Spherical submicrometer-sized silica particles were prepared by the sol-gel method and deposited as a monolayer onto silicon wafers, in order to use them as a mask to create regular arrays of nanoscale surface features. Thus, by e-gun evaporation of a 50 nm thick Ag film through the silica mask, Ag nanostructures were obtained after removal of the silica monolayer. In order to tailor the mask characteristics (size and interparticle spacing), the silica masks were irradiated at room temperature with 4 and 6 MeV Si ions at different fluences up to 5×10¹⁵ ion/cm², perpendicularly to the sample surface. After the irradiation the silica particles turned into oblate particles, as a result of the increase of the particle dimension perpendicular to the ion beam and the decrease in the parallel direction. By this way, the mask openings of the silica particle monolayer were modified as a function of the irradiation parameters, and the subsequent Ag e-gun evaporation allowed the formation of ordered arrays of Ag features. The size, shape and interparticle spacing of both the silica particles and the Ag deposits were determined by scanning electron microscopy.