Enhanced sub 20-nm FinFET performance by stacked gate dielectric with less oxygen vacancies featuring higher current drive capability and superior reliability

HK-2/HK-1 stacked dielectric was proposed as the gate dielectric for sub-20 nm FinFET technology. Compared to single HK-1 dielectric, the stacked gate dielectric exhibits superior performance in terms of improved drive current by 20~22% and increased transconductance by ~22%. The main reason accounting for the better performance, besides the higher gate capacitance by 4%, is the enhanced carrier mobility by ~33% resulting from less remote scattering due to smaller amount of charged oxygen vacancies which was physically confirmed by EELS and XPS. Owing to the reduced oxygen vacancies, from bias temperature instability and lifetime test, the stacked gate dielectric demonstrates augmented reliability as well. Most importantly, HK-1 and HK-2 are common dielectrics completely compatible with typical processes, rendering the stacked dielectric a promising one for next-generation FinFETs technology.