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

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.