Monolayer-level controlled incorporation of nitrogen at Si–SiO2 interfaces using remote plasma processing

We demonstrate three different ways to incorporate nitrogen at Si–SiO2 interfaces: (i) an O2/He plasma oxidation of the Si surface followed by an N2/He plasma nitridation, (ii) an N2/He plasma nitridation of the Si surface, and (iii) a Si3N4 film deposition on to the Si surface. The two-step interface formation, the O2/He plasma oxidation followed by the N2/He plasma nitridation, is shown to yield significantly better interface device properties than the other two approaches. These differences in interface properties are explained by an application of constraint theory based on comparisons of the average bonding coordination of the dielectric layer at the interface with the Si substrate.