Materials tend to follow a classical homoepitaxial growth mechanism when there is a strong interaction between the deposited material and the substrate. An example of this would be aluminium grown on aluminium substrate. For strongly interacting substrates, the interaction with the substrate is stronger than the interaction between atoms of the deposited material. A higher temperature is associated with 2D growth, making annealing a reasonable approach to create a conformal film. In contrast, the opposite becomes true for growth on a weakly interacting substrate. Here, the interactions between the atoms in the deposited material are stronger than the interaction with the substrate. Consequently, increased temperature tends to promote 3D growth. This leads to faceted structures and rough surfaces which are not desirable for interconnects. Additionally, while migration of atoms across the surface can occur, Gervilla et al. described that upward migration of atoms to form new layers is not possible on strongly interacting substrates. This is a crucial difference between the two mechanisms. By enhancing the adhesion between the adatoms and the substrate a homoepitaxial growth mechanism, of for example copper on a nitride, can be promoted, which in turn promotes 2D growth of the thin film. Computing the activation energies for atoms to migrate between layers lets us determine which mechanism is dominant based on the magnitude of the activation energy. The different migration pathways for homoepitaxial growth and weakly interacting substrates are shown in Figure ).