Nanolithography in the quasi-far field based on the destructive interference effect of surface plasmon polaritons

On the principle of phase-shift mask, the metal segment of a sub-wavelength Ag grating on a quartz substrate is used as a phase-shifting layer in this photolithography method. When the radiation modes of the surface plasmon polaritons (SPPs) excited on the Ag surface have optical phase opposite to that of the waves emitting from the slits, destructive interference occurs and the diffraction limit can be broken through. The SPPs excited on the surface between Ag and water can be transformed into propagation modes in the photoresist. Therefore, nanolithography can be achieved in the quasi-far field with this method.