Structural and electrical properties of ultra-thin high-k ZrO2 film on nitride passivated Ge(100) prepared by PEALD

Abstract

The study of ultrathin ZrO2 films grown on surface passivated germanium substrates by plasma enhanced Atomic Layer Deposition (PEALD) has been carried out. Nitride passivation has been used to form an interfacial layer between ZrO2/Ge. The ultra-thin ZrO2 film deposited with thickness of ~5.75nm and refractive index of ~2.05 as observed through ellipsometry. The Ge3d, Zr3d, N1s and O1s are XPS core level spectra's confirm the formation of GeON and ZrO2 ultra-thin films. The AFM results show the roughness of deposited films as low as 0.3nm. The effect of post metallization annealing (PMA) on electrical properties of Au/Cr/ZrO2/GeON/Ge capacitors has been investigated. The improvement in k value (~38) and an EOT value (~0.5nm) after PMA on Ge/GeON/ZrO2 stack has been observed. The flat band voltage and hysteresis of post metallization annealed devices has been reduced as compared to that of without PMA GeON/ZrO2 stack.