Comparing the chemical properties of evaporated and sputtered niobium films on oxidized Si(1 0 0) wafers – preparation of oxynitride films

Abstract

Five hundred nanometers of niobium films have been deposited on silicon(1 0 0) wafers with 100 or 300 nm thermally grown oxide by electron beam evaporation and DC magnetron sputtering. SEM and AFM investigations revealed smaller crystallites and rougher surfaces for the evaporated films. The differences in film morphology resulted in lower reflection intensities in XRD for the as-deposited evaporated films. In order to investigate the influence of the structural properties on their chemical reactivities, in a first set of experiments the films were nitrided with molecular nitrogen by rapid thermal processing (RTP) at varying temperatures. In another set of experiments after nitridation in nitrogen at 1000 °C an oxidation step in molecular oxygen at varying temperatures followed. The films showed different reactivities, leading to different rates of nitridation and oxidation. Sputtered films were less reactive than the evaporated films, deduced from the sequence of reaction products dependent on reaction temperature. XRD data indicated that oxynitrides have formed. Elemental depth profiles were measured by secondary ion mass spectrometry (SIMS).