HfO 2 / SiO 2 interface chemistry studied by synchrotron radiation x-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy using synchrotron radiation has been used to investigate the ${\mathrm{HfO}}_2/{\mathrm{SiO}}_2$ interface chemistry of high-quality 0.6 and 2.5 nm ${\mathrm{HfO}}_2\text{/0.6\hspace{0.17em}}\mathrm{nm}$ ${\mathrm{SiO}}_2/\mathrm{Si}$ structures. The high energy resolution (0.15 eV) along with the high brightness level allows us to separate, unambiguously, on both Hf $\text{4f}$ and Si $\text{2p}$ core-level spectra, interfacial Hf–silicate bonds from bulk ${\mathrm{HfO}}_2$ and ${\mathrm{SiO}}_2$ contributions, thus making possible subsequent quantitative treatments and modeling of the interfacial layer structure. Careful assessment of the energy shift of the interfacial components shows that Si-rich Hf silicates are present. The underlying assumption that initial-state contribution dominates the observed Si $\text{2p}$ shift is briefly discussed.