Underlayer effects on texture evolution in copper films

The roughness of the underlying deposition surface was modified to affect the microstructure of physical vapor deposited (PVD) Cu seed layers, which in turn, impacted the properties of the overlying plated Cu films. Several plating thicknesses were investigated to observe the evolution of the plated Cu film texture after recrystallization. The texture of the plated Cu film is closely correlated to that of the underlying PVD Cu, in which Cu (111) texture increases with decreasing surface roughness. As plated Cu film thickness increases, the effects of the Cu seed layer texture play a smaller role on the plated Cu texture properties. A weak (311) texture component, exhibited in the as-plated Cu films, disappears after the films are exposed to room temperature annealing. After room temperature annealing, the Cu (111) texture intensity showed a small increase at the expense of the random volume fraction in plated films that undergo recrystallization. Because cross-sectional transmission electron microscopy revealed that the grain sizes of the room temperature annealed Cu films were comparable among the samples, grain orientation was the primary aspect of the microstructure that was impacted by the underlayer morphology.