Failure Analysis of 100 nm AlGaN/GaN HEMTs Stressed under On- and Off-State Stress

A systematic investigation of the effect of temperature and electric field on the degradation of 100 nm AlGaN/GaN HEMTs stressed under on- and off-state conditions has been carried out. The shape of the degradation behavior is analyzed and compared between stress conditions. The shape parameter of an Avrami-model was found to be reduced at higher temperatures. Failure analysis was performed by delayering with subsequent SEM and AFM investigation of the semiconductor surface. All devices showed surface damage in the vicinity of the drain-sided gate-edge. Devices stressed at high voltage and high temperature exhibited more and deeper pits than devices stressed at low drain-bias and low temperature, even though all devices have been stressed to the same electrical degradation of 10 % decrease in I DSS.