Aperture-time of oxygen-precursor for minimum silicon incorporation into the interface-layer in atomic layer deposition-grown HfO₂/Si nanofilms

Hafnium oxide nanofilms were grown with atomic layer deposition on H-terminated Si (001) wafers employing tetrakis dimethyl amino hafnium (TDMA-Hf) and water as precursors. While the number of cycles (30) and the aperture-time for TDMA-Hf (0.08 s) were kept constant, the aperture-time (⁠$τH2O$⁠) for the oxidant-agent (H₂O) was varied from 0 to 0.10 s. The structure of the films was characterized with robust analysis employing angle-resolved x-ray photoelectron spectroscopy. In addition to a ∼1 nm hafnium oxide layer, a hafnium silicate interface layer, also ∼1 nm thick, is formed for $τH2O$ > 0. The incorporation degree of silicon into the interface layer (i.e., the value of 1 − x in Hf_xSi_1−xO_y) shows a minimum of 0.32 for $τH2O$ = 0.04 s. By employing the simultaneous method during peak-fitting analysis, it was possible to clearly resolve the contribution from the silicate and from oxide to the O 1s spectra, allowing for the assessment of the oxygen composition of each layer as a function of oxidant aperture time. The uncertainties of the peak areas and on the thickness and composition of the layers were calculated employing a rigorous approach.