Diffusion barrier properties of metalorganic chemical vapor deposition -WNx compared with other barrier materials

Abstract

Tungsten nitride (WNx) is a potentially strong candidate for Cu diffusion barrier. The WNx. films were deposited by chemical vapor deposition (CVD) using W(CO)(6) and NH3 sources at 430degreesC. The diffusion barrier properties of WNx, were investigated by comparison with other materials. In order to study the barrier properties, Cu[barrier/substrate structures were fabricated. A 120-nm-thick Cu film was deposited by evaporation onto various barrier materials including CVD-WNx,, CVD-W, and sputter-deposited Ti,Ta, and TaN. After annealing for I It in argon, variations in the film sheet resistances and the x-ray diffraction patterns were examined. Both results showed that a 15-nm-thick W2N film prevented Cu diffusion up to 600degreesC, and started to fail at 620degreesC, while no barrier and the CVD-W barrier samples failed at 100-150degreesC and 525-550degreesC, respectively. Also, 20 nm sputtered Ti,Ta, and TaN films failed at 400-450degreesC, 550-575degreesC, and 650-700degreesC, respectively, in our annealing conditions. From these results, our WNx, deposited by CVD using the simple, nonfluorine precursor, W(CO)(6), can be evaluated as a competent diffusion barrier candidate. (C) 2004 American Vaccum Society.