Colloidal silica particles are being intensively studied due to their potential applications in catalysis, intelligent materials, optoelectronic devices, photonic bandgap crystals, masks for lithographic nanopatterning, etc. For this work, spherical submicrometer-sized silica particles were prepared by the Stöber method and deposited as a monolayer onto silicon wafers by means of a spin coater system. This sample is then used as a mask to create regular arrays of nanoscale surface features, such as Ag and Au metallic deposits. Ion beam modified masks were used to tailor the size and arrangement of these deposits on Si substrates as a function of the ion fluence. Indeed, amorphous glassy materials like silicon dioxide can undergo extreme deformations under exposure to high-energy beams, which induce damage and structural changes in solids due to energy losses of MeV heavy ions via ionization events and atomic collisions. Some of the samples were irradiated at room temperature with Si ions at 4 and 6 MeV and fluences up to 0.3×10¹⁵ Si/cm², under an angle of 90° with respect 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 and a subsequent Ag or Au evaporation allowed the formation of ordered arrays of Ag or Au features, after removal of the silica particles. The size, size distribution and shape of both the silica particles and the array of metallic deposits were determined by scanning electron microscopy.

 

Juan-Carlos Cheang-Wong*, Instituto de Física, Universidad Nacional Autónoma de México, Mexico
Eder Reséndiz, Instituto de Física, Universidad Nacional Autónoma de México, Mexico
Ulises Morales, Instituto de Física, Universidad Nacional Autónoma de México, Mexico

*presenting author