Au electromigration and Ti segregation in TiPtAu gate of PHEMTs

Abstract

In the paper, an evaluation structure was designed to investigate the degradation of gate metal in PHEMTs, and it can be used to separately appraise the resisted electromigration levels of the evaporated Ti/Pt/Au and the electroplated Au. The results show that the electromigration resistant level of electroplated Au of Ti/Pt/Au-Au is at least four times lower than that of the evaporated Ti/Pt/Au. For the elements of Au, Ga and Ti in gate metal of Ti/Pt/Au-Au, the degradation of diffusing migration was observed by SIMS. In addition, serious segregation and influx for the element of Ti destroyed the performance of the Schottky barrier in gate structure.