Evanescent wave interference lithography for surface nano-structuring

Surface nano-structuring on photoresist beyond the diffraction limit has been investigated by using total internal reflection induced evanescence wave interference with a Lloyd's mirror. The size of the patterns can be down to 80 nm with the incident laser wavelength, λ, of 325 nm, less than λ/4 resolution. This may be attributed to laser induced evanescent wave, which has a shorter wavelength than that of the incident laser in air. The energy distribution of evanescent wave interference patterns was studied theoretically. It shows good agreement with the experiments. This technique can be used to improve traditional laser interference lithography to get smaller feature sizes with a simple modification by putting a prism in front of the sample only