Fabrication of Nb Superconducting Nanowires by Nanoimprint Lithography

Abstract

Nanoimprint lithography (NIL) is considered to be an attractive nonconventional lithographic technique in the fabrication of nanostructures with many advantages including low cost, high throughput, and high resolution on relatively large areas. In this paper, NIL was used to pattern superconducting nanowires with meander structures based on ultrathin (~4 nm) Nb films deposited by dc-magnetron sputtering at room temperature. A combination of thermal-NIL and UV-NIL was exploited to transfer the meander pattern from the imprint hard mold to Nb films. The hard mold, etched into a Si wafer, was defined by e-beam lithography (EBL), which was nonexpendable due to the application of IPS as a soft mold to transfer the pattern to the imprint resist in the NIL process. Superconducting properties such as transition temperature T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> and critical current density J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> were measured on the NIL-made Nb nanowires. The results are compared with those of EBL-made nanowires.