Anisotropic arrayed nano-slots metasurfaces fabrication by reflective plasmonic lens beyond near field optical lithography

1. The permittivities obtained by the spectroscopic ellipsometry (SE850) The permittivities are obtained by the spectroscopic ellipsometry (SE850). The following Table. S1 shows the experimental parameters for determination the permittivities of Cr, PR and Ag. Table. S1 Measurement the perimittivities with ellipsometry 2. Optimizing the thickness of film The thicknesses of Cr, PR and Ag are mainly determined by considering both the calculated imaging property and the convenience of structure fabrication, pattern transfer process. In theory, reflective imaging with sub-diffraction resolution usually occurs as the permittivity of Ag matches that of resist layer at the used light wavelength. But the imaging property would be greatly affected by the thickness of the films. To show this point, the Fig. S1 presents the imaging field dependence on the variant thickness of Cr, PR and Ag film, for 50nm width dense lines pattern with L/S =1:1. For instance, PR with thickness 20 nm shows better imaging contrast than that of 30 nm, due to the enhanced excitation of surface plasmon in this case. But this would result in the difficulty of pattern transfer from PR to Ag with small PR thickness. So we choose 30 nm thickness of PR. Similar problems lies in the design of Cr and Ag films (Fig. S1b and S1d). Usually, Ag and Cr must be thick enough, at least larger than the skin depth, to block light transmission and help to get high contrast imaging. On the other hand, the FIB milling and IBE etching process require thin films. So 40 nm Cr and 50 nm Ag are employed in our experiments.