Fabrication of sub-25 nm diameter pillar nanoimprint molds with smooth sidewalls using self-perfection by liquefaction and reactive ion etching

Self-perfection by liquefaction (SPEL) was used to fabricate nanoimprint molds with an array of sub-25 nm diameter pillars (200 nm period), resulting in nearly perfect cylindrical shape and smooth sidewalls. SPEL turned an array of irregularly shaped Cr polygons into an array of nearly perfect circular dots with small diameter. The Cr dot arrays were then transferred to SiO₂ or Si pillar arrays by means of reactive ion etching to produce imprint molds. High-fidelity nanoimprint lithography using the pillar molds was also demonstrated.