these plates, the wafers are rubbed against fine abrasive polishing pads along with polishing slurry to give a mirror like finish
Establish optimum flatness. Eliminate surface damage. Minimise contamination level
High rejection rate Rework cost
The lapping process helps to achieve the maximum wafer flatness. Wafer flatness measured as TotalThicknessVariation (TTV) in microns is one of critical-to-quality (CTQ) requirements for a silicon wafer. This project aimed to reduce the number of TTV rejects in the lapping process.
1 Literature review