In situ calibration technique for photoelastic modulator in ellipsometry

Abstract

The modulation amplitude of a phase modulator is calibrated under a fixed incident angle in photoelastic modulation (PEM) ellipsometry. In addition to its modulation amplitude (Delta(o)), we also calibrated its static phase retardation at 632.8 nm. The ellipsometric parameters of a sample were measured by a multiple harmonic intensity ratio technique and proved that ellipsometric parameters can be obtained under various modulation amplitudes. Since the physical size of PEM is constant, we calibrated the modulation amplitude at multiple wavelengths by setting the Delta(o) value at 0.383 for 568.2 nm. These calibrations provided enough information for establishing an in situ/real time spectroscopic ellipsometry. (C) 2003 Elsevier B.V. All rights reserved.