Turn-on speed of grounded gate nMOS ESD protection transistors

The turn-on speed of nMOS transistors (nMOST) is of paramount importance for robust Charged Device Model (CDM) protection circuitry. In this paper the nMOST turn-on time has been measured for the first time in the sub-halve nanosecond range with a commercial e-beam tester. The method may be used to improve CDM-ESD hardness by investigating the CDM pulse responses within circuit. Furthermore it is shown that the CDM results of various protection layouts can be simulated with a SPICE model.