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Proceedings Paper

Creating 3D structures with a direct-write grayscale photomask made from Sn/In bimetallic films
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Paper Abstract

Bilayer thermal resist Sn/In films have been found to be promising analogue direct-write photomask materials. The bimetallic films turn to be more transparent after a laser exposure which raises the films above the eutectic temperature. Laser converted layers are oxidized to a controlled extent, depending on the laser exposure energy. The exposure causes a change of absorption at 365nm from 3OD to 0.22OD. The thermal resist shows near wavelength invariance from IR to UV. The Sn/In films, each layer ~40 nm thick, were DC-sputtered onto glass slides or quartz substrates. To make grayscale photomasks the samples are placed on a computer-controlled high accuracy X-Y table. The computer takes a bitmap gray-scale pattern as the input and modulates an optical shutter, which in turn, controls the actual power of a CW Argon laser (514 nm) beam applied to the thermal resist according to the gray-scale value. Sn/In photomasks have been used together with a standard mask aligner to successfully make 3D patterns on Shipley SPR2FX-1.3 photoresist. CF4/O2 plasma etching has been used to transfer the 3D patterns to SiO2 substrates. XRD analysis shows that laser power determines the extent of oxidation of the metal films.

Paper Details

Date Published: 15 July 2004
PDF: 12 pages
Proc. SPIE 5339, Photon Processing in Microelectronics and Photonics III, (15 July 2004); doi: 10.1117/12.529492
Show Author Affiliations
Glenn Chapman, Simon Fraser Univ. (Canada)
Yuqiang Tu, Simon Fraser Univ. (Canada)
Jun Peng, Simon Fraser Univ. (Canada)

Published in SPIE Proceedings Vol. 5339:
Photon Processing in Microelectronics and Photonics III
Jan J. Dubowski; Peter R. Herman; Friedrich G. Bachmann; Willem Hoving; Jim Fieret; David B. Geohegan; Frank Träger; Kunihiko Washio; Alberto Pique; Xianfan Xu; Tatsuo Okada, Editor(s)

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