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Journal of Micro/Nanolithography, MEMS, and MOEMS

Fabrication of three-dimensional millimeter-height structures using direct ultraviolet lithography on liquid-state photoresist for simple and fast manufacturing
Author(s): Jungkwun Kim; Yong-Kyu Yoon
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Paper Abstract

A rapid three-dimensional (3-D) ultraviolet (UV) lithography process for the fabrication of millimeter-tall high aspect ratio complex structures is presented. The liquid-state negative-tone photosensitive polyurethane, LF55GN, has been directly photopatterned using multidirectionally projected UV light for 3-D micropattern formation. The proposed lithographic scheme enabled us to overcome the maximum height obtained with a photopatternable epoxy, SU8, which has been conventionally most commonly used for the fabrication of tall and high aspect ratio microstructures. Also, the fabrication process time has been significantly reduced by eliminating photoresist-baking steps. Computer-controlled multidirectional UV lithography has been employed to fabricate 3-D structures, where the UV-exposure substrate is dynamically tilt-rotating during UV exposure to create various 3-D ray traces in the polyurethane layer. LF55GN has been characterized to provide feasible fabrication conditions for the multidirectional UV lithography. Very tall structures including a 6-mm tall triangular slab and a 5-mm tall hexablaze have been successfully fabricated. A 4.5-mm tall air-lifted polymer-core bowtie monopole antenna, which is the tallest monopole structure fabricated by photolithography and subsequent metallization, has been successfully demonstrated. The antenna shows a resonant radiation frequency of 12.34 GHz, a return loss of 36 dB, and a 10 dB bandwidth of 7%.

Paper Details

Date Published: 15 July 2015
PDF: 8 pages
J. Micro/Nanolith. MEMS MOEMS 14(3) 033504 doi: 10.1117/1.JMM.14.3.033504
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 14, Issue 3
Show Author Affiliations
Jungkwun Kim, Univ. of Pennsylvania (United States)
Yong-Kyu Yoon, Univ. of Florida (United States)

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