Abrasive tool making process – material – or composition – With synthetic resin
Reexamination Certificate
2000-08-28
2004-05-18
Marcheschi, Michael (Department: 1755)
Abrasive tool making process, material, or composition
With synthetic resin
C051S307000, C051S308000, C051S309000, C051S293000, C051S295000
Reexamination Certificate
active
06736869
ABSTRACT:
TECHNICAL FIELD
This invention relates to planarizing pads and methods and apparatuses for forming planarizing pads for planarizing microelectronic substrates.
BACKGROUND OF THE INVENTION
Mechanical and chemical-mechanical planarization 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
schematically illustrates an existing web-format planarizing machine
10
for planarizing a substrate
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 planarizing pad
40
is positioned. The top-panel
16
is generally a rigid plate to provide a flat, solid surface to which a particular section of the planarizing pad
40
may be secured during planarization.
The planarizing machine
10
also has a plurality of rollers to guide, position and hold the planarizing pad
40
over the top-panel
16
. The rollers include a supply roller
20
, idler rollers
21
, guide rollers
22
, and a take-up roller
23
. The supply roller
20
carries an unused or pre-operative portion of the planarizing pad
40
, and the take-up roller
23
carries a used or post-operative portion of the planarizing pad
40
. Additionally, the left idler roller
21
and the upper guide roller
22
stretch the planarizing pad
40
over the top-panel
16
to hold the planarizing pad
40
stationary during operation. A motor (not shown) drives at least one of the supply roller
20
and the take-up roller
23
to sequentially advance the planarizing pad
40
across the top-panel
16
. Accordingly, clean pre-operative sections of the planarizing pad
40
may be quickly substituted for used sections to provide a consistent surface for planarizing and/or cleaning the substrate
12
.
The web-format planarizing machine
10
also has a carrier assembly
30
that controls and protects the substrate
12
during planarization. The carrier assembly
30
generally has a substrate holder
32
to pick up, hold and release the substrate
12
at appropriate stages of the planarizing process. Several nozzles
33
attached to the substrate holder
32
dispense a planarizing solution
44
onto a planarizing surface
42
of the planarizing pad
40
. The carrier assembly
30
also generally has a support gantry
34
carrying a drive assembly
35
that can translate along the gantry
34
. The drive assembly
35
generally has an 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 substrate holder
32
via a terminal shaft
39
such that the drive assembly
35
orbits the substrate holder
32
about an axis B—B (as indicated by arrow “R
1
”). The terminal shaft
39
may also rotate the substrate holder
32
about its central axis C—C (as indicated by arrow “R
2
”).
The planarizing pad
40
and the planarizing solution
44
defme a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the substrate
12
. The planarizing pad
40
used in the web-format planarizing machine
10
is typically a fixed-abrasive planarizing pad in which abrasive particles are fixedly bonded to a suspension material. In fixed-abrasive applications, the planarizing solution is a “clean solution” without abrasive particles. In other applications, the planarizing pad
40
may be a non-abrasive pad without abrasive particles. The planarizing solutions
44
used with the non-abrasive planarizing pads are typically CMP slurries with abrasive particles and chemicals.
To planarize the substrate
12
with the planarizing machine
10
, the carrier assembly
30
presses the substrate
12
against the planarizing surface
42
of the planarizing pad
40
in the presence of the planarizing solution
44
. The drive assembly
35
then orbits the substrate holder
32
about the axis B—B, and optionally rotates the substrate holder
32
about the axis C—C, to translate the substrate
12
across the planarizing surface
42
. As a result, the abrasive particles and/or the chemicals in the planarizing medium remove material from the surface of the substrate
12
.
The CMP processes should consistently and accurately produce a uniformly planar surface on the substrate
12
to enable precise fabrication of circuits and photopatterns. During the fabrication of transistors, contacts, interconnects and other features, many substrates and/or substrate assemblies develop large “step heights” that create a highly topographic surface across the substrate assembly. Yet, as the density of integrated circuits increases, it is necessary to have a planar substrate surface at several intermediate stages during the fabrication of devices on a substrate assembly because non-uniform substrate surfaces significantly increase the difficulty of forming sub-micron features. For example, it is difficult to accurately focus photo patterns to within tolerances approaching 0.1 micron on non-uniform substrate surfaces because sub-micron photolithographic equipment generally has a very limited depth of field. Thus, CMP processes are often used to transform a topographical substrate surface into a highly uniform, planar substrate surface.
One conventional approach for improving the uniformity of the microelectronic substrate
12
is to engage the microelectronic substrate
12
with a planarizing pad
40
having a textured planarizing surface
42
. For example, as shown in
FIG. 2
, the planarizing pad
40
can include spaced-apart texture elements
41
. The texture elements
41
can improve the planarizafion of the microelectronic substrate
12
(
FIG. 1
) by retaining the planarizing liquid
44
(
FIG. 1
) in the interstices between the texture elements. Accordingly, the texture elements
41
increase the amount of planarizing liquid in contact with the microelectronic substrate
12
and increase the planarizing rate and surface uniformity of the microelectronic substrate
12
.
One conventional method for forming the texture elements
41
is to engage a mold
50
with the planarizing pad
40
while the planarizing pad
40
is in a semi-solid or plastic state. For example, the mold
50
can include columnar apertures
51
that produce corresponding columnar texture elements
41
in the planarizing pad
40
. One drawback with the foregoing fabrication method is that the mold
50
may deform the texture elements
41
as the mold
50
is withdrawn from the planarizing pad
40
. For example, the planarizing pad material may adhere to the mold
50
or portions of the mold
50
such that the upper surfaces of the texture elements
41
develop sharp edges or other asperities
43
. The asperities
43
can scratch or otherwise damage the microelectronic substrate
12
during planarization.
SUMMARY OF THE INVENTION
The present invention is directed toward methods and apparatuses for forming planarizing pads for planarizing microelectronic substrates. A method in accordance with one aspect of the invention includes separating a planarizing pad material into discrete elements and disposing the discrete elements on a support material. The discrete elements are disposed on the support material so that portions of the discrete elements are spaced apart from each other and project from the support material. The discrete elements are configured to engage the microelectronic substrate and to remove material from the microelectronic substrate when the microelectronic substrate contacts the discrete elements and at least one of the planarizing pad and the microelectronic substrate is moved relative to the other.
In one aspect of the invention, at least a portion of the planarizing pad material is in a liquid phase and separating the planarizing pad material includes forming discr
Agarwal Vishnu K.
Chopra Dinesh
Marcheschi Michael
Micro)n Technology, Inc.
Perkins Coie LLP
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