Nanoimprint lithography combined with ultrasonic vibration on polycarbonate

We have succeeded in transferring nanopatterns to the surface of a polycarbonate sheet by combining thermal nanoimprint lithography with ultrasonic vibration at a low temperature. The mold pattern was a cross-mark for alignment consisting of lines and spaces or a dot pattern with widths of 500 and 750 nm. The mold was fabricated by dry etching a Si substrate using micro-electro-mechanical-system (MEMS) fabrication technology. The experiment was executed using an original system that was used to build a 19 kHz ultrasonic vibration unit with a maximum magnitude of 1.8 mu m for a thermal nanoimprint lithography device. Typically, the optimal heating temperature in thermal nanoimprint lithography using polycarbonate is 180 degrees C, but when ultrasonic vibration is applied, it becomes possible to mold nanopatterns at a lower temperature (160 degrees C). As a result, the process time of a thermal cycle could be cut in half, thus improving the throughput greatly.