Chemical mechanical polishing apparatus

Details Chemical mechanical polishing apparatus Chemical mechanical polishing apparatus

2002-01-15

2003-06-10

Morgan, Eileen P. (Department: 3723)

Abrading

Accessory

Dressing

C451S444000, C451S056000

Reexamination Certificate

active

06575820

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a chemical mechanical polishing (CMP) apparatus. In particular, the present invention relates to a washer for the CMP apparatus.
2. Description of the Related Art
A process commonly used in fabrication of integrated circuits to create a planar topography is chemical mechanical polishing (CMP) process. This process involves chemically removing a surface while also mechanically grinding or polishing it. The combined action of surface chemical reaction and mechanical polishing allows for a controlled, layer by layer removal of a desired material from the wafer surface, resulting in a preferential removal of protruding surface topography and a planarized wafer surface.
However, if the CMP process is out of control, the wafer's surface becomes non-uniform. For an etching process, if contact windows or via holes are formed on a substrate with a non-uniform level, the endpoint of the etching process is not easy to maintain. Some contact windows or via holes may be overetched; some contact windows or via holes may not reach the predetermined depth and thereby experience open circuits. For a lithography process, the accuracy of the exposure is easily lost. With the increase of integration, elements are shrunk and it is important to smooth the substrate surface to a uniform level.
FIG. 1
schematically illustrates a conventional CMP apparatus
100
with a platen
110
, a dresser
120
, a wafer carrier
150
, and a washer
160
.
Referring to
FIG. 2
, a polishing pad
112
of polyester is positioned on the platen
110
, and a slurry is positioned on the polishing pad
112
. The wafer carrier
150
includes a guide ring
152
, a top ring
154
and a backing ring
156
. The top ring
154
is supported on the backing ring
156
. The guide ring
152
is positioned on the outer periphery of the top ring
154
to surround wafer
102
so that the wafer
102
is not disengaged from the wafer carrier
150
. The wafer is polished while being pressed between the wafer carrier
150
and the platen
110
.
After polishing, the polishing pad
112
is washed by the dresser
120
. However, some residue, from the reactant of the slurry and the removed surface layer, still remains on the polishing pad
112
. If the residue is not removed, it can damage the resulting polished wafer.
FIG. 3
shows the top view of the CMP apparatus. After removing the wafer
102
from the platen
110
by the wafer carrier
150
, the dresser
120
is moved on the platen
110
and the polishing pad
112
is cleaned by clockwise or counterclockwise action of the dresser
120
. The residue in the polishing pad
112
is scraped by the dresser
120
every one or several turns of the CMP process. The dresser
120
is then washed by immersion in the washer
160
filled with water to remove the residue attached to a bottom disk
125
of the dresser
120
. The dresser
120
rotates in the washer
160
to make water flow. The flowing water removes the residue.
However, using the flowing water to remove all of the residue is difficult. Conventionally, the bottom disk
125
is frequently changed by shutting down the CMP apparatus, to prevent the residue from damaging the wafers.
SUMMARY OF THE INVENTION
The present invention provides a CMP apparatus comprising a platen, a wafer carrier, a washer with a cleaning device, and a dresser. A polishing pad is disposed on the platen. The wafer carrier holds a wafer on the polishing pad, and the wafer carrier can move on to and off of the polishing pad. The dresser has a bottom disk contacting the polishing pad, and can move between the polishing pad and the washer. A diamond zone disposed on the bottom disk can clean the polishing pad, and the cleaning device can clean the diamond zone.
The cleaning device can be at least one scrubber disposed in the lower part of the washer, or an ultrasonic device, or combination thereof.


REFERENCES:
patent: 5961377 (1999-10-01), Jeong
patent: 6126530 (2000-10-01), Hirata
patent: 6241588 (2001-06-01), Brown et al.
patent: 6343977 (2002-02-01), Peng et al.

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