Fabrication of nanodot array molds by using an inorganic electron-beam resist and a postexposure bake

Abstract

Nanoimprint lithography (NIL) is regarded as the lithographic technology of the next generation. The photolithography is advancing to perform resolution of 32nm. Although photolithography and high-voltage-acceleration (>50kV) electron-beam-lithography (EBL) techniques are currently used in commercialized lithography, these two methods involve high costs. The authors therefore attempted to fabricate arrays of dots, each with a diameter of 20nm or less, by using low-voltage-acceleration EBL. NIMO-P0701 was used as a positive-type inorganic EB resist in this study and a combination of NIMO-P0701 and low-acceleration-voltage EBL was established. Attempts were then made to use a postexposure bake (PEB) to further reduce the size of the dot array patterns. Finally, the developed dot array mold was transferred by UV-NIL without dry etching. As a result, arrays of dots with a diameter of 20 or 10nm were fabricated by EBL at an acceleration voltage of 4kV and subsequent PEB. The resulting mold was developed with buffered hydrofluoric acid. The developed NIMO-P0701 pattern was used for NIL, and pattern transfer to a UV-curable resin was successfully achieved. In this case, the optimum transfer pressure was 4MPa. Additionally, dot arrays initially produced with diameters of 30 and 18nm were shrunk to sizes of 20 and 10nm, respectively, by means of PEB.