Hydrogen passivation of PolySilicon MOSFET's from a plasma Nitride source

Abstract

Improvements in polysilicon grain-boundary passivation techniques have made polysilicon MOSFET's increasingly attractive, as vertically stackable circuit components in applications, where high mobility is not a primary requirement. A simple method for the "last step" passivation of grain boundaries in polysilicon MOSFET's is presented. The method involves diffusion of atomic hydrogen at 450°C from a plasma-deposited compressive silicon nitride layer for reaction at silicon grain-boundary dangling bond sites. By use of this technique, ON/OFF current ratios of greater than 10⁶can be achieved with drive currents that are sufficient for many circuit applications.