Patent ID: 8591749

Claim:
A method of manufacturing a phase-shifting photomask having a self-aligned rim-shifting element, the method comprising: applying a first patterning film and a second patterning film to a first portion of a transparent substrate; etching the transparent substrate to a depth to remove a second portion of the transparent substrate not beneath the first and second patterning films to thereby define a third portion of the transparent substrate above the depth to which the transparent substrate is selectively etched, and a fourth portion of the transparent substrate above the depth to which the transparent substrate is selectively etched; applying a conformal film to the transparent substrate; using anisotropic etching to form a first sidewall spacer on the third portion of the transparent substrate, and a second sidewall spacer on the fourth portion of the transparent substrate; applying an additional photoresist layer atop the second patterning film, the second sidewall spacer, and an area of the transparent substrate adjacent the second sidewall spacer; etching the third portion of the transparent substrate and the first portion of the transparent substrate, beneath the first sidewall spacer to undercut an area beneath the first patterning film; etching the first portion of the transparent substrate beneath the additional photoresist layer, to undercut the area of the transparent substrate adjacent the second sidewall spacer; removing the additional photoresist layer to thereby yield a positive sidewall portion of the transparent substrate, above the first portion of the transparent substrate; and removing the first and second patterning films; wherein the etched transparent substrate forms a self-aligned undercut rim-shifting element.