Nanoimprint mold manufacturing with focused ion beam

Nanoimprint lithography (NIL) is an emerging low cost technique for reproducing sub-45 nm pattern in various applications; however, manufacturing the mold for nanoimprint has been a key challenge in expense and resolution. Focused Ion Beams (FIB) has been known for high resolution but low throughput work in TEM sample preparation, and its extremely well defined 7 nm diameter Ga⁺ beam make it also a suitable tool for mold manufacturing for nanoimprint, which enable mass reproduction of the FIB work. We find features down to 30 nm can be made with FIB, the actual line width to beam diameter ratio is around 5-6 for an aspect ratio less than 2. A higher than 2 aspect ratio may result in re-deposition of the milled out substrate. Re-deposition can be reduced by a shorter dwell time or gas-assisted etching. There is a trade off between dwell time and feature integrity. Best results can be achieved with high hardness materials; the lack of conductivity for some materials can be remedied with s thin layer of Pt coating on the surface before FIB jobs.