Appeal No. 2001-0776
Application 09/276,043
gate 21 is formed on gate oxide 19, and then tungsten layer 25 is
formed on top of polysilicon gate 21. See FIGS. 1A-1C and column
2, lines 1-58.
Mendonca is directed to a substrate 11 which typically
comprises polysilicon, and an overlying insulating layer 13 which
typically comprises silicon dioxide. An aperture is formed in
layer 13, and a tungsten layer 14 is filled therein. See column
2, lines 16-30 and Figure 1 of Mendonca. Mendonca teaches to
deposit the tungsten using a low pressure CVD process. The
tungsten is then nitrided. See column 2, lines 55-68. Following
the nitriding step, a tungsten layer is formed as desired,
preferably by hydrogen reduction of tungsten hexafluoride. See
column 3, lines 1-3. Therefore, Mendonca is directed to
depositing on a silicon substrate, a tungsten layer, followed by
nitriding the tungsten layer, followed by the deposition of
tungsten on top of the nitrided tungsten layer.
To the contrary, Chow is directed to forming a gate oxide
layer 19 on the top surface of substrate 11, and then a
polysilicon gate is formed on top of the gate oxide layer 19, and
then a tungsten layer 25 is deposited on top of the polysilicon
gate 21, as stated, supra. See column 2, lines 6-46 of Chow. If
one of ordinary skill in the art would incorporate the steps of
Mendonca as proposed by the examiner on pages 6-7 of the answer,
the intended interconnection of Chow would be destroyed, i.e.,
the polysilicon gate 21 would not be formed. In this context, we
therefore agree with appellants’ position that the combination is
improper. (brief, page 6).
In view of the above, we reverse this rejection.
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