The high-current snapback characteristics of MOSFET’s with different channel lengths and widths, gate oxide thicknesses, and substrate dopings were studied to determine their effectiveness in electrostatic discharge stress protection. Filamentary conduction was not observed for currents up to 7 mA/um of channel width for a pulse-width of 500 ns. MOSFET’s with shorter channel lengths require lower voltages to sustain the same current, independent of gate oxide thickness. Increasing the substrate doping does not necessarily reduce the high current voltage. These trends can be explained using a simple lateral n-p-n bipolar transistor snapback model.