A Study On The Modeling Of FinFET Device Based On BSIM-CMG

As the traditional bulk CMOS process feature scale shrink below 100 nm,there are a number of detrimental effects such as random dopant fluctuation,short-channel effects,and mobility degradation,which is a serious limit to continued scaling of the device.As a solution to break through the device scale limit,FinFET has become an important issue in the VLSI research.Compared to bulk CMOS,FinFET's 3-D multi-gate structure enhances the control of the channel and effectively suppresses the short-channel effect(SCE)and the Drain Induced Barrier Lowering(DIBL)effect etc.Circuit simulation is the basis of IC circuit design,and requires the device to have a precise model.The traditional planar models are no longer able to accurately characterize the behavior of stereoscopic FinFET,which brings new challenges to device modeling.Therefore,developing a model suitable for multi-gate stereoscopic FinFET process has an important theoretical significance and profoud practical prospects.Nowadays,there are two multi-gate compact models BSIM-IMG and BSIM-CMG.BSIM-IMG is suitable for independent double-gate MOSFETs,which the front gate and back gate have different gate workfunctions,biases,dielectric thicknesses and materials.Compared to IMG,BSIM-CMG is suitable for common multi-gate MOSFETs,which multiple gates have the same gate workfunctions,biases,dielectric thicknesses and materials.Based on the common gate model BSIM-CMG,this thesis researchs the surface potential model suitable for FinFET devices and proposes a specific parameter extraction process.Experimental results show excellent agreement between the test data and simulation data over different bias voltages and larger frequency range.The main work of this research are summarized as follows:(1)The physical structure and working principle of planar MOSFETs are elaborated.The structural features and advantages of various multi-gate devices are briefly described from planar devices to 3-D devices.The working principle of FinFET devices and the compact model for multi-gate devices are elaborated in detail.(2)The surface potential model mechanism and equation of MOS device are analyzed.The basic method of BSIM-CMG model modeling is researched,and several important physical characteristics models are described hierarchically.(3)The method of parameter extraction of FinFET model based on BSIM-CMG is described in detail.The test environment and steps of parameter extraction of BSIM-CMG model are elaborated.The model based on BSIM-CMG is established under the ICCAP tool environment.Experimental verification of N-substrate and P-substrate FinFET devices is also performed.(4)A modeling method suitable for FinFET varactor is proposed based on the extracted FinFET model.The specific parameter extraction process is elaborated.The feasibility and accuracy of FinFET varactor based on BSIM-CMG are verified by comparing the results of the C-V,Q-V and small signal S-parameters of FinFET varactor.