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

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 ~5.75 nm 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 0.3 nm. 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 (~0.5 nm) 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.