Controlling Work Function and Damaging Effects of Sputtered RuO2 Gate Electrodes by Changing Oxygen Gas Ratio during Sputtering

Abstract

RuO2 metal gates were fabricated by a reactive sputtering method under different O-2 gas ratios. For the given sputtering power of 60 W, a similar to 13% O-2 ratio was the critical level below or over which RuO2 film has hyperstoichiometric and stoichiometric compositions, which resulted in a difference in the effective work function by similar to 0.2 eV. The stoichiometric RuO2 film imposes almost no damaging effect to the underlying SiO2 and HfO2 gate dielectrics. The RuO2 gate decreased the equivalent oxide thickness by similar to 0.5 nm and leakage current by around two orders of magnitude compared to the Pt-gated samples.