Optical properties of surface micromachined mirrors with etch holes

TitleOptical properties of surface micromachined mirrors with etch holes
Publication TypeJournal Article
Year of Publication1999
AuthorsJ Zou, M Balberg, C Byrne, C Liu, and DJ Brady
JournalJournal of Microelectromechanical Systems
Volume8
Start Page506
Issue4
Pagination506 - 513
Date Published12/1999
Abstract

We have investigated the optical properties of surface-micromachined polycrystalline silicon reflectors within the visible spectral range at five different wavelengths. The measurement results of the reflectivity of various microreflectors at four different incident angles (20°, 30°, 45°, and 60°) are presented. Optical properties of microreflectors realized using the multiuser MEMS process (MUMPS) have been investigated. Our studies have found that etch holes, widely used in the surface micromachining process to reduce the time for releasing structures by sacrificial undercutting, have a great influence on the optical properties of micromachined mirrors. Diffraction patterns created by two-dimensional etch-hole arrays on micromachined mirrors have been investigated. The diffraction by etch holes obeys the Fraunhofer diffraction theory when a collimated light source (e.g., a laser beam) is incident. We have shown that when the dimension of etch holes increases, an increasing portion of the incident power will be diffracted and transmitted due to etch holes, leading to decreasing reflectivity of surface micromachined mirrors.

DOI10.1109/84.809066
Short TitleJournal of Microelectromechanical Systems