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Ru thin films were deposited by plasma enhanced atomic layer deposition using MethylCyclopentadienylPyrrolylRuthenium (MeCpPy)Ru and N2/NH3 plasma. The growth characteristics have been studied on titanium nitride or tantalum nitride substrates of various thicknesses. On SiO2, a large incubation period has been observed, which can be resolved by the use of a metal nitride layer of ∼ 0.8 nm. The growth characteristics of Ru layers deposited on ultra-thin metal nitride layers are similar to those on thick metal nitride substrates despite the fact that the metal nitride layers are not fully closed. Scaled Ru/metal nitride stacks were deposited in narrow lines down to 25 nm width. Thinning of the metal nitride does not impact the conformality of the Ru layer in the narrow lines. For the thinnest lines the Ru deposited on the side wall showed a more granular structure when compared to the bottom of the trench, which is attributed to the plasma directionality during the deposition process. [ABSTRACT FROM AUTHOR]

Abstract: Thin (<4nm) Physical Vapor Deposited (PVD) Ru-10at.% Ta films were evaluated as diffusion barriers and seed enhancement layers for Cu metallization in sub 25nm trenches. The ratio of Ru/Ta on blanket wafers could be influenced by changing the process conditions. However, a difference in Ru/Ta ratio did not influence the thermal stability of the layers during High Temperature X-ray Diffraction (HT-XRD) measurements as all RuTa films exhibited good thermal properties since no Cu-silicide formation was observed for temperatures below 500°C. The RuTa films also passed an 85°C/85% relative humidity (RH) test of one week of storage in order to test the H2O barrier integrity of the films. Furthermore no difference was found when testing the O2 barrier integrity during 300s anneals at various temperatures between 250°C and 500°C. Good Cu fill of 20nm trenches (AR 4:1) patterned in oxide was achieved when combining the RuTa films with PVD Cu seed layers with thicknesses ranging from 7 to 20nm and Cu plating. When compared to a Ta(N)/Ta barrier, relatively high electrical yields (60–80%) were obtained for structures with CDs <30nm when combining RuTa films with PVD Cu seed layers as thin as 7nm (on field), hence evidencing the seed enhancement ability of these layers. [Copyright &y& Elsevier]