The effects of epoxy die bonding on the reliability of pseudomorphic GaAs/InGaAs/AlGaAs HEMTs

During elevated temperature bias stress of pseudomorphic GaAs/InGaAs/AlGaAs HEMTs long term changes in Ids, gm and breakdown voltage are observed. DC parametric analysis identifies at least two separate mechanisms responsible for the changes in Ids and gm and a further mechanism responsible for changes in breakdown voltage. Unique activation energies are associated with each mechanism. The rate of degradation of all parameters is significantly different for devices assembled with conductive epoxy rather than solder. This is a consequence of both the heat cycle associated with solder bonding and the presence of gaseous contaminants.