Thermal stability in a-Si/HfSiO(N)/Si gate stack structures studied by photoemission spectroscopy using synchrotron radiation

Abstract

We have investigated thermal stability in amorphous-Si/HfSiO(N) gate stack structures using synchrotron-radiation photoemission spectroscopy. Core-level photoemission spectra depending on annealing temperature have revealed the mechanism of metallization reaction at the upper interface between a-Si cap layer and HfSiO(N) films under ultrahigh vacuum annealing. Silicidation reaction starts by annealing at 700 °C for both HfSiO and HfSiON films. By annealing at 800 °C, metallization reaction is rapidly promoted for the HfSiO film, while the Hf-silicide component changes into the Hf-nitride component due to its thermal stability and metallization reaction mildly proceeds for the HfSiON films.