Comparison of the trap behavior between ZrO 2 and HfO 2 gate stack nMOSFETs by 1/f noise and random telegraph noise

Low-frequency (1/ f ) noise characteristics of 28-nm nMOSFETs with ZrO 2 /SiO 2 and HfO 2 /SiO 2 dielectric gate stacks have been investigated. The observed lower 1/ f noise level in ZrO 2 devices, as compared with that in HfO 2 devices, is attributed to the reduction in tunneling attenuation length and in trap density simultaneously. Experimental results showed that the trap behavior of ZrO 2 /SiO 2 dielectric gate stack changes not only the trap location from a high- k layer to a SiO 2 interfacial layer but also the noise-dominated mechanism from carrier number fluctuation to the unified fluctuation model, which includes number fluctuation and correlated mobility fluctuation.