Specific features of the capacitance and mobility behaviors in FinFET structures

This paper discusses experimental characterization of the gate-to-channel capacitance and the effective mobility in two types of FinFET structures: 1) with poly-Si/SiO₂ and 2) TaN/high-k dielectric gate stacks. Surprisingly, these two systems exhibit the same common features in terms of mobility and capacitance behavior of narrow-fin devices vs. quasi-planar wide-fin devices in spite of their rather different fabrication processes. Specific features revealed in effective capacitance and mobility behaviors of narrow-fin devices are discussed. We suggest that observations of the essentially lower effective dielectric capacitance and improved mobility values, in particular, the electron mobility, in narrow-fin devices compared to wide-fin devices (for both poly-Si/SiO₂ and TaN/high-k dielectric gate stacks) is related to a deeper inversion charge centroid in FinFETs operating in double-gate regime.