Kinetic investigation of copper film oxidation by spectroscopic ellipsometry and reflectometry

Abstract

This article presents the oxidation kinetics of Cu thin films in dry and wet oxygen at temperatures from 100 to 600 °C. Spectroscopic ellipsometry and reflectometry, which yield refractive index and thickness of the Cu oxide, were used in kinetic study of Cu film oxidation. Cabrera–Mott (C–M) theory was used for the calculation of oxidation activation energies, yielding 0.68 eV for dry oxidation and 0.43 eV for wet oxidation. The scanning electron microscopy (SEM) and Rutherford backscattering spectrometry were used to investigate the cross-sectional profile, grain size, and chemical composition of the Cu oxides. A formula for Cu oxide thickness calculation was derived from the C–M theory and experimental data. Good agreement has been observed in thickness values from formula calculation, spectroscopic reflectance and SEM has been confirmed. A study of the effect of trace O2 on Cu film anneal is also presented.