High-resolution capability of optical near-field imprint lithography

We propose a novel method to increase the resolution of imprint lithography by introducing strong localization of the optical near-field intensity, depending on the mold structure. By optimizing the thickness of the metallic film on a SiO₂ line-and-space (LS) mold without a sidewall coating, we confirmed that the optical near-field strongly localizes at the edge of the mold, using a finite-difference time-domain calculation method. Based on the calculated results, we performed optical near-field imprint lithography using a mold with metallized (20-nm-thick Al without a sidewall coating) SiO₂ LS with a 300-nm half-pitch that was 200-nm deep with illumination using the g-line (λ=436 nm), and obtained features as narrow as 50 nm wide. PACS 81.16.Nd; 81.16.Rf