Improving 300Mm Si Wafer Planarization Process with a Wholistic Approach

Despite the widespread usage of chemical mechanical polishing (CMP) on wafer planarization, the understanding of mechanism behind CMP remains incomplete, particularly with regards to affecting the global flatness of silicon substrate wafers. To address the knowledge gap, this study systematically investigates the final CMP process of 300 mm Si wafers focusing on the impact of various process parameters on overall planarity. With the assistance from a numerical model for the material removal, it is observed that several factors, including retaining ring design, pad characteristics, rotation speed, slurry flow rate, and polishing pressure all have an impact on the material removal rate (MRR). However, these factors do not necessarily change the relative MRR profile. Overall, our findings show that with a wholistic approach, the final polish (FP) process’ effect on the global planarization of 300mm Si wafers changes from worsening by 16nm to improving by 35nm in average.