Comprehensive Study of Quasi-Ballistic Transport in High-kappa/Metal Gate nMOSFETs

Abstract

We study quasi-ballistic transport in nanoscale high-kappa/metal gate nMOSFETs based on radio-frequency (RF) S-parameter analysis. An RF S-parameter-based simple experimental methodology is used for direct extraction of device parameters (i.e., L(eff), R(sd), and C(inv)) and the effective carrier velocity v(eff) from the targeted short-channel devices. Furthermore, an analytical top-of-the-barrier model, which self-consistently solves the Schrodinger-Poisson equations, is used to determine the ballistic carrier velocity v(inj) at the top of the barrier near the source. Based on the results of the experimental extraction and analytical calculations, backscattering coefficient r(sat) and ballistic ratio BR(sat) are calculated to assess the degree of the transport ballisticity for nMOSFETs. It is found that conventional high-kappa/metal gate nMOSFETs will approach a ballistic limit at an effective gate length L(eff) of approximately 7 nm.