A thermal model for the initiation of programming in metal-to-metal amorphous-silicon antifuses is described, The current and field crowding at the edges of the via cause the temperature at the via corners to increase due to Joule heating. Programming is initiated when the temperature at the via edges reaches the melting temperature of amorphous silicon. The model presented in this work explains how the thickness of the amorphous-silicon layer, the ambient temperature. and the duration of the programming pulse affect the programming process. (C) 1999 The Electrochemical Society. S0013-4651(98)06-089-3. All rights reserved.

The ON state of metal-to-metal amorphous-silicon antifuses suffers from two reliability concerns: switch-off and dc-stress failure. The switch-off current and dc-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 dc-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.

A model for the growth of a conducting filament in metal-to-metal amorphous-silicon antifuses is presented. The transition from a high-resistance state to a low-resistance one is initiated by the formation of a localized hot spot. The growth of the filament occurs by melting the surrounding amorphous silicon. The latent heat required for filament growth is provided by the power dissipation in the melt. As the filament grows, power dissipation drops rapidly and the growth slows. For a given set of programming conditions and at a certain value of the melt radius, the power dissipation in the filament is no longer sufficient to provide the energy needed for the growth process. This condition leads to ending the filament growth. The thermal model presented here predicts several characteristics of the ON state, such as the dependence of the final filament radius rfil on the programming voltage Vpp and the series resistance Rser. It also predicts that the ON resistance is inversely related to the programming voltage Vpp. The model predictions agree with experimental results.