The ON state of metal-to-metal amorphous-silicon antifuses suffers from two reliability concerns: switch-off and de-stress failure. The switch-off current and de-stress lifetime are strongly dependent on the temperature of the conducting filament and hence, on the programming current and ambient temperature. Numerical simulations of the filament temperature in the ON state were carried out to explain the experimental characteristics obtained in this work such as the dependence of the switch off and de-stress failures on ambient temperature, stress current, and programming current. The temperature in the conducting filament is found to increase as the square of the stress current. The temperature and power dissipation at switch off are found to be independent of the programming current. The temperature at switch off is determined to be approximately 1500°C. The ON-state device lifetime decreases exponentially with increasing stress current and ambient temperature. Numerical simulations of the temperature in the ON state successfully explain the experimentally observed increase in switch-off currents with programming current and the exponential decrease in device lifetime with increasing programming currents, stress currents, and ambient temperature. © 1998 American Institute of Physics.