MODELED TUNNEL CURRENTS FOR HIGH DIELECTRIC-CONSTANT DIELECTRICS

The effect of dielectric constant and barrier height on the WKB modele d tunnel currents of MOS capacitors with effective oxide thickness of 2.0 nm is described. We first present the WKB numerical model used to determine the tunneling currents. The results of this model indicate t hat alternative dielectrics with higher dielectric constants show lowe r tunneling currents than SiO2 at expected operating voltages. The res ults of SiO2/alternative dielectric stacks indicate currents which are asymmetric with electric field direction. The tunneling current of th ese stacks at low biases decreases with decreasing SiO2 thickness. Fur thermore, as the dielectric constant of an insulator increased, the ef fect of a thin layer of SiO2 on the current characteristics of the die lectric stack increases.