Fluid flow in UV nanoimprint lithography with patterned templatesby Jain, A; Spann, A; Cochrane, A; Schunk, PR; Bonnecaze, RT
Fluid flow in UV nanoimprint lithography with patterned template is simulated to study the effect of pattern directionality on droplet merging, throughput and defectivity. Flow in high density patterns is simulated by using an anisotropic permeability. A method to calculate the permeability for templates with line and space patterns is presented. It is found that the directionality of the pattern results in anisotropic spreading of the droplets. The droplets flow faster in the direction of the pattern resulting in channelized unfilled regions. These regions fill slowly because the permeability in the direction normal to the patterns is low. A modified hexagonal arrangement for droplet dispensing is proposed in which the filling time is lower than square and hexagonal droplet arrangements. Simulations are carried out with different multi-patterned template and droplet dispensing schemes. Dispensing droplets such that their volume is sufficient to fill the features locally is found to be the optimum dispensing scheme to minimize filling time.