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Optical Engineering

Linear array of complementary metal oxide semiconductor double-pass metal micromirrors
Author(s): Johannes Buehler; Franz-Peter Steiner; Roland Hauert; Henry Baltes
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Paper Abstract

Low-cost linear arrays of deflectable micromirrors using a CMOS-compatible process to define both on-chip circuitry and the mirror structure are presented. The mirrors consist of the CMOS second metal layer deposited in two successive passes in order to establish a thick metal layer for the stiff mirror plate as well as a thin one for the flexible hinges. The mirrors are released by sacrificial aluminum and oxide etching. Supercritical point drying is performed in order to avoid sticking of the mirrors to the substrate. The mirrors are electrostatically deflected by biasing the address electrodes implanted into the substrate underneath the mirror plate. Full angular deflection by ± 4.8 deg of a 30 3 40-µm2 plate is achieved with a driving voltage of 11 V. On-chip circuitry adjacent to each mirror allows one to address the pixels with 5-V data pulses. The reflectance of the aluminum surface for wavelengths between 400 and 700 nm was measured to be 83% to 89%. The mirror surface was further characterized using Auger spectroscopy, showing that no optically relevant surface modifications occur during postprocessing. The surface rms roughness measured by atomic force microscopy is on the order of 25 nm.

Paper Details

Date Published: 1 May 1997
PDF: 8 pages
Opt. Eng. 36(5) doi: 10.1117/1.601346
Published in: Optical Engineering Volume 36, Issue 5
Show Author Affiliations
Johannes Buehler, ETH Zuerich (Switzerland)
Franz-Peter Steiner, ETH Zuerich (Switzerland)
Roland Hauert, Swiss Federal Labs. (Switzerland)
Henry Baltes, ETH Zuerich (Switzerland)

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