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Article
Bilayer Lift-Off Process for Aluminum Metallization
Physics Faculty Research
  • Thomas E. Wilson, Marshall University
  • Konstantin Korolev
  • Nathaniel A. Crow
Document Type
Article
Publication Date
1-1-2015
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

Comments

The version of record is available from the publisher at http://dx.doi.org/10.1117/1.JMM.14.1.014501. Copyright © 2015 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Reprinted with permission. All rights reserved.

Citation Information
Thomas E. Wilson, Konstantin A. Korolev and Nathaniel A. Crow, “Bilayer Lift-Off Process for Aluminum Metallization,” Journal of Micro/Nanolithography MEMS MOEMS, 14(1), 014501-1, (2015).