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Proceedings Paper

Optimization of SU-8 processing for integrated optics
Author(s): Thomas A. Anhoj; Anders M. Jorgensen; Dan A. Zauner; Jörg Hübner
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Paper Abstract

In order to create high-performance integrated optical components based on polymers, such as on-chip spectrometers for lab-on-a-chip, significant process optimization is needed. Here is reported on the results of investigations concerning two aspects of processing of 40 μm thick coatings of the negative photoresist SU-8: 1) development of a process to remove the edge bead after spin coating, in order to reduce proximity effects in the exposure process, and 2) an investigation of parameters in the baking and exposure steps in order to optimize the lithographic resolution. Both aspects were investigated through design of experiment (DOE) and related statistical analysis. The first DOE investigated the significance of eight process parameters in solvent based edge bead removal (EBR), and involved 51 experiments. The optimized process based on the experimental series reduced the edge bead from approximately 30 μm to less than 1 μm, in effect eliminating it. The second DOE covered six parameters; two in the soft bake step, the exposure time, and three in the post-exposure bake. This DOE contained 64 experiments and resulted in significant resolution improvement. Because of the optimization the trench resolution was improved from a starting point of 6 μm to 2.5 μm, and the ridge resolution improved from 7 μm to 5 μm. As a final outcome the best procedure also results in crack-free films which do not delaminate.

Paper Details

Date Published: 23 January 2006
PDF: 12 pages
Proc. SPIE 6110, Micromachining Technology for Micro-Optics and Nano-Optics IV, 611009 (23 January 2006); doi: 10.1117/12.646489
Show Author Affiliations
Thomas A. Anhoj, Technical Univ. of Denmark (Denmark)
Anders M. Jorgensen, Technical Univ. of Denmark (Denmark)
Dan A. Zauner, Technical Univ. of Denmark (Denmark)
Jörg Hübner, Technical Univ. of Denmark (Denmark)

Published in SPIE Proceedings Vol. 6110:
Micromachining Technology for Micro-Optics and Nano-Optics IV
Eric G. Johnson; Gregory P. Nordin; Thomas J. Suleski, Editor(s)

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