ISFET threshold voltage programming in CMOS using electron tunnelling

Ion sensitive field effect transistors (ISFETs) fabricated in standard CMOS process are effectively floating gate devices. These ISFETs generally suffer from large threshold voltage variations owing to trapped charges. Aiming to reduce mismatch in ISFET arrays, it is shown in this reported work that Fowler-Nordheim electron tunnelling can be used to program charges in the floating gate of an ISFET in order to control its threshold voltage. The threshold voltage of a p-ISFET fabricated in 0.35 m CMOS process was shifted by 3.45 V in a pH 7.0 buffer solution.