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Optical Engineering

Micromirror arrays using KOH:H2O micromachining of silicon for lens templates, geodesic lenses, and other applications
Author(s): Don L. Kendall; William P. Eaton; Ronald P. Manginell; Thomas G. Digges
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Paper Abstract

Micromirrors having diameters from a few micrometers to several millimeters have been produced on (100) silicon by wet-chemical etching in KOH:H2O. The f/#'s range from about 2.5 to at least 10. The microroughness of an etched mirror with diameter 550 μm and 9.6-μm sagitta is less than 5 nm and its surface figure is within 0.5 μm of a perfect sphere. Data over a wide range of diameters are presented and a semiempirical model is developed to explain the behavior. The concordance of the normalized etched profiles for all diameter mirrors demonstrates that the etching is dominated by surface reaction rather than diffusion limitation. Design and fabrication schemes are presented for making a wide range of mirror diameters and focal lengths, for both single micromirrors and arrays. The etched depressions can be used as templates for microlenses and as substrates for geodesic waveguide lenses and arrays. Chem-mechanical polishing on the etched structures reduces the edge curvature and produces oblate spheroidal surfaces, both of which should improve geodesic lens behavior. The etched structures can also be used as variable crystal orientation substrates for epitaxial nucleation and various surface analysis studies.

Paper Details

Date Published: 1 November 1994
PDF: 11 pages
Opt. Eng. 33(11) doi: 10.1117/12.179881
Published in: Optical Engineering Volume 33, Issue 11
Show Author Affiliations
Don L. Kendall, Univ. of New Mexico (United States)
William P. Eaton, Univ. of New Mexico (United States)
Ronald P. Manginell, Univ. of New Mexico (United States)
Thomas G. Digges, Virginia Semiconductor, Inc. (United States)

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