Interdiffusion studies for HfO₂/Si by GIXR and XPS

Interdiffusion at the interface between an HfO₂thin film and a Si substrate was studied using grazing incidence x-ray reflectivity (GIXR) and x-ray photoelectron spectroscopy (XPS). HfO₂thin films were deposited on Si sub strates by the sputtering of a metal-Hf layer, and then they were oxidized/annealed in a N₂/O₂gas mixture with different O₂concentrations. The GIXR and XPS results showed that the out-diffusion of Si atoms from the substrate increased with the oxygen concentration during high temperature annealing, and consequently, it resulted in the formation of a Si-rich Hf-silicate interlayer, i.e., lower-density Hf-silicate with greater thickness. The GIXR results of the interfacial structures were in agreement with the results of XPS and cross-sectional transmission electron microscopy.