A dishing model for chemical mechanical polishing of metal interconnect structures

It is well known that dishing occurred in metal CMP leads to considerable wafer surface non-planarity and causes an increase in interconnect resistance. Thus, a closed-form solution for quantitative prediction of dishing is needed. A contact-mechanics-based approach to describe the steady-state dishing occurred in metal CMP process for interconnect structures is presented. The theory is validated through comparison with experimental data in the literature. Once validated, the model is used to quantify the effect of pattern geometry on dishing. It is shown that the predictions of the model agree reasonably well with the experimental results measured in 10% overpolishing time.