Phase shifting reticle fabrication using ion implantation

Abstract

A method of fabricating a phase shifting reticle that can be used as a mask in photolithographic processes such as semiconductor wafer patterning. A transparent quartz substrate is subjected to high voltage ion bombardment to produce patterns of ion implant areas on the substrate. By carefully selecting the dopants for ion implantation and closely controlling the implantation process, areas on the substrate are produced having an absorption property for forming an opaque light blocking area or indexes of refraction different than the quartz substrate and selected to achieve a 0.degree. to 180.degree. phase shift area. This produces a repetitive pattern of alternating light transmission openings and phase shifters having opaque light blockers on either side. Additionally, tapered phase shifters may be implanted into the substrate to extend from a 180.degree. phase shift area into a light transmission opening at a 0.degree. phase shift.

Dependencies are inferred from the claim text.