Direct laser writing of microstructures on optically opaque and reflective surfaces

• The dependence of feature size on substrate's reflection coefficient is determined experimentally.
• 3D structuring on the boundary of glass/Au is possible by carefully choosing fabrication parameters.
• A possibility to fabricate polymeric structures with submicrometer resolution with up to 1 mm/s sample translation velocities is demonstrated.

Direct laser writing (DLW) based on ultra-localized polymerization is an efficient way to produce three-dimensional (3D) micro/nano-structures for diverse applications in science and industry. It is attractive for its flexibility to materialize CAD models out of wide spectrum of materials on the desired substrates. In case of direct laser lithography, photo-crosslinking can be achieved by tightly focusing ultrashort laser pulses to a photo- or thermo-polymers. Selectively exposing material to laser radiation allows creating fully 3D structures with submicrometer spatial resolution. In this paper we present DLW results of hybrid organic–inorganic material SZ2080 on optically opaque and reflective surfaces, such as silicon and various metals (Cr, Ti, Au). Our studies prove that one can precisely fabricate 2D and 3D structures with lower than 1μm spatial resolution even on glossy or rough surfaces (surface roughness rms 0.068–0.670μm) using sample translation velocities of up to 1 mm/s. Using femtosecond high pulse repetition rate laser, sample translation velocity can reach over 1 mm/s ensuring repeatable submicrometer structuring resolution.