Appeal No. 2000-0769
Application 08/997,326
the obviousness of providing a silicon channel layer on a
poly-SiGe layer.
We accept Appellants' statement that pseudomorphic SiGe
and polycrystalline SiGe are mutually exclusive crystal forms.
Solomon discusses that a pseudomorphic alloy layer is under
strain (col. 1, lines 43-52), implying a single crystal layer
because a polycrystalline layer cannot be under strain because
any strain ends at the grain boundaries. Solomon discusses
that it is desirable to have a germanium alloy channel with a
single crystal interface to silicon (col. 2, lines 14-19),
which further supports the statement that a pseudomorphic
layer is a single crystal. Solomon states that the transport
properties of the channel are improved because the holes are
confined to the interface between the pseudomorphic SiGe alloy
layer and the silicon layer 3 and because the alloy layer is
strained causing the energy of the light hole band to be
lowered (col. 4, lines 33-40). It appears that the beneficial
results of the silicon channel layer in Solomon are due solely
to the pseudomorphic nature of the alloy layer. Thus, there
is no reason why one of ordinary skill in the art would expect
that applying a silicon channel layer to a poly-SiGe alloy
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