A Monolithic Three-Axis Accelerometer with Wafer-Level Package by CMOS MEMS Process

This paper presents a monolithic three-axis accelerometer with wafer-level package by CMOS MEMS process. The compositions of the microstructure are selected from CMOS layers in order to suppress the in-plane and out-of-plane bending deflection caused by the residual stresses in multiple layers. A switched-capacitor sensing circuit with a trimming mechanism is used to amplify the capacitive signal, and decrease the output dc offset voltage to ensure the desired output voltage swing. The CMOS MEMS wafer is capped with a silicon wafer using a polymer-based material. The measured sensitivities with and without a wafer-level package range from 113 mV/G to 124 mV/G for the in-plane (x-axis, y-axis) accelerometer, and from 50 mV/G to 53 mV/G for the z-axis accelerometer, respectively.

[1]  Stefan Finkbeiner,et al.  MEMS for automotive and consumer electronics , 2013, 2013 Proceedings of the European Solid-State Device Research Conference (ESSDERC).

[3]  Benedetto Vigna.  MEMS Epiphany , 2009, 2009 IEEE 22nd International Conference on Micro Electro Mechanical Systems.

[4]  C. Tan,et al.  3D CMOS-MEMS stacking with TSV-less and face-to-face direct metal bonding , 2014, 2014 Symposium on VLSI Technology (VLSI-Technology): Digest of Technical Papers.

[5]  M. Offenberg,et al.  A surface micromachined silicon gyroscope using a thick polysilicon layer , 1999, Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.99CH36291).

[6]  Ying-Zong Juang,et al.  Implementation of a monolithic capacitive accelerometer in a wafer-level 0.18 µm CMOS MEMS process , 2012 .