Research On On-Chip Temperature Monitoring Method And New Structure Of GaN HEMT Devices

Wide band gap gallium nitride(GaN)power semiconductor has the advantages of high power conversion efficiency,fast working speed and high power density,which can break through the performance limits of traditional Si based power semiconductors.At present,GaN power devices have been widely used in the field of fast charge,and their applications in high-end fields such as data centers and new energy vehicles have just started.However,while pursuing high power density in practical applications,the selfheating effect of GaN power devices gradually becomes prominent,which becomes the main bottleneck limiting GaN power semiconductor technology to the application field of higher power efficiency and higher power density.In this thesis,a new real-time junction temperature monitoring technology for GaN power devices is proposed,and a new structure for GaN power devices with distributed junction temperature monitoring unit integrated on chip is developed,aiming at the common problems faced by the industry in the application of high power density,such as the increase of device power consumption,the decrease of power efficiency and the decline of device reliability caused by significant self-heating effect.Research on GaN power device structure design technology of on-chip junction temperature detector was carried out,and distributed junction temperature monitoring unit was designed to realize real-time junction temperature monitoring at different local locations of the device.Furthermore,GaN device overtemperature protection(OTP)circuit based on integrated temperature monitoring unit was implemented for the junction temperature maximum area inside the chip.The main research contents of this thesis are as follows:(1)Electrothermic coupling simulation was conducted based on p-GaN gate enhanced GaN HEMT devices.According to the working conditions of the device’s actual application scenarios,it was found that the extremal point of junction temperature of the device was closely related to the extremal point of electric field strength,and it was located near the drain side region of the gate.Furthermore,the chip layout of GaN HEMT device with embedded distributed temperature monitoring unit was designed according to the spatial location of junction temperature extremum inside the device,and the whole chip process was prepared.Finally,the basic electrical characteristics of GaN devices with temperature monitoring units were tested,and the thermal characteristics of temperature monitoring units were tested separately,and the temperature coefficient of temperature monitoring units was determined to be 3000ppm/℃.(2)Practical applications based on GaN HEMTs with embedded temperature monitoring units.Firstly,the function and accuracy of the temperature monitoring unit are verified and explored.The results show that the real-time monitoring accuracy of the temperature monitoring unit can reach more than 96%.Then,the temperature monitoring unit is applied to the distributed real-time junction temperature monitoring of different spatial locations of the whole chip.It is found that in the position of the chip layout,the temperature of the area near gate(G)PAD and source(S)PAD is relatively high,while the temperature of the area far away from gate(G)PAD and source(S)PAD is relatively low.Finally,a GaN device over-temperature protection(OTP)circuit based on integrated temperature monitoring unit is designed for the junction temperature extremum area inside the chip.