Focused-ion-beam repair of phase-shift photomasks

Abstract

Phase-shift photolithography is emerging as an important new technology for sub-half-micron design rule circuits. Unfortunately part of the price paid for the improvements in spatial resolution and process latitude afforded by phase-shift lithography is increased mask defect printing sensitivity. The minimum printable defect size, 0.3 microns (on the mask) for I-line steppers at 0.35 microns, is roughly half that for conventional photomasks. This paper examines the issues associated with extending high resolution focused ion beam mask repair to phase-shift masks.