SELF-ALIGNED METHOD OF MAKING PHASE-SHIFTING LITHOGRAPHIC MASKS HAVING THREE OR MORE PHASE-SHIFTS

摘要

A phase-shifting lithographic mask having two or more self-alignedphase-shifting regions is fabricated by a sequence of etchings of the phase-shiftingmask using a protective resist layer having three or more regions (411, 412, 410,401) that have been subjected to mutually different doses (including possibly zero)of actinic radiation--such as electron beam, ion beam, or photon beam radiation. Aself-aligned opaque region (901) can be supplied by in-situ carbonization ofremaining resist material.