Self-aligned nickel-platinum silicide oxidation

The oxidation of nickel silicide during selective wet etch is investigated for stable contact resistance. This paper describes chemical reactions of nickel-platinum alloy silicide during selective wet etch used to remove unsilicided Ni(Pt). These reactions depend on the nature of silicide phases and selective etch process parameters. For silicide formation conditions such as silicidation temperature, a silicon oxide layer is observed after selective wet etch, replacing nickel silicide layer formed during the first thermal treatment. The mechanism of oxide formation and growth related to the interaction between selective wet etch chemistries and Ni(Pt) silicidation is then discussed. Thanks to the monosilicide phase formation this detrimental phenomenon can be prevented.