In this paper, we study the effect of the height and diameter of vertically aligned silicon structures on their optical properties. Structures with different geometry were formed using nanosphere lithography and dry etching. Nanosphere lithography was realized with 0.9 and 2 μm latex spheres. The etching process was carried out through a formed mask (template) composed of 0.9 and 2 μm latex spheres, respectively. The diameter of the spheres and the etching time determined the size of the formed structures and their optical properties. A significant reduction of the total reflection with height as well as blue shift of the minimum with diameter decrease were observed.