A Full Wafer-Scale PAML Modeling Approach for Predicting CMP

Chemical mechanical polishing (CMP) is a complex, multi-scale problem with several order of physics. As it is a subtractive manufacturing process, it involves cutting tool–workpiece interaction. The cutting tool in CMP are nanoscale abrasives trapped in the contact between the workpiece (wafer) and a soft, rotating pad. These abrasives are suspended in a liquid medium and transported across the interface to provide even material removal. The current model presents an expansive wafer-scale framework that not only accounts for the solid–solid contact mechanics and wear, but also utilizes the mechanics of the slurry through fluid and particle dynamics. Results from this work include the temporal evolution of hydrodynamic fluid pressure, contact stress and material removal at the die and wafer scales. Comparisons with published CMP experiments have been made, and the results are favorable. Parametric studies have been conducted to predict the influence of different polishing parameters on the material removal rate. With this new framework, the entire wafer–pad interface can be studied under the influence of the four major physical interactions (contact mechanics, fluid mechanics, particle mechanics, wear). The result is a significantly faster multi-physical model that can simulate realistic CMP conditions without sacrificing accuracy.