Observation of heterogeneous, nanoscale deformation on damascene interconnects with a polymeric dielectric

Scanning probe microscopy was used to generate out-of-plane deformation maps around vias in single level Cu-polyimide damascene interconnect structures subjected to a room temperature to 350°C thermal cycle. The deformation maps are obtained by subtracting the before images from the after images. The deformation of the Cu is shown to be highly heterogeneous on the micrometer scale. Evidence on Cu-Ta interfacial sliding, Cu-Cu grain boundary sliding, and diffusion creep is presented.