Repair of opaque defects in photomasks using focused ion beams

Abstract

Optical lithography of semiconductor microcircuits relies upon the use of chromium-on-glass masks or reticles. Opaque defects in the mask pattern due to excess of chromium can be repaired by the use of focused ion beams and commercial mask repair systems are now available. During the repair process, ions are implanted into the glass substrate of the mask, giving rise to a stain when the mask is inspected or used for lithography.