Some aspects of new Cu(NbC) films

Abstract

In this study, new barrier-free Cu(NbC) alloy films with two different thicknesses, i.e., 8 and 300 nm, containing 0.3 at% C and 0.5 at% Nb, which are deposited via co-sputtering on three types of substrates, viz., Si, stainless steel and polyimide (PI), have been developed, annealed, measured and analysed. The resistivity value of the new 300-nm-thick films atop Si substrates is $$3.07~\upmu \Omega ~\hbox {cm}$$ after annealing at $$450^{\circ }\hbox {C}$$ for 200 h. The low resistivity and diffusion depth of the new films exhibit their good quality in anti-oxidation stability in a high-temperature environment. The films also display high-adhesive strength atop either stainless-steel or PI substrates, $${\sim }$$ 7–8 times greater than that of their pure-Cu counterparts. In sharp contrast, the antibacterial ratio of the new films is $${\sim }96\%$$ while that of their pure-Cu counterparts is 0%. In addition, the contact angles of Cu(NbC) films are greater than those of their pure-Cu counterparts, resulting in a far superior antibacterial efficacy for the new films to pure-Cu films against, for example, Staphylococcus aureus BCRC 10451. With these desirable merits, the new films seem to be a good candidate material for bacteria killing and prevention, reduction of legionella spread inside hospitals and / or large buildings, biological medical care systems and advanced surgical tools. The new films deposited on PI substrates also seem to be suitable for making supple electrically conductive parts or devices, such as flexible panels, keyboards, screens, smartphones embedded in smart textiles and so forth.