High Current Transient Induced Junction Shorts

The essential cause for junction shorts is second breakdown which requires thermal gradients and temperature magnitudes in excess of the intrinsic temperature associated with the materials. From the thermal and current gradient analysis, the following was shown: a. The shorts will follow the lowest resistance path. For a typical microcircuit, this path will occur immediately between the nearest aluminum silicon contacts and in the silicon region adjacent to the Si-SiO2 interface. b. The cause of hot spot formation arises primarily from spreading resistance considerations and not from a localized breakdown mechanism. This is true at least for the pulse widths studied here. c. For pulse widths shorter than 10 useconds, there should be no difference in the power required to cause failure and the device technology, i.e., glassivated, junction isolated or dielectrically isolated devices. This is due to the relatively long thermal time constants resulting from either poor thermal conductivity in the case of the glass or long distances from the dissipating junction in the case of dielectric isolation. d. The junction isolated technology should be relatively uniform in terms of power dissipation. e. Combining the results of gradients and magnitude, the cause for the wide spread in power required for failure has not been specifically identified. The differences in technologies cannot be important for these pulse widths, and the spreading resistance associated with the intrinsic temperature, while not identical, should be relatively uniform from one manufacturer to another. f.