Interface and material characterization of thin Al2O3 layers deposited by ALD using TMA/H2O

Thin Al2O3 layers were grown by atomic layer deposition using trimethylaluminum (TMA) and water as precursors on 1.2 nm thermal SiO2 and HF cleaned Si surfaces. The stoichiometry and the contamination (H, OH and C) of as-deposited and N-2 annealed thick Al2O3 layers were characterized by secondary ion mass spectrometry (SIMS), elastic recoil detection analysis (ERDA) and X-ray photoelectron spectroscopy (XPS). We show a perturbed region (approximate to5 nm thick) at the Al2O3/Si interface by XPS and Auger electron spectrometry (AES). Post-deposition annealings induced important interface oxidation, Si atoms injection and SiO2/Al2O3 mixture whereas the initial interface was abrupt. Silicon oxidation before Al2O3 growth highly limits interfacial oxidation and improves interfacial quality. We proposed that OH groups may play a key role to explain silicon oxidation during post-deposition annealings in inert ambience with low oxygen contamination levels. (C) 2002 Elsevier Science Ltd. All rights reserved.