CMOS gate stack structures and processes

摘要

A semiconductor device includes a substrate having a semiconducting surface having formed therein a first active region and a second active region, where the first active region consists of a substantially undoped layer at the surface and a highly doped screening layer of a first conductivity type beneath the first substantially undoped layer, and the second active region consists of a second substantially undoped layer at the surface and a second highly doped screening layer of a second conductivity type beneath the second substantially undoped layer. The semiconductor device also includes a gate stack formed in each of the first active region and the second active region consists of at least one gate dielectric layer and a layer of a metal, where the metal has a workfunction that is substantially midgap with respect to the semiconducting surface.