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Journal of Micro/Nanolithography, MEMS, and MOEMS

Accurate layer thickness control and planarization for multilayer SU-8 structures
Author(s): Novak E. S. Farrington; Stavros Iezekiel
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Paper Abstract

A technique is developed to enable accurate layer thickness control and planarization in a multilayer SU-8 2000 micromachining process, while maintaining a high quality surface finish. Relying on carefully controlled mechanical lapping and polishing stages, layer thicknesses from 30-400 μm have been routinely achieved to an accuracy of ±3 μm with excellent planarity. High-aspect ratio structures (intended for use in a millimeter-wave engineering application) with up to five layers and of 770-μm thickness have been fabricated using this method. The quality of the resulting surfaces has been investigated and characterized using scanning probe microscopy: a typical rms surface roughness of around 10 nm has been measured. The problem of air-bubble formation and migration encountered during the lapping stage has been documented along with a technique for their elimination. It is also shown that the common problem of the expansion of the lower layers in a multilayer structure due to solvent reabsorption can be effectively eliminated through careful process optimization.

Paper Details

Date Published: 1 January 2011
PDF: 7 pages
J. Micro/Nanolith. 10(1) 013019 doi: 10.1117/1.3563599
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 10, Issue 1
Show Author Affiliations
Novak E. S. Farrington, e2v technologies (UK) Ltd. (United Kingdom)
Stavros Iezekiel, Univ. of Cyprus (Cyprus)

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