Summary and Future Research

Abstract

An industry failure analysis database was used to evaluate the relative impact of EOS phenomena on device failure across the different product families and to identify the dominant EOS-related failure mechanisms affecting different products. A set of different devices was selected as test vehicles for this analysis. A test procedure was specified and used to consistently reproduce the dominant failure mechanisms observed in the field for the selected set of devices. Two kinds of unipolar stresses were used square-pulse testing and ESD-HBM. Stressing a number of units for each selected device type allowed us to determine the power- and current-to-failure profiles for individual devices. Detailed failure analysis results indicated that the specified test procedure consistently reproduced the given set of dominant failure mechanisms. The differences seen in the measured power profiles were qualitatively explained by failure analysis in terms of the the failure location, the layout style, and the stress level. Qualitative correlation was found between the layout style and the device’s ability to sustain EOS/ESD stress as measured by the power profiles. It was shown that good IC ESD-HBM performance does not guarantee adequate EOS robustness. The power-to-failure profile was introduced to evaluate design changes of I/O protection structures in view of EOS hardness. The results in Chapter 2 suggested that power-to-failure profiles can be used to set the design goals for I/O protection against EOS and ESD and could be used as a relative measure of EOS hardness of I/O protection circuits.