Structural and electrical properties of the interfacial layer in sputter deposited LaAlO3/Si thin films

In order to investigate the effects of the sputter deposition parameters and the influence of the post-deposition thermal treatment on the LaAlO3/ Si interface, Rutherford Backscattering Spectrometry (RBS), ion channeling, Nuclear Reaction Analysis (NRA), X-ray Photoemission Spectroscopy (XPS), Capacitance-Voltage measurements and Spectroscopic Ellipsometry (SE) were performed on LaAlO3/Si or RuO2/LaAlO3/Si Metal-Oxide-Semiconductor (MOS) structures. RBS-channeling revealed that the Si surface damage due to sputtering deposition at LaAlO3/Si interface is reduced when increasing the deposition pressure, between 0.5 and 5 Pa, and when annealing the films in 1 atm of O-2 at 450 degrees C. XPS spectra were correlated to RBS and NRA measurements. Even if the formation of a low-kappa interfacial layer is demonstrated by SE measurements, high deposition pressure and post-deposition annealing in O-2 at 600 degrees C were found to be the best procedure to improve the electrical characteristics of MOS structures in terms of fixed charge and slow trap densities. For these parameters, the K value was found to be 14, and the equivalent interfacial thickness was estimated to be 1.3 nm, which is lower that most of the previously reported values. (C) 2007 Elsevier B.V. All rights reserved.