Research On Short-circuit Reliability Of 650V P-GaN HEMT Devices

With the continuous advancement of semiconductor technology,Gallium Nitride(GaN)devices have gradually played an important role in the fields of high frequency and high voltage due to their advantages of fast switching speed and high withstand voltage,and have entered the stage of commercialization.Among them,the high electron mobility transistor with p-type GaN cap layer(pGaN HEMT)is the most mature commercialized,but it still has some reliability problems.When the device is short-circuited,the electrical parameters may degradade,and even burnout failure will occur.Therefore,it is of great significance to study the short-circuit reliability of p-GaN HEMT devices.The failure mechanism of p-GaN HEMT devices under short-circuit stress are studied through the short-circuit test platform combined with the computer-aided design(TCAD)simulation platform Silvaco.The research results show that under a single high-voltage/high-current short-circuit stress,energy accumulation occurs in the channel under the device field plate due to high current density and high resistance,resulting in a sharp rise in the lattice temperature under the field plate.It eventually leads to the burn-out of the the device due to the temperature limit of the device.Based on the above short-circuit failure mechanism,a p-type buried layer is added under the drain.Compared with the original structure,the improved structure can reduce the temperature peak when short circuit occurs by 13.3%,and the short circuit robustness of the device is significantly improved.In addition,the degradation mechanism of the electrical parameters of the device under repeated short-circuit stress is studied.The results show that the high electric field under repeated short-circuit stress leads to the impact ionization in the barrier layer under the gate of the device,and after the short-circuit stress is removed,partially ionized electrons still exist there,causing the shifts in the threshold voltage and the gate leakage current.At the same time,the high temperature shock caused by the repeated short-circuit stress will also damage the barrier layer between the gate and the drain,causing electron traps to appear in the barrier layer and increasing the on-resistance.