FOCUSED ION-BEAM ASSISTED ETCHING OF QUARTZ IN XEF2 WITHOUT TRANSMITTANCE REDUCTION FOR PHASE-SHIFTING MASK REPAIR

Focused ion beam (FIB) assisted etching of quartz by a Ga FIB and XeF2 gas was studied for the purpose of avoiding the transmittance reduction by a Ga FIB. Transmittance was above 99% with the existence of XeF2 to the extent that the etching yield was more than 1.7 times larger than that of sputtering. It was also found that postetching above 15 nm by a Ga FIB and XeF2 gas after the Ga ion implantation recovered the transmittance. These techniques will be applied to repairing phase shifting masks without transmittance reduction.