Band offsets and chemical bonding states in N-plasma-treated HfSiON gate stacks studied by photoelectron spectroscopy and x-ray absorption spectroscopy

We have investigated valence band and conduction band electronic structures and interfacial chemical bonding states of nitrogen-plasma-treated HfSiON∕SiON gate stacks on Si substrates with and without rapid thermal annealing by photoelectron spectroscopy and x-ray absorption spectroscopy to correlate them with electrical properties. We have found that the N3 component in N 1s can be correlated with electron trapping. Photoelectron spectra and O K-edge absorption spectra confirm the existence of the SiO2-rich phase-separated area in HfSiON films. Band offsets for the HfSiON∕Si and the SiO2-rich HfSiON∕Si are determined to be 2.5 and 4.2eV for valence band and 1.7 and 3.6eV for conduction band, respectively.