Analysis on contact and flow features in CMP process

Chemical mechanical polishing/ planarization (CMP) has evolved into a key technology of integrated circuit (IC) industry to accomplish wafer surface polishing with high precision1]. To a larger extent, however, CMP is still a black art, i.e. empirical or…

Analysis on contact and flow features in CMP process

Contact pressure and flow features of chemical mechanical polishing/planarization (CMP) process were analyzed,taking advantage of the one-dimensional contact model of two layers and considering slurry flows. In this model,deformations of the bulk pad substrate and the asperities were considered. The deformations of the bulk pad sub- strate and the asperity layer,as well as the contact pressure and fluid pressure,were revealed with nu- merical methods. Numerical simulation results show a counterintuitive phenomenon: a diverging clear- ance is formed in the leading region of the wafer and thereby it gives rise to a suction pressure (subambi- ent pressure). A high stress concentration is pre- sented at the wafer edge and thereby over polishing can be introduced. The research provides some theoretical explanations for these two fundamental features of usual CMP processes.