Abstrakt
Two of the main characteristics of a thin film defining many film properties are film thickness and grain size. Film hardness, electrical conductivity, and film stress evolution are all connected to the size of constituent grains. Both thickness and grain size are strongly connected and depend on the deposition technique. A common method to prepare nanocrystalline thin films of different thicknesses is via physical vapor deposition, where the columnar character of the deposited grains is typical. As a result, grain size is increased with film thickness. A way to alter the grain size while the film thickness remains constant is via recrystallization and grain growth during the heat treatment.
Al-based 50 nm thick films were prepared by DC magnetron sputtering onto a dissolvable surface. Free standing films were prepared and their microstructure was characterized in transmission electron microscope (TEM). Preferential orientation of grains was analyzed by Automated phase and orientation mapping equipped in TEM (ACOM-TEM). The films were then annealed in-situ in TEM to monitor the structure changes and recrystallization mechanisms. The experimental procedure was then simulated by molecular dynamics (MD) where the parameters as grain size and orientation can be precisely controlled and the results were compared.