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.