Study On GaN FinFET Dual-gate Devices And Slanted Side-gate

With the development of the semiconductor industry,the requirements for semiconductor materials are also increasing.As a third-generation semiconductor,GaN has shown many unique advantages.Gallium nitride based high electron mobility transistors(HEMTs)is widely used in microwave,high power and other fields by the reason of its high current density,high output power,high working frequency,excellent resistance to irradiation and etc..And with the development of integrated circuits,the device size will continue to decrease in order to meet the increase in integration,and the short channel effect will become an important factor that constrains the reduction of device size.FinFET has a threedimensional gate electrode structure,and its side gate can control two-dimensional electron gas(2DEG)from the sidewall,its gate control capability is enhanced to suppress shortchannel effects.On the other hand,enhanced devices can be realized by the side-gate depletion of two-dimensional electron gas.This article proposes a FinFET device with a slanted side-gate structure,based on the simulation,for the side gates of two types of FinFET devices(Dual-gate FinFET)and conventional three-dimensional FinFET devices(Tri-gate FinFET),the characteristics of the slanted side gate structure device are studied.At the same time,The effects of different device structures on Dual-gate FinFET were also studied.The research contents of this paper mainly include the following aspects:The Silvaco TCAD simulation software is used to simulate Tri-gate devices with different gate widths firstly.The simulation results are close to the experimental results,which proves the rationality of the simulation framework in this discussion.Then three-dimensional simulations were performed on two types of Al GaN/GaN FinFET devices(Dual-gate,Trigate).By comparing and analyzing the DC characteristics of two FinFET devices with different Fin widths,it is found that for Tri-gate devices,when the Fin width is below 100 nm,the side gate dominates,and the Fin width increases gradually and the top gate dominates.When the Fin width is reduced to 30 nm,the Dual-gate device changes from depletion mode to enhancement mode.It can be seen that the effective depletion width of the two-side electron gas from the single-side gate is 15 nm.For the gate height,the height of 40 nm is the critical point.The 40 nm part can provide effective gate control.The part with a gate height greater than 40 nm has little effect on the two-dimensional electron gas.The height of the device side gate should reach at least 40 nm.When the period width increases,the ratio of the width of the source access region to the channel width increases,which brings greater current drive capability and increases the peak output current and transconductance.The gate length changes with 300 nm as the critical point.When the gate length is greater than 300 nm,the threshold voltage changes less as the gate length becomes larger,and the transconductance peak value decreases.When the gate length is less than 300 nm,the gate voltage significantly positive shift and the transconductance peak increases as the gate length increases.Based on the research of different structural parameters,a high linearity dual-gate device with transconductance compensation is designed,its transconductance is flat in the range of-1V to 2VFinally,a slanted gate structure was introduced into the Dual-gate device and simulated.The drain-side slanted side gate structure effectively improve the electric field distribution in the Fin channel and thus improve the charge distribution in the Fin channel.The slanted side gate structure has a negative shift voltage compared to conventional devices.Based on this,the equivalent gate length of a slanted side gate structure is defined.Compared to a conventional side gate device with an equivalent gate length,the peak transconductance of the slanted side gate are increased,the gate control ability has been improved.The sourceside slanted side-gate structure has little effect on device performance.In the Tri-gate device,a slanted side gate structure is introduced and simulated.Among it,the peak value of the transconductance of the slanted side gate structure is improved compared with its equivalent gate length device.After that,we showed the preparation process and layout design of the slanted side-gate Tri-gate device we designed.