Reflow Phenomenon Analysis of Large Scale Integrated Cu Interconnections in Via Holes by Viscoelastic Deformation Simulation

The reflow phenomenon of Cu interconnections deposited over via holes was analyzed by viscoelastic deformation simulation using a finite-element method to clarify the embedding mechanism of Cu interconnections into via holes in a novel dual-damascene fabrication technology, which combined sputter deposition and high-pressure annealing. Cu is considered to be a viscoelastic body, and the stress distribution and deformation behavior of Cu interconnections were calculated. As a result, the deformation behavior of the Cu interconnections exhibited close agreement between the calculated and the observed values. From our series of results, we inferred that Cu interconnections are embedded into via holes by the creep deformation mechanism defined in this study during the high-pressure annealing process.