XPS study of SiO thin films and SiO-metal interfaces

Abstract

X-ray photoelectron spectroscopy has been used to study the chemical structure of stoichiometric SiO thin films. The Si 2p line of silicon binding energy is found at 101.7 eV, and deconvoluted spectra show that at least four distributions of the type Si-(Si_4-yO_y) exist in the films. The result is consistent with a random-binding model but differ from it for quantitative distribution. The interfacial layer between the SiO thin film and a nickel electrode has also been investigated by the same technique. Chemical reactions are found to occur between the oxide and nickel ions to form silicides: Ni₂Si at the interface and NiSi deep inside the insulator. A probable diffusion of both Si and Ni atoms divides the insulator into two regions: one which is rich in Si at the interface and the other rich in SiO₂ in the insulator. The results obtained explain qualitatively some electrical properties of the metal-SiO-metal structures.