Process options to enable (sub-)1e-9 Ohm.cm2 contact resistivity on Si devices

This paper introduces the investigations on ultralow metal/semiconductor contact resistivity (ρc). First, we build a multiring circular transmission line model (MR-CTLM), a novel ρc test structure with simple process and high accuracy for rigorous ρc study. Based on that, we explore process options to achieve ultralow ρc on n-Si. We obtain high carrier concentration of ∼9e20 cm−3 by in situ P doped Si:P epitaxy followed by ms laser annealing. Besides, we use a pre-contact amorphization plus Ti silicidation technique to fabricate TiSix/Si:P contacts and achieve ultralow ρc of 1.5e–9 Ohm.cm2. Finally, we discuss sub-1e-9 Ohm.cm2 ρc solutions for future CMOS technology node.