Thermal- and Plasma-Enhanced Copper Film Deposition via a Combined Synthesis-Transport CVD Technique†

Metallic copper thin layers are deposited by means of a modified metal-organic (MO)CVD method via passing formic acid vapor through a finely dispersed powder of a solid metal-containing reactant (Cu/CuO) under thermal and plasma activation. To characterize the copper layers obtained, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and UV-vis spectroscopy, scanning electron microscopy (SEM), diffraction of synchrotron radiation (DSR) analyses, and laser interferometry, are used. The layers are found to be crystalline with a nanometer-scale grain structure, the parameters of which depend on the experimental conditions and chemical composition, with a predominant content of copper in the metallic state, Cu⁰. It is revealed that the plasma activation causes a decrease in the mean size of copper grains, as well as film thickness. Average growth rates inherent in the films obtained under thermal and plasma conditions are calculated. Based on studying the composition of a gas-phase copper complex synthesized, a schematic diagram of chemical conversion is suggested for the combined synthesis-transport process (CST).