A patterning device carries a pattern of features to be transferred onto a substrate using a lithographic apparatus. The patterning device is free of light absorber material, at least in an area. The pattern of features in the area may include a dense array of lines, trenches, dots or holes. Individual lines, holes, etc. are defined in at least one direction by pairs of edges between regions of different phase in the patterning device. A distance between the pair of edges in the at least one direction is at least 15% smaller than a size of the individual feature to be formed on the substrate once adjusted by a magnification factor, if any, of the lithographic apparatus. The patterning device may be adapted for use in EUV lithography. The patterning device may be adapted for use in a negative tone resist and development process.