Applicability of step-coverage Modeling to TiO2 thin films in atomic layer deposition

Abstract

The applicability of a step-coverage model in atomic layer deposition was extended to the deposition of TiO2 films, focusing on the effect of a precursor partial pressure and a deposition temperature, as well as the number of cycles in step coverage. Using the extracted model parameters, step coverage depending on the number of cycles was predicted, which shows a nonlinear dependence of film thickness inside a hole on the number of cycles because the area of a hole entrance decreases as the deposition proceeds. The experimental data agreed well with the model predictions. To confirm the validity of the step-coverage model, the effect of a precursor partial pressure and a deposition temperature on step coverage was also investigated. The flux of precursors that strikes the flat surface is the model parameter related to a precursor partial pressure, and the initial sticking probability and the adsorption order are the model parameters related to a deposition temperature. For different experimental conditions, by obtaining the model parameters related to changed experimental conditions from the experimental data at the flat surface, film thickness per cycle at the bottom inside a hole depending on precursor injection time could be predicted within reasonable accuracy. (c) 2007 The Electrochemical Society.