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

Abstract Thin Al 2 O 3 layers were grown by atomic layer deposition using trimethylaluminum (TMA) and water as precursors on 1.2 nm thermal SiO 2 and HF cleaned Si surfaces. The stoichiometry and the contamination (H, OH and C) of as-deposited and N 2 annealed thick Al 2 O 3 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 (≈5 nm thick) at the Al 2 O 3 /Si interface by XPS and Auger electron spectrometry (AES). Post-deposition annealings induced important interface oxidation, Si atoms injection and SiO 2 /Al 2 O 3 mixture whereas the initial interface was abrupt. Silicon oxidation before Al 2 O 3 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.