Appeal No. 2003-1298
Application No. 09/369,579
1. An isolation structure, comprising:
a semiconductor substrate having first and
second separate active regions each extending to a
top surface of the semiconductor substrate;
a field oxide region having a convex top
surface opposite a convex bottom surface, wherein:
the convex bottom surface extends within said
semiconductor substrate below said top surface of
said semiconductor substrate, and
the convex top surface extends above the top
surface of the semiconductor substrate;
a first isolation trench filled with an oxide
dielectric material, extending into the
semiconductor substrate, and extending above the top
surface of the semiconductor substrate, wherein:
the first isolation trench has first and
second opposite sides;
the first side of the first isolation
trench makes contact with the field oxide
region;
the second side of the first isolation
trench makes contact with the first active
region; and
said material filling said first isolation
trench constitutes a structural barrier between
the opposite sides of said first isolation
trench that separates said field oxide region
from said first active region, thus preventing
the contact between said first active region
and said field oxide region and preventing the
encroachment of material from said field oxide
region into said first active region;
a second isolation trench filled with said
oxide dielectric material, extending into the
semiconductor substrate, and extending above the top
surface of the semiconductor substrate, wherein:
the second isolation trench has first and
second opposite sides;
the first side of the second isolation
trench makes contact with the field oxide
region;
the second side of the second isolation
trench makes contact with the second active
region; and
said material filling said second
isolation trench constitutes a structural
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