Analysis of dc-sputtered Si 3N 4-films using X-ray diffraction and computer simulation

Abstract

Amorphous stoichiometric Si 3N 4 was produced by physical vapour deposition. Atomic distances and coordination numbers have been determined by wide angle X-ray scattering. Comparison of X-ray data with computer simulation indicated that a satisfying middle-range structure model can be constructed by consideration of topological rules only. The main topological unit is a combination of four- and sixfold rings. The construction of a larger network with such topological units leads to the formation of additional larger rings. Analysis of the small angle X-ray scattering shows the existence of electron density inhomogeneities with a two-dimensional mass distribution. On another length scale, distinct columnar regions with a diameter of more than 1 μm were shown by using the scanning electron microscopy.