A method for forming a phase shift mask is presented. The method includes providing a substrate including a transparent material having first, second and third regions, the third region being disposed between the first and second regions. The method also includes forming a light reducing layer on a first major surface of the substrate. The light reducing layer is patterned to form a patterned light reducing layer having sidewalls defining openings to expose the first and second regions. The patterned light reducing layer is processed to transform the sidewalls of the patterned light reducing layer to angled sidewalls having an angle of less than 90° from a plane of the first major surface of the substrate. The angled sidewalls improve intensity balance of an image-formed by light-transmitted through the mask.