Friction Behavior of CMP Slurries Based on Novel Organic Particles

With the integration of copper as interconnect and low k materials as dielectric, the CMP community is facing an ever increasing demand on reducing defectivity without scarifying production throughput. One such strategy is to significantly lower the polishing pressure to below 1 psi. Such a move has placed tremendous challenges to the tool manufactures, consumable suppliers (especially the slurry vendors), and end-users. It is a challenge to remain the high throughput (MRR and selectivity) at low down force without using harsh abrasives. For the first time, we recently report the use of novel hydrophilic organic particles for metal CMP. Unlike conventional abrasive particles such silica or alumina, these unique particles are designed to specifically interact with the metal surface to be polished and significantly modify the rheological behavior of the slurry. The obvious advantage of using such particles is the reduction of defects during CMP. The consequence of using such particles is also its ability to provide unsurpassed high selectivity in removal rate for copper over barrier and dielectric materials due to their weak interaction with these particles. The added benefit for slurry that uses such particles is to allow CMP process conducted at a lower down force without compromising the throughput. In this talk, some basic physical and chemical characteristics of the particles and slurry will be first presented. The friction beavior of these new slurries in relation to conventional slurries on blanket wafers will be discussed. The impact of particle hydrophobicity on the friction behviors of the slurries will be explored.