Silicate formation at the interface of Hf-oxide as a high-k dielectrics and Si(0 0 1) surfaces

The composition and chemical bonding of the first atoms across the interface between Si(0 0 1) and the gate dielectrics determine the quality of gate stacks. An analysis of that hidden interface is a challenge as it requires high sensitivity in both elemental and chemical state information. We used synchrotron radiation (SR) based photoelectron spectroscopy and, in particular, X-ray absorption spectroscopy in total electron yield and total fluorescence yield at the Si2p and the O1s edges to address this issue. We report on results for Hf oxide prepared by ALD and compare to Pr2O3/Si(0 0 1). For Hf oxide thin films we find evidence for the silicate formation at the interface as derived from the characteristic features in the X-ray absorption spectra at the Si2p and the O1s edges. Resonant photoelectron spectroscopy is used to analyze the absorption band in detail. Following the resonant profiles of initial and final states we deduce from the resonant behaviour a charge donation via a Si-induced charge transfer.