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Journal of Micro/Nanolithography, MEMS, and MOEMS • Open Access

Intensity and phase fields behind phase-shifting masks studied with high-resolution interference microscopy

Paper Abstract

We try to find out the details of how light fields behind the structures of photomasks develop in order to determine the best conditions and designs for proximity printing. The parameters that we use approach real situations like structure printing at proximity gaps of 20 to 50  μm and structure sizes down to 2  μm. This is the first time that an experimental analysis of light propagation through a mask is presented in detail, which includes information on intensity and phase. We use high-resolution interference microscopy (HRIM) for the measurement. HRIM is a Mach–Zehnder interferometer, which is capable of recording three-dimensional distributions of intensity and phase with diffraction-limited resolution. Our characterization technique allows plotting the evolution of the desired light field, usually called the aerial image, and therefore gives access to the printable structure until the desired proximity gap. Here, we discuss in detail the evolution of intensity and phase fields of elbow or corner structures at different positions behind a phase mask and interpret the main parameters. Of particular interest are tolerances against proximity gap variation and the theoretical explanation of the resolution in printed structures.

Paper Details

Date Published: 29 January 2016
PDF: 8 pages
J. Micro/Nanolith. MEMS MOEMS 15(2) 021203 doi: 10.1117/1.JMM.15.2.021203
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 15, Issue 2
Show Author Affiliations
Krishnaparvathy Puthankovilakam, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Toralf Scharf, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Myun-Sik Kim, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Ali Naqavi, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Hans Peter Herzig, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Tina Weichelt, Friedrich-Schiller-Univ. Jena (Germany)
Uwe D. Zeitner, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Uwe Vogler, SUSS MicroOptics SA (Switzerland)
Reinhard Voelkel, SUSS MicroOptics SA (Switzerland)

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