Reliability assessment of germanium gate stacks with promising initial characteristics

摘要

This work reports on the reliability assessment of germanium (Ge) gate stacks with promising initial electrical properties, with focus on trap generation under a constant electric stress field (E_(stress)). Initial Ge gate stack properties do not necessarily mean highly robust reliability when it is considered that traps are newly generated under high E_(stress). A small amount of yttrium- or scandium oxide-doped GeO_2 (Y-GeO_2 or Sc-GeO_2, respectively) significantly reduces trap generation in Ge gate stacks without deterioration of the interface. This is explained by the increase in the average coordination number (N_(av)) of the modified GeO_2 network that results from the doping.