Roles of high-k and interfacial layers on TDDB reliability studied with HfAlOX/SiO2 stacked gate dielectrics

The objective of this paper is to clarify the primary roles of high-k layer and of interfacial layer on the TDDB lifetime in order to provide a guideline for realizing adequate TDDB reliability and also for the further high-k material selection. HfAlO(N)/SiO(N) and HfON/SiON stacked gate dielectrics has been fabricated with various deposition conditions and thicknesses. Electrical characteristics were evaluated with n+ and p+ poly-Si gated n- and p-channel MOSFETs. It was found that TDDB reliability depends of the thickness of high-k layer, regardless of the nitrogen concentration.