Monolithically Vertical Integration with Capacitive Proximity and Inductive Force Sensor with Sensing Range Enhancement

This study proposes the design to vertically integrate capacitive proximity and inductive force sensors on a single chip (Fig. 1) based on the TSMC 0.18 µm 1P6M CMOS platform. Merits of proposed design are: (1) Vertical SoC on CMOS chip: extending the inductive-coil force sensor in [1] to integrate with interdigitated-electrodes (IDE) capacitive proximity sensor in identical sensing area to ensure co-axial signal output, (2) For inductive force sensor: modifying the relationship between coil and ferromagnetic bump to improve the linearity of output signal and further increase the sensing range. (3) For capacitive proximity sensor: using ferromagnetic tactile bump as floating potential to enhance sensing range and sensitivity. Measurements show the sensitivities of force sensor is 1.1nH/N in Z-axis for 0~15N. Sensing range and sensitivity of proximity sensor are 0.1~1.8mm and 0.56fF/mm.