A general optimization for slurry injection position and injection rate during chemical mechanical polishing, which is valid for the Rodel SUBA 400 pad with 150, 200, and 300 mm wafers and the Rodel POLITEX DG pad with 200 mm wafer, is presented. The existing experimental data for the Rodel IC 1000 pad with 3 in, wafer reconfirms this general optimization for slurry injection position. This general optimization for slurry injection radial position R-i is at the wafer edge R-we for three azimuth angles, 3, 6. and 9 o'clock considered. A maximum mean gray scale and a minimum nonuniformity can be simultaneously obtained by using R-i/R-we = 1. The general optimum slurry injection rate Q is 150 mL/min, however, 100 mL/min would be suggested for the 150 and 200 mm wafers because of significant reduction of slurry usage with little changes of mean gray scale and nonuniformity.