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L. CHEN & TOM RITZDORF, Semitool Inc., Kalispell, Montana, USA

ABSTRACT

Anovel approach is presented in this paper for inlaid copper metallisation. Contrary to the traditional approach regarding seed layer application, an ultra-thin copper flash layer, serving as an adhesion layer, is deposited by a PVD process. This flash adhesion layer is conformally enhanced from Semitool’s specially formulated plating solutions by electroplating. The ECD seed layer is then used as a base for copper deposition from an acid copper sulfate plating bath. The advantage of depositing an ultra-thin copper flash adhesion layer and ECD seed layer, rather than a relatively thick PVD copper seed layer, is that pinching off of small trenches or vias can be avoided, while ensuring adequate sidewall coverage.