Modeling pattern density dependent bump formation in copper electrochemical deposition

A model and simulator that describe the dependence of deposition rate and bump formation on pattern density during electrochemical deposition (ECD) are presented. A curvature-enhanced ECD model from the recent literature [A.C. West et al., Electrochem. Solid-State Lett., 4, C50, (2001)] is used in a feature scale process simulator to explain bump formation and to qualitatively explain some observed pattern density effects. Experimentally, it is known that ECD topographies can be different when features are clustered together compared to isolated features. Although it is difficult to experimentally quantify the extent of bumping over patterned regions of wafers, the curvature-based models for bumping are at least qualitatively consistent with reported trends in deposit shape with feature density.