A Study of Gold Ball Bond Intermetallic Formation in PEDs using Infra-Red Microscopy

A novel technique, using infra-red microscopy in the reflection mode, has been used to examine gold-aluminium bond interconnections rapidly by imaging through the bulk silicon. Its use has led to the characterisation of the Au-Al interf ace and the degree of intermetallic formation in terms of a unique IR footprint. The database of footprints obtained from a range of heat-treated commercial product has allowed a good understanding of the bond quality and its possible effect on device reliability. Comparison with results from conventional failure analysis (FA) techniques has demonstrated its use for field failures. The method is eminently suitable as a tool for both qualification and testing exercises and for field failures.