfaces without also removing significant amounts of material from low regions. It is also difficult to quickly remove material from a blanket substrate surface. For example, many existing CMP techniques that can selectively remove material from high regions on a topographical substrate surface are limited because they have very low polishing rates of the blanket surface. Such topographically selective CMP techniques are thus ineffective at expediently removing material from the blanket surface. Conversely, existing CMP techniques that have high polishing rates of blanket surfaces do not remove high regions on topographical surfaces without also removing material from low regions. Thus, existing CMP techniques generally do not provide both highly selective planarization of high regions on topographical
Meikle Scott G.
Robinson Karl M.
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