The Impact of an Ultrathin Y2O3 Layer on GeO2 Passivation in Ge MOS Gate Stacks

Abstract

This paper investigates the impact of an atomic layer-deposited Y2O3 dielectric on the passivation of a GeO2 layer in GeO2-based Ge gate stacks. The equivalent oxide thickness scalability and thermal stability of the ultrathin Y2O3 layer are evaluated at different Y2O3 thicknesses and annealing conditions in detail. Experimental results show that a Y2O3 layer thickness of 1.0 nm is required to serve as a GeO2 passivation layerwhile retaining gate-stack performance at 400 C-o postdeposition annealing. However, at a higher annealing temperature of 500 C-o, the barrier property deteriorates and allows GeO desorption. The proposed gate-stack implies the applicability of a Y2O3 passivation method for further scaled GeO2-based Ge gate stacks.