Asymmetric fluid-structure dynamics in nanoscale imprint lithography

force, lb504540353025201510500 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5time, sFigure 5.8 Force corresponding to single s-curve actuation5.4.2 Double S-Curve Motion ProfileFrom both the experiments and the simulation, it was noticed that theresults, especially in the final base layer thickness and measured forces could beimproved, at the least, through a better feedforward actuation scheme.Furthermore, since the force is proportional to the approach velocity of thetemplate and inversely proportional to h 3 , this actuation was separated into twosegments. The first segment occurs for large base layers. For large base layers,say above 500 nm, the actuators should move the template assembly faster thanfor thinner base layers. The motion profile of the actuators for this scheme isillustrated in Figure 5.9. It was assumed that the motors could provide thespecified motion and that the controller was an ideal high bandwidth controller.The simulation time was 0 ≤ t ≤ 0.5 seconds. In the first 0.05 seconds, the72