Process for fabricating a device using nitrogen implantation into silicide layer

A process for device fabrication comprising:

• forming a layer of dielectric material on a silicon substrate with n-type and p-type regions therein;
• forming a silicon layer of amorphous or polysilicon over the dielectric layer;
• forming a refractory metal silicide layer over said amorphous or polysilicon layer;
• directing an n-type dopant species at a first portion of the refractory metal silicide layer thereby causing the n-type dopant species to implant in the silicide;
• directing a nitrogen dopant at the first portion of the refractory metal silicide layer thereby causing the nitrogen dopant species to implant in the silicide;
• directing a p-type dopant at a second portion of the refractory metal silicide layer thereby causing the p-type dopant species to implant in the silicide;
• and
• performing an anneal at a temperature that is sufficient to cause at least some of both the n-type dopant and the p-type dopant to migrate from the silicide layer to the underlying layer of amorphous silicon or polysilicon,
• wherein the nitrogen dopant reduces diffusion of the p-type dopant in the first portion of the refractory metal silicide layer.