OBIRCH analysis of electrostatic discharge ICs

ESD sensitive test was performed to verify the design of circuit protection unit. The failure ICs were analyzed by OBIRCH technique. Three anomalous thermally sensitive sites were localized including I/O and VCCIOs. OBIRCH analysis confirmed the failure sites were directly connect to the pads, mostly ESD protection units, decoupling capacitor and internal inverter. Physical failure analysis confirmed the OBIRCH findings, and revealed that improper triggering of ggNMOS structure and gate oxide breakdown were the root causes, the effectiveness and robustness of the structure need improvement. The suspect was also verified against failure data measured using TLP testing. All these experimental investigations were carried out in order to develop optimized protection structures against ESD.