Atomic layer deposition of Ru thin film using N-2/H-2 plasma as a reactant

Abstract

Ruthenium (Ru) thin films were grown by atomic layer deposition using IMBCHRu [(eta 6-1-Isopropyl-4-MethylBenzene)(eta 4-CycloHexa-1,3-diene)Ruthenium(0)] as a precursor and a nitrogen-hydrogen mixture (N-2/H-2) plasma as a reactant, at the substrate temperature of 270 degrees C. In the wide range of the ratios of N-2 and total gas flow rates (fN(2)/N-2+H-2) from 0.12 to 0.70, pure Ru films with negligible nitrogen incorporation of 0.5 at.% were obtained, with resistivities ranging from similar to 20 to similar to 30 mu Omega cm. A growth rate of 0.057 nm/cycle and negligible incubation cycle for the growth on SiO2 was observed, indicating the fast nucleation of Ru. The Ru films formed polycrystalline and columnar grain structures with a hexagonal-close-packed phase. Its resistivity was dependent on the crystallinity, which could be controlled by varying the deposition parameters such as plasma power and pulsing time. Cu was electroplated on a 10-nm-thick Ru film. Interestingly, it was found that the nitrogen could be incorporated into Ru at a higher reactant gas ratio of 0.86. The N-incorporated Ru film (similar to 20 at.% of N) formed a nanocrystalline and non-columnar grain structure with the resistivity of similar to 340 mu Omega cm. (C) 2012 Elsevier B. V. All rights reserved.