Atomic layer deposition of ruthenium films from (Ethylcyclopentadienyl)(pyrrolyl)ruthenium and oxygen

Ru films were grown by atomic layer deposition in the temperature range of 275-350°C using (ethylcyclopentadienyl)(pyrrolyl)ruthenium and air or oxygen as precursors on HF-etched Si, SiO2, ZrO2, and TiN substrates. Conformal growth was examined on three-dimensional silicon substrates with 20:1 aspect ratio. ZrO2 promoted the nucleation of Ru most efficiently compared to other substrates, but the films roughened quickly on ZrO2 with increasing film thickness. The minimum number of cycles required to form continuous and conductive metal layers could be decreased by increasing the length of the oxygen pulse. In order to obtain well-conducting Ru films growth to thicknesses of at least 8-10 nm on any surface was necessary. Resistivities in the ranges of 30-60 and 14-16 µ ohm cm were achieved for 4-6 and 10-15 nm thick films, respectively. Delamination became an issue in the Ru films grown to thicknesses about 10 nm and higher.