LARGE-SCALE EXCIMER-LASER PRODUCTION OF SUBMICRON PERIODIC STRUCTURES ON POLYMER SURFACES

By absorption of a polarized excimer laser beam of low fluence a new class of submicron laser induced structures is produced on various polymer surfaces. Parallel ripples of less than 0.2 mum spacing in the direction of the electric field are obtained with the ArF or KrF radiation when it is strongly absorbed by the polymer. The amplitude of the roughening increases with the number of pulses used, with a maximum obtained after one thousand. Several polymers in thin or thick films of commercial or laboratory origin can be textured in air or in vacuum or both depending on the chemical structure. Fluence is below the ablation threshold and must be chosen in a narrow window, which depends on the polymer and the wavelength used. The obtained relief is observed by SEM, TEM and characterized by ellipsometry. Structures are obtained also by irradiation of thin film (2000 angstrom) coated on silicon wafers. In many applications, a controlled submicron level roughening of surfaces is desired. Owing to the simplicity of this irradiation procedure large scale surface treatments are possible.