A method to minimize test time for accelerated ageing of pHEMT's by analysis of the electronic fingerprint of the initial stage of degradation

Accelerated life testing provides a necessary tool for reliability validati on but is generally very time-consuming as standard test take up to 2000 ho urs to proceed. In this article, results on the early stages of the ageing of pHEMT transistors are presented and it is shown that the necessary test time can be decreased from 2000 hours to 144 hours without loss of data con fidence. This has been enabled by the application of an insitu measurement method where the ageing of the device under test is characterized during th e stress phase. Two main degradation factors can be identified in good agre ement with findings reported in literature. The data have been successfully correlated with standard test results performed on a 2000 hours time scale . (C) 2000 Elsevier Science Ltd. All rights reserved.