Design and fabrication of a micro-opto-mechanical-systems accelerometer based on intensity modulation of light fabricated by a modified deep-reactive-ion-etching process using silicon-on-insulator wafer

Abstract

Accelerometers that work based on intensity modulation of light are more sensitive, economically feasible, and have a simpler fabrication process compared to wavelength modulation. A micro-opto-electro-mechanical-system accelerometer based on intensity modulation of light is designed and fabricated. A movable shutter that is attached to the proof mass is designed to change the intensity of light. Moreover, the mechanical part is designed to improve the overall sensitivity and linear behavior in the measurement range. The designed accelerometer is fabricated by a deep-reactive-ion-etching (DRIE) process. The DRIE process used in this report is based on a Bosch-like process, which uses [Formula: see text] and a mixture of [Formula: see text], [Formula: see text], and [Formula: see text] gases in etching and passivation subsequences, respectively. This method has a lower plasma density and a higher base pressure and causes higher verticality, which results in lower optical efficiency loss in comparison with the Bosch process. Furthermore, the functional characteristics of the accelerometer are derived with analytical and numerical methods, and the results are compared. The functional characteristics of the accelerometer are as follows: a resonant frequency of 0.56 kHz, a mechanical sensitivity of [Formula: see text], an optical sensitivity of [Formula: see text], an overall sensitivity of [Formula: see text], a footprint of [Formula: see text], a measurement range of [Formula: see text], a mechanical cross axis sensitivity of [Formula: see text], and an overall cross axis sensitivity of [Formula: see text]. These functional characteristics make the design appropriate for a large range of applications.