Methods, apparatus, and system for minimizing defectivity in top-coat-free immersion photolithography are provided. Embodiments include forming a photomask by defining a first pattern including a main functional pattern in the photomask; and defining a second pattern including a sub-resolution fill pattern in the photomask in areas between or and/or within structures of the first pattern, the fill pattern having a pitch or range of pitches smaller than a minimum resolved pitch of the lithographic exposure and/or at least a part of the sub-resolution structures of the sub-resolution fill pattern not substantially modifying an imaging of any structure of the main functional pattern in the lithographic exposure.