Ultrashallow junctions formed by C coimplantation with spike plus submelt laser annealing

Abstract

A leading candidate for the formation of the ultrashallow junctions needed for Lg⩽45nm devices is the combination of coimplantation of a diffusion-retarding species such as carbon with a high temperature, millisecond annealing process after the conventional spike annealing. C coimplantation with B+ for p-type metal-oxide semiconductor and P+ for n-type metal-oxide semiconductor combined with conventional spike annealing produces reduced junction depths and improved dopant activation and profile abruptness, compared to similar implants without the coimplanted species. Addition of submelt laser annealing may further improve junction activation, but the dominant impact is gate depletion reduction, in that way, delaying the need to introduce metal gates. Devices show that the overlap capacitance is reduced, consistent with the shallower junction depths and reduced lateral diffusion. The improved dopant activation manifests itself in reduced series resistance and improved Ion values. Finally, scanning spreading resistance microscopy measurements confirm the shallow junction depths and reduced lateral diffusion.