Nucleation of ultrathin silver layer by magnetron sputtering in Ar/N2 plasma

We focus our attention on the study of the initial stage of the silver growth. The silver layers were deposited by RF magnetron sputtering in pure argon or its mixture with nitrogen. The initial stage of the nucleation and the layer growth was studied by means of the optical and electrical monitoring, which are based on a principle of in-situ spectral ellipsometry. The measured data were fitted to a mathematical model. The nano-granular character of the grown layer is revealed by resonant features in the extinction coefficient spectra in visible spectral range. Thus, the mode of the layer growth (Volmer–Weber or Stranski–Krastanov) was clearly distinguished in the monitored data. The microstructure of the completed layer was further analyzed by X-ray diffraction (XRD) and atomic force microscopy (AFM). In this work, we show that the growth mode of the silver can be controlled by the deposition condition. We also present a method for preparation of an ultra-thin, continuous and smooth silver layer. The nucleation process is significantly influenced by presence of the nitrogen in the sputtering gas.

► Silver layer growth was monitored by in-situ spectroscopic ellipsometry.
► The growth mode was indicated by a presence of surface plasmon resonance peak.
► Addition of nitrogen in the sputtering gas influences the silver growth mode.
► We report a preparation of the ultra-thin, smooth and continuous silver layer.