Impact of static and dynamic stress on threshold voltage instability in high-k/metal gate n-channel metal-oxide-semiconductor field-effect transistors

Abstract

This letter investigates the impact of static and dynamic stress on threshold voltage (Vth) instability in ultrathin n-channel metal-oxide-semiconductor field-effect transistors with hafnium-based gate stacks. Experimental results indicate Vth shift under dynamic stress is more serious than that under static stress due to charge trapping within the high-k dielectric. Capacitance-voltage techniques demonstrated that electron trapping under dynamic stress was located in the high-k dielectric near the source/drain overlap region rather than throughout the overall dielectric layer. This implies in real circuit operation, the phenomenon of electrons trapped in high-k near the source/drain overlap is the main issue affecting Vth instability.