Appeal No. 1998-0970
Application 07/995,325
g) removing a natural oxide film from a surface of
the impurity diffusion region in the contact hole by
reducing with a reactive gas at an ambient temperature of
600-1000E C so as to effect gas-phase etching to activate
an exposed surface of the impurity diffusion region;
h) applying a gas containing an impurity component
which has same conductivity type as that of the impurity
diffusion region to the surface of semiconductor
substrate and heating the semiconductor substrate at a
temperature of 600-900E C to form an impurity film which
contains the impurity component and is adsorbed on the
activated exposed surface of the impurity diffusion
region and in the contact hole;
i) annealing the impurity diffusion region and the
impurity film to diffuse the impurity component from the
impurity film to a depth into the impurity diffusion
region; and
j) filling the contact hole with an electrically
conductive layer to produce electrical contact between
the impurity diffusion region and the electrically
conductive layer via the impurity film.
The Examiner relies on the following prior art:
Griswold 3,247,032 April 19,
1966
Nickl 3,506,508 April 14,
1970
Tsunashima et al. (Tsunashima) 4,791,074 December 13,
1988
Allman et al. (Allman) 4,855,258 August 8,
1989
(filed October 22,
1987)
Gong et al. (Gong), A metal-oxide-silicon field-effect
transistor made by means of solid-phase doping, J. Appl.
Phys. 65(11), 1 June 1989, pp. 4435-4437.
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