Growth of stoichiometric Cu3N thin films by reactive magnetron sputtering

Copper nitride (Cu3N) is a thermally unstable material; therefore both the deposition of a stoichiometric sample and the reliable characterization of its properties constitute a big challenge. We reported here the growth of stoichiometric Cu3N films on Si (1 0 0) wafer by reactive magnetron sputtering of Cu target using pure nitrogen as working gas. At a low substrate temperature (60 °C), a combination of high working pressure (>0.7 Pa) and low RF power supply (<150 W) favors the formation of stoichiometric deposits. With the pressure at 0.9 Pa and the RF power below 100 W, the deposits are [0 0 1]-oriented and consist of cubic Cu3N grains, which are typically 40 nm in dimension. The lattice constant is 0.383 nm as determined by both X-ray diffraction and transmission electron microscopy; and the electrical resistivity measurement reveals a typical deficit semiconductor behavior in the cubic Cu3N. The thermal decomposition temperature, being reported within 100–470 °C, was determined to be ∼350 °C as indicated by the presence of Cu (1 1 1) and (0 0 2) reflections after prolonged annealing.