Asymmetric fluid-structure dynamics in nanoscale imprint lithography

Chapter 3: Active Stage DesignThe practical development of the SFIL process requires that the baselayers are thin and uniform. An active stage machine is currently being designedand implemented to allow scientific studies of the imprinting process. Thismachine will have independent, high-resolution actuators and a feedback controlsystem to squeeze the etch barrier fluid prior to UV exposure. The requirementsand embodiment of such an active stage system are presented in this chapter.3.1 OPTIMIZING BASE LAYER THICKNESS, ORIENTATION ALIGNMENT,AND THROUGHPUTThe ideal imprint process would lead to an etch barrier with a zero base layerthickness. However, a zero base layer thickness cannot be obtained in finite timewith finite pressure. From the analysis in chapter 2, it can be seen that for a finitepressure an infinite time is required to obtain a zero base layer thickness.Experimental results from the multi-imprint machine support this theoreticalresult in that base layers below 100 nm have been very difficult to achieve. Inreality, there is a tradeoff between throughput and base layer thickness since athinner base layer would require more time to achieve. If a base layer of uniformthickness and of the order of the imprinted features (typically 200 nm) isobtained, then a preliminary etching can eliminate the base layer without affectingthe fidelity of the imprinted features. Therefore, a base layer thickness in therange of 100 to 200 nm would provide an optimal solution to both throughputrequirements and imprinted feature fidelity.In the initial test beds for SFIL development, a coarse, micron-level precalibrationstage ensures that any initial orientation misalignment of the template41