Low power finfet ph-sensor with high-sensitivity voltage readout

Low power n-channel fully depleted local-SOI FinFET integrated sensors have been developed and validated for the amplification of pH sensing signals. A simple architecture with one FinFET connected as depletion-mode load and another one as driving sensor, provides a maximum readout gain of 6.6 V/V with a maximum pH readout sensitivity of 185 mV/pH, at 2 V operation. By comparing the proposed amplifier with a single sensing FinFET the threshold voltage shift readout is shown to be 4.4 times larger. High-k dielectric HfO₂ has been used to maximize both sensing and electronic performances. The FinFETs have been fabricated on bulk silicon by a local-SOI technique. FinFET thickness (T_Fin) and height (H_Fin) achieved are in the range of 20 nm ≤ T Fin ≤ 40 nm and 65 nm ≤ H_Fin ≤ 120 nm.