Co-implantation with conventional spike anneal solutions for 45nm n-type metal-oxide-semiconductor ultra-shallow junction formation

Abstract

Co-implantation schemes for sub-65nm n-type extension formation have been explored. These included phosphorous (P) and arsenic (As) implants into crystalline Si as well as combinations using higher energy silicon pre-amorphization implant (PAI) steps together with low energy carbon (C) implantation. Dopant energies were varied between 500eV and 1keV, with C dose of1×1015cm−2 and P and As doses of 7×1014cm−2. The anneal step was a fast ramp-up and ramp-down spike at 1050°C. Comparisons with dopant-only implants or with PAI and dopant only showed these two schemes to give deeper, more gradual and less well activated junctions than when combined with C. The best result was obtained using a 25keV Si PAI, 6keV C and 1keV P, resulting in a junction depth of 20.5nm at 1×1019cm−3, and Rs=318Ω∕◻ and a 3nm∕dec trailing slope.