Appeal No. 2002-0321
Application No. 09/014,729
forming a layer comprised of titanium and nitride on said
siliconcontaining layer, said layer comprised of titanium
and nitride having a thickness;
forming a layer comprised of tungsten on said layer
comprised of titanium and nitride, said layer comprised of
tungsten having a thickness;
forming a layer comprised of silicon and nitride on said
layer comprised of tungsten, said layer comprised of silicon
and nitride having a thickness;
patterning and selectively etching said layer comprised
of silicon and nitride to expose a portion of said layer
comprised of tungsten, said step of selectively etching of
said layer comprised of silicon and nitride being selective
against etching said layer comprised of tungsten;
selectively etching said exposed portion of said layer
comprised of tungsten substantially simultaneously with
etching a portion of said layer comprised of titanium and
nitride so as to expose a portion of said silicon-containing
layer, said step of selectively etching said exposed portion
of said layer comprised of tungsten being selective against
etching said layer of comprised of silicon and nitride; and
then, selectively etching said exposed portion of said
silicon-containing layer so as to expose a portion of said
gate insulator, said step of selectively etching said
exposed portion of said silicon-containing layer being
selectively against etching said layer comprised of titanium
and nitride, said layer comprised of tungsten, and said
layer comprised of silicon and nitride substantially
unetched.
The examiner relies upon the following references as
evidence of obviousness:
Wu 5,543,362 Aug. 06, 1996
Agnello 5,897,349 Apr. 27, 1999
Autryve 5,935,877 Aug. 10, 1999
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