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Proceedings Paper

Optical metrology of micro- and nanostructures at PTB: status and future developments
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Paper Abstract

Today, various types of high resolution dimensional metrology instrumentation are in use for a quantitative characterisation of micro- and nanostructures. Although sophisticated ultra high resolution microscopic techniques like SEM and AFM are available, optical methods like microscopy and scatterometry are still of interest and are important because they are non-destructive, fast and have a good in-line capability. At PTB different optical tools are used for high-resolution metrology. Our standard instrument for CD metrology is a special UV transmission microscope. A new 193nm microscope is currently under development which will meet future requirements at least for the 32nm node as specified in the ITRS roadmap. A special alternating grazing incidence dark field microscope is used to measure the width of single features down to 100nm. For grating structures, we developed an optical diffractometer for pitch calibrations with an uncertainty down to 10 pm. Recently we realised a DUV scatterometer and ellipsometer capable to measure accurately CD, edge profile, layer thickness, and optical parameters. A versatile EUV scatterometer can be used to characterise absorber structures e. g. on EUV photomasks. For accurate measurements a thorough modelling on the basis of rigorous diffraction calculation is essential, which accounts for both polarisation effects and the 3D geometry of the structures. We use the rigorous coupled wave analysis (RCWA) method and the finite elements (FEM) method. We present an overview of PTB's current and future activities in optical high-resolution metrology and how these systems compare to ultra-high resolution microscopy like SEM or AFM.

Paper Details

Date Published: 3 October 2008
PDF: 12 pages
Proc. SPIE 7155, Ninth International Symposium on Laser Metrology, 71550V (3 October 2008); doi: 10.1117/12.814531
Show Author Affiliations
Bernd Bodermann, Physikalisch-Technische Bundesanstalt (Germany)
Egbert Buhr, Physikalisch-Technische Bundesanstalt (Germany)
Gerd Ehret, Physikalisch-Technische Bundesanstalt (Germany)
Frank Scholze, Physikalisch-Technische Bundesanstalt (Germany)
Matthias Wurm, Physikalisch-Technische Bundesanstalt (Germany)

Published in SPIE Proceedings Vol. 7155:
Ninth International Symposium on Laser Metrology
Chenggen Quan; Anand Asundi, Editor(s)

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