To deposit metals onto these complex three-dimensional structures, atomic layer deposition (ALD) is the leading technique that allows for conformal and uniform deposition of atomic scale metal thin films with precise thickness control. ALD of a metal consists of two self-limiting half cycles, namely a metal precursor reaction, followed by a purge to remove undesired precursors, and a reduction pulse, where the metal centre is reduced, followed by another pulse. The advantage of ALD is in it self-limiting nature, where reactions will, in principle, stop after all available surface sites are consumed thus allowing fine control over thickness, high uniformity and high conformality. The ALD of metal thin films can be operated at a low temperatures, typically 300K to 600K, when plasma-enhanced ALD (PE-ALD) is applied. For example, Ag thin film was deposited at 393.15K using Ag(fod)(PEt3) together with plasma-activated hydrogen. Ru thin film was deposited at 543.15K using Ru(EtCp)2 and NH3 plasma. For the deposition of metals, an oxygen source, such as O3 and H2O, will cause unwanted oxygen contamination. Thus, a non-oxidizing reactant is preferred for PE-ALD of metals, where N-plasma is used with typical plasma sources being NH3 or a mixture of N2 and H2. Cyclopentadienyl (Cp, C5H5)-based metal precursors, such as bis(cyclopentadienyl)cobalt(II) (CoCp2) and Bis(ethylcyclopentadienyl)ruthenium(II) (Ru(EtCp)2), are the most commonly used precursors for ALD of Ru and Co. The structure of Cp-based metal precursors is that the Cp ligands coordinate to the metal centre and each Cp ligand has five metal-C bonds, which yields monomeric thermally stable precursors. The precursor properties can be modified by functionalizing the Cp ligand with different substituents, which can result in enhanced volatility, thermal stability and decreased melting points. The reported growth-per-cycle (GPC) for PE-ALD of Ru 24 using Ru(EtCp)2 and N-plasma varies from 0.2Å/cycle (NH3 plasma, PE-ALD temperature at 373K to 543K) to 0.38Å/cycle 7 (N2/H2 plasma, PE-ALD temperature at 473K). The PE-ALD of Co thin films using CoCp2 is highly dependent on plasma source, where NH3 plasma or a mixture of N2 and H2 can result in high quality and low impurity Co thin films, but separated N2 and H2 plasma pulses yield low quality and high impurity Co thin films. The significance of active NxHy (x = 0 or 1, y = 0, 1 or 2) radicals in plasma ALD of Co together with surface NHx (x = 1 or 2) terminations were described in our previous studies in eliminating Cp ligands in the metal precursor pulse and in the plasma pulse in addition to removing from the growing film and regenerating the surface NHx terminations at the post-plasma stage to be ready for the next deposition cycle.