A Research On Reliability Of P-GaN Gate AlGaN/GaN HEMT Under Electrothermal Coupling Stress

With the progress of science and technology and the development of society,GaN high electron mobility transistor has become a research hotspot in the field of semiconductor technology because of its unique advantages such as wide band gap,high operating frequency and high critical breakdown electric field,Among them,p-GaN gate enhanced GaN HEMT(p-GaN HEMT,p-GaN gate e-mode Al GaN / GaN HEMT)power devices are widely favored by academia and industry as a preferred solution in highfrequency and high-power applications.However,with the development of GaN HEMT power devices,higher working voltage,higher working frequency and higher integration will bring higher power density,which will inevitably make the devices work in the working state of high temperature and high electric field.Now the device reliability induced by high power density has become the bottleneck and obstacle restricting the further development of GaN HEMT power devices.At present,it is an urgent problem to clarify the degradation and failure mechanism of p-GaN HEMT devices in the environment of high temperature and high electric field and improve the stability of devices in this environment.Starting from the actual high power density application scenario.This thesis studies the device reliability of p-GaN HEMT device under the stress condition of simultaneous coupling of high electric field and strong thermal field in this environment.The main research contents of this thesis are as follows:(1)Under the actual high power density application of p-GaN HEMT device,the high electric field in the device is serious,which is often accompanied by serious self heating effect.The device will withstand the coupling of electrical stress and thermal stress,and there is a special stress environment.In this thesis,by injecting a constant current into the drain of the device when the p-GaN HEMT device is turned on,the device is in the environment of electrothermal coupling stress,The reliability and stability of the device under electrothermal coupling stress are deeply explored through multiple groups of control experiments.The phenomena of threshold voltage instability and saturated output current degradation dominated by thermal stress under this stress are found,and the key factors inducing the characteristic degradation of the device after stress are revealed.(2)According to the actual device structure and experimental bias parameter setting,the physical modeling and electrothermal simulation of the device are carried out through sentaurus TCAD.Combined with the device control experimental results and simulation results,the location of the phenomenon of threshold voltage instability and saturated output current degradation,as well as the physical mechanism of internal carrier transport and trap behavior are pointed out,and a complete p-GaN HEMT electrothermal coupling stress degradation theory is established.It provides a theoretical basis for clarifying the internal mechanism of device characteristic degradation and subsequent reliability reinforcement.(3)Aiming at the key factor of p-GaN HEMT device under electrothermal coupling stress-junction temperature,the non-destructive junction temperature characterization of p-GaN HEMT device is carried out by using the junction temperature characterization method of thermosensitive electrical parameters,and the junction thermal resistance R ?JC measurement,analyze the thermal resistance value of each layer of the device,and verify the feasibility of the junction temperature characterization method of thermal electric parameters for p-GaN HEMT devices,which lays a foundation for further solving the problems of thermal reliability and thermal management of Gan devices.