Appeal No. 2000-1991
Application No. 08/587,417
a photoresist layer having window openings over isolations areas
to be formed in the silicon substrate, the silicon nitride layer
and the pad oxide layer having respective thicknesses in a ratio
of at least 10:1, (ii) growing a field oxide within the tapered
recess such that an upper surface of the field oxide is
substantially above an upper surface of the silicon substrate,
without substantial formation of a bird’s head, and
(iii) removing the silicon nitride layer and the pad oxide layer
from the silicon substrate. The invention is well illustrated in
Figure 2 of the appellants’ disclosure. The following claim
further defines the invention.
1. A method of isolating a semiconductor device comprising
the steps of:
forming a tapered recess in a silicon substrate having
thereon, in sequential order, a pad oxide layer having a
thickness between 3 nm and about 50 nm, a silicon nitride layer,
and a photoresist layer having window openings over isolation
areas to be formed in said silicon substrate, said silicon
nitride layer and said pad oxide layer having respective
thicknesses in a ratio of at least 10:1,
growing a field oxide within said tapered recess such that
an upper surface of said field oxide is substantially above an
upper surface of said silicon substrate, without substantial
formation of a bird’s head, and
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