Depth Profile of high-κ dielectrics/Si structure using AR-XPS

High-κ dielectrics have been studied extensively as an alternative to silicon oxide in the next generation of MOSFETs. Transition metal oxides such as HfO_2, ZrO_2 and rare earth metal oxide such as Lu_2O_3 and their silicates have attracted much attention because of high dielectric constant, high thermal stability and high energy barriers at the interface for electrons and holes in Si. In the formation process of high-K dielectrics on Si substrate, the transition layer(TL) consisting of silicate layer is intentionally or inevitably formed between high-K dielectrics and Si substrate. SiO2/Si interfacial TL must be also formed between this silicate layer and Si substrate. The interface state density and the carrier transport in the channel region must be seriously affected by the composition and electronic structure of this TL. Therefore, in the this study, the non-destructive compositional depth profiling of TL between rare earth metal oxide LuOx and Si(100) substrate is performed using AR-XPS. It was found from the present depth profiling analysis that Lu-silicate was formed after post deposition annealing at 400℃. The conduction and valence band alignments of the transition layer were also determined from the measurement of O 1s photoelectron spectra and valence band spectra so that conduction and valence band discontinuities at the interface are 1.88 eV and 3.0 eV respectively.