Mechanical force-displacement transduction structure for performance enhancement of CMOS-MEMS pressure sensor

This study implements a mechanical force-displacement transduction structure in Fig.1a using the TSMC 0.18μm 1P6M CMOS process to improve CMOS-MEMS capacitive pressure sensor. The membrane will be deformed by pressure and cause the sensing-gap change between undeformed movable-electrode and fixed-electrode. Feature of this study is CMOS-MEMS deformed membrane and undeformed movable-electrode to enable the parallel-plate gap-closing pressure detection. Thus, the performance of pressure sensor can be improved. In comparison, the design with mechanical force-displacement transduction structure will increase sensitivity for 61% in pressure range (100kPa–60kPa). Moreover, sensitivity (non-linearity) of proposed design changes from 2.1fF/kPa (1.7%) to 1.9fF/kPa (2.5%) as pressure range changed from 100∼60kPa to 100∼20kPa. However, sensitivity (non-linearity) of existing design significantly drops from 1.3fF/kPa (1.5%) to 1.0fF/kPa (13.7%) as pressure range changed.