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Proceedings Paper

On-chip replication of high-sag micro-optical components fabricated by direct laser writing
Author(s): Daniel Asselin; Patrice Topart; Lieyi Sheng; Felix Cayer; Sebastien Leclair; Min Wang; Hubert Jerominek
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Paper Abstract

This paper describes the fabrication of very high-sag (up to 42 μm) microlenses by direct laser writing and their integration onto a simple microoptical bench processed by conventional microfabrication technologies pertaining to MOEMS. At the heart of such a work is INO's laser writer. It is based on a He-Cd laser operating at 442 nm whose intensity can be modulated up to 1024 levels, and on a 40 nm accuracy X-Y translation stage. Laser writing into thick photoresist layers introduces however particular problems in terms of the roughness achievable. Simulations show that the writing beam diameter, the line-to-line spacing and the translation stage accuracy contribute to some unavoidable residual roughness. By applying optimized laser writing parameters, arrays of 1 x 5 aspherical microlenses were fabricated in a thick positive photoresist, along with alignment marks concurrently generated for on-chip alignment purposes. The microlenses were successfully integrated with a microoptical bench by first generating a UV-transparent mold from the photoresist laser written master. The microlenses imprinted in the mold were then replicated in a layer of hybrid glass material cast on the microoptical bench by UV-embossing with a modified MA6 mask aligner. The uniformity of focal lengths was approximately 3% as determined from best fits of profilometric traces. The replication with alignment of this array in a hybrid glass material was demonstrated on a 12 mm x 12 mm microoptical bench chip. An alignment accuracy of less than 5 μm was obtained. The replication error was less than about 4%. The measured surface roughness was 50-60 nm RMS, in good agreement with simulation results.

Paper Details

Date Published: 22 January 2005
PDF: 11 pages
Proc. SPIE 5720, Micromachining Technology for Micro-Optics and Nano-Optics III, (22 January 2005); doi: 10.1117/12.591719
Show Author Affiliations
Daniel Asselin, INO (Canada)
Patrice Topart, INO (Canada)
Lieyi Sheng, INO (Canada)
Felix Cayer, INO (Canada)
Sebastien Leclair, INO (Canada)
Min Wang, INO (Canada)
Hubert Jerominek, INO (Canada)

Published in SPIE Proceedings Vol. 5720:
Micromachining Technology for Micro-Optics and Nano-Optics III
Eric G. Johnson; Gregory P. Nordin; Thomas J. Suleski, Editor(s)

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