Variable optimization for chemical mechanical polishing

Slurry is often used in chemical mechanical polishing (CMP) as a polishing additive. When a spinning wafer carrier applies a pressure on a wafer toward a pad, the wafer carrier in the polishing process will drag the slurry sputtered on the pad into the narrow gap between the wafer and the pad. In this study, we determine the features of the slurry transports between the pad and the wafer by conducting experiments to develop a method of decreasing the nonuniformity of the polishing process. In this study, we apply experimental design methods to the statistical analysis of chemical mechanical polishing in manufacturing for each operation parameter. The four design parameters of CMP include the rotation speed of the pad, injection position, the rotation speed of the wafer, and slurry mass flow. The procedure for optimization search for the minimum object value and its corresponding input set values was validated and compared with that for the same search for the original experimental data. Performance indexes were improved. The procedure provided an easy and feasible approach to CMP system design.