Interface instabilities and electronic properties of ZrO ₂ on silicon (100)

The interface stability of Zr-based high-k dielectrics with an oxide buffer layer was studied using x-ray and ultraviolet photoemission spectroscopy. The Zirconium oxide films were characterized in situ in a stepwise sequence in order to explore their chemical stability and electronic properties as a function of film thickness and processing conditions. The buffer layers were found to serve to lower the interface state density and to address the high temperature instabilities of ZrO ₂ in direct contact with Si. It was proposed that the As grown films contain excess oxygen resulting in a charge transfer from the Si substrate to the internal (ZrO ₂SiO ₂) interface.