Noise as a characterization tool for reliability under illumination of transfer gate transistor for image sensors applications

This paper presents reliability investigations on specific CMOS transistors for image sensors applications. Reliability tests under sunlight illumination show an ageing effect of the transistors. It is shown that the degradation of the transfer gate structure is linked to a modulation of the conduction path. Modification of the channel position influences the interaction between carriers in the channel and oxide traps next to the interface. The evolution of the 1/f noise performances of the transfer gate transistor is studied. The distinctiveness of the noise variation with different stress conditions is thoroughly discussed and the mechanisms at the origin of these phenomena are explained.