The CMOS-MEMS 3-axis capacitive accelerometer to meet the commercial specifications

Abstract

This study presents the world first post-CMOS 3-axis accelerometer to meet the commercial specifications using the 0.18μm standard CMOS process and one-step vapor HF post CMOS process. The novel pure-metal hollow springs and high stiffness proof-mass successfully resist the thermal deformation issues. Moreover, the special arrangement of out-of-plane spring, proof mass, and sensing electrodes of Z-axis accelerometer can further compensate the thermal deformation induced capacitance as common mode. The device has been batch fabricated on an 8-inch wafer and followed with standard LGA (Land-Grid-Array) package with a yield higher than 90%. Measurements in Table1 show the 3×3×1mm3 LGA packaged accelerometer chip meets current commercial products specifications.