US Patent 10074727 Low resistivity wrap-around contacts

Low resistivity, wrap-around contact structures are provided in nanosheet devices, vertical FETs, and FinFETs. Such contact structures are obtained by delivering dopants to source/drain regions using a highly conformal, doped metal layer. The conformal, doped metal layer may be formed by ALD or CVD using a titanium tetraiodide precursor. Dopants within the conformal, doped metal layer are delivered during the formation of wrap-around metal silicide or metal germano-silicide regions. Dopant segregation at silicide/silicon interfaces or germano-silicide/silicon interfaces reduces contact resistance in the wrap-around contact structures. A contact metal layer electrically communicates with the wrap-around contact structures.