Effect of La2O3Capping Layer Thickness on Hot-Carrier Degradation of n-Channel Metal–Oxide–Semiconductor Field-Effect Transistors with High-k/Metal Gate Stacks

The effect of La2O3 capping layer thickness on the hot-carrier degradation of n-channel metal–oxide–semiconductor field-effect transistors (n-MOSFETs) with high-k/metal gate stacks is investigated. The hot-carrier degradation is monitored by measuring the threshold voltage Vth, transconductance gm, and subthreshold slope SS. As the thickness of the La2O3 layer increases, Vth degradation is enhanced regardless of whether the La2O3 layer is deposited above or below the HfSiO layer. The generation of interface traps induced by hot-carrier stress is intensified with an increase in the bottom capping layer thickness. On the other hand, the generation of oxide traps induced by hot-carrier stress is intensified with an increase in the top capping layer thickness.