Some embodiments include formation of polymer spacers along sacrificial material, removal of the sacrificial material, and utilization of the polymer spacers as masks during fabrication of integrated circuitry. The polymer spacer masks may, for example, be utilized to pattern flash gates of a flash memory array. In some embodiments, the polymer is simultaneously formed across large sacrificial structures and small sacrificial structures. The polymer is thicker across the large sacrificial structures than across the small sacrificial structures, and such difference in thickness is utilized to fabricate high density structures and low-density structures with a single photomask.