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Expanded beam (macro-imaging) ellipsometry

 
: Fried, M.; Juhasz, G.; Major, C.; Petrik, P.; Polgar, O.; Horvath, Z.; Nutsch, A.

:

Tompkins, H.G.:
5th International Conference on Spectroscopic Ellipsometry, ICSE 2010 : Held in Albany NY, USA from May 23 to May 29, 2010
Amsterdam: Elsevier, 2011 (Thin solid films 519.2011, Nr.9)
ISSN: 0040-6090
pp.2730-2736
International Conference on Spectroscopic Ellipsometry (ICSE) <5, 2010, Albany/NY>
English
Conference Paper, Journal Article
Fraunhofer IISB ()

Abstract
Our aim was to make possible to use spectroscopic ellipsometry for mapping purposes during one measuring cycle (minimum one rotation period of polarizer or analyzer) on many sample points. Our new technique uses non-collimated (non-parallel, mostly diffuse) illumination with an angle of incidence sensitive pinhole camera detector system and it works as an unusual kind of imaging ellipsometry. Adding multicolour supplemets, it provides spectral (a few wavelengths on a 2D image or a full spectrum along a line) information from rapid measurements of many points on a large (several dm2) area. This technique can be expanded by upscaling the geometry (upscaling the dimensions of the instrument, and characteristic imaging parameters such as focal lengths, distances, etc.). The lateral resolution is limited by the minimum resolved-angle determined by the detector system, mainly by the diameter of the pinhole. (The diameter of the pinhole is a compromise between the light intensity and the lateral resolution.) Small-aperture (25 mm diameter) polarizers are incorporated into both the polarization state generator (PSG) and polarization state detection (PSD) components of the instrument. The detection is almost without background because the pinhole serves as a filter against the scattered light. One rapid measuring cycle (less than 10 s) is enough to determine the polarization state at all the points inside the illuminated area. The collected data can be processed very fast (seconds) providing nearly real-time thicknesses and/or refractive index maps over many points of the sample surface even in the case of multilayer samples. The speed of the measuring system makes it suitable for using even on production lines. The necessary (in each sample-point different) angle-of-incidence and the mirror-effect calibration are made via well-known and optimized structures such as silicon/silicon-dioxide samples. The precision is suitable for detecting sub-nanometer thickness and a refractive index change of 0.01. The method can be used for mapping and quality control in the case of large area solar cell table production lines even in a vacuum chamber with 5-10mm lateral resolution.

: http://publica.fraunhofer.de/documents/N-163333.html