Synchrotron XPS and EXAFS identification of chemical state and crystal phase changes of HfO2 films doped with Si, N, Al, and La

The recent industry wide investigation of incorporating various elemental dopant species into HfO₂ to achieve higher-k gate dielectric alloy materials in order to maintain the rapid pace of scaling according to Moore´s Law has been expanded to include enhancement of the SiO/HfO interface dipole to tune the effective work function (EWF) of n and p-type gate electrodes. This work illustrates the value of high resolution synchrotron X-ray photoemission spectroscopy (XPS), X-ray photoabsorption spectroscopy (XAS), and extended X-ray absorption fine structure (EXAFS) techniques to identify changes in chemical state bonding and associated crystalline polymorph transitions as a function of dopant species and anneal parameters. Direct correlation of these spectra with representative device data greatly elucidates critical process optimization pathways.