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A Direct Molding Technique to Fabricate Silica Micro-Optical Components

Published online by Cambridge University Press:  10 February 2011

Choon-Keat Terence Lee ,
Michael J. Vasile  and
Jost Goettert
Choon-Keat Terence Lee
Affiliation:
Institute for Micromanufacturing Louisiana Tech University Ruston, LA 71272
Michael J. Vasile
Affiliation:
Institute for Micromanufacturing Louisiana Tech University Ruston, LA 71272
Jost Goettert
Affiliation:
Institute for Micromanufacturing Louisiana Tech University Ruston, LA 71272
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Abstract

A technology for the direct molding and release of silica micro-optical components in polymethyl methacrylate (PMMA) molds is developed. The objectives of this work are to bypass some of the usual steps in deep x-ray lithography (DXRL) and to determine the suitability of GR650 resin (methylpolysilsequioxane) for molding thick, high aspect ratio structures. The process is initiated by DXRL exposure of PMMA, followed by spin-on glass application, a cure at 85°C to set the shape of the resin, followed by demolding. The cure is below the glass transition temperature of PMMA and the demolding process allows re-use of the mold. There is no need for electroforming in the replication process. PMMA molds with thickness of 250, 350 and 500 um were fabricated by DXRL and standard resist development. A novel metal sacrificial layer technique is used in the release process with initial yield of about 50%. Microoptical elements that were fabricated include lenses, prisms, grating structures and transmission test structures. These components are cured above 400°C after release, to convert the organosilicon polymer to a silica-like material. Weight loss from the high temperature cure was in the range of 15 to 25%, while linear dimensions of the components decreased by about 1%. Composition of the molded, cured structures was measured by XPS depth profiles.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 546: Symposium AA – Materials Science of Microelectromechanical Systems (MEMS)… , 1998 , 189
Copyright
Copyright © Materials Research Society 1999

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