Growth processes and electrical characteristics of silicon nitride films formed on Si(100) by radical nitrogen

We have investigated nitridation processes on clean Si(100)-2 x I surfaces and the electrical characteristics of metal-insulator-semiconductor (MIS) capacitors with nitride films formed by radical nitrogen. The radical nitrogen exposure to Si surfaces at 500degreesC initially causes both nitridation of Si and local detachment reactions on the surface. It is found from scanning tunneling microscopy and scanning tunneling spectroscopy that the nitridation proceeds in a layer-by-layer manner in which a continuous film is formed by the coalescence of two-dimensional islands. At nitride thicknesses above 0.6 nm, the nitride film is homogeneously formed over the entire surface. The MIS capacitor with a 5.4-nm-thick nitride film formed by radical nitrogen shows low hysteresis of less than 0.1 V and low leakage current density. These electrical properties indicate that the nitride films formed by radical nitrogen are applicable to gate insulators.