Robust operation of copper chemical mechanical polishing

The unusual concentration effect in copper chemical mechanical polishing (CMP) is verified experimentally and operation-relevant models are derived. First, the well-known Preston equation is modified by taking the concentration effects into account. Next, a linear model is proposed to describe dishing as functions of and typical operation variables. Combining both models, we are able to locate feasible operation region without constraint violation. Finally, the robust operation procedure is incorporated into a realistic CMP operation strategy: soft landing. A systematic procedure is proposed to ensure robust operation for copper CMP.