X-ray diffraction pole figure evidence for (111) sidewall texture of electroplated Cu in submicron damascene trenches

The crystallographic texture of electroplated Cu in damascene trenches has been examined by x-ray diffraction pole figure analysis. The influence of two post-plating treatments on the resulting orientation of (111) planes of the Cu inside the trenches are compared. When the as-deposited small-grained Cu is allowed to recrystallize at room temperature before chemical mechanical polishing of the overlying Cu, we observe only a (111) fiber texture of the Cu inside the trenches. In contrast, when the overlying material is polished away before recrystallization of the small-grained Cu, pole figures show evidence of sidewall texture of the (111) planes in addition to the (111) fiber texture in the as-deposited as well as the annealed state. The presence or absence of a sidewall texture component in the pole figures offers insight into the evolution of the microstructure of damascene Cu.