Chemical mechanical polishing (or planarization) is the most popular technique for removing the surface irregularities of silicon wafers. In the CMP process, the use of slurries with abrasive particles (e.g. silica) allows achievement of highly smooth and planar material surfaces by combining chemical and mechanical actions. The role of the nanoparticles in the CMP process is to remove impurities without adhering to the silicon wafer. Moreover, the particle size has to be monitored because it affects the rate of removal and wafer defects. The particle size, as well as the electrostatic repulsion between slurry particles and the wafer surface, thus drive the success of a CMP process.