Polishing pad for a chemical mechanical polishing process

Details Polishing pad for a chemical mechanical polishing process Polishing pad for a chemical mechanical polishing process

2001-07-26

2003-04-08

Gray, Linda (Department: 1734)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C015S209100, C451S526000, C451S528000, C451S529000, C451S533000, C156S257000, C156S263000, C156S268000, C156S293000

Reexamination Certificate

active

06544373

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of fabricating a composite polishing pad for a chemical mechanical polishing process.
2. Description of the Prior Art
Chemical mechanical polishing (CMP) is a method of polishing materials, such as a semiconductor wafer, to a high degree of planarity and uniformity. The process is used to planarize a semiconductor wafer prior to the fabrication of microelectronic circuitry thereon, and is also used to remove high-elevation features created during the fabrication of the microelectronic circuitry on the surface of the semiconductor wafer.
Please refer to FIG.
1
.
FIG. 1
is of a cross-sectional diagram of a semiconductor wafer
10
. The semiconductor wafer
10
comprises a substrate
12
, a conductive layer
14
positioned on the surface of the substrate
12
and a dielectric layer
16
positioned on the surface of the substrate
12
. The dielectric layer
16
covers the conductive layer
14
. Please refer to FIG.
2
.
FIG. 2
is of a perspective view of a chemical mechanical polishing apparatus
20
. The chemical mechanical polishing apparatus
20
comprises a polishing table
22
, a polishing pad
24
set on the polishing table
22
, a holder
28
for pressing the semiconductor wafer
10
onto the polishing pad
24
, a slurry supply apparatus
30
for supplying a slurry to polish the semiconductor wafer
10
, and a conditioner
32
to control the distribution of the slurry on the polishing pad and to remove polished material that is formed during the polishing process.
Please refer to FIG.
3
and FIG.
4
.
FIG. 3
is a top view of the polishing pad
24
, and
FIG. 4
is a cross-sectional diagram of the polishing pad according to the prior art. The polishing pad
24
comprises three concentric circular grooves
26
. The slurry drops from the slurry supply apparatus
30
to the surface of the polishing pad
24
and flows along the concentric circular grooves
26
so as to distribute the slurry over the surface of the polishing pad.
According to the prior art, the semiconductor wafer
10
is set in the holder
28
before performing the chemical mechanical polishing process. The back surface of the semiconductor wafer
10
is held by the holder
28
and the front surface of the semiconductor wafer
10
is pressed onto the surface of the polishing pad
24
. During the chemical mechanical polishing process, the holder
28
rotates counterclockwise and moves to-and-fro, and the polishing table
22
also rotates counterclockwise. The relative motion of the semiconductor wafer
10
with the polishing pad
24
polishes the front surface of the semiconductor wafer
10
. The surface of the semiconductor wafer
10
becomes globally planar after the chemical mechanical polishing process, as shown in FIG.
5
.
Generally speaking, the polishing pads used in CMP of metal wire comprise hard (for example: IC-1000) and soft (for example: POLITEX) polishing pads. The former provides fast removal rate and great planarization effect, but the scratch problems isoccured. The latter can prevent scratch problems and provide a fine polishing effect and good cleaning performance, but the dishing problem of aluminum wire is induced. Therefore, in the prior CMP hard polishing pad is first used to polish the surface of the semiconductor wafer and then a soft polishing pad is used for further polishing so as to complete the planarization process. Two polishing processes are necessary to performed respectively, so both high time cost and consumption cost of polishing pads are required incurred resulting in a low efficiency of in the CMP.
SUMMARY OF INVENTION
It is therefore a primary objective of the present invention to provide a method of fabricating composite polishing pads used in chemical-mechanical process to solve the above-mentioned problems.
The present invention provides a method of fabricating a composite polishing pad. The method first provides a first polishing pad comprising a glue layer on a surface of the first polishing pad and a plurality of hard polishing materials positioned on the glue layer. Then portions of the first polishing pad are punched off to remove portions of the hard polishing material positioned on the surface of the first polishing pad so as to form a plurality of holes penetrating the first polishing pad. Thereafter, a second polishing pad comprising a glue layer on a surface of the second polishing pad is provided, and a plurality of soft polishing materials adhere to the glue layer. Then portions of the soft polishing material positioned on the surface of the second polishing pad are removed while retaining the glue layer, and the soft polishing material retained on the surface of the second polishing pad completely matches the holes formed in the first polishing pad. Finally, the first polishing pad is stuck on the surface of the second polishing pad so as to form a composite polishing pad comprising a pattern formed by the hard and soft polishing materials on the surface of the composite polishing pad.
The polishing pad fabricated by the present invention comprises a pattern formed by the hard and soft polishing materials on the surface of the polishing pad, so the composite polishing pad simultaneously providesa good removal rate and a great polishing effect. Only one polishing process is required to complete the planarization process, so the time and cost of the chemical-mechanical process is reduced.


REFERENCES:
patent: 3507739 (1970-04-01), Jacobs
patent: 4274232 (1981-06-01), Wylde
patent: 5609517 (1997-03-01), Lofaro

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