We report ALD-Ru thin films using a new carbonyl-based Ru precursor and compare the results with various nonoxidizing reactants such as H2, NH3, CO molecule and NH3, N2, H2, N2+H2 mixture plasma. In addition, we also investigatd ALD-Ru process with post annealing and in-situ periodic plasma treatment to improve ALD-Ru film quality. The Ru film was deposited at the deposition temperature ranging from 100 to 150 C and at the chamber pressure from 1 to 50 Torr. In the case of using N2 and H2 mixture plasma as a reactant, it was possible to deposit Ru film even at a substrate temperature of 100C and the film resistivity of ∼ 70 µΩ·cm was deposited after annealing and in-situ plasma treatment. It was shown that ALD-Ru film with the resistivity of ∼ 25 µΩ·cm could be prepapred using H2 molecules at 150C with increasing chamber pressure up to 30 Torr. The step coverage of ALD-Ru films deposited using H2 molecuels and at the chamber pressure of 30 Torr was excellent, around 100 % at dual trench structure with aspect ratio of ∼ 6.3. It should be noted that ALD-Ru films deposited using H2 molecules contained no oxygen and carbon impurities while Ru films using deposited diluted O2 has oxygen and carbon impurities by secondary ion mass spectrometry depth profile. And electro-plating of Cu is successfully possible on ALD-Ru deposited using H2 molecules at 30 Torr.