Step Height Reduction Efficiency

The chemical-mechanical polishing or planarization (CMP) process is a complex interplay between the wafer and the consumables involved. The consumables include slurry, pad, conditioner, and so on. During polishing, the pad carries the slurry and delivers it to the wafer surface. It also transmits the normal and shear forces from the polisher to the wafer. Therefore, polishing pad plays a critical role in the CMP process and influences the outcomes such as material removal rate (MRR), within-wafer nonuniformity (WIWNU), wafer-to-wafer nonuniformity (WTWNU), step height reduction efficiency (SHRE), and defect counts. 

FIGURE 5.6 Comparison of patterned wafer profile and step height reduction efficiency (SHRE) for polishing on ICIOOO and NCP pads (a) Wafer profile before polishing, (b) wafer profile after polishing, (c) SHRE on ICIOOO pad, (d) SHRE on NCP pad. 

FIGURE 5.7 Comparison of normalized patterned wafer step height reduction efficiency (SHRE) for polishing on ICIOOO and various NCP pads. 

Step Height Reduction Efficiency and Overpolishing Window... 

FIGURE 11.24 Dependency of step height reduction efficiency on electrical conductivity of the liquid used for ECP-DI polishing (from Ref. 32). 

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