Slurry residues

IG-Hydrogenation An advanced version of the Bergius process in which the initial product of coal gasification is refined by centrifugation and the slurry residue is carbonized. 

Fig. 8. SEM micrograph of a typical oxide CMP slurry residue after CMP.

Post-CMP cleaning and drying have been recently highlighted as one of the most difficult challenges in terms of yield improvement [17]. In addition to some of the basic requirements such as removal of slurry residues and contaminants from the polished wafers, a comprehensive post-CMP cleaning process must also address issues such as watermark-less drying for... 

List the key attributes for a post-CMP cleaning solution in order to remove the silica slurry residue from silicon, silicon dioxide, silicon nitride, copper, or tungsten surfaces. 

Typically, slurry residues are due to strong adhesion of some abrasive particles to the oxide surface of the wafer. For some more complex slurry formulations, it is possible to leave organic residues [32,33] on the wafer surface as well. In some rare cases, it is also possible to leave pad residues, pad debris on the wafer surface, especially when an improper pad break-in procedure is combined with an inadequate post-CMP cleaning. Figures 17.8 and 17.9 show some representative residues on a polished oxide surface. 

Fig. 3. Heavy slurry residue accumulated in the recess area (alignment mark) after standard Fe(N03) 3 W CMP process.

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