Atomic Layer Deposition of Ru Thin Films Using a Ru(0) Metallorganic Precursor and O2

Ruthenium (Ru) thin filmswere grown on thermally-grown SiO2 substrate using atomic layer deposition (ALD) by a sequential supply of a zero-valent metallorganic precursor, (ethylbenzyl) (1-ethyl-1,4-cyclohexadienyl) Ru(0) (EBECHRu, C16H22Ru), and molecular oxygen (O-2) between 140 and 350 degrees C while the typical temperature was 225 degrees C. A self-limiting film growth was confirmed at the deposition temperature of 225 degrees C and the growth rate was similar to 0.042 nm/cycle on the SiO2 substrate with a negligible number of incubation cycles (approximately 3 cycles). Plan-view transmission electron microscopy analysis showed that nucleation was started after only 3 ALD cycles and the maximum nuclei density of 1.67 x 10(12)/cm(2) was obtained after 7 ALD cycles. A continuous Ru film with a thickness of similar to 2.3 nm was formed after 60 ALD cycles. The film resistivity was decreased with increasing deposition temperature, which was closely related to its crystallinity and microstructure, and the minimum resistivity of similar to 14 mu Omega-cm was obtained at the deposition temperature of 350 degrees C. The step coverage of the film deposited between 225 and 270 degrees C was approximately 100% over the contact holes (bottom diameter: 0.065 mu m) with a high aspect ratio (32: 1). Finally, the ALD-Ru film was successfully evaluated in terms of its performance as a seed layer for Cu electroplating and as a bottom electrode for a metal-insulator-metal capacitor using an ALD-TiO2 single layer or an ALD HfO2/La2O3/HfO2 multilayer as a dielectric. (C) 2012 The Electrochemical Society.