Data Storage Systems Center

Chemical mechanical polishing (CMP) is a manufacturing process that is commonly used to planarize integrated circuits and data storage devices during fabrication. The CMP process involves the wafer sample being mounted onto a rotating carrier and pressed against a rotating polyurethane pad that is flooded with slurry. The slurry itself is a chemically reactive fluid containing suspended abrasive particles. The relative motion between the wafer, pad, and particles causes surface wear in both surfaces. In order to develop a predictive capability for CMP, a number of models have been formulated which focus on certain aspects of the CMP process. However, there are very few models that integrate all of the important aspects of CMP into a single framework. Therefore, the focus of this study involves the development of a multi-physics modeling tool that models all of the important interactions in CMP—namely fluid mechanics, contact mechanics, and particle dynamics—and incorporates all of them into a single framework for predicting wear. Each of the constituent models was formulated separately and compared to experiment before being combined into the integrated framework. The resultant model, called the Particle-Augmented Mixed Lubrication (PAML) model, was used to predict wear in silico from a measured surface topography during CMP. The results from the PAML simulation were compared to experimental measurements.