Strategies for optimal chemical mechanical polishing (CMP) slurry design

Chemical mechanical polishing (CMP) has become the preferred route for achieving wafer-level global planarization in microelectronics device manufacturing. However, the micro- to molecular-level mechanisms that control its performance and optimization are not well understood. In CMP, complex slurry chemistries react with the first few atomic layers on the wafer surfaces forming a chemically modified film. This film is subsequently mechanically abraded by nanosized slurry particles to achieve local and global planarity for multi-level metalization. For optimal CMP performance, high material removal rates with minimal surface defectivity are required. This can be achieved by controlling the extent of interparticle and particle-substrate interactions, which are facilitated through the manipulation of the slurry composition, solution chemistry, as well as operational parameters. Interparticle interactions must be engineered to maintain slurry stability to minimize the number and extent of surface defects during polishing while maintaining adequate removal rates. The fundamental considerations, which are necessary for the development of high performance CMP slurries, are discussed in this article through model silica CMP systems.