Self-images contrast enhancement for displacement Talbot lithography by means of composite mesoscale amplitude-phase masks

摘要

We propose a new design of composite wavelength-scale amplitude-phase diffraction grating as applied to the displacement Talbot lithography. The grating is composed of a conventional metal amplitude binary mask with superposed dielectric phase steps and provides for manyfold optical contrast enhancement of the integrated 'Talbot carpet' as opposed to the amplitude and phase masks purely. By means of the finite element calculations, we analyze the spatial field structure in the proposed gratings with different geometric ridge shapes and show that due to Mie-type resonances excitation the semielliptical dielectric steps in the combination with metal amplitude mask demonstrate excellent spatial resolution (similar to lambda/4) and highest optical contrast (similar to 22 dB) of integrated Talbot self-images.