OPTIMIZATION OF FIB METHODS FOR PHASE-SHIFT MASK DEFECT REPAIR

Two new methods have been proposed to optimize the focused ion beam (F IB) technique for repair of phase shift masks (PSMs). The alternating box method is used to eliminate the post FIB repair phase trench defec t and the biased method to eliminate the gallium staining effect. Both methods require only a change of sputtering or beam scanning strategy . Rim, halftone and embedded PSMs for contact hole and poly line featu res with programmed defects have been fabricated and repaired by the n ew methods. computer simulation and experimental photolithography have confirmed that opaque defects can be repaired by the optimized FIB te chnique without leaving any post repair ''ghost'' defects.