Property changes of aluminum oxide thin films deposited by atomic layer deposition under photon radiation

Aluminum oxide thin films were deposited by atomic layer deposition (ALD) using trimethyl aluminum and water under UV radiation. Films were prepared at two different deposition temperatures of 260 and 370 degrees C. The films deposited at 370 degrees C had a higher O/Al atomic ratio than those deposited at 260 degrees C. The upper valence band (VB) spectrum, observed by X-ray photoelectron spectroscopy (XPS), of the aluminum oxide thin film deposited under UV radiation during water purge was different from that of a nonradiated thin film, indicating a structural change by the UV radiation. For the film deposited at 370 S C, the effective mass (m*) was estimated to be larger than 0.35m(0), and an effective electron barrier height of 3.8 eV was obtained for m* = 0.4m(0) by fitting the I-V curve with the Fowler-Nordheim (FN) tunneling model. The films, of which leakage current densities were reduced by UV radiation, showed an increase in electron barrier height for FN tunneling conduction. In addition, the conduction band offset with Si, calculated from the VB offsets and the bandgap values obtained by XPS, was also increased for the UV-radiated sample. (C) 2006 The Electrochemical Society.