High removal rate of polysilicon and high selectivity between silicon and oxide, are two important performance targets in DRAM chemical mechanical polishing (CMP). Traditionally, the polysilicon CMP is dominated by mechanical effects, owing to the relatively inert chemical property of silicon. We have shown that chemistry also played an important role in polysilicon polishing. In this paper, a novel polysilicon CMP slurry with an optimized chemistry is reported. It is specifically formulated for DRAM polysilicon polishing. It exhibits high removal rate, high selectivity (silicon/oxide), low defects and excellent surface quality.

Chemical mechanical planarization (CMP) is a critical technology for the copper damascene process. With the development of more advanced technology nodes, New challenges have emerged for the conventional CMP processes--the need for using lower down force while maintaining removal rate to avoid low-k/ultra-low k dielectric film damage and wide over polishing window. Also, surface defects especially corrosion related defects become more stringent as copper line becomes narrower and narrower. In this paper, we share our current efforts and associated results to develop the novel copper slurry for such CMP process. The slurries with different organic additives were evaluated for removal rate, dishing rate, electrochemical analysis and anti-corrosion capability. Based on these results, a novel copper slurry has been developed and it shows the excellent CMP performance.

IC market demand for flash memories showed a significant growth trend in recent years. In manufacturing of flash memories, one of the most important processes is forming floating gate or control gate, which is greatly influenced by gate-poly CMP performance. To prepare a floating gate or control gate, a poly-silicon (poly) layer will be deposited on the active area (AA) , which is between the STI trench structures, typically HDP oxide. Then through CMP technique, the overburdened poly will be removed, with no poly residue on the top of HDP surface and leaving a certain thickness of AA poly whose top surface is planar with HDP top surface. However, in the case that a poly layer and a silicon dioxide layer are being polished, the removal rate of poly-silicon will tend to be much higher than that of silicon dioxide, resulting in recess between the STI trench structures and a non-planarized surface. To overcome this issue, we report here a novel poly CMP slurry that has the self-stopping capability and good planarization efficiency, with which the excellent surface planarity, poly dishing and poly residue clearance were obtained on 300 mm patterned wafers.