Appeal No. 2002-2223
Application No. 09/475,891
BACKGROUND
Appellant’s invention relates to the manufacture of a semiconductor device.
Specifically the invention is directed to a process for etching unmasked areas of a
gate stack having an anti-reflective coating layer formed on a doped silicon layer on
a silicon oxide layer on a substrate. The anti-reflective coating is etched with a
breakthrough etch until the silicon layer is exposed. The silicon layer is then etched
with a bulk etch until about 40% of the silicon layer remains. The remaining silicon
layer is etched with a high-selectivity etch until the silicon oxide is exposed. The
remaining silicon layer is over etched with a very high-selectivity etch until silicon
residues are cleared. (Brief, p. 2). Claim 12, which is representative of the claimed
invention, appears below:
12. A method for etching unmasked areas of a gate stack having an
anti reflective coating layer formed on a doped silicon layer on a
silicon oxide on a substrate, comprising;
placing the substrate into an etch chamber;
etching the anti reflective coating layer with a breakthrough etch until
the silicon layer is exposed;
etching the silicon layer with a bulk etch until about 40% of the
silicon layer remains;
-2-
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