Nucleation and growth of rf triode-sputtered gold films

Abstract

The nucleation and growth of rf triode-sputtered gold films, whose electrical and optical properties were previously reported, are described in detail. Electron micrographs show that the rate of formation of nucleated particles is greater than 2×1012 cm−2 sec−1. The resultant island particle density at a nominal film thickness (NFT) of 10 Å is 2×1012 cm−2. Linear alignment (chaining) of tiny nucleated island particles is observed. The growth of the island particles as irregularly shaped flattened platelets is attributed to the influence of electron charge. The islands become completely interconnected by tiny gold bridges when the surface coverage is 50% at a NFT of 30 Å. Diffraction mode and off-axis dark-field microscopy reveal that the island particles are composed of randomly oriented crystallites. Histograms of the crystallite size distribution for a large number of films showed that the crystallite size increases with NFT up to 100 Å; above 100 Å the mean crystallite size remains constant at 85 Å.