Micromirror Angle Dependence with Etchant Choice on <100> Silicon Via Wet Etching

Al-Hafidh, M., Wilson, R. , Glidle, A., Reboud, J. , Kelly, A. and Cooper, J.M. (2019) Micromirror Angle Dependence with Etchant Choice on <100> Silicon Via Wet Etching. In: 2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO), Cork, Ireland, 23-26 Jul 2018, ISBN 9781538653364 (doi: 10.1109/NANO.2018.8626355)

Abstract

In creating mirrored silicon structures for micro-optics, the smoothness of the surface and etch rate are crucial parameters. We demonstrate a method of creating both 45° and 90° etch-planes from monocrystalline silicon for use as retro-reflective sidewalls in a microfluidic device. The technique uses the same photolithographic pattern orientation, but with two different etchants. Etching on <;100> direction in Si(100) with potassium hydroxide (KOH) gives vertical surfaces (where e.g. the high surface tension influences etching of crystallographic silicon planes), whilst tetramethylammonium hydroxide (TMAH) gives 45° sidewalls. We illustrate the use of these fabricated structures by creating arrays of micromirrors that enable an optical beam to be reflected parallel back and forth from 45° and -45° tilted vertical structures. This device has potential uses in optofluidic spectroscopic applications, where there is a need to increase the effective pathlength of a beam through a sample whilst keeping the device as small as possible.

• Item Type: Conference Proceedings
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wilson, Dr Robert and Glidle, Dr Andrew and Al-Hafidh, Ms Maab and Cooper, Professor Jonathan and Reboud, Professor Julien and Kelly, Professor Anthony
• Authors: Al-Hafidh, M., Wilson, R., Glidle, A., Reboud, J., Kelly, A., and Cooper, J.M.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering; College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• ISSN: 1944-9380
• ISBN: 9781538653364
• Published Online: 28 January 2019
• Copyright Holders: Copyright © 2018 IEEE
• First Published: First published in 2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO)
• Publisher Policy: Reproduced in accordance with the publisher copyright policy