High-Vacuum Package for MEMS Inertial Sensors

High-sensitivity resonant vibratory microelectromechanical systems (MEMS) sensors are typically vacuum packaged in discreet packages. Wafer-scale vacuum packaging offers size, weight, and cost advantages, and the packages are more shock and vibration tolerant. However, the high internal pressures and leak rates achieved to date through wafer-scale vacuum packaging have rendered this an approach suitable for only the lowest performance devices. For this project, Creare Inc. and the NASA Jet Propulsion Laboratory (JPL) have teamed to develop an advanced wafer-level packaging approach that offers the extremely low, sustained vacuum levels required for long-term, high-Q operation of navigation grade MEMS inertial sensors. The packaging approach also addresses susceptibility to temperature changes, mechanical vibration, and shock. The basic principles for producing and maintaining extreme vacuum levels, on which this packaging approach is based, have already been demonstrated by JPL in a sealed sensor package. In Phase I, the team will further show the feasibility of the approach at wafer scale by designing a generic sensor package and modeling its performance. In Phase II, the team will demonstrate the package performance using packaged vacuum sensors and an extremely sensitive MEMS gyroscope being developed for military firing control systems.