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Measurement of surface topographies in the nm-range for power chip technologies by a modified low-coherence interferometer

: Taudt, Christopher; Baselt, Tobias; Nelsen, Bryan L.; Aßmann, Heiko; Greiner, Andreas; Koch, Edmund; Hartmann, Paul

Fulltext urn:nbn:de:0011-n-4151355 (494 KByte PDF)
MD5 Fingerprint: 3b17c36ec3b35428376ab5dba0e2588e
Copyright Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
Created on: 01.03.2017

Soskind, Y.G. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Photonic Instrumentation Engineering III : 17-18 February 2016, San Francisco, California, United States
Bellingham, WA: SPIE, 2016 (Proceedings of SPIE 9754)
ISBN: 9781628419894
Paper 97540H, 7 pp.
Conference "Photonic Instrumentation Engineering" <3, 2016, San Francisco/Calif.>
Bundesministerium für Bildung und Forschung BMBF
03FH004PX3; Dispersionsmessplatz
Conference Paper, Electronic Publication
Fraunhofer IWS ()
dispersion based measurements; in-line characterization; interferometric measurement; low-coherence interferometry; optical metrology; surface profilometry

This work introduces a modified low-coherence interferometry approach for nanometer surface-prolometry. The key component of the interferometer is an element with known dispersion which defines the measurement range as well as the resolution. This dispersive element delivers a controlled phase variation which can be detected in the spectral domain and used to reconstruct height differences on a sample. In the chosen setup, both axial resolution and measurement range are tunable by the choice of the dispersive element. The basic working principle was demonstrated by a laboratory setup equipped with a supercontinuum light source (Δλ= 400-1700 nm). Initial experiments were carried out to characterize steps of 101 nm on a silicon height standard. The results showed that the system delivers an accuracy of about 11.8 nm. These measurements also served as a calibration for the second set of measurements. The second experiment consisted of the measurement of the bevel of a silicon wafer. The modified low-coherence interferometer could be utilized to reproduce the slope on the edge within the previously estimated accuracy. The main advantage of the proposed measurement approach is the possibility to collect data without the need for mechanically moving parts.