Identify Failure Signatures For Different Electrostatic Discharge Models

Electrostatic discharge (ESD) damage to IC(Integrated Circuit) has been paid more attention than ever. This paper introduces generation of static electricity, three kinds of ESD models and test methods, and ESD protection circuit. ESD failure mode, failure mechanism, experiment plan and results, and failure signature of the three ESD models are discussed. This work will help for identifying ESD failure model and for finding ESD source in failure analysis.While obvious Electrical Over-Stress may be physically evidenced by cracked packages, carbonized mold compound, burnt-out bond wires and massive visual damage to the metal on the die surface. The more subtle ESD failure is not visible at low magnification. However in most instances, the observation of discoloration will provide a means of differentiating between the EOS and the ESD events.Failure signatures between HBM (Human Body Model) and MM (Machine Model) show some variation in morphology but they are located in the same ESD protective structure. In all cases no physical anomaly was observed after decapsulation. Scanning electronic microscope examination was required in conjunction with deprocessing to establish physical failure site morphology and final location of the physical damage. Due to the much lower threshold voltage required for electrical failure and higher peak of discharge current, the damages for MM are more severe.The physical failures for CDM (Charged Device Model) occur at the input buffer circuit with gate oxide damage or poly-silicon damage, located in core circuitry not in peripheral circuitry of the die. This location is beyond...