Design and processing experiments of a new miniaturized capacitive triaxial accelerometer

A new accelerometer design is presented, which enables accelerations to be measured along three axes by using only one seismic mass. Two versions have been designed. The larger version has an input range of +/- 8g and a relative capacitance change of about 200% (full scale). The smaller version has an input range of +/- 10g and a relative capacitance change of about 100% (full scale). The dimensions are 5 mm x 4.8 mm x 1.4 mm and 2.2 mm x 2.0 mm x 1.3 mm, respectively. The chosen technology is bulk micromachining, so the seismic mass is fabricated in an anisotropic wet etch step. The etchant is aqueous KOH, saturated with isopropyl alcohol. A [110] strip corner undercutting compensation technique has been adapted. It is shown that a full three-axis accelerometer can be fabricated in silicon by adapting the state-of-the-art micromachining tools. (C) 1998 Elsevier Science S.A. All rights reserved.