Probing stress effects in HfO2 gate stacks with time dependent measurements

Abstract Effects of constant voltage stress (CVS) on gate stacks consisting of an ALD HfO 2 dielectric with various interfacial layers were studied with time dependent sensing measurements: DC I – V , pulse I – V , and charge pumping (CP) at different frequencies. The process of injected electron trapping/de-trapping on pre-existing defects in the bulk of the high- κ film was found to constitute the major contribution to the time dependence of the threshold voltage ( V t ) shift during stress. The trap generation observed with the low frequency CP measurements is suggested to occur within the interfacial oxide layer or the interfacial layer/high- κ interface, with only a minor effect on V t .