X-ray photoelectron spectroscopy characterisation of high-k dielectric Al2O3 and HfO2 layers deposited on SiO2/Si surface

Ultra thin Al2O3 and HfO2 films (UP to similar to6 nm) were deposited on SiO2/Si wafers by atomic layer chemical vapour deposition (ALCVD(TM,1)) and studied by exsitu X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE). The thickness of these high-k layers (including the thickness of the interfacial SiO2 film) were determined by XPS and compared to the ellipsometry values. No silicate was detected at the interface. The XPS results for the bandgap (6.7 eV for Al2O3 and 5.25 eV for HfO2) are in good agreement with the SE measured values (6.26 eV for Al2O3 and 5.78 eV for HfO2). The growth rate of the high-k oxide layers and the effective attenuation length (EAL) of Si2p electrons in them were estimated; the measured EAL (2.75 nm in Al2O3 and 2.3 nm in HfO2) are in fair agreement with the NIST database values. (C) 2004 Elsevier B.V. All rights reserved.