Atomic layer deposition (ALD) of tungsten carbide nitride (WC0.7N0.3) on a low-k (dielectric constant) dielectric aromatic polymer material is investigated. It is feasible to deposit thin WC0.7N0.3 films on polymers, but applying a nitrogen–oxygen (N2–O2) based plasma to the surface prior to ALD can significantly enhance the growth. The creation of polar surface groups by the plasma treatment is derived from the water contact angle and from O 1s to C 1s peak ratio extracted from x-ray photoelectron spectroscopy. Rutherford backscattering spectra and contact angle measurements revealed a typical ALD growth with at least two successive regimes. The first is controlled by the substrate surface, while during the last a constant amount of ALD material is added with each cycle. The plasma treatments create adsorption sites on the surface and therefore effectively enhance the growth and shorten the duration of the first regime. This observation is attributed to an improved initial ALD precursor adsorption. However, ALD island formation on the treated polymer is not merely a function of the number of available adsorption sites but depends also on the structure and composition of the substrate surface. The minimum thickness of a continuous ALD film is ∼10 nm on untreated polymer while on top of a N2 rich reactive ion etch plasma-treated polymer the WC0.7N0.3 film becomes continuous between 1.4 and 2.3 nm.

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On nanoscale laminate structures, the interface cannot be identified any longer as the separation between two films of bulk materials. The formation of the interface defines the final composition and structure of the laminate structure. As such, the characterization of the interface becomes an important challenge. In this work the nanoscale laminate structures were formed by atomic layer deposition (ALD) of tungsten nitride carbide and tantalum nitride thin films on dense dielectrics [silicon carbide and silicon oxide (SiO2)]. The laminates were studied using x-ray reflectivity. The starting substrate surface is a primary factor in determining the density of the ALD layer. Moreover, in some cases, electron-density perturbations are observed in the vicinity of the interfacial region. A characterization strategy, using a density contrast layer between the silicon substrate and the SiO2 dielectric is presented. Depending on the chemical nature of precursors and substrate, ALD processes can either form specific interfacial organization or induce dielectric modifications, in any case, leading to unexpected metal-dielectric interactions.

The ongoing transition to lower dimension devices requires the replacement of SiO 2 by a lower-k dielectric insulator. Such materials are porous, introducing the need for sealing against penetration of gaseous and/or liquid species during subsequent processing. In this work, we investigate the effect of different plasma treatments on a porous low-k polymer film. Ion bombardment induces the formation of a dense surface layer capable of sealing the polymer. A competing etching reaction by the plasma gases determines the extent of the densified layer. Structural and chemical changes induced by the plasma treatments can extend into the bulk of the film and irreversibly change its properties. Exposing the plasma treated films to chemical precursors during an atomic layer deposition process is used to test sealing. The sealing behavior is discussed in view of the reactivity of the plasma and the post sealing temperature treatment.