Slurry engineering for self-stopping, dishing free SiO2-CMP

A new type of slurry, in which much surfactant was added into a conventional CeO2 slurry, was developed for SiO2 chemical mechanical polishing (CMP). The new slurry has unique characteristics. Because the polishing rate drops as planarization progresses, polishing can stop automatically. Therefore, it is easy to control the remaining thickness. Moreover, it is possible to planarize a surface without any dishing, even at a wide depressed portion (4 mm). Therefore, the global planarization within a chip can be obtained without any stopping layer or design limitations.