Abstract
This study utilize TSMC 0.35um Mixed Signal 2P4M Polycide process and post process to design and fabricate a reduced structure deflection capacitive type fully differential CMOS-MEMS accelerometer. In general, accelerometer fabricated with CMOS-MEMS process face issue of severe deflection due to residual stress. The merit of this study is to etch away polysilicon which is embedded in the bottom part of structure at the end of process, which is the same as traditional dry etching process. Field oxide(FOX), which contribute highest level of residual stress, is then be removed simultaneously. Deflection of structure can be reduced thereof. Overall characterization of the device is: (1) integrate MEMS and IC monolithically with CMOS-MEMS technique, (2) amplify sensing signal and eliminate common mode noise through fully differential sensing, and (3) etch away polysilicon under the structure to reduce deflection.