Effect of substrate temperature on the physical properties of copper nitride films by r.f. reactive sputtering

Deposition of copper nitride films are of significant interest because of their low thermal stability and semiconducting characteristics resulting in emerging applications in optical memories and laser writing. Copper nitride films are deposited by 13.56 MHz r.f. reactive sputtering (in the nitrogen plasma environment), keeping the substrates at 30°C (no deliberate heating of the substrate), 75°C and 150°C. Crystalline phases of the films are identified by grazing angle X-ray diffraction (GAXRD) technique. With an increase in substrate temperature, the film orients strongly towards the (100) plane of the Cu3N phase. Surface morphology of the films studied by atomic force microscopy (AFM) indicates an increase in grain size and a decrease in surface roughness in the films with increasing substrate temperature. Agglomeration effect of grains are observed at the substrate temperature corresponding to 75°C. The bandgap of the films are found by UV-VIS absorption spectroscopy varying from 1.3 to 1.76 eV. Stoichiometry of the films is determined by heavy ion elastic recoil detection analysis (ERDA) technique with a ΔE–E detector telescope. This study provides insight into the importance of substrate temperature on the characteristics of copper nitride films.