Abstract: A pillar array is printed in positive photoresist using an optical mask (108) having an array of features (310) corresponding to the pillars. The pillars' width/length dimensions are below the exposure wavelength. Superior results can be achieved (less peeling off of the pillars and less overexposure at the center of each pillar) if the mask features (310) are downsized relative to the pillars' target sizes, and the exposure energy is reduced. Negative photoresist (with a dark field mask) can be used, and can provide good results (in terms of pillars peeling-off) if the combined area of the features (410) corresponding to the pillars is smaller than the area between the features (410).