Sub-10 nm structures on silicon by thermal dewetting of platinum

Abstract

A study of the dewetting behavior of platinum-thin-films on silicon was carried out todetermine how variation of dewetting parameters affects the evolution of film morphologyand to pinpoint which parameters yielded the smallest, most circular features. Platinumfilm thickness as well as dewetting time and temperature were varied and the filmmorphology characterized by means of scanning electron microscopy (SEM) analysis. Twodifferent pathways of dewetting predicted in the literature (Vrij 1966 Discuss. Faraday Soc.42 23, Becker et al 2003 Nat. Mater. 2 59–63) were observed. Depending on the initialcriteria, restructuring of the film occurred via hole or droplet formation. Withincreased annealing time, a transition from an intermediate network structure toseparated islands occurred. In addition, the formation of multilayered films, silicidecrystals and nanowires occurred for certain parameters. Nevertheless, the dewettingbehavior witnessed could be related to physical processes. Droplets with a meandiameter of 9 nm were formed by using a 1.5 nm thick platinum film annealed at800 °C for 30 s. To demonstrate the suitability of the annealed films for further processing, we thenused the dewetted films as masks for reactive ion etching to transfer the pattern into thesilicon substrate, forming tapered nanopillars.