Modeling the laser acceleration of hot spot formation

The He-Ne laser irradiation of the reverse biased CB junction of RF power transistors, proposed in a previous work as a new wafer level reliability screen test, is analyzed based on the modeling of the laser-induced acceleration of the hot spot formation. The model values for the laser-induced current density at a deep level center explain the very high acceleration factor experimentally obtained if an avalanche multiplication of current-temperature at the hot spot area is assumed. The model proves the efficiency of the test for reliability screening of the chips, relative to the hot spot formation.