Experimental demonstration of supercell photonic crystal in super-resolution photolithography

The versatile photonic crystals are quite attractive, especially in regulating the transmission of light. Here, a supercell photonic crystal (SPC) composed of ternary dielectric multilayers is proposed for manipulating the evanescent waves, and demonstrated experimentally in super-resolution photolithography forwhat we believe to be the first time. Based on the spatial frequency selection function of the SPC, only the anticipant diffracted waves with high-<i>k</i> could be propagated, making it possible to produce sub-diffraction-limited patterns with high uniformity and contrast. Benefited from the low-loss character of the dielectric multilayers, the selected high-<i>k</i> waves can be transmitted subsequently through a long air distance. Besides, the asymmetric arrangement of SPC also leads to the multilayers performing satisfactory thickness robustness, which can greatly relax the requirement in preparation. Combining optimized grating masks, sub-diffraction-limited patterns with a half-pitch of ∼65 nm (∼0.16<i>λ</i>) could be obtained from both 1^st and 2^nd order diffracted waves under situations where the working distance reaches 160 nm, which will significantly alleviate the difficulty in mechanical control and mask fabrication. This work shows the functional versatility of SPC and presents a feasible way in manipulating evanescent waves. It is also meaningful for promoting super-resolution photolithography towards practical application.