Micromachined Precision Inertial Instruments

This program focuses on developing inertial-grade micromachined accelerometers and gyroscopes and their associated electronics and packaging for use in a variety of military and commercial applications. During the project timeline in-plane, out-of-plane and monolithic 3-axis accelerometers have been developed with their interface electronics. Analysis, simulation, fabrication, and testing techniques for these accelerometer systems have been developed. All different types of accelerometers have been tested with the interface electronics. 1.08μg open-loop and 10μg closed-loop resolution have been achieved with out-of-plane accelerometers. For in-plane accelerometers open-loop resolutions are 80μg and 1.6μg for SOG and all-silicon devices, respectively. Single-chip, three-axis accelerometers are consistent with the out-of-plane and all-silicon in-plane accelerometers. Polysilicon ring gyroscopes utilizing high aspect ratio combined poly and single crystal silicon (HARPSS) technology has been developed. This technology provides tall structure (~80μm) and large sense/drive gaps, which are essential to achieve high performance gyroscopes. The gyroscopes are tested with readout electronics, control circuitry, and quadrature control loop, and achieve a quality factor of 1,200 and 2°/sec in 10Hz BW. A single crystal silicon gyroscope has been developed in order to obtain small parasitics, large quality factor, and large structural mass. This device has 150μm thick single crystal silicon on a glass substrate, large (10μm) sense/drive gap. The single crystal silicon gyroscope achieves a quality factor of 12,000, good linearity (0.02%), large sensitivity (132 mV/°/sec), and low output noise (10.4 °/hr/√Hz).