An interlayer of face centered cubic (fcc) Co4N has demonstrated significant improvements in adhesion between copper and diffusion barrier layers. This fcc phase of Co4N was prepared by chemical vapor deposition (CVD) using bis(N-tert-butyl-N′-ethyl-propionamidinato)cobalt(II) and a reactant mixture of NH3 and H2 at substrate temperatures from 100 to 180°C. The Co/N atomic ratio and the phase of cobalt nitride film can be modified by adjusting the ratio of NH3 and H2 in the gas feedstock. The cobalt nitride films prepared by CVD are smooth, highly conformal, and stable against intermixing with copper up to at least 400°C. This fcc cobalt nitride material has very strong adhesion to copper due to the small lattice mismatch (−1 to 2%) between fcc-Co4N and fcc Cu. Copper wires should be stabilized against failure by electromigration when fcc cobalt nitride interlayers are placed between the copper and surrounding diffusion barriers.

Cu seed layers for future interconnects must have conformal step coverage, smooth surface morphology, and strong adhesion. Conformal deposition had been achieved by chemical vapor deposition (CVD), but CVD Cu films have rough surfaces and poor adhesion. In this paper, conformal, smooth, adherent, continuous, and thin (<9nm) Cu films were made by CVD. CuON was deposited from a Cu-amidinate precursor, normalH2O , and NH3 at 140– 180°C on Ru. Crystallites in the deposited film have either a Cu2O or Cu3N structure depending on the ratio of normalH2O to NH3 . As-deposited CuON films have a smooth surface morphology [ ∼0.5nm root-mean-square (rms) roughness] and are highly conformal ( 95% step coverage in 40:1 aspect ratio holes). The CuON films were then reduced with remote hydrogen plasma near room temperature to minimize agglomeration of the thin Cu films during reduction. After reduction, CuON films having a Cu2O crystal structure showed a higher density Cu film (95%) than those having a Cu3N crystal structure (84%) . Both reduced Cu films had a smooth morphology ( ∼1nm rms roughness). Thus, deposition of a CuON film having a Cu2O crystal structure and then reduction with remote hydrogen plasma can make Cu layers that can serve as seed layers of future Cu interconnects.

Metallic nanoparticles (NPs) with tunable physical, optical and catalytic properties have a wide range of applications including various optoelectronics, sensors and fuel cells. In this paper, we demonstrate the evolution of various physical properties, configurations, size and density of palladium (Pd) nanostructures on sapphire(AlO) (0001) by the systematic control of deposition amount (DA) at distinct annealing temperatures. The transformation of the deposited thin films into various Pd NPs is achieved by the dewetting of the thin film by means of surface diffusion, nucleation, Volmer-Weber growth and surface energy minimization mechanism. Depending on the evolution of size, density and configuration, five distinctive regimes of Pd nanostructures are demonstrated: (i) nucleation and evolution of small NPs between 1 and 3 nm, (ii) medium NPs with the dominating vertical growth between 5 and 20 nm, (iii) laterally expanded large NPs between 30 and 40 nm, (iv) irregular coalesced Pd NPs between 50 and 80 nm and (v) voids evolution between 100 and 200 nm. Initial film thickness and annealing temperature play major roles on the dewetting process and the resulting Pd nanostructures are notably distinguished. The fabricated Pd nanostructures influence the lattice vibration modes of sapphire(0001) such as gradual decrement in the intensity and left-shift of the peak position with increased surface coverage. In addition, the optical properties are studied by UV-VIS-NIR (300-1100 nm) reflectance spectra, which shows the reflectance, absorption and scattering over the wavelength and are closely related to the morphology evolution of Pd nanostructures.

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