Analysis on Material Removal Rate in Wafer Chemical Mechanical Polishing Based on Trajectory of Abrasives

摘要

Chemical mechanical polishing (CMP) has become the key technology of achieving wafer global planarization in ULSI, but its material removal mechanisms are still not completely understood. The wafer CMP is a technology combining the chemical action with the mechanical action. The chemical reaction layer on wafer surface is mainly removed by the mechanical action of the particles in slurry and the pad. And the friction and scratch action of particles against the wafer surface plays an important role in removing wafer material. The scratch length produced by abrasives on the wafer surface has a direct influence on the material removal rate (MRR). In this paper, the distribution forms of abrasives in CMP process are analyzed by experimental results firstly. Then the relationships between the wafer, the abrasive and the polishing pad are analyzed based on kinematics and contact mechanics. According to the track length of abrasives on the wafer surface, the relationships between the MRR and the polishing velocity are obtained. The analyzing results are in accord with experimental results. The conclusion provides a theoretical guide to further understanding the material removal mechanism of wafer in CMP.