Characterization of HfO2 and hafnium silicate films on SiO 2/Si

Abstract

As the MOSFET SiO2-based gate dielectric layer approaches its fundamental physical limits, the investigation of high-k oxides is ongoing in order to determine which oxides can best continue the scaling of the MOSFET. HfO2 and hafnium silicates are leading candidates due to their relatively large band gaps, thermal stability in proximity to Si and relatively high dielectric constants. We have used a combination of x-ray photoemission spectroscopy (XPS) and spectroscopic ellipsometry (SE) to measure the band offsets between the high-k layers and the Si substrates. Shifts in band alignment that occur upon deposition of the HfO2 layer and annealing of the HfO2/SiO2/Si film stack will be discussed in light of XPS spectra. Non-destructive compositional depth profiles constructed from angle resolved XPS data will also be presented and film thicknesses determined from them will be compared to thicknesses measured by SE. © 2009 American Institute of Physics.