The NH3 Nitridation Effects on a Al2O3 Passivation by Atomic Layer Deposition (ALD) in the HfO2/GaAs Systems

Abstract

We investigated the nitridation effects on a passivating Al2O3 layer formed by atomic layer deposition (ALD) process at the interface of HfO2/GaAs. Results reveal that formation of Ga-O is suppressed greatly when annealed under NH3 ambient for the HfO2/GaAs system. Moreover if the Al2O3 layer is thick enough, diffusion of Ga into the high-k dielectric is blocked effectively, even after heat treatment at 500oC. This not only suppresses formation of interfacial oxide, but also improves the electrical properties. The nitrogen contents present in NH3 ambient lead to a decrease in the interfacial layer, which in turn decreases the effective oxide thickness (EOT). Results of chemical analyses by x-ray photoelectron spectroscopy (XPS) and micro-structure analyses by high-resolution transmission electron microscopy (HR-TEM) are presented.