Electronic device with dopant diffusion barrier and tunable work function and methods of making same

Abstract

A method of fabricating a semiconductive film stack for use as a polysilicon germanium gate electrode to address problems associated with implant and diffusion of dopants. Achieving a sufficiently high active dopant concentration at a gate-dielectric interface while avoiding gate penetration of dopants such as boron is problematic. A higher gate implant dosage or annealing temperature is needed, and boron penetration through the thin gate oxide is inevitably enhanced. Both problems are exacerbated as the gate dielectric becomes thinner. In order to achieve a high level of active dopant concentration next to the gate dielectric without experiencing problems associated with gate depletion and penetration, a method and procedures of applying a diffusion-blocking layer is described with respect to an exemplary MOSFET application. However, a diffusion-blocking concept is also presented, which is readily amenable to a variety of semiconductor related technologies.