Micro-opto-mechanical devices fabricated by anisotropic etching of [110] silicon

Abstract

Anisotropic etching of [110] silicon is used to fabricate high-aspect-ratio stationary microstructures and low-voltage electrostatic microactuators suitable for optical applications. The atomically-smooth (111) sidewalls resulting from anisotropic etching of [110] silicon provide large-area, optical-quality surfaces. The reflectivities of such (111) surfaces, which can be used as mirrors, were measured using a He-Ne laser and were found to be nearly the same as those for the mirror polished surface of a typical [100] silicon wafer. Thin silicon plates with widths less than 2 /spl mu/m were found to be partially transparent (even at the range of He-Ne laser wavelength of 632.8 nm) and could be used as beam splitters. A novel electrostatically-actuated micromirror was fabricated by [110] silicon etching and subsequent bonding to a glass substrate. The micromirror provides an optical beam deflection of 0.7 degrees for a 25 V excitation.