Interfacial characteristics of N-incorporated HfAlO high-k thin films

The characteristics of N-incorporated HfO2-Al2O3 alloy films (HfAlO) were investigated by high-resolution x-ray photoelectron spectroscopy (XPS), near-edge x-ray absorption fine structure (NEXAFS), medium-energy ion scattering (MEIS), and capacitance-voltage measurements. The core-level energy states, Hf 4f and Al 2p peaks of a 15 Angstrom thick film showed a shift to lower binding energy, resulting from the incorporation of nitrogen into the films. Absorption spectra of the O K edge of HfAlO were affected mainly by the Al2O3 in the film, and not by HfO2 after nitridation by NH3 annealing. The NEXAFS of N K edge and XPS data related to the chemical state suggested that the incorporated N atom is dominantly bonded to Al2O3, and not to HfO2. Moreover, MEIS results implied that there is a significant incorporation of N at the interface between the alloy film and Si. The incorporation of N effectively suppressed the leakage current without an increase in interfacial layer thickness, while the interfacial state of the N-incorporated films increased somewhat. (C) 2004 American Institute of Physics.