Decomposition of thin Au films on flat and structured Si substrate by annealing

Thin metallic films are unstable under thermal treatment and disintegrate into particles in a process known as solid state dewetting. This process was studied by annealing 30 nm thin gold films, deposited on flat and structured silicon substrates, by means of electron scanning microscopy and electron backscattered diffraction. Two different modes of decomposition were observed; formation of doughnut-shaped islands which coalesced into dendritic particles of gold with a network of gold particles in between, and patterns which start as circular holes with pronounced rims and subsequently develop in a typical pattern. In the case of structured substrates confinement of particles within ridges was observed for deep scratches, while shallower scratches allowed some spill over of the material.