Atomic Layer Deposition of Ruthenium and Ruthenium Oxide Using a Zero-Oxidation State Precursor

Atomic layer deposition (ALD) processes are reported for ruthenium (Ru) and ruthenium oxide (RuO2) using a zero-oxidation state liquid precursor, eta(4)-2,3-dimethylbutadiene ruthenium tricarbonyl [Ru(DMBD)(CO)(3)]. Both ALD Ru and RuO2 films were deposited using alternating N2-purge-separated pulses of Ru(DMBD) (CO)(3) and O-2. ALD Ru metal films were deposited via short (2 s) pulses of O-2. Ru films have an ALD temperature window from 290 to 320 degrees C with a GPC of 0.067 nm/ cycle and a negligible nucleation delay' on SiO2. Ru films show a strong hexagonal crystal structure with low resistivity of approximately 14 mu Omega cm at 320 degrees C. RuO2 films were deposited using longer (20 s) pulses of either molecular O-2 or O-2 plasma. RuO2 films deposited via thermal ALD using molecular O-2 have a temperature window from 220 to 240 degrees C with a GPC and nucleation delay on SiO2 of 0.065 nm/cycle and 35 cycles, respectively. Thermal ALD RuO2 films show a distinct rutile phase microstructure with a resistivity of approximately 62 mu Omega cm. In comparison to thermal ALD, the PEALD RuOx films show a lower growth rate and higher nucleation delay of 0.029 nm/cycle and 76 cycles, respectively. PEALD RuOx films also exhibit less distinct crystallinity and a higher resistivity of 377 mu Omega cm.