Atomic Layer Deposition of Nickel Carbide from a Nickel Amidinate Precursor and Hydrogen Plasma

A new atomic layer deposition (ALD) process for depositing nickel carbide (Ni3Cx) thin films is reported, using bis(N,N′-di-tert-butylacetamidinato)nickel(II) and H2 plasma. The process shows a good layer-by-layer film growth behavior with a saturated film growth rate of 0.039 nm/cycle for a fairly wide process temperature window from 75 to 250 °C. Comprehensive material characterizations are performed on the Ni3Cx films deposited at 95 °C with various H2 plasma pulse lengths from 5 to 12 s, and no appreciable difference is found with the change of the plasma pulse length. The deposited Ni3Cx films are fairly pure, smooth, and conductive, and the x in the nominal formula of Ni3Cx is approximately 0.7. The ALD Ni3Cx films are polycrystalline with a rhombohedral Ni3C crystal structure, and the films are free of nanocrystalline graphite or amorphous carbon. Last, we demonstrate that, by using this ALD process, highly uniform Ni3Cx films can be conformally deposited into deep narrow trenches with an aspect ratio as high as 20:1, which thereby highlights the broad and promising applicability of this process for conformal Ni3Cx film coatings on complex high-aspect-ratio 3D architectures in general.