Low temperature atomic layer deposition of Ru thin films using a new carbonyl-based Ru precursor and non-oxidizing reactants; Applications to the seed layer for Cu metallization

We report ALD-Ru thin films using a new carbonyl-based Ru precursor and compare the results with various nonoxidizing reactants such as H 2 , NH 3 , CO molecule and NH 3 , N 2 , H 2 , N 2 +H 2 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 N 2 and H 2 mixture plasma as a reactant, it was possible to deposit Ru film even at a substrate temperature of 100C 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 H 2 molecules at 150C with increasing chamber pressure up to 30 Torr. The step coverage of ALD-Ru films deposited using H 2 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 H 2 molecules contained no oxygen and carbon impurities while Ru films using deposited diluted O 2 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 H 2 molecules at 30 Torr.