Inertial Sensor Design at Dynamic Range Extremes: Integrated CMOS-MEMS high-g and mu-g accelerometers

Recent technology trends have seen an increasing commercial use of MEMS accelerometers in gaming platforms, mobile devices, and navigation solutions, among other applications. However a gap exists in the availability of integrated MEMS accelerometers that operate at either extreme of the dynamic range of accelerometers.;The work accomplished in this research addresses this gap in the design of integrated CMOS-MEMS high-g accelerometers and integrated Si-CMOS-MEMS micro-g accelerometers. The high-g sensor design is a 3-axis integrated solution that is unique compared to sensors that operate in a similar dynamic range but are not integrated, and are therefore larger in both volume and size. The CMOS -MEMS high-g sensor designs build on previously demonstrated capacitive CMOS-MEMS accelerometers, designed with resonant frequencies in the single kHz range, and noise limits as low as 45 microg/√Hz [Tsai] [Lakdawala] [Xie]. The design has been fabricated and shock tested up to 30,000 g.;The design of a 3-axis Si-CMOS-MEMS low noise, low drift micro-g accelerometer integrated on a single chip is a novel addition to current navigation-grade inertial sensor technology that operate in a similar dynamic range, but also do not include integrated sensors and therefore suffer in comparison in their volume and weight.;The work also addresses a gap in understanding of the dominant causes of bias drift, and lays the foundation for potential bias drift compensation. Finite element simulations, as well as temperature sensors and on-chip stress sensors are used to understand the relationship between environmental changes and sensor bias. The on-chip stress sensors indicate that other on-chip sensors could eventually be integrated with MEMS sensors to provide bias drift compensation, and thus significantly increasing sensor accuracy for applications where the sensor output is integrated over long periods of time.