Phase shifting interferometric imaging ellipsometer

Abstract

A novel imaging ellipsometer has been developed; the phase shifting interferometric imaging ellipsometer (PSIIE) is the first ellipsometer to use phase-shifting interferometry for data acquisition. The only moving part in the system is a solid state PZT. The PSIIE uses a polarization interferometer, followed by a Wollaston prism, to obtain simultaneously, samples of the S and P polarization component interferograms. Interferogram. phase yields the ellipsometric parameter, Δ, while the fringe modulation yields the tangent of the ellipsometric parameter Ψ. The instrument can perform multiple wavelength and multiple angle-of-incidence ellipsometry over the entire visible range with the addition of a tunable laser source. Repeatability of the prototype instrument approaches 0.15° for the measurement of Δ, and 0.4° for Ψ. Absolute accuracies are 1° for Δ and Ψ. Calculations indicate that hardware and software improvements would achieve a precision and absolute accuracy below 0.1°.