Microstructural and component evolution of self-assembled nanoperiod multilayered carbon-copper films with deposition pressure

Here, we report a facile synthesis method for the fabrication of various nanoperiod multilayers in carbon-copper films only by conveniently changing the deposition pressure from the reactive magnetron sputter process. To obtain the nano-multilayered structure with different number of layers, only one single sputtering target of copper is used at gas pressure varied from 0.4 Pa to 1.2 Pa by flowing gas mixture of argon and methane, while 600W DC input power is applied to a copper target. The influence of deposition pressure on the microstructure and constitution of the films are investigated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The results show that carbon-rich layers and copper-rich layers are alternately arranged to self-organize the multilayered structure in the carbon-copper films, both of the carbon-rich layer and copper-rich layer constitute a period. The amount of layers in the multilayered structure is found to decrease with the deposition pressure, the film deposited with 0.4 Pa has the maximum layers and the highest copper content compared with the other deposition pressure. Effects of the growth condition on the growth rate, the number of the layers and the energy of plasmas during deposition process are discussed. Based on the (a) influence of the effect of carbon absorbed on the copper target leading to target poisoning, (b) influence of deposition pressure on the energy of etching ions and (c) the energetic ions bombardment enhanced inter diffusion of deposition ions, the mechanism of self-organized formation of nano-multilayer in the carbon-copper films with various number of layer is proposed.