Ti-Containing Cu<sub>3</sub>N Nanostructure Thin Films: Experiment and Simulation on Reactive Magnetron Sputter-Assisted Nitridation

Abstract

Ti-containing Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N (Ti:Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N) thin films were deposited on Si(111), quartz, and stainless steel substrates using reactive dc magnetron sputtering at N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ambient. The significance of nitrogen pressure and that of Ti accommodation on structure and microstructure, composition, deposition rate, and mechanical hardness of the as-deposited Ti-Cu-N thin films were experimentally and theoretically discussed. Crystallinity was determined using X-ray diffractometry and varied from Cu to Cu+ Ti:Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N composite and finally textured Ti:Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N structure with (100) preferred orientation depending on N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pressure. The mean crystallite size of Ti:Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N is around 21 nm. Elemental concentration was recognized using energy-dispersive X-ray spectroscopy. The elemental Ti:Cu ratio in as-deposited films is around half of the original target. The reflected N neutrals from the cathode and their initial energy were calculated by means of the transport of ions in matter Monte Carlo simulation and simple binary collision model, respectively. The mean energy of the sputtered particles was estimated by introducing an appropriate distribution in the vicinity of the target surface. Energy dissipation during mass transport through the gas phase was considered to estimate the final energy of the sputtered particles toward the substrate surface. To predict the composition of Ti-Cu-N films, energy and angular contribution of sputtering yield was introduced. The calculated values for the elemental Ti:Cu ratio are in agreement with experimental ones. The pressure-dependent behavior of deposition rate was described using a proposed formula as well. Film hardness was measured by Vickers microhardness test and its minimal value was 1.75 GPa for Ti:Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N films.