Printability and repair of defects in rim and attenuated phase shift masks

Rim and attenuated phase shift masks can extend the range of i-line optical stepper lithography to 0.4 μm with enhanced depth of field. The repair of defects through subtractive and additive methods using focused ion beams is critical to the future success of the technology. Printability tests and simulation studies demonstrate the hierarchy of defects in which both rPSM and aPSM types are less tolerant of absorbing/attenuating defects, but more tolerant of clear defects than the corresponding conventional BIM. Repair trials reveal the existence of a new type of post repair defect - the phase trench - but also clearly demonstrate the feasibility of repair using FIB methods.