Tackling hillocks growth after aluminum CMP

The surface of polished aluminum damascene structures is subject to strong growth of hillock structures, which is increased by elevated temperatures. Such hillock structures interfere with subsequent processing and should therefore be removed. We present an easy “repolishing” method, which employs provoked post-CMP growth of hillocks by annealing, and subsequent removal of the newly grown hillocks by a short, additional polishing step. Investigation with atomic-force and secondary electron microscopy indicates a significant decrease of the density and height of the hillock structures.