Approaches to rapid resist spreading on dispensing based UV-NIL

Reduction of resist filling time was investigated with the aim of improving UV-nanoimprint lithography (UV-NIL) throughput. A novel low volatility, low viscosity resist was developed to enable ink-jetting with minute resist droplets and imprinting under reduced air atmosphere. Direct observation of resist spreading showed that the resist filling process is composed of three steps: A) capillary bridge formation, B) resist spreading, and C) air bubble dissolution. Resist filling time was drastically decreased by changing the atmosphere from helium to a reduced air atmosphere of 0.02MPa. A comparison of 0.7pl and 6pl resist droplets showed that reducing resist droplet size while increasing area density also reduces resist filling time. Improved bubble dissolution speed is thought to result from imprinting under reduced air atmosphere. Moreover, ink-jetting smaller size resist droplets with higher density is thought to have an effect on reducing the time of each of the three steps, particularly bubble dissolution time. Combining dispensing-NIL with imprinting in vacuum is expected to improve UV-NIL throughput.