Tungsten CMP Applications

Microelectronic Applications of Chemical Mechanical Planarization, Edited by Yuzhuo Li Copyright 2008 John Wiley Sons, Inc. 

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Ferric nitrate has also been used widely as an oxidizer in W CMP slurries. As a matter of fact, ferric nitrate based slurry was successfully used for tungsten CMP applications long before its application to copper films. Unlike copper, however, tungsten does not usually require the use of inhibitors in the slurries. Tungsten is a much harder metal in comparison to copper. Under oxidizing condition, tungsten has much better passivation characteristics. More... 

Wang Y-L, Liu C, Feng M-S, Tseng W-T. The exothermic reaction and temperature measurement for tungsten CMP technology and its application on endpoint detection. Mater Chem Phys 1998 52 17-22. 

In contrast to the above example of high selectivity, which uses a low removal rate of nickel, other MEMS-related applications require higher Ni removal rates. Using alumina-based slurries originally developed for tungsten CMP, the addition of oxidizers like H2O2 can lead to a fourfold increase in Ni polishing rate [27,28]. 

The first metal CMP application to be used in the industry was W CMP. Tungsten CMP slurries typically... 

Typical applications Si stock poHsh, tungsten CMP Si final poHsh, tungsten CMP, post-CMP buff Si stock, ILD CMP, STI, metal damascene CMP ILD CMP, STI, metal dual damascene... 

Application(s) Si stock polish tungsten damascene CMP Si final polish CMP post-CMP buff Si stock ILD CMP metal dual damascene ILD CMP shallow trench Isolation metal dual damascene... 

The acceptance of chemical mechanical planarization (CMP) as a manufacturable process for state-of-the-art interconnect technology has made it possible to rely on CMP technology for numerous semiconductor manufacturing process applications. These applications include shallow trench isolation (STI), deep trench capacitors, local tungsten interconnects, inter-level-dielectric (ILD) planarization, and copper damascene. In this chapter. 

What specific slurry health concerns are seen in oxide, tungsten, and copper/ low-fe CMP processes, and what metrology approaches are appropriate in these applications to actively monitor and maintain slurry quality Identify potential areas of improvement in the next-generation CMP slurry management. Review various approaches employed for slurry reuse and CMP waste management. What potential may they have in reducing CMP cost of ownership ... 

We have described a new type of slurry application system that can be used instead of or in parallel with the standard slurry applicator on most single wafer CMP tools. The system is easily installed, simple, and passive, but can sometimes deliver slurry savings of as much as 50% with no change in removal rate or nonuniformity, possibly with a bonus in the form of defect reduction. While not suitable for every process, it works well for a significant number of common processes that use silica slurries and foamed or porous pads. These include oxide removal processes (including some cerium-based processes), tungsten polishing processes, and some copper and barrier... 

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