Alternating phase-shifting mask (Alt.PSM) technology is the mast effective approach to expand resolution limitation and expand the process window of lithography. Currently, etched quartz Alt.PSMs have been introduced not only for device development but also for production use. Adapting the etched quartz structure, we need to consider about transmission difference between etched and un-etched regions. So, side-etching method has been used for such structure of Alt.PSMs. We have been supplying AIt.PSMs with side-etching and single trench structures for the mass-production of KrF lithography. As design rule of device pattern have been tightening, in 100nm node and further, narrow chrome width limits the undercut width and which should be optimized for ArF lithography. Moreover, proximity effect has been reported for the shifter edge type AIt.PSMs as pitch dependency of printed line CD. We will report about the side-etching optimization whether limited undercut width can compensate the CD imbalance between etched and un-etched regions. Or, how much bias adding at space width of etched regions can compensate it, or how undercut and space biasing combination affect CD imbalance. We also discuss about whether the line bias can correct to targeted line CD. Finally, we will summarize which structure is recommended for 100nm-node AIt.PSM for ArF lithography. On the other hand, for the case the undercut structure turns out to be difficult in the 100nm-Alt.PSM manufacturing, we will report preliminary manufacturing results of the new structure.
