The Optimizations Of Independent Multi-gate NC-FinFET And Low Power Logic Circuit Design

There is a fundamental thermal limit of sub-threshold slope(SS)for the current CMOS/FinFET technologies,i.e.,the minimum of SS is 60mV/dec at room temperature,which is called as famous "Boltzmann tyranny" argument."Boltzmann tyranny" brings about the minimum operational voltage and switching energy of a transistor.Therefore,current CMOS/FinFET technologie devices are in urgent need of improvement to overcome these problems as the device size cannot be reduced.Negative Capacitance Field-Effect Transistor(NCFET)is a novel device that can effectively improve the SS.NCFET uses a material with a negative capacitance characteristic for the gate oxide layer,which allows the negative capacitance of the gate oxide layer can be regarded as a voltage amplifier,thereby amplifying the internal gate voltage,and then improving the SS of the device.In this paper,we present a NCFET with Metal-Ferroelectric-Metal-Insulator-Semiconductor-Insulator-Metal structure,called as Independent Multi-Gate NC-FinFET(NC-IMG-FinFET),whose structure of the front-gate and the back-gate is asymmetrical,and the back-gate is mainly used to adjust the threshold voltage of the device.NC-IMG-FinFET overcomes the "Boltzmann tyranny" limitation,thus has a lower operating voltage.And the threshold voltage of NC-IMG-FinFET is adjustable,it is suitable for the design of low-power circuits.In order to develop research of NC-IMG-FinFET,following works mainly done in this work:1.NC-IMG-FinFET was constructed.The appropriate physical structure of the NC-IMG-FinFET had been designed,and a suitable ferroelectric material was selected.2.The NC-IMG-FinFET was modeled.The capacitance model of NC-IMG-FinFET had been constructed.And then the relationship between surface potential,SS,leakage and on-current with capacitance of each part of the NC-IMG-FinFET were derived,it provides theoretical support for device performance optimization.3.A simulation model of Hspice for the NC-IMG-FinFET was constructed.This paper adopt the discrete model construction to link the L-K model of ferroelectric with the BSIM model of the Independent Multi-Gate device.A simulation model for Hspice of device and circuit simulation had been built.4.The physical parameters optimization of the NC-IMG-FinFET had been completed.With the help of simulation model and theoretical analysis,the applicable range and influence trend of ferroelectric thickness,common insulation thickness,bulk thickness and gate work function were clarified,and the device parameters of the optimized NC-IMG-FinFET were determined.5.The circuit simulation verification was performed.The performances of the circuit composed of the baseline device and NC-IMG-FinFET were compared by simulating the typical combined circuit and sequential circuit.The design method adopted in this paper is: Predicting the influence of structure parameter variation on device performance according to the constructed device model,and then optimizing and simulating the NC-IMG-FinFET with NC-IMG-FinFET simulation model by Hspice.The circuit operating mode ofNC-IMG-FinFET was determined according to the device characteristics.The circuit performance was measured by considering both the circuit power consumption and circuit delay.Some Low-power integrated circuits were built.The simulation results are consistent with the theoretical analysis results,showing that,NC-IMG-FinFET has better performances and is more suitable for low power circuit design.Compared with the baseline FinFET,NC-IMG-FinFET realize smaller leakage and larger on-current at lower operating voltage,and the power consumption and power consumption delay products of the optimized NC-IMG-FinFET circuits are generally optimized by 50% ~ 80%.The low power performance of the circuit is obviously improved,which is because of the operating voltage of the NC-IMG-FinFET is reduced and the SS is significantly improved.