Scaling Theory for FinFETs Based on 3-D Effects Investigation

In this paper, the scaling theory of fin field-effect transistors (FinFETs) has been established by a 3D analytical solution and numerical simulation of Poisson´s equation in the channel region. Considering the impact of ionized dopant in channel and source/drain on the potential distribution, respectively, the 3D Poisson´s equation is analytically solved through the superposition method. Based on the analysis of the minimum channel potential, which is approximated from the evanescent mode, a useful and simple subthreshold-swing (S) model is proposed for design consideration. According to the derived scaling length, a FinFETs structure is superior in controlling short-channel effects (SCEs). A ratio of channel length to scaling length larger than three is required for optimization. Meanwhile, it is noticed that the gate material with relative dielectric constant of about ten could sufficiently suppress SCEs