Role of NH3 feeding period to realize high-quality nickel films by hot-wire-assisted atomic layer deposition

• Highly pure Ni films were achieved using NiCp2 and NH2 radicals at 250 °C.
• To acquire low resistive Ni film, carbon content need to be reduced below 2.2 at. %.
• The incubation period for HW-ALD is short so very thin film can be formed.

We succeeded in depositing nickel films by hot-wire-assisted atomic layer deposition (HW-ALD) using nickelocene [Ni(C5H5)2] as a precursor and NH2 radical as a reducing agent, respectively. NH2 radical was generated with the assist of hot-wire and reduced the adsorbed nickelocene. Highly pure and low resistive Ni films have been formed, at low deposition temperature of 250 °C. The fraction of carbon was about 1 at. % in Ni films and there was no nitrogen contamination, though we used NH2 radical as the reducing agent. The lowest resistivity of Ni film was about 27.9 μΩ cm without a post-annealing. We demonstrated the NH3 feeding period was very important to the fraction of carbon in Ni films, which influenced the resistivity and microstructure of nickel films largely.

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