Dewetting of Au and AuPt alloy films: A dewetting zone model

When thin metal films are annealed they can degrade into particles. This happens even at annealing temperatures below the melting point and is known as solid-state dewetting or agglomeration. The solid-state dewetting behaviour of 15-35 nm thick Au and 20 nm thick AuPt films on SiNx/SiO2/Si substrates was investigated in the temperature range of 500-900 degrees C in air. Morphology maps were created based on which a dewetting zone model is proposed. The morphology maps can be divided into three zones: a zone where the film remains continuous, a zone where dewetting takes place, and a zone where dewetting is complete. Coverage measurements can be used to determine zone boundaries and the activation energy for void growth, which was 1.05+/-0.1 eV in the case of Au. The influence of film thickness and alloying on the dewetting behaviour was studied; both factors had only an influence at low annealing temperatures, with the influence of alloying being more pronounced than the influence of film thickness. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794028]