Influence of magnetic field on the reaction mechanisms of plasma-assisted atomic layer deposition of Al2O3

In this paper the time-evaluation diagnostics of plasma-assisted atomic layer deposition (PA-ALD) of Al2O3 thin film were performed, in which the spectroscopic ellipsometry and mass spectrometry were used in-situ monitoring group reactions. We obtain that the nucleation density and film growth rate of PA-ALD were increased along with the magnetic field strength. The film growth in the initial cycles was switched from island mode to layer-by-layer mode. Besides, in no magnetic field deposition O radicals were consumed at the surface in whole process by combustion-like reaction with the surface -CH3 ligand when the deposition was processed in O-2 plasma period, whereas under the magnetic field deposition, the O radicals were consumed much quickly in the first several seconds. Additionally, in magnetic field assistance process the main by-product were C2H4, C2H2 and CH4, then releasing gases were CO2, CO and H2O. We result that the reaction mechanisms under the magnetic field assistance might be totally different from normal PA-ALD, or thermal-ALD process. (C) 2012 Elsevier B.V. All rights reserved.