A physically based mobility model for MOSFET numerical simulation

A new modeling for the surface mobilities based on theoretical and experimental surface mobility studies has been implemented in the MINIMOS two-dimensional MOSFET current-voltage characterization program. The new model includes the following scattering mechanisms: surface and bulk acoustical and optical-intervalley phonons, bulk ionized impurities, oxide charges, surface roughness, dipoles or neutral surface states at the oxide-silicon interface, as well as hot-carrier mobility reduction in high longitudinal electric fields. The resultant combined mobility of this model is compared with Selberherr´s mobility model, which he employed in the MINIMOS program. Selberherr´s surface mobility is smaller at low fields than this, as well as other experimentally observed mobilities, However, a detailed comparison of the computed drain current-voltage characteristics of many devices showed excellent agreement between the Selberherr model and this model in the subthreshold range and a less than about 20-percent difference in the strong inversion range. The new model may be preferred since it has no adjustable parameters and all parameters were obtained by careful independent measurements on large-area and long-channel devices and data analyses based on fundamental physical models.