Methods for extending working distance using modified photonic crystal for near-field lithography.

Near-field lithography has evident advantages in fabricating super-resolution nano-patterns. However, the working distance (WD) is limited due to the exponential decay characteristic of the evanescent waves. Here, we proposed a novel photolithography method based on a modified photonic crystal (PC), where a defect layer is embedded into the all-dielectric multilayer structure. It is shown that this design can amend the photonic band gap and enhance the desired high-waves dramatically, then the WD in air conditions could be extended greatly, which would drastically relax the engineering challenges for introducing the near-field lithography into real-world manufacturing applications. Typically, deep subwavelength patterns with a half-pitch of 32 nm (i.e.,/6) could be formed in photoresist layer at an air WD of 100 nm. Moreover, it is revealed that diversified two-dimensional patterns could be produced with a single exposure using linear polarized light. The analyses indicate that this improved dielectric PC is applicable for near-field lithography to produce super-resolution periodic patterns with large WD, strong field intensity, and great uniformity.