Doped polysilicon to retard boron diffusion into and through thin gate

Abstract

An embodiment of the instant invention is a method of fabricating a semiconductor device which includes a dielectric layer situated between a conductive structure and a semiconductor substrate, the method comprising the steps of: forming the dielectric layer (layer 14) on the semiconductor substrate (substrate 12); forming the conductive structure (structure 18) on the dielectric layer; doping the conductive structure with boron; and doping the conductive structure with a dopant which inhibits the diffusion of boron. The semiconductor device may be a PMOS transistor or a capacitor. Preferably, the conductive structure is a gate structure. The dielectric layer is, preferably, comprised of a material selected from the group consisting of: an oxide, an oxide/oxide stack, an oxide/nitride stack, and an oxynitride. Preferably, the dopant which inhibits the diffusion of boron comprises at least one group III or group IV element. More specifically, it is preferably comprised of: carbon, germanium, and any combination thereof. Preferably, the steps of doping the conductive structure with boron and doping the conductive structure with a dopant which inhibits the diffusion of boron are accomplished substantially simultaneously, or the step of doping the conductive structure with boron is preformed prior to the step of doping the conductive structure with a dopant which inhibits the diffusion of boron are accomplished substantially simultaneously.