Patent ID: 6878627

Claim:
A method of forming a semiconductor device on a silicon based substrate comprising the steps of: (a) forming a transistor which includes at least one source/drain region in the silicon based substrate; and (b) depositing a first metal layer on the silicon based substrate and in contact with said at least one source/drain region, said first metal layer including Cobalt (Co); and (c) depositing a second metal layer on at least selected portions of the first metal layer including in said at least one source/drain region, said second metal layer including an alloy of Cobalt and a refractory metal; and (d) performing a first heat treatment so as to convert at least part of said first metal layer and the silicon based substrate into a first silicide composition having one or more cobalt silicide phases, said one or more cobalt silicide phases being characterized by a first resistivity; (e) performing a second heat treatment so as to convert said first composition, including said one or more cobalt silicide phases, into a second silicide composition containing primarily a lower resistivity cobalt silicide phase, said lower resistivity cobalt silicide phase having a resistivity substantially less than said first resistivity; wherein a cobalt silicide contact is formed in said source/drain region.