Out-diffusion of Ga and As atoms into dielectric films in SiOx /GaAs and SiNy/GaAs systems

Residual Ga and As atoms in SiOx and SiNy dielectric films deposited on GaAs were investigated by Rutherford backscattering spectroscopy and particle-induced x-ray emission techniques. Both Ga and As atoms were detected in the films after high temperature heat treatment, and even in the films as-deposited. The magnitude of the residual atoms presumably out-diffused from GaAs substrates was of the order of 1×1019 /cm3. The concentration of Ga atoms prevails over that of As atoms in SiOx/GaAs systems as is generally known, and vice versa in SiNy/GaAs systems after heat treatment. Dynamic behavior of Ga and As atoms in the films as functions of annealing temperature and annealing time cannot be explained by a simple diffusion mechanism. A model is proposed that the damaged layer around the interface of the systems is responsible for the anomalous out-diffusion phenomena.