Appeal No. 1998-1850
Application No. 08/596,613
BACKGROUND
The invention is directed to a method of forming an electrical contact on a silicon
substrate, which includes etching a contact opening over an active region in the wafer and
implanting metal ions into the contact opening. Representative claim 1 is reproduced
below.
1. A method of forming an electrical contact on a silicon substrate, the method
comprising the steps of:
providing a silicon substrate;
forming a dual gate structure on the silicon substrate with an aperture in the
dual gate structure;
forming a layer of silicon nitride over the dual gate structure, the silicon
nitride layer entering into the aperture and substantially insulating the dual gate
structure from the aperture;
forming an insulating layer over the silicon nitride layer and the aperture;
planarizing the insulating layer;
forming a contact opening through the insulating layer to the silicon
substrate, the contact opening including at least a portion of the aperture, the
contact opening having a bottom and an aspect ratio greater than about 4 to 1;
implanting metal ions into the contact opening; and
annealing the silicon substrate at a temperature and for a time sufficient to
result in the formation of a metal silicide layer of substantially uniform thickness in
the bottom of the contact opening, the metal silicide layer including the implanted
metal ions.
The examiner relies on the following evidence:
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