A metal/high-k gate stack with a p-type band edge effective work function (EWF) of about 5.0 eV is demonstrated using a thin WAlx capping layer. The WAlx stack exhibits a lower threshold voltage (higher flatband voltage) value and better equivalent oxide thickness scalability than previously reported high EWF gate stacks using an AlOx cap. The WAlx cap p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) show significantly improved negative bias temperature instability (NBTI) characteristics than AlOx -capped pMOSFETs, which is attributed to negligible diffusion of Al into the interfacial oxide layer adjacent to the Si substrate.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)