Appeal No. 2003-1690
Application 09/635,061
was expected that a significantly better dielectric strength
would be exhibited for this structure. However, the resulting
dielectric strength was only marginally better than that of
device 110” (col. 3, lines 4-9).
In Ipri’s disclosed prior approach to improving dielectric
strength relied upon by the examiner (answer, page 5), a silicon
dioxide layer (417) was formed by thermally oxidizing the surface
of a silicon island (416), and a layer of silicon nitride (419)
was deposited over that layer and over the exposed portions of
the wafer surface (414) to provide the desired gate dielectric
thickness (T, figure 4) on the silicon island (col. 3, line 53 -
col. 4, line 1). Ipri teaches that “[a]lthough the structure 410
[formed by the prior art process relied upon by the examiner]
also presents an improvement in dielectric strength compared to
the devices 110 and 210, “it is inherently more unreliable due to
the presence of a gate dielectric which comprises two dissimilar
materials” (col. 4, lines 4-8).2
2 Ipri’s approach to improving the dielectric strength is to
form a silicon island on an insulating substrate, thermally
oxidize the surface of the silicon island to form a silicon
dioxide layer thereon, depositing a silicon layer on the oxidized
island and the exposed portion of the substrate surface, and
oxidizing the entire silicon layer to form a silicon dioxide
layer that covers the island and the exposed wafer surface
(col. 4, lines 28-55; figures 5A-E).
5
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