A tri-fold inertial measurement unit fabricated with a batch 3-D assembly process

This paper reports a tri-fold inertial measurement unit (IMU) that is fabricated with a batch-mode 3-D assembly process. Each chip of a tri-fold die includes a single axis z-gyroscope and 0–2 lateral-accelerometers. The tri-fold dies are batch-mounted on sidewalls of silicon cavities on a wafer to form 6-axis IMUs. The accelerometer has a measured bias instability of 6.8 µg and a noise floor of 66 µg/rt-Hz. The gyroscope has a measured bias instability of 29 °/hr and an angle random walk of 0.020 °/s/rt-Hz (1.2 °/rt-hr).