Room-temperature grain growth in sputter-deposited Cu films

The microstructure of sputter-deposited Cu films is shown to be unstable at room temperature (RT). The average grain size increases significantly during RT storage for a couple of hours after deposition. This RT grain growth is shown to be very dependent on the deposition parameters (substrate temperature and sputter gas pressure) and hence on the microstructure of the as-deposited film. The microstructure of sputter-deposited films is usually summarized in a structure-growth-zone model. It is found that significant RT grain growth only occurs for Cu layers with a zone-T-type, as-deposited microstructure.