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Proceedings Paper

Half-tone proximity lithography
Author(s): Torsten Harzendorf; Lorenz Stuerzebecher; Uwe Vogler; Uwe D. Zeitner; Reinhard Voelkel
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Paper Abstract

The half-tone lithography using pixilated chromium masks in a projection stepper is an established technology in micro-optics fabrication. However, the projection lithography tool is comparably expensive and the achievable lateral resolution is typically limited. By using pixel diffraction effects, binary and continuous profile lithography with submicron resolution can be installed on a conventional mask aligner. To achieve this goal the control of both, the angular spectrum of the illumination and the mask features is essential. We used a novel micro-optics based illumination system referred as "MO Exposure Optics System" in a SUSS MicroTec MA6 mask aligner for the dedicated shaping of the angular illumination distribution. In combination with an adapted lithography mask the formation of a desired intensity distribution in the resist layer is possible. A general mathematic model describes the relation between the angular spectrum of the mask illumination, pixel size and pitch in the mask, proximity distance and propagated field, which also includes special cases like Talbot imaging. We show that a wide range of different micro-optical structures can be optimized by controlling the light diffraction in proximity lithography. Parameter settings were found for submicron binary pattern up to continuous profile structures with extensions up to several tens of microns. An additional interesting application of this approach is the combination of binary and continuous profiles in single elements, e.g. micro lenses with diffractive correction or AR structures. Experimental results achieved for blazed gratings with a period of 2 microns are presented.

Paper Details

Date Published: 13 May 2010
PDF: 10 pages
Proc. SPIE 7716, Micro-Optics 2010, 77160Y (13 May 2010); doi: 10.1117/12.854307
Show Author Affiliations
Torsten Harzendorf, Fraunhofer Institut für Angewandte Optik und Feinmechanik (Germany)
Lorenz Stuerzebecher, Fraunhofer Institut für Angewandte Optik und Feinmechanik (Germany)
Uwe Vogler, SUSS MicroOptics SA (Switzerland)
Uwe D. Zeitner, Fraunhofer Institut für Angewandte Optik und Feinmechanik (Germany)
Reinhard Voelkel, SUSS MicroOptics SA (Switzerland)


Published in SPIE Proceedings Vol. 7716:
Micro-Optics 2010
Hugo Thienpont; Peter Van Daele; Jürgen Mohr; Hans Zappe, Editor(s)

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