Lithography printability review: an application on advanced photomask production for enhancing mask yield and cycle time

In the advanced technology photomask manufacturing industry, it is challenging to produce defect-free photomasks, especially for the increasingly smaller critical dimension current days . Since the 193nm immersion scanner numerical aperture (1.35) has remained the same as in previous nodes, more mult i-patterning and aggressive source mask optimizat ion illumination sources are being used to print smaller feature crit ical dimensions (CDs) and pitches. To accommodate such specialized sources, more model -based mask OPC and ILT are being used, making mask designs very complicated. This in turn makes mask manufacturing very challenging , especially for the defect inspection, repair, and metrology processes that are used to guarantee defect-free masks. So, it is necessary to develop an application for handling mask defects. In this paper, we introduce a new application called LPR (Lithography Printability Review) to verify any outlier defects or repairs before the mask ships to the wafer fab. The paper details how LPR works in the mask-making flow and how the LPR module is set up. This application has been tightly integrated with KLA’s server and inspectors. The paper concludes with showing the benefits realized in mask making cycle time as a result of implementing LPR into a high volume advanced photomask production line.