White-light ellipsometer with geometric phase shifter

Abstract

We describe a simple spectroscopic ellipsometer that uses a geometric phase shifter and a white-light source to generate a small number of phase-stepped intensities I(λ), which are recorded by a spectrometer. The ellipsometric angles ψ and Δ are easily calculated from these intensities at each wavelength simultaneously. We show that errors in Δ due to the nonideal behavior of the achromatic quarter-wave plate in the phase shifter can be made small by suitably adjusting the azimuth of the linearly polarized light incident on the sample. Two silicon dioxide films were measured with this instrument between 450 and 850 nm and yielded best fit film thicknesses of 1000.6±0.1 Å and 20.6±0.1 Å, in excellent agreement with those obtained using a commercial ellipsometer.

A 4+1 phase shifting algorithm for rotating-compensator spectroscopic ellipsometry

“…Compared to the spectra taken in Watkins' ellipsometers [3][4], the spectrum taken by RSCE has two harmonic frequency components: …”

“…Spectroscopic ellisometry is widely used in semiconductor industry owing to its significant power to characterize thinfilm structures [1][2][3][4]. Rotating compensator is a common modulation method for spectroscopic ellipsometry [1][2].…”

“…al. reported three white-light ellipsometers with phase shifting technology [3][4]. The ellipsometric parameters are analyzed by the phase shifting algorithm using data taken with rotating the analyzer [3], with rotating the achromatic half retarder [3], or by using the Soleil-Babinet compensator (SBC) [4].…”

Toward the generation of broadband optical vortices: extending the spectral range of a q-plate by polarization-selective filtering

“…A decade ago, it was suggested that additional polarization sensitive [36] or spatial filtering [37] can significantly broaden the spectral performance of Pancharatnam-Berry phase elements. However, the experimental efforts were confined to far-infrared spectral range and did not demonstrate the polarization sensitive beam cleaning as spatial filtering was performed instead [37].…”

A three-spectrum method for accurate calibration of bi-plate zero-order retarder

“…Under the method, rotations are needed for both the polarizer and analyzer. Thus, polarization independent light source and spectrometer are required for the spectral-calibration with Lin's method [7] .…”