Photoelectron diffraction study and structure determination of ultrathin hafnium silicide layers on silicon(1 0 0) using Mg Kα radiation and synchrotron light

In order to increase the switching speed and the efficiency of modern semiconductor devices a further down scaling is desired. Thus, the SiO2 gate dielectric might be replaced by layers of a material with a much higher dielectric constant like HfO2. A major problem of the system HfO2/Si(1 0 0) is the silicidation of hafnium at the interface. Therefore, ultrathin films (3-30 Å) of HfSi2 on Si(1 0 0) were investigated by photoelectron spectroscopy, low-energy electron diffraction and X-ray photoelectron diffraction. Synchrotron light with an energy of hν = 180 eV was used for excitation. First results were obtained using a Mg X-ray tube (hν = 1253.6 eV). In order to determine the structure of the films, the recorded photoelectron diffraction patterns were compared to computer simulations of model structures. The simulations for the low-energy measurements were performed using the program MSPHD. As a result a modified zirconium silicide structure is presented in order to describe the structure of ultrathin HfSi2 films on Si(1 0 0).