Chemical mechanical polishing (CMP) is a process that reduces step height by making the flat surface when several types of layers are accumulated in a semiconductor device. The three main factors affecting CMP are pad, slurry and conditioner. Among these factors, the pad helps the flow of the slurry and polish the wafer with direct contact. Through changing characteristic of pad that is number of grooves, design of groove, depth and width of pitch, we can control wafer removal rates, with-in wafer non-uniformity and roughness. In this study we added a radial groove (RG) at the circular groove (CG) pad to investigate what effect of the RG to Cu CMP. A study was conducted on how the number of RG affects the slurry flow, how changes in slurry flow affect the pressure distribution between the pad and the wafer, and how this affects CMP. The number of RG was divided into 0, 8, 16, 32, and the actual CMP process and simulation experiment were conducted together. In simulation part, we use computational fluid dynamics (CFD) to compare for slurry transport rates according to the number of RG. Fig. 1 shows the removal rates according to the number of RG, and when the number of RG increases to 32, it shows that removal rates of RG pad is almost 23% higher than CG pad. We consider that these results are related to changes in slurry flow during polishing. This is due to role of RG in quickly replacing the old slurry with the new slurry. Figure 1