Instrumentation considerations in multichannel ellipsometry for real-time spectroscopy

Abstract

Experimental procedures are described to enhance the accuracy of a novel rotating polarizer multichannel ellipsometer, designed to real-time spectroscopic studies of film growth and surfaces. For the fastest such instrument 128-point (ψ,Δ) spectra from 1.5 to 4.5 eV can be acquired in less than 10 ms. Ellipsometry places stringent demands on the photodiode-array-based detection system, as the irradiance incident on the separate pixels is waveform analyzed. A detailed characterization of the detection system is presented which provides the means to correct for stray light, image persistence, non-linearity, and integration errors. We also outline techniques for characterization of imperfections associated with the source and polarization optics. We present calibration and data reduction equations which have been derived to include source and polarization system imperfection parameters to first order.