Failure Analysis of Multilayer-Metal-Packaged Power Devices for Abnormal Thermal Response

Because of the nature of multilayered structure and their metal characteristics, it is difficult to conduct failure analysis on multilayer-metal-packaged power devices with abnormal thermal characteristics using conventional techniques. In order to overcome this challenge, a systematic solution is proposed. Firstly, the failure cause of abnormal thermal response for power devices is identified as the problem of heat dissipation through electrical tests and analysis of diode forward voltage $(V_{\mathrm{SD}})$ curves. Secondly, specific failure sites of power devices were located by the structure function analysis and the X-CT test. Finally, the failure site was analyzed by physical failure analysis techniques, and the specific failure cause was validated and further analyzed by microscopic observations and EDS. It was found that the oxidation of back metallization led to the formation of solder voids which resulted in the above failure.