Engineering gap fill, microstructure and film composition of electroplated copper for on-chip metallization

Electroplated Cu is being used by the major semiconductor manufacturers as an interconnect material, because it offers a lower line resistance and better electromigration performance over conventional Al metallization. This paper describes the mechanism of "super-fill" as well as gap fill, microstructure, and film composition of electroplated copper. A combination of optimized Cu plating additive chemistry and current waveform enable complete gap fill of 0.07-0.1 /spl mu/m features (AR>10:1) as well as strong [111] texture, large grains (>3 /spl mu/m) with a large fraction of twin grain boundaries and controlled impurity content in electroplated Cu films. Electroplating process stability was maintained through the on-line analysis (p/t<0.3) of organic and inorganic bath ingredients and their replenishment.