Growth and characterization of atomic layer deposited WC[sub 0.7]N[sub 0.3] on polymer films.

Atomic layer deposition (ALD) of tungsten carbide nitride (WC[sub 0.7]N[sub 0.3]) on a low-k (dielectric constant) dielectric aromatic polymer material is investigated. It is feasible to deposit thin WC[sub 0.7]N[sub 0.3] films on polymers, but applying a nitrogen–oxygen (N[sub 2]–O[sub 2]) 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 N[sub 2] rich reactive ion etch plasma-treated polymer the WC[sub 0.7]N[sub 0.3] film becomes continuous between 1.4 and 2.3 nm. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]