| As one of the new nano-devices,negative capacitance field effect transistor(NCFET)can improve device performance and effectively reduce power consumption.Therefore,it is considered to be the next generation ultra-low power integrated circuit technology that can be used in the field of Internet of things.Aiming at the negative capacitance phenomenon caused by adding ferroelectric materials to the gate of small-size multi-gate devices with different structures,this thesis discusses the influence of negative capacitance effect on the electrical characteristics of multi-gate transistors with different structures,which is simulated and verified by Synopsys’ computer aided design(TCAD)tool.Firstly,this thesis expounds the mechanism of negative capacitance produced by ferroelectric materials,analyzes the mechanism that the negative capacitance effect makes the subthreshold swing(SS)of traditional field effect transistor(MOSFET)breaking through the theoretical limit at room temperature,and models and analyzes the basic NCFET composed of ferroelectric capacitance and MOSFET.Secondly,ferroelectric materials are applied to double-gate devices to construct negative capacitance double-gate transistors(DG-NC-FET).The carrier analytical model of double gate devices is introduced,and the transfer characteristic curves of DG-NC-FET at drain voltages of 0.7V and 0.05 V are discussed.The results show that the negative capacitance effect can effectively reduce the subthreshold swing and improve the driving current.In addition,the impact of random doping fluctuation(RDF)on DG-NC-FET in manufacturing process is reduced.Thirdly,compared with the traditional three-gate FinFET,whether n-type or p-type devices,the negative capacitance FinFET(NC-FinFET)can significantly suppress the drain induced barrier lowering(DIBL)effect,and the output characteristic curve shows a clear negative differential resistance(NDR)phenomenon.With the increase of ferroelectric layer thickness,the off current of NC-FinFET gradually decreases,while the driving current gradually increases,and the NDR effect gradually weakens.The negative capacitance inverter(NC-inv)based on NC-FinFET has faster switching response,and the static random access memory(NC-SRAM)composed of 6 NC-FinFETs shows higher static noise margin and anti-interference ability.Finally,compared to the NC-FinFET with the same structural parameters,the negative capacitance gate-all-around nanosheet transistor(NC-NSFET)has better DC characteristics.Furthermore,higher total gate capacitance,transconductance and cut-off frequency are also observed in AC small signal analysis.The switching characteristics of the inverter based on NC-NSFET are discussed.The results show that the static noise margin of NC-SRAM in three states is improved.This thesis verifies the power consumption reduction and performance improvement of current and future mainstream multi-gate transistors combined with negative capacitance effect.It provides performance evaluation for their digital circuit applications in the early stage. |
