Interferometric Imaging Ellipsometer for Characterizing the Physical Parameters of a Grown Oxide Layer

Abstract

Interferometric and ellipsometric techniques are widely used in object characterization, investigation and testing. Both techniques are crucial for industrial sectors in manufacturing and production. In this work, an interferometric imaging ellipsometry method has been developed to measure the ellipsometric parameters Ψ, Δ and thickness t of native oxide layer formed on a copper thin film at wide angle of incidence 57.8–80.2º instantaneously. In this system, Michelson interferometer is illuminated with 45° polarized laser beam of 30 mm diameter. The produced fringes are split by a polarizing beam splitter (PBS) into p- and s- polarization fringes. The interferograms are captured separately by two CCD sensors at the reference and the measurement states without moving any parts in the optical system for each state. The detected p- and s- interferograms are analyzed using ImageJ software for mathematically calculating the values of Ψ, Δ and t of the oxide layer grown on copper thin film surface. The proposed method avoids the offset errors and the probable misalignment resulting from the beam and the optical components. In addition, it gathers the information of the interference pattern with the state of polarization of light for accurate, precise and real time contrast images. The oxide layer thickness is determined under controlled environment with high accuracy and low uncertainty. The results obtained by the proposed technique are consistent with the spectroscopic ellipsometer measurements.