Ultra-thin high-quality silicon nitride films on Si(111)

Ultra-thin silicon nitride films grown by exposure of Si(111) substrates to a flux of atomic nitrogen at temperatures between 700 °C and 1050 °C have been investigated by means of X-ray spectromicroscopy, atomic force microscopy, X-ray reflectivity, and X-ray photoemission spectroscopy. The films show a Si3N4 stoichiometry. For reactive nitride growth at temperatures below 800 °C, a smooth surface and interface morphology is found. Higher temperatures lead to the formation of rough films with holes and grooves of increasing size, approaching a lateral size of several hundred nanometers for growth temperatures above 900 °C. Nonetheless, X-ray spectromicroscopy shows that the bottom of the holes consists of Si3N4.