Measurement of Vth variation due to STI stress and inverse narrow channel effect at ultra-low voltage in a variability-suppressed process

Abstract

This paper demonstrates notable impact of V_th shift due to STI-induced dopant redistribution on ultra-low voltage designs. 2.5X I_on change at ultra-low voltages due to STI was measured on a 65nm SOTB CMOS process. Serious 6X I_on change due to inverse narrow channel effects was also observed. We propose ring oscillator based measurement procedure observing V_th shift by exploiting flexible V_th controllability by backgate biasing of SOTB process.