Investigation of pickup effect for multi-fingered ESD devices in 0.5 μm 5V/ 18V CDMOS process

Pickup effect for 5V NMOS and 18V lateral double-diffused NMOS under electrostatic discharge (ESD) stress is investigated and characterised by a transmission line pulse test system in a standard 0.5 μm 5V/18V CDMOS process, respectively. Experimental results show that 5V low-voltage multi-fingered NMOS devices cannot be turned-on uniformly with more added inner pickups and thus the ESD robustness degrades. For 18V high-voltage multi-fingered LDNMOS structures, it is critical to merge all pickups with the P-well guard-ring of the device to achieve uniform current conduction and better ESD performance.