Nanostructuring of PMMA, GaAs, SiC and Si samples by focused XUV laser beam

We report results of ablation experiments of different materials through Ni grid with an intense XUV laser beam. As a source of XUV radiation (energy of about 100 J) with wavelength of 46.9 nm was used high-current capillary discharge driver. Ablated footprints were analyzed by optical microscope and by an atomic-force microscope (AFM). It was found that structure and period of diffraction pattern on PMMA sample (both in ablation and desorption area) depend on the distance from grid to the sample surface. Depth of ablation craters in a single window of PMMA for single shot was about of 80 nm, and period changes from 400 nm (on the edge) to 190 nm (in the middle) for grid further from surface, and from 400 nm (on the edge) to 10 nm (in the middle) for closer grid. Contrary to this, no diffraction patterns in ablation region and only slightly visible on the edge in the desorption region were observed on the surface of GaAs, SiC and Si samples for single shot. Depth of ablated craters in ablation region was about 100 nm for GaAs, 20 nm for Si and up to 5 nm for SiC. In desorption region depth of ablated craters is relatively shallow (up to 5 nm for GaAs and up to 2 nm for Si and SiC). In the case of irradiation samples by 5 shots ablated craters are deeper, but situation with diffraction pattern is the same as in the case of single shot for all materials.