Metallization Reliability and Defectivity in Compound Semiconductors

Compound semiconductor devices are in mass volume production yet our understanding of reliability and defectivity of III-V materials is still evolving.  Process-induced defects in electroplated Au interconnect metallization on GaAs devices were detected during the course of reliability testing.  Abnormally high lognormal sigmas (σ > 0.7) indicated the existence of a bi-modal failure mechanism.  A distinct early lifetime failure mode was observed along with the intrinsic electromigration metallization wear-out failure mode.  Increased temperature stress showed only a slight acceleration on the early failure mechanism but selection of a higher resistance degradation failure percentage criterion reduced the extent of these early failures.  Physical characterization of the electroplated Au film revealed as-deposited nanoscale voids. Elimination of these voids through process improvement as well as suggested mechanisms for the early failures is discussed.