PROJECT TITLE :

Monolithic CMOS—MEMS Pure Oxide Tri-Axis Accelerometers for Temperature Stabilization and Performance Enhancement

ABSTRACT:

A complementary metal–oxide–semiconduc-tor (CMOS)–microelectromechanical system (MEMS) accelero-meter with stacked pure oxide layers as mechanical structures was developed. Metal layers were confined to the sensing electrodes and electrical routings; the metal–oxide composite in the CMOS–MEMS accelerometer was distributed in restricted regions. This style has 2 major advantages: one) the thermal deformation of suspended MEMS structures resulting from a mismatch in the coefficients of thermal growth of the metal and also the oxide in the metal–oxide films is suppressed; and a couple of) the parasitic capacitance of the sensing electrode routing underneath the proof mass is reduced. So, the accelerometer has higher sensitivity and reduced thermal drift. The curvature of the mechanical structures are improved within the temperature span and also the noise floor is lowered. In the complete temperature span (thirty °C–90 °C), modification in the radius of curvature per unit amendment within the temperature was 0.08%/°C for the in-plane accelerometer and 0.37%/°C for the out-of-plane accelerometer. Compared with the standard metal–oxide style, the proposed pure oxide style yielded a >twenty-fold improvement in radius of curvature modification per unit temperature amendment for the in-plane accelerometer and a fivefold improvement for the out-of-plane accelerometer. Moreover, the noise floor was reduced to 0.forty ( $x$ -axis), zero.twenty one ( $y$ -axis), and 0.ninety four mG Hz $^-1/2$ ( $z$ -axis), respectively, a two.two–seven.vi-fold improvement compared with the metal–oxide design. [2015-0012]