Statistical demonstration of silicide-like uniform and ultra-low specific contact resistivity using a metal/high-k/Si stack in a sidewall contact test structure

Abstract

We demonstrate a 300mm wafer scale conformal contact process to achieve uniform ultra-low specific contact resistivity (ρ_c) for metal/high-k/n⁺Si (MIS) contacts. To achieve conformal contacts, we use a sidewall TLM (STLM) test structure that helps to minimize current crowding effect and variability. A systematic study is provided by varying doping density (N_D), high-k material (LaO_x, ZrO_x and TiO_x) and high-k thickness (t_d) to optimize ρ_c. The obtained ρ_c and its uniformity are found to be comparable with standard nickel silicide technology, with a possibility of further improvement by use of lower work-function metal.