We report on a novel microellipsometer that uses a spatially filtered high-numerical-aperture (NA) lens for large-angle ellipsometric illumination and high spatial resolution. A radially symmetric ellipsometric signal is achieved with two half-wave plates to produce a pure polarization rotation and a birefringent cube as a radial analyzer. This radial symmetry offers a better signal-to-noise ratio compared with other microellipsometer techniques. Ellipsometric measurement with a spatial resolution of 0.5 μm is performed with a He-Ne (632.8-nm) laser source and an objective lens with an NA of 0.8. Experimental data on SiO<sub>2</sub> samples with different thicknesses are in good agreement with spectroscopic ellipsometer results. We acquired ellipsometric images of photoresist microstructure through scanning the sample. Surface profiles of the photoresist microstructure are derived from the ellipsometric data and compared with the results from a stylus profiler.
© 2002 Optical Society of America
(070.6110) Fourier optics and signal processing : Spatial filtering
(120.2130) Instrumentation, measurement, and metrology : Ellipsometry and polarimetry
(260.1440) Physical optics : Birefringence
(260.5430) Physical optics : Polarization
Qiwen Zhan and James R. Leger, "Microellipsometer with Radial Symmetry," Appl. Opt. 41, 4630-4637 (2002)