Interferometric temperature mapping during ESD stress and failure analysis of smart power technology ESD protection devices

Breakdown homogeneity and triggering of bipolar transistor action are studied in smart power technology ESD protection devices via measurements of temperature distribution and thermal dynamics by a laser interferometric technique. Temperature changes in the devices biased in the avalanche multiplication or snapback region are monitored by ns-time scale measurements of the optical phase shift. The distribution of the temperature-induced phase shift is correlated with the position of ESD damage obtained by backside IR microscopy.