Research on failure analysis and method of GaN-based HEMTs

The reliability of GaN-based high electron mobility transistors (HEMTs) is of great importance due to the special characteristics of AlGaN/GaN heterostructure such as intense polarization effect, high material defect density, strong electric field working condition, complicated process etc. Failure analysis is the premise and foundation to improve reliability of semiconductor devices. However, there is less research on failure analysis method about HEMTs at present. In this paper, an effective method of failure analysis of HEMT is presented to analyze the failure reason of electrical stress on many occasions, and a corresponding case analysis of HEMT is carried out. Following the unique complementary detection process of electrical testing, thermal radiation and photon emission, device failure position can be determined rapidly and failure mode and mechanism can be analyzed by this method. A 4-finger GaN-based HEMT with a operating voltage of 28V and a gate width of 1.25mm are analyzed according to this failure analysis method. Two failure positions were localized and the failure mode and mechanism were determined by comprehensive analysis of testing images and data. Finally, several improvements in design and process of GaN-based HEMTs are proposed, which is a valuable reference on the failure analysis and reliability enhancement of HEMT devices.