Appeal No. 94-0809
Application 07/707,365
Fig. 3A does not show a plurality of “insulating regions on
a substrate.” However, Nishizaka teaches at col. 1, l. 18-24:
In a conventional process for providing the
trench separation, field oxidation films are formed
at predetermined regions on a p-semiconductor substrate
by use of a selective oxidation method at a first stage.
Although plural field oxidation films are provided on
plural regions of the substrate, a limited section
including only one field oxidation film will be
explained hereinafter.
Fig. 3B shows that all the aforementioned films and layers
“and an upper portion of the substrate 1 are selectively etched
to provide element separating trenches 8" (col. 3, l. 66, to
col. 4, l. 2).
Fig. 3C shows that the “inner surface of the element
separating trenches 8 is oxidized to provide trench oxidation
films 9" (col. 4, l. 3-5).
Fig. 3D shows that “the trench oxidation films 9 are removed
on the bottom surface” (col. 4, l. 10-11), “a polycrystalline
silicon layer 10 is grown on an overall surface . . . so that the
element separating trenches 8 are buried with polycrystalline
silicon layer 10" (col. 4, l. 12-16) which “may be doped with
impurities to be the same conduction type as that of substrate 1"
(col. 4, l. 17-18), and “the polycrystalline silicon layer 10 is
etched back on the silicon nitride film 6" (col. 4, l. 18-20).
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