Thermal stability of copper nitride films prepared by rf magnetron sputtering

Abstract

Copper nitride films were prepared by the rf magnetron sputtering method using Ar and N 2 as working gas. The nitrification degree of the films was studied by changing the N 2 fraction or the substrate temperature under the N 2 fraction of 30%. The films deposited under different N 2 fraction were also annealed at temperature range of 100–300°C in order to study the thermal stability of the films. X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the films. It was shown that the films grow along the [100] orientation and the preferential growth becomes heavier with increasing N 2 fraction. The size of the Cu 3N grain is estimated to be on the order of nanometers, and the grain size increases with increasing N 2 fraction. The Cu 3N phase is thermally unstable in vacuum even at 100°C. During the deposition under the N 2 fraction of 30%, the highest substrate temperature to form the Cu 3N phase ranges from 200 to 250°C. Good agreement between XRD and XPS analysis was obtained in characterizing the film structures. The observed phenomena are discussed briefly.