Lithography

Fabrication of three-dimensional millimeter-height structures using direct ultraviolet lithography on liquid-state photoresist for simple and fast manufacturing

[+] Author Affiliations
Jungkwun Kim

University of Pennsylvania, Department of Electrical and Systems Engineering, Philadelphia, Pennsylvania 19104, United States

Yong-Kyu Yoon

University of Florida, Department of Electrical and Computer Engineering, Gainesville, Florida 32611, United States

J. Micro/Nanolith. MEMS MOEMS. 14(3), 033504 (Jul 15, 2015). doi:10.1117/1.JMM.14.3.033504
History: Received April 14, 2015; Accepted June 17, 2015
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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%.

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© 2015 Society of Photo-Optical Instrumentation Engineers

Citation

Jungkwun Kim and Yong-Kyu Yoon
"Fabrication of three-dimensional millimeter-height structures using direct ultraviolet lithography on liquid-state photoresist for simple and fast manufacturing", J. Micro/Nanolith. MEMS MOEMS. 14(3), 033504 (Jul 15, 2015). ; http://dx.doi.org/10.1117/1.JMM.14.3.033504


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