Electrothermal simulation tools for analysis and design of ESD protection devices (NMOSFET)

Two- and three-dimensional simulators have been developed to investigate the electrothermal operation of semiconductor devices and conditions for onset of thermally activated second breakdown. There are two distinct breakdown modes, one associated with a pn-junction and the other with a resistor, that can cause thermal breakdown in transistors. Simple structures have been studied for a better understanding of second breakdown. Simulations coupled with experimental results also allow the evaluation of failure thresholds of MOS devices under ESD stress conditions. It is noted that 2-D simulations are pessimistic in predicting the failure thresholds and should be used for a study of qualitative trends only.<>