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Journal of Micro/Nanolithography, MEMS, and MOEMS

Bilayer lift-off process for aluminum metallization
Author(s): Thomas E. Wilson; Konstantin A. Korolev; Nathaniel A. Crow
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Paper Abstract

Recently published reports in the literature for bilayer lift-off processes have described recipes for the patterning of metals that have recommended metal-ion-free developers, which do etch aluminum. We report the first measurement of the dissolution rate of a commercial lift-off resist (LOR) in a sodium-based buffered commercial developer that does not etch aluminum. We describe a reliable lift-off recipe that is safe for multiple process steps in patterning thin (<100  nm) and thick aluminum devices with micron-feature sizes. Our patterning recipe consists of an acid cleaning of the substrate, the bilayer (positive photoresist/LOR) deposition and development, the sputtering of the aluminum film along with a palladium capping layer and finally, the lift-off of the metal film by immersion in the LOR solvent. The insertion into the recipe of postexposure and sequential develop-bake-develop process steps are necessary for an acceptable undercut. Our recipe also eliminates any need for accompanying sonication during lift-off that could lead to delamination of the metal pattern from the substrate. Fine patterns were achieved for both 100-nm-thick granular aluminum/palladium bilayer bolometers and 500-nm-thick aluminum gratings with 6-μm lines and 4-μm spaces.

Paper Details

Date Published: 20 January 2015
PDF: 5 pages
J. Micro/Nanolith. 14(1) 014501 doi: 10.1117/1.JMM.14.1.014501
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 14, Issue 1
Show Author Affiliations
Thomas E. Wilson, Marshall Univ. (United States)
Konstantin A. Korolev, Marshall Univ. (United States)
Nathaniel A. Crow, Marshall Univ. School of Medicine (United States)

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