Thermal Imaging at Multiple Time Instants for Study of Self-Heating and ESD Phenomena

A 2D backside transient interferometric mapping (TIM) method for nanosecond thermal energy imaging at multiple time instants during a single stress event is introduced. The method is based on fringe interferometry and the interferograms are analyzed using the Fast Fourier Transform technique. The method is applied to investigate moving current filaments in smart power DMOS transistors and in electrostatic discharge (ESD) protection devices exhibiting non-repeatable triggering behavior under ESD-like stress. The method additionally allows the extraction of instantaneous 2D power dissipation density (P2D), which represents the current density distribution in the devices.