THRESHOLD VOLTAGE MODELS OF THE NARROW-GATE EFFECT IN MICRON AND SUB-MICRON MOSFETS

Modeling of the narrow gate effect on the threshold voltage shift ( DELTA V//T) and the effective channel width (W//C//E) by Ji and Sah, based on the solution of the Poisson equation for the two-dimensional (2-D) potential distribution using the depletion approximation, has been improved by removing the depletion approximation. A simple two-parameter analytical formula for predicting the threshold voltage shift of a narrow gate MOSFET with gate width (W//G) in the micron and submicron ranges, was proposed and tested against 2-D numerical results. Both parameters can be extracted easily from the theoretical 2-D computed or experimental drain conductance-gate voltage characteristics. The new model shows that the threshold voltage shift of any given MOSFET with a known W//C//E can be determined based only on one test device. Therefore, in applications, computation time can be reduced considerably by using the proposed analytical formula to compute the threshold voltage of any given MOSFET.