A monolithic inertial measurement unit fabricated with improved DRIE post-CMOS process

This paper reports a monolithic CMOS MEMS inertial measurement unit (IMU), which is composed of a 3-axis accelerometer, a Z-axis and a lateral-axis gyroscope. The IMU is integrated with interface circuits on a 5×5mm² foundry CMOS chip and fabricated with an improved DRIE post-CMOS bulk micromachining process. The new process incorporates a metal deposition to provide a thermal path for isolated structures during DRIE etching. The X/Y-axis accelerometer achieves a sensitivity of 191mV/g with a noise floor of 35μg/VHz, and those parameters of the Z-axis are 124mV/g and 56μg/VHz, respectively. The Z-axis gyroscope has a sensitivity of 0.3mV/°/s and a noise floor of 0.2°/s/VHz. The characterization of X/Y-axis gyroscope is ongoing.