Interdiffusion studies for HfO2/Si by GIXR and XPS

Abstract

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.