Direct-Liquid-Injection Chemical Vapor Deposition of Nickel Nitride Films and Their Reduction to Nickel Films

Abstract

Smooth and continuous films of nickel nitride (NiNx) with excellent step coverage were deposited from a novel nickel amidinate precursor, Ni(MeC(NtBu)2)2, and either ammonia (NH3) or a mixture of NH3 and hydrogen (H2) gases as co-reactants. The reactants were injected together in direct-liquid-injection chemical vapor deposition (DLI-CVD) processes at substrate temperatures of 160−200 °C. Depending on the ratio of NH3 to H2 gases during deposition, the Ni:N atomic ratio in DLI-CVD NiNx films could be varied from ∼3:1 to ∼15:1, having either a cubic nickel structure or a mixture of hexagonal Ni3N and cubic Ni4N crystal structures with an incorporation of nitrogen as low as 6%. The chemical vapor deposition (CVD) growth rates of NiNx could be increased to more than 5 nm/min. The CVD films were smooth and continuous, and they had ∼100% step coverage in high-aspect-ratio (>50:1) holes. The as-deposited NiNx films had resistivities as low as ∼50 μΩ cm for film thicknesses of ∼25 nm. Annealing of the films in H2 at 160 °C or hydrogen plasma treatment at room temperature removed the nitrogen and led to pure nickel films.