Contact Resistivity of NiPtSi on n-doped Silicon Activated by Laser Annealing

Abstract

Reducing specific contact resistivity of the silicide to silicon interface is advantageous to achieve high planar density and high drive current FET devices. Measuring the differential resistivities at different low voltage bias conditions of four terminal Kelvin test structures with a range of contact sizes has proven particularly effective in characterizing the linearity behavior and specific contact resistivity. This study shows that adding laser activation annealing for an n+ doped silicon contacted by a standard NiPt silicide is found to significantly improve the contact electrical properties. Initial results with only rapid thermal anneal activation show a size dependence of the contact resistivity with non-linear behavior exhibiting maximum resistance at zero bias, and contact resistivities ranging from 4×10^-8 Ω-cm² to 4×10^-7 Ω-cm². Adding laser anneal after the rapid thermal anneal gives ohmic behavior, for contact down to 50nm in size, with a specific contact resistivity of 1×10^-8 Ω-cm². The metal-to-silicide contact resistance was measured separately using a novel test structure and it was confirmed to be negligible. We describe our device structure, our experimental methodology, and the implications of our results for future devices.