Establishment of Production Process and Assurance Method for Alternating Phase Shift Masks

摘要

Alternating phase shift masks (AltPSMs) are effective in reducing MEF. However, AltPSMs have been used in device development, not in production, because phase-defect assurance has not been sufficient. An assurance method for 180- and 150-nm rule AltPSMs was established by the use of both MD>2000 and KLA/STARlight. We have started production of defect-free AltPSMs with quartz etched shifters and single trench structure s by a two-step quartz etching process, which has an advantage of low phase-defect density.