A Study Of Low Density Drain AlGaN/GaN HEMT Processing And Breakdown Voltage Feature

With the rapid development of Science and Technology, Gallium nitride(GaN) material on behalf of the third generation semiconductor materials has shown superior application prospect in the fields of high temperature, high frequency and microwave devices, owing to its wide bandgap, high electron saturation velocity and terrific characteristic of working stability. And what’s more, AlGaN/Ga N high-electron-mobility transistors(HEMTs) are widely exploited in aspects of wireless communication and Radar for its potential. Flourine plasma treatment is extensively applied to recessing gate in GaN devices and fabricating enhancement mode devices, so it’s of great importance to study AlGaN/GaN HEMTs treated by fluorine plasma. In this paper, the studies on Low Density Drain AlGaN/GaN HEMTs by flourine plasma treatment through the following three aspects: 1. Based on the current fluorine plasma etching process, the different power that fluorine plasma treatment on the drain-side of gate edge in the device is used, the influence of different fluorine plasma treatment power on AlGa N/GaN HEMTs is studied. This paper mainly makes comparison on three different devices by 50 w, 100 w and 150 w fluorine plasma treatment power under 60 s etching time, respectively. It is found that with the increase of fluorine plasma treatment power, there is a decrease in the trans feature of AlGaN/GaN high-electron-mobility transistors(HEMTs);the threshold voltage is floating forward the positive position; for the breakdown feature, the breakdown voltage of a normal AlGaN/GaN HEMT in the chip is about 100V; the breakdown voltage of a AlGaN/GaN HEMT under 50 w fluorine plasma treatment power in the chip is about 130 v,increased by 30% comparing to normal ones; the breakdown voltage of a AlGaN/GaN HEMT under 100 w fluorine plasma treatment power in the chip is about 165 v,increased by 65% comparing to normal ones, while the breakdown voltage of a AlGaN/GaN HEMT under 150 w fluorine plasma treatment power in the chip is about 170 v,increased by 70% comparing to normal ones. 2. Based on the current fluorine plasma etching process, the different time that fluorine plasma treatment on the drain-side of gate edge in the device is used, the influence of different fluorine plasma treatment time on AlGaN/GaN HEMTs is studied. This paper mainly makes comparison on three different devices by 0s, 60 s and 120 s fluorine plasma treatment time under 100 w etching power, respectively. It is found that with the increase of fluorine plasma treatment time, there is a decrease in the trans feature of AlGaN/GaN high-electron-mobility transistors(HEMTs);the threshold voltage is floating forward the positive position; for the breakdown feature, the breakdown voltage of a normal AlGa N/GaN HEMT in the chip is about 100V; the breakdown voltage of a AlGaN/GaN HEMT under(100w 60s) fluorine plasma treatment condition in the chip is about 180 v,increased by 80% comparing to normal ones; the breakdown voltage of a AlGaN/GaN HEMT under(100w 120s) fluorine plasma treatment condition in the chip is about 200 v,increased by 100% comparing to normal ones. 3. Based on the current fluorine plasma etching process, the same condition that fluorine plasma treatment on the drain-side of gate edge in the device is used, the influence of different fluorine plasma treatment time on AlGaN/GaN HEMTs is studied. This paper mainly makes comparison on several different devices by 0um、 0.3um、0.5um、0.6um、0.7um、0.9um、1.1um and 1.3um fluorine plasma treatment length under(100w 60s) etching condition, respectively. It is found that with the increase of fluorine plasma treatment length, there is a decrease in the trans feature of AlGaN/GaN high-electron-mobility transistors(HEMTs);the threshold voltage is floating slightly forward the positive position and then holds; for the breakdown feature, as the LDD length increasing,the breakdown voltages of the devices first increase to a peak value and then fall, research has been made on this phenomenon,finally we get the range of best length.