Chip-Scale Inertial Measurement Unit Utilizing Folded MEMS Fabrication

    Mr. Monty Rivers

MAE, UC Irvine

January 14, 2011

Abstract

Integration of inertial measurement units (IMUs) into compact systems is desired for several applications such as defense, aerospace, and consumer electronics.  Current methods for creating a miniature IMU utilize PCB assemblies, multi-axis sensors, multiple sensors on a single die, or a combination of all three. Inherent challenges of these approaches results in either limited miniaturization or a compromise in performance of the overall IMU. Therefore a new approach to fabrication of a chip-level IMU is explored using foldable MEMS structures. The folded-chip method utilizes a 3-D foldable SOI backbone suitable for high-aspect ratio sensor fabrication. Assembly is done on the wafer level forming a compact 6-axis system of sensors. Accelerometers and gyroscopes are fabricated in parallel with the folded structure on the same substrate, and are electrically and mechanically interfaced through integrated flexible polyimide film hinges and interlocking silicon latches. Using high aspect ratio SOI based fabrication, high-performance single axis sensors with low cross-axis sensitivity are assembled to fit inside a package volume less than 1 cm³. Structural characterization of the folded IMU structures has been performed, and methods for additional reinforcement are explored.