Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2000-09-05
2002-10-08
Eley, Timothy V. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C438S690000, C438S700000
Reexamination Certificate
active
06461226
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus used in semiconductor fabrication, and more particularly, to a chemical mechanical polishing pad.
BACKGROUND OF THE INVENTION
During the manufacture of multilayer integrated circuits, it is desirable to effect planarization of the integrated circuit structures in the form of semiconductor wafers. This is usually accomplished by chemical mechanical polishing (CMP).
FIG. 1
shows a cross-sectional view of a conventional CMP apparatus
10
, which includes a rotating table
12
having a polishing pad
14
disposed thereon, and a wafer carrier
16
that holds a wafer
18
. The wafer
18
is held in an inverted position against the polishing pad
14
, with the side to be polished against the polishing pad. A predetermined pressure is exerted on the wafer
18
against the polishing pad
14
. As shown in
FIG. 2
, an enlarged cross-sectional view, a slurry
19
is applied between the wafer
18
and the polishing pad
14
. In operation, the polishing pad
14
and the wafer
18
rotate in relation to one another. The wafer is polished by mechanical abrasion from the polishing pad
14
and particles in the slurry
19
and by chemical action from the slurry
19
on the polishing pad
14
. Apparatus for polishing semiconductor wafers are well-known in the art. Such planarization apparatus are manufactured by IPEC Planar and the SpeedFam Corporation among others.
In a typical CMP process, two polishing pads are used. The semiconductor wafer is first polished by using a hard pad on a primary rotating table. The hard pad planarizes the wafer surface by removing material on higher raised areas
21
faster than in lower areas
23
. The wafer is then polished by using a soft pad and a lower downward force on a secondary rotating table. The soft pad removes any residual material or slurry residue on the wafer surface and improves the with-in-wafer uniformity of the wafer. During the CMP process, the CMP apparatus will generate, either chemically or mechanically, unwanted particles that degrade the performance of the circuits. When the wafer is transferred from the primary table to the secondary table, the slurry becomes dry and hard due to contact with the air. A cleaning step is required. The cleaning step may include scrubbing, rinsing and spin-drying. This cleaning step undesirably reduces production efficiency. Moreover, the transferring of the wafer between the primary table and the secondary table creates the potential for contamination of the clean environment necessary during wafer fabrication.
REFERENCES:
patent: 3841031 (1974-10-01), Walsh
patent: 5910043 (1999-06-01), Manzonie et al.
patent: 5919082 (1999-07-01), Walker et al.
patent: 6062958 (2000-05-01), Wright et al.
patent: 6340326 (2002-01-01), Kistler et al.
Blakely , Sokoloff, Taylor & Zafman LLP
Eley Timothy V.
ProMos Technologies Inc.
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