Ageing under illumination of MOS transistors for active pixel sensors (APS) applications

This paper presents new reliability investigations on CMOS transistors for active pixels sensors (APS) applications. Reliability tests under sunlight illumination show an ageing effect of the transistors. The dependence of the degradation with light intensity and stress bias has been studied. The use of borderless silicon nitride is suspected to be responsible of this degradation: charges in this nitride can move under illumination and modulate the conductivity of a special implantation region of the transistor.