Methods of lithography, methods for forming patterning tools, and patterning tools are described. One such patterning tool include an active region that forms a first diffraction image on a lens when in use, and an inactive region that forms a second diffraction image on a lens when in use. The inactive region includes a pattern of phase shifting features formed in a substantially transparent material of the patterning tool. Patterning tools and methods, as described, can be used to compensate for lens distortion from effects such as localized heating.