Bridging The Gaps Between Mask Inspection/Review Systems And Actual Wafer Printability Using Computational Metrology And Inspection (Cmi) Technologies

Computational techniques have become increasingly important to improve resolution of optical lithography. Advanced computational lithography technologies, such as inverse lithography (ILT) and source mask optimization (SMO), are needed to print the most challenging layers, such as contact and metal, at the 20nm node and beyond. In order to deploy SMO and ILT into production, improvements and upgrades of mask manufacturing technology are required. These include writing, inspection, defect review, and repair. For example, mask plane inspection detects defect at highest resolution, but does not correlate accurately with scanner images. Aerial plane mask inspection and AIMS (TM) produce images close to those of a scanner, but except fot the latest AIMS-32 (TM), it does not have the flexibility needed to capture all the characteristics of free-form illumination. Advanced Computational Inspection and Metrology provides solutions to many of these issues.