Research On The Model And Electrical Characteristics Of Three-dimensional Metal-oxide-semiconductor Field-effect Transistor

As the continuous improvement of chip integration,the metal-oxide-semiconductor field effect transistor(MOSFET)is restricted by the short channel effects in the process of scaling down.focuses on the three-dimensional structure.The three-dimensional(3D)MOS devices,FinFET and cylindrical surrounding double-gate MOSFET(CSDG MOSFET),improve the gate control capability by increasing the gate control area of the channel,thereby increasing the drain-source current and suppressing the short channel effect.The 3D MOS devices are the development direction of the future device.Therefore,establish the model of FinFET and CSDG MOSFET and study their electrical characteristics are of great significance for the better understanding and application of these 3D MOS devices.In this paper,the potential and current of FinFET and CSDG MOSFET are modeled,and the influence of different structural parameters on the electrical characteristics of FinFET and CSDG MOSFET are studied.The electric potential model of FinFET was obtained by solving separate solutions of two-dimensional(2D)Poisson's equation for both symmetric and asymmetric double gate FinFET and combining them using the perimeter-weighted sum approach.The current model of FinFET was obtained by integrating the charge density of channel.The electrical characteristics of FinFET under different parameters are analyzed and discussed.The results show that the minimum surface potential along the channel of FinFET increases with the decrease of the gate length,and decreases with the decrease of Finheight,Finwidth or gate dielectric layer thickness;The high-k gate dielectric material increases the gate control capability of the FinFET to increase output current by increasing the gate capacitance;The center of the fin is the leakiest path in the FinFET.The output current of FinFET decreases with the increase of channel length and the thickness of gate dielectric.For the potential model of CSDG MOSFET,the 2D Poisson equation in the cylindrical coordinate is decomposed into the sum of the one-dimensional(1D)Poisson equation and the 2D Laplace equation,and they are respectively solved with the boundary conditions to obtain the potential of CSDG MOSFET.The drain-source current model of CSDG MOSFET is established by further integrating the inverse charge along the channel.Numerical simulation verifies the accuracy of the potential model and current model of CSDG MOSFET.The electrical characteristics of CSDG MOSFET device are analyzed and discussed.The results show that the outer gate's minimum surface potential along the channel of CSDG MOSFET decreases with the increase of gate dielectric constant of gate dielectric layer.The threshold voltage of CSDG MOSFET decreases when the gate dielectric constant increases.The drain-source current and transconductance of CSDG MOSFET increase with the increase of the gate dielectric constant.Moreover,with the scaling down of device parameters,the charge density of channel inversion of CSDG MOSFET decreases,and its drain-source current and transconductance also decrease.The performance of FinFET,CSDG MOSFET and surrounding gate MOSFET is compared.With larger gate control area,CSDG MOSFET shows better drive current,subthreshold swing and DIBL value than FinFET.Compared with the planar MOSFET and surrounding gate MOSFET,FinFET and CSDG MOSFET have stronger gate control capability,better output characteristic and better immunity to short channel effect.