Analysis of Chemical and Mechanical Factors in CMP Processes for Improving Material Removal Rate

As the design rules for electric microdevices gets smaller, the requirement for the production process gets more severe. For example, the nanolevel defect free with a higher throughput performance is required for chemical mechanical polish (CMP). To achieve such a level of requirement, slurry and process development based on the mechanism needs to be done. In this study, the platen motor current was monitored and used to establish an energy model for material removal rate during CMP. By using the motor current as a measure of friction, the conversion of abrasion and heat to the mechanical energy was modeled. The results show that, for silicon dioxide layer obtained by plasma-enhanced chemical vapor deposition from mixture of reactive gases such as oxygen and tetraethoxysilane (PE-TEOS), silicon nitride, and silicon, the material removal rate is dominated by the mechanical energy independent of slurry properties such as pH, particle size, or material. As a result, maximizing the friction (i.e., motor current) during CMP is a key parameter in maximizing the material removal rate. Using this method, it was determined that, in addition to size, the irregularly shaped abrasive has an advantage over the spherical shaped abrasive.