Interface of atomic layer deposited Al2O3 on H‐terminated silicon

Abstract

AbstractAl2O3 films 1 to 20 nm thick were deposited as alternative high‐κ gate dielectric on hydrogen‐terminated silicon by Atomic Layer Deposition (ALD) and characterized by Synchrotron X‐ray Photoelectron Spec‐troscopy (SXPS), Fourier Transform Infrared (FTIR) absorption spectroscopy and admittance measure‐ments. The SXPS results indicate that about 60% of the original Si–H surface bonds are preserved at the Al2O3/Si interface and this is confirmed by monitoring the Si–H stretching modes by FTIR spectroscopy in the Attenuated Total Reflection (ATR) mode both before and after ALD of Al2O3. The remaining 40% of Si–H bonds are replaced by Si–O bonds as verified by SXPS. In addition, a fraction of a monolayer of SiO2 forms on top of the Al2O3 dielectric during deposition. The presence of OH‐groups at a level of 3% of the total oxygen content was detected throughout the Al2O3 layer through a chemically shifted O 1s component in SXPS. Admittance measurements give a dielectric constant of 9.12, but a relatively high density of interface traps between 1011 and 1012 cm–2 eV–1. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)