Scalability and reliability characteristics of cvd hf o2 gate dielectrics with HfN electrodes for advanced CMOS applications

Abstract

Metal-oxide-semiconductor (MOS) devices using a thermally robust HfNHf O2 gate stack were fabricated. The equivalent oxide thickness of HfNHf O2 gate stack has been aggressively scaled down to 0.75 and 0.95 nm for MOS capacitors and metal-oxide-semiconductor field effect transistors, respectively, after a thermal budget required by the conventional complementary metal-oxide- semiconductor gate-first process. The reliability issues such as time-dependent dielectric breakdown (TDDB) and bias temperature instability (BTI) of the HfNHf O2 devices are studied. The stress electric-field-dependent TDDB characteristics are demonstrated and explained by a model taking into account the high energetic carrier trapping in the Hf O2 and at the Hf O2 Si interfacial layer. The polarity dependent BTI characteristics are observed which can be explained by a generalized reaction-diffusion model. These intrinsic reliability characteristics are correlated with the low pre-existing charge traps in Hf O2 gate stack resulting from a high temperature postdeposition annealing of the HfNHf O2 gate stack. © 2007 The Electrochemical Society.