Improving periodic uniformity of area-type LIPSS on Si wafer using a flat-top beam femtosecond NIR laser

Abstract Fabrication of line- and area-type laser-induced periodic surface structures (LIPSS) induced by a flat-top beam provides improved periodic uniformity in structure compared to fabrication with a Gaussian beam. Improved periodic uniformity induces high reproducibility and high performance through signal uniformity. Especially, this characteristic makes LIPSS induced by flat-top beam can be applied in structural color, hydrophobicity control and surface-enhanced Raman scattering. To demonstrate the improved periodic uniformity, the periods of the LIPSSs induced by Gaussian and flat-top beams are analyzed. Period uniformity is evaluated by applying the fast Fourier transformation to atomic force microscopy data. Improved periodic uniformity is observed in the area-type LIPSS induced by a flat-top beam. This is because of the peak of line width induced by the Gaussian beam profile characteristic. Consequently, area-type LIPSSs induced by a flat-top beam exhibit improved periodic uniformity.