Abstract
In this study, we report an ultrasonic nanoimprint lithography (U-NIL) method which can overcome the drawbacks of energy consumption and long process time occurred in conventional NIL methods. Instead of using heaters in conventional NIL, the proposed U-NIL employs an ultrasonic source located on the top of mold to generate high frequency vibration causing the increase of temperature to soften and to melt the thermoplastic polymer. The ultrasonic source is induced by the transducer consisting of a number of piezoelectric ceramic discs, sandwiched between two aluminum metal blocks. A novel ultrasonic NIL technology and ultrasonic imprinted machine have been developed and set up. To investigate the effects of imprinted resist thickness and mold geometries on the polymer flow and the temperature distribution of U-NIL through numerical have been simulated. In simulations, the velocity fields in imprinting stage and the temperature distributions in ultrasonic vibrations are performed under the variations of convexity width, cavity width, and thickness of imprinted polymer resist. Moreover, the combined effects of the imprinting stage and ultrasonic vibrations in U-NIL process are discussed. The experimental results demonstrated that vibratory energy could be concentrated in transferring the topography of mold’s surface into the polymer. We conclude that the proposed U-NIL process has the potential to become a novel nanoimprinting method.