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Journal of Micro/Nanolithography, MEMS, and MOEMS

Demonstration of fabricating a needle array by the combination of x-ray grayscale mask with the lithografie, galvanoformung, abformung process
Author(s): Harutaka Mekaru; Takayuki Takano; Koichi Awazu; Masaharu Takahashi; Ryutaro Maeda
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Paper Abstract

We demonstrated fabricating a needle array of polycarbonate (PC) and polymethyl methacrylate (PMMA) by using a 3-D LIGA (lithografie, galvanoformung, abformung) process. The diameter of the bottom of the needle was about 50 µm, and the height was 135 µm. Although the LIGA process is commonly applied for making structures with vertical sidewalls, the use of an x-ray grayscale mask in the LIGA process has made it possible to fabricate needle-shaped structures. The x-ray grayscale mask was composed of a Si x-ray absorber and an SU-8 membrane. The sidewall of the x-ray absorber was diagonally processed by Si tapered-trench-etching technology such that the transmission intensity of x rays could be changed locally. The x-ray lithography experiment was executed by using this x-ray grayscale mask on a beamline BL-4 in the TERAS synchrotron radiation facility at National Institute of Advanced Industrial Science and Technology (AIST). By using this facility, a PMMA resist master with three-dimensional (3-D) structures was made. A Pt layer was then sputter-deposited as a seed layer on the PMMA resist master, and a Ni mold was fabricated by electroforming technology. In addition, a needle array of PC and PMMA was produced by hot embossing technology. Self-assembled monolayers (SAMs) of a release agent were required on the surface of the mold pattern to achieve a complete molding. Thus, we succeeded in extending the LIGA process to three dimensions by the use of an x-ray grayscale mask.

Paper Details

Date Published: 1 July 2009
PDF: 9 pages
J. Micro/Nanolith. 8(3) 033010 doi: 10.1117/1.3158617
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 8, Issue 3
Show Author Affiliations
Harutaka Mekaru, National Institute of Advanced Industrial Science and Technology (Japan)
Takayuki Takano, National Institute of Advanced Industrial Science and Technology (Japan)
Koichi Awazu, National Institute of Advanced Industrial Science and Technology (Japan)
Masaharu Takahashi, National Institute of Advanced Industrial Science and Technology (Japan)
Ryutaro Maeda, National Institute of Advanced Industrial Science and Technology (Japan)


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