Step coverage modeling of thin films in atomic layer deposition

A film growth model on microfeatures is proposed to evaluate step coverage depending on precursor injection time in atomic layer deposition. The proposed model is based on that the chemisorption rate of precursors at a certain position along the depth of a microfeature is determined by the total flux of precursors and the sticking probability. The total flux includes the flux coming from the entrance of a microfeature and the flux reflected from other positions inside a microfeature, and the sticking probability depends on the surface coverage of chemisorbed precursor, which is a function of precursor injection time. The proposed model was applied to the deposition of Al2O3 films on 0.3μm diameter holes with an aspect ratio of 10. It was confirmed that the experimental data for step coverage depending on precursor injection time follow the trend predicted by the proposed model.