METHOD OF FORMING COBALT-DISILICIDE CONTACTS USING A COBALT-CARBON ALLOY THIN FILM

摘要

A method of forming cobalt-disilicide contacts on source/drain regions and a polysilicon gate electrode of an MOS transistor using a cobalt-carbon alloy thin film. The method of the present invention comprises the steps of (a) forming an MOS transistor on a silicon substrate, with source/drain regions and a polysilicon gate electrode of the MOS transistor; (b) depositing a carbon-containing cobalt layer overlying the resultant of the (a) step; and (c) annealing the carbon-containing cobalt layer to form an epitaxial CoSi2 layer over the source/drain regions and a CoSi2 single crystal layer over the polysilicon gate electrode, respectively. According to the present invention, the CoSi2 contact formation process is simplified because it does not require deposition steps of interlayers and a TiN protection layer, and their subsequent heat treatments. In addition, an epitaxial CoSi2 layer with low resistivity and high reproducibility can be formed by the deposition of a cobalt-carbon alloy thin film and its subsequent heat treatment. The chemical vapor deposited CoSi2 layer has enhanced step coverage and uniform interface characteristics suitable for the interconnection process of an ultra fine contact structure.