Ramifications of lubrication theory on imprint lithography

During photo-imprint lithography processes, such as Step and Flash Imprint Lithography, a fluid is displaced from the gap between a template and a substrate. Since the width of the template is much greater than the gap height from which the fluid is being expelled, lubrication theory approximations can be applied to the equations of continuity and momentum that describe the fluid behavior. Several methods of fluid delivery have been evaluated for Step and Flash Imprint Lithography, in particular, but are applicable to other imprint lithography techniques. This paper summarizes the forces generated using three primary template actuation schemes: constant velocity; constant applied force; constant applied pressure. It also compares the force required to displace a single droplet to that of a spincoated film, and the force to displace a fixed volume of fluid in a single droplet to that of the same volume divided into n identical droplets. The multi-droplet approach has been proposed and implemented as an effective alternative means of fluid delivery for dispensing low viscosity imprint solutions.