Silicon-compatible waveguides used for an integrated opto-mechanical pressure sensor

We present the investigation of different types of silicon-compatible optic al waveguides and the possibility to use them in an opto-mechanical pressur e sensor. Silicon-based integrated optics appears as an attractive domain o f applications for micromachining and allows the development of micro-opto- mechanical systems (MOEMS). Optical systems integrated on silicon are of sp ecial interest because of their process compatibility with CMOS technology. The work is focused on the fabrication of an opto-mechanical pressure sens or based on a Mach-Zehnder interferometer, integrated with photodiodes and diaphragms. Micromechanical, optical and microelectronic structures are fab ricated on the same silicon substrate. The mechanical part is a cascade of three diaphragms, made by wet anisotropic etching of the substrate. For opt ical waveguides we experimented with different materials: Si3N4, SiON, poly imides, SiC, and amorphous silicon. We investigated the optical properties of these materials, technological processes and the possibility to integrat e them in a microsystem. (C) 2001 Elsevier Science B.V. All rights reserved .