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

Smooth and continuous films of nickel nitride (NiNx) with excellent step coverage were deposited from a novel nickel amidinate precursor, Ni(MeC((NBu)-Bu-t)(2))(2) and either ammonia (NH3) or a mixture of NH3 and hydrogen (H-2) 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 degrees C. Depending on the ratio of NH3 to H-2 gases during deposition, the Ni:N atomic ratio in DLI-CVD NiNx films could be varied from similar to 3:1 to similar 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 similar to 100% step coverage in high-aspect-ratio (>50:1) holes. The as-deposited NiNx films had resistivities as low as similar to 50 mu Omega cm for film thicknesses of similar to 25 nm. Annealing of the films in H-2 at 160 degrees C or hydrogen plasma treatment at room temperature removed the nitrogen and led to pure nickel films.