Analysis of On-Chip Metal Micro-Electrode for CMOS ISFETs

In this paper the usage of an on-chip metal electrode for CMOS ISFET has been analysed. It is firstly shown that metal electrode can not provide constant potential as other conventional electrodes. Besides that this paper demonstrates the ions distribution and its corresponding deviated potential when ISFETs are detecting extreme small volume. Finally a 2-D simulation result indicates the potential gradient when a vertical on-chip electrode is applied and suggests that a minimum distance of 2um is desired for robust ISFET design with on-chip electrode.