Atomic Layer Deposition of Ru Thin Films Using 2,4-(dimethylpentadienyl)(ethylcyclopentadienyl) Ru by a Liquid Injection System

Ru thin films were grown on TiO₂/Si and bare-Si substrates by atomic-layer-deposition using 2,4-(dimethylpentadienyl)(ethylcyclopentadienyl)Ru and O₂ as Ru precursor and reactant, respectively. Negligible RuO₂ was formed even with an excessive oxygen dose. Ru films on TiO₂/Si substrate showed smoother surface morphology compared to Ru films on bare-Si substrate. Although abnormal grain growth of Ru films appeared at annealing temperature > 700degC, agglomeration of Ru films was not observed. Al-incorporated TiO₂ (ATO) films were grown on Ru films and the electrical properties of the capacitor were investigated in order to evaluate the properties of bottom Ru films. The leakage current density of an ATO film with an equivalent oxide thickness of 0.7 nm was 10^-7 A/cm² at + 1 V. Therefore, Ru films grown by ALD are very promising as the capacitor electrodes of future dynamic random access memories.