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Proceedings Paper

A photolithographic process for grossly nonplanar substrates
Author(s): Gavin L. Williams; Richard P. McWilliam; Jesus Toriz-Garcia; Richard Curry; Andrew Maiden; N. Luke Seed; Alan Purvis; Peter A. Ivey
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Paper Abstract

We describe a technique whereby photolithography has been extended to the patterning of near micron-scale features onto grossly non-planar substrates. Examples will be given of track widths down to ten microns patterned over surfaces with vertical dimensions in excess of one centimetre - far outside the normal bounds of photolithography. The technique enables many novel microsystem packaging schemes and provides an alternative to the direct-write methods that are traditionally employed for patterning non-planar surfaces. The technique is based on the computation of the phase/amplitude distribution on the mask that, when illuminated with light of sufficient spatial coherence, will recreate the desired non-planar light distribution. This has some similarities to existing RET and inverse lithography techniques, but is extended to grossly non-planar surfaces. Exposure of an electrophoretic photoresist-coated substrate to the light field created by the mask enables the non-planar pattern to be transferred to the substrate. The holographic mask contains localized Fresnel patterns. We discuss the analytical methods used for their computation, the approximations necessary to enable mask manufacture and the effects of these approximations on image quality. We also discuss more general numerical methods of mask computation.

Paper Details

Date Published: 1 April 2008
PDF: 9 pages
Proc. SPIE 6921, Emerging Lithographic Technologies XII, 69212E (1 April 2008); doi: 10.1117/12.769148
Show Author Affiliations
Gavin L. Williams, Univ. of Sheffield (United Kingdom)
Richard P. McWilliam, Durham Univ. (United Kingdom)
Jesus Toriz-Garcia, Univ. of Sheffield (United Kingdom)
Richard Curry, Durham Univ. (United Kingdom)
Andrew Maiden, Univ. of Sheffield (United Kingdom)
N. Luke Seed, Univ. of Sheffield (United Kingdom)
Alan Purvis, Durham Univ. (United Kingdom)
Peter A. Ivey, Innotec Ltd. (United Kingdom)

Published in SPIE Proceedings Vol. 6921:
Emerging Lithographic Technologies XII
Frank M. Schellenberg, Editor(s)

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