Localization and Physical Analysis of Defects in Degraded Power HEMT p-GaN Transistors Stressed with DC Voltage Surge and Voltage with Switching Stress
摘要
This paper presents a methodology for the physical analysis of defects on p-GaN power HEMTs that have been electrically stressed under DC surge or voltage switching stresses. The methodology includes a backside approach for sample preparation and defect localization. It is crucial to adapt the preparation process according to the position of the defect in the device structure (including metallurgy, dielectric layers, epitaxy, etc.), which depends on the type of stress applied. In our study of the reliability of the transistor under increased electrical stress in lifetime operation mode, failure analysis is used to identify the weakest areas in the design with respect to the type of stress applied. This paper presents a failure analysis consisting of techniques such as electrical characterization, photon emission microscopy and lock-in thermography for defect localization, focused ion beam slice and view, transmission electron microscopy analysis, and frontside conductive atomic force microscopy after immersion in hydrofluoric acid.