Novel electrostatic discharge protection structure for a monolithic gas sensor systems-on-a-chip

A new on-chip electrostatic discharge (ESD) protection scheme is demonstrated for microelectromechanical systems (MEMS)-based embedded sensor (ES) system-on-a-chip (SoC). The ESD protection scheme includes ground-referenced protection cells implemented with novel multifinger thyristor-type devices for (1) input/output (I/O) protection; (2) power supply clamp; (3) protection at the internal sensor electrodes. The I-V characteristics of the thyristor-type protection cells are adjusted to provide an optimum ESD protection per unit area. Transmission line pulsing (TLP) measurements and ESD testing show superb high conductance on-state I-V characteristics with no latch-up problem when thyristor-type devices are subjected to an ESD event, while very low leakage current is obtained at the SoC operating voltage.