A novel approach to resolve recoverable gate-emitter shorted failure due to top metal removal for IGBT device in power integrated module

Recent advancement in high-voltage and high power technology in PIM have been remarkable, and PIM are being used for the applications of GTO thyristor. Power Integrated Module (PIM) is an integrated power module combines high-performance IGBTs with rugged anti-parallel diodes on multi-layered module package. This presents a challenge to perform advance die-level failure analysis due to the special assembly structure compare to conventional electronic component that encapsulated by mold compound. It also posed a higher difficulties on Obirch analysis of recoverable Gate-Emitter shorted failure after top metal layer removal. Topside and backside techniques were evaluated to preserve the defect of recoverable Gate-Emitter shorted failure IGBT device before Obirch analysis and FIB cut. This paper aims to explore the best method to preserve and analyze the defect which is a pre-requisite for a successful identification of the failure mechanism before further investigations.