Advanced W-CMP Slurry for High Planarity

Advanced tungsten chemical mechanical polishing (CMP) slurry for high planarity was developed. The key technologies to achieve the high planarity were optimization of selectivity between W and SiO2 removal rate (RR) and the easiness of cleaning after polishing. Selectivity was found as an important parameter which affects the planarity. Various selective slurries by changing abrasive and oxidizer were evaluated and non-selective slurry shows the best planarity among all the slurries. Additionally, the effect of post CMP cleaning for planarity was indicated. HF cleaning, witch is for surface contamination removal, causes deterioration of the planarity. The slurry which was tested in this study does not need HF cleaning resulting in keeping high planarity after post CMP cleaning. The developed slurry in this study satisfies the target of planarity for 65nm and beyond.