Pad Effects on Slurry Flows in CMP System
Chemical mechanical polishing (CMP) is a widely adopted technique to achieve high level of global and local planarity required in modern integrate circuit (IC) industries, wherein the pad properties weigh heavily on the final performance. A preliminary two-dimensional wafer-scale flow model for CMP is presented considering the roughness, the elasticity, as well as the porosity of the pad. Numerical simulations were conducted to show the slurry flow features’ variations due to pad parameters change. The results show that the porosity of the pad is conducive to slurry delivering, and small porous parameter will lead to prominent increase of load capability, accounting for larger material removal rate (MRR) whilst the elasticity of the pad has a more complex influence. The rough surface carries additional fluid in the valleys of the polishing pad thereby provide some chemical reactions. The model will shed lights on the mechanism of CMP process, which is for a long time considered as a difficult circle to square.
Jitai NIU, Zuyan LIU, Cheng JIN and Guangtao Zhou
C. H. Zhang and J. Q. Zhang, "Pad Effects on Slurry Flows in CMP System", Materials Science Forum, Vols. 575-578, pp. 1222-1227, 2008