Contact structures in semiconductor devices

A semiconductor device, comprising:

• first and second gate structures disposed on first and second fin structures, respectively;
• an n-type source/drain (S/D) region and a p-type S/D region disposed on the first fin structure and the second fin structure, respectively;
• first and second contact structures disposed on the n-type and p-type S/D regions, respectively,
• wherein the first contact structure comprises a ternary compound layer disposed on the n-type S/D region, a first n-type work function metal (nWFM) silicide layer disposed on the ternary compound layer, and a first contact plug disposed on the first nWFM silicide layer, and
• wherein the second contact structure comprises a p-type work function metal (pWFM) silicide layer disposed on the second S/D regions, a second nWFM silicide layer disposed on the pWFM silicide layer, and a second contact plug disposed on the pWFM silicide layer;
• and
• a dipole layer disposed at an interface between the ternary compound layer and the n-type S/D region.

A method, comprising:

• forming first and second fin structures on a substrate;
• forming first and second source/drain (S/D) regions on the first and second fin structures, respectively;
• forming first and second contact openings on the first and second S/D regions, respectively;
• selectively forming a p-type work function metal (pWFM) silicide layer on the second S/D region;
• forming a doped n-type work function metal (nWFM) silicide layer on the pWFM silicide layer and on the first S/D region;
• forming a ternary compound layer between the doped nWFM silicide layer and the first S/D region;
• and
• forming first and second contact plugs within the first and second contact openings.