This paper reports an integrated 3-axis CMOS-MEMS accelerometer with single proof mass. Sensor design, fabrication process are introduced and detailed characterization of this small-sized accelerometer is addressed. Compared to the previously reported 3-axis accelerometers, most of which employ thin-film structures and hybrid integration approach, this accelerometer features bulk single-crystal silicon (SCS) structure and monolithic integration with the conditioning circuits. The overall noise is greatly reduced by optimizing the circuit noise and the Brownian noise of MEMS device. To reduce the device size, it employs a unique shared proof mass scheme, where the z-axis sensing element is embedded in the lateral proof mass. Quasi-static, dynamic and temperature characterization of the integrated accelerometer were performed in all three axes. Due to the thick SCS microstructures, the Brownian noise of the sensor was greatly reduced, allowing improved overall device performance. Sensitivities of 560 mV/g and 320 mV/g were measured in lateral axes and z-axis. Due to its asymmetrical structure, the z-axis sensing element demonstrated different cross talks from x- and y-axis. The low-power, low-noise, high sensitivity of this compact device suggests its wide potential applications in physiological monitoring, engineering monitoring and portable electronics.
Journal: TechConnect Briefs
Volume: 3, Technical Proceedings of the 2007 NSTI Nanotechnology Conference and Trade Show, Volume 3
Published: May 20, 2007
Pages: 13 - 16
Industry sector: Sensors, MEMS, Electronics
Topic: MEMS & NEMS Devices, Modeling & Applications