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Proceedings Paper

Optimization methods for 3D lithography process utilizing DMD-based maskless grayscale photolithography system
Author(s): Xiaoxu Ma; Yoshiki Kato; Yoshikazu Hirai; Floris van Kempen; Fred van Keulen; Toshiyuki Tsuchiya; Osamu Tabata
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Paper Abstract

Digital Micromirror Device (DMD)-based grayscale lithography is a promising tool for three dimensional (3D) microstructuring of thick-film photoresist since it is a maskless process, provides possibility for the free-form of 3D microstructures, and therefore rapid and cost-effective microfabrication. However, process parameter determination lacks efficient optimization tool, and thus conventional look-up table (indicating the relationship between development depth and exposure dose value under a fixed development time) approach with manual try-and-error adjustment is still gold standard. In this paper, we firstly present a complete “input target-output parameters” single exposure optimization method for 3D microstructuring utilizing DMD-based grayscale lithography. This numerical optimization based on lithography simulation and sensitivity analysis can automatically optimize a combination of three process parameters for target microstructure; exposure dose pattern, a focal position, and development time. Through a series of experiments using a 20 μm thick positive photoresist, validity of the proposed optimization approach has been successfully verified. Secondly, with the purpose of further advancing accuracy and improve the uniformity of precision for the target area, a multiple exposure optimization method is proposed. The simulated results proved that the multiple exposure optimization method is a promising strategy to further improve precision for thicker photoresist structure.

Paper Details

Date Published: 18 March 2015
PDF: 10 pages
Proc. SPIE 9426, Optical Microlithography XXVIII, 94260F (18 March 2015); doi: 10.1117/12.2084486
Show Author Affiliations
Xiaoxu Ma, Kyoto Univ. (Japan)
Yoshiki Kato, Kyoto Univ. (Japan)
Yoshikazu Hirai, Kyoto Univ. (Japan)
Floris van Kempen, Technische Univ. Delft (Netherlands)
Fred van Keulen, Technische Univ. Delft (Netherlands)
Toshiyuki Tsuchiya, Kyoto Univ. (Japan)
Osamu Tabata, Kyoto Univ. (Japan)

Published in SPIE Proceedings Vol. 9426:
Optical Microlithography XXVIII
Kafai Lai; Andreas Erdmann, Editor(s)

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