Contents lists available at ScienceDirect Microelectronics Reliability journal homepage: www.elsevier.com/locate/microrel Effect of HTRB lifetest on AlGaN/GaN HEMTs under different voltages and temperatures stresses Omar Chihani a,b, ⁎ , Loic Theolier a , Alain Bensoussan b , Jean-Yves Deletage a , André Durier b , Eric Woirgard a a Univ. Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, F-33400 Talence, France b IRT Saint-Exupery, 3 rue Tarfaya, F-31405 Toulouse, France ARTICLE INFO Keywords: AlGaN/GaN HEMTs Step-stress Failure mechanism Lifetest ABSTRACT Space and transport industries are facing a strong global competition which is setting economic constraints on the entire supply chain. In order to address decreasing development costs and to propose new features, com- ponents-off-the-shelf (COTS) have become a very attractive solution. This paper investigates the degradation of AlGaN/GaN HEMTs COTS submitted to HTRB lifetest. Temperature and voltage step stresses were applied to untangle the effect of each stressor. The main aim is to establish a lifetime model, taking into account several degradation mechanisms, over a large range of temperatures and voltages. The experimental outcomes highlight the activation of different failure mechanisms occurring during the stress tests, and which depend from the different temperature and voltage working ranges. In this work, experimental analysis has been performed in order to characterize the root cause behind the activation of these multiple failure mechanisms and estimate the operative range where they may superimpose. 1. Introduction Power GaN transistors have demonstrated to be excellent devices for application in power electronics. Gallium nitride has a wide band gap (3.4 eV), that allows operation in high temperature. Moreover, GaN transistors can remain functional up to 500 °C [1]. This could reduce the size and the weight of the cooling systems. GaN has a breakdown field of 3.3 MV·cm -1 , which is ten times higher than silicon. For the same breakdown voltage, GaN transistors can be ten times smaller than silicon ones. In addition, the two-dimensional electron gas presents a high density (> 10 13 cm -2 ) and a high mobility (> 2000 cm 2 /Vs [2]). These characteristics enable components to be operated at high fre- quencies and allow the weight reduction of passive components in critical block such as converters. However, these components need yet to meet the high reliability standards demanded by the automotive and aerospace industry. The reliability of normally-on GaN HEMTs was addressed in several re- searches [3–6]. Recently, some good work has been done in order to understand the failure mechanisms of normally-off GaN HEMTs with p- gate [7,8]. However, much more work is still needed to understand the failure mechanisms especially for normally-off HEMTs. In this work normally-off industrial COTS HEMTs have been submitted to High Temperature Reverse Bias (HTRB). Different tem- peratures and voltages have been applied to distinguish the effect of each stressor and have a better understanding of the activated failure mechanisms. 2. Device, characterization and aging protocol description 2.1. Device under test characteristics The device under test (DUT) is a 200 V enhancement mode power AlGaN/GaN HEMT. This device has a typical R DSon of 50 mΩ and a maximum continuous drain current of 8.5 A. The gate of this compo- nent is composed of a P-GaN layer (55 nm) under a TiN layer (90 nm). The gate length is 0.48 μm and the distance between the drain and the source is 6.8 μm. In order to carry out the high temperature aging tests, these devices were soldered using SAC305 on high TG FR4 PCB or polyimide (see Fig. 1). 2.2. Aging and characterization protocol In this work, different DUTs were submitted to HTRB lifetests using https://doi.org/10.1016/j.microrel.2018.07.076 Received 31 May 2018; Received in revised form 6 July 2018; Accepted 6 July 2018 ⁎ Corresponding author. E-mail address: Omar.chihani@u-bordeaux.fr (O. Chihani). Microelectronics Reliability 88–90 (2018) 402–405 0026-2714/ © 2018 Elsevier Ltd. All rights reserved. T