Appeal No. 2005-1220
Application No. 09/270,606 Page 9
concomitantly, effective slurry layer thickness during
the polishing process.
The ideal polishing characteristic of FIG. 1 implies
that all pattern dependence may be eliminated because,
regardless of size or density, high structure areas
polish at the same rate as a flat blanket wafer.
Therefore, as the invention is implemented in
conjunction with a judicious choice of polishing
parameters such as down force, etc., the polishing
characteristics of FIG. 1 may be closely approximated.
When practicing the preferred embodiment of the
invention, a down force of five to ten psi is applied.
A table rotation rate of about 20 to 100 rpm is
established, as is a spindle rotation rate of about 20
to 100 rpm. A slurry flow rate of 0.50 to 500 ml/min.
is maintained.
In a more universal sense, the method of the invention
may be used for general global planarization. Use of
this method will increase process margin and reduce or
eliminate the need to include dummy structures in
circuit layouts.
Although a preferred embodiment of the method of the
invention has been disclosed herein, it will be
appreciated that further variations and modification
may be made thereto without departing from the scope of
the invention as defined in the appended claims.
Looking at appellant’s Figures 7(A) and 7(B) (copy attached
to the brief), for example, the low area rate 84 (a-d) is
described by appellant as being close to zero not withstanding
that the graph depicts that 1,000 angstroms of the low areas of
the oxide surface polished is removed prior to a convergence
point being reached during the polishing operation (see, e.g.,
label 84d in Figure 7A). Likewise in appellant’s Figure 8, label
94d suggests that nearly 2,000 angstroms of the low areas of the
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