Reliability testing of InPHEMT's using electrical stress methods

In this paper, we discuss the results of three different electrical stress tests on InP-based HEMT's and their implications toward reliability. These are hot electron (AE) stress, transmission line pulse (TLP) measurements, a nd RF overdrive stress, Some processing parameters have been varied to inve stigate their influence on reliability issues. HE stress is performed on a set of Si3N4 passivated devices with increasing recess width. Degradation i s observed to be largely dependent on recess width, due to changes at the I nAlAs-Si3N4. interface. With TLP measurements, an ESD-like reliability stud y is performed on devices with different types of Schottky barriers, Althou gh epilayers with In0.40Al0.60 as Schottky material show improved breakdown and leakage characteristics over In0.52Al0.48As, pulsed stress tests revea l an earlier breakdown. Finally, the degradation under large-signal RF over drive stress is determined with a nonlinear network measurement system (NNM S), Both on- and off-state degradation are studied with this set-up, Result s appeared to be strongly dependent on the phase difference between the str ess voltage waves applied at the device ports.