A Qualitative Approach on FinFET Devices Characteristics

FinFET devices are comprehensively investigated owing to the projection for application in the CMOS integrated circuits fabrication. Deducing MOSFET size have great influence on electrostatic characteristic.The indiscriminate variations of the characteristics lead to a divergence effect which is imperative from the point of view of design and manufacture. In this paper different types of the possible variations of FinFET characteristics are discussed. We have considered only n-channel devices. The behaviour of hole mobility in multigate devices is of course of great importance.[1-2].We discusse simulation study on electronmobility in FINFET with electric field applied.Mobility enhancement is observed in devices with thinner silicon film, when higher field is applied, which can be attributed to "volume inversion" in FINFET. Index-Terms—FinFET, mobility, electrical characteristics. INTRODUCTION: The continuing scaling of CMOS (Complementary Metal-Oxide-Semiconductor) technology requires noteworthy innovations in different fields, from short channel effect restraint to carrier transport improvement [3-7].As devices get smaller further and further,the problem with conventional MOSFETs are increasing. We are facing severel problem such as VT rolloff ,drain induced barrier lowering (DIBL), increasing leakage current and so on . Solving one problem leads to another. To solved the problem several MOSFET has been introduced such as double gate,FinFET,Trigate,Foregate,All around gate and so on.We will discuss here the eletrostatic characteristic of FinFET such as current – voltage curves, mobility variation with electric field on MOSFET. The distinguishing characteristic of the FinFET is that the conducting channel is wrapped by a thin silicon "fin", which forms the gate of the device. The thickness of the fin (measured in the direction from source to drain) determines the effective channel length of the device. It is very important to know the characteristics of MOSFET to work properly from this aspect we tried to discuss the qualitative feature of FinFET characteristics. THEORY: All the MOSFET characteristics are expressed as functions of the values of the surface potential at the source and drain ends. In the threshold voltage approach separate solutions are available for different regions of MOSFET operation (Fig. 1). For FinFET Fig. Device structure used in this study .(FinFET consists of a vertical Si fin controlled by self_aligned double gate) Linear Region. It is the region in which ds I , increases linearly with ds v , for a given g v ( > t v ). To a first approximation, ds I , in the linear region is given by ds ds t g ox ds v v v v L W C I ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − − = 2 2 μ where μ is mobility of the carriers (electrons for nMOST) in the channel (inversion) region, Cox is the gate oxide capacitance per unit area, W/L is device width to length ratio and t v is threshold voltage. Saturation Region. In this region ds I no longer increases as ds v increases. Once more to a first rough calculation, ds I in the saturation region is given by L W C I ox ds μ = g v