Interface of atomic layer deposited Al₂O₃ on H‐terminated silicon

Al 2 O 3 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 Al 2 O 3 /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 Al 2 O 3 . 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 SiO 2 forms on top of the Al 2 O 3 dielectric during deposition. The presence of OH‐groups at a level of 3% of the total oxygen content was detected throughout the Al 2 O 3 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 10 11 and 10 12 cm –2 eV –1 . (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)