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Time evolution of the resist deformation process in the thermal nanoimprint lithography ͑NIL͒ has been investigated by both experiment and simulation study. For the numerical simulation, the authors newly developed a simulator using generalized Maxwell model as the viscoelastic constitutive model in conventional finite element method, which handles the complete NIL operations including resist pressing, cooling, and demolding processes. The dependency on the linewidth of the filling rate was investigated by both experiments and simulation and they sufficiently agreed with each other. It is confirmed that narrow pattern ͑high aspect ratio pattern͒ was difficult to be filled in a short period under the same imprinting pressure.

Time-evolutional analyses of an intermittent line-and-space patterning in thermal nanoimprint were performed both experimentally and numerically. The constitutive model of polymers in finite element numerical analyses was a viscoelastic model based on the generalized Maxwell model and the Williams-Landel-Ferry (WLF) law so that polymer deformation was strain-history and temperature dependent. We performed uniaxial vibrational tests and numerical inverse analyses to identify material properties of the viscoelastic model for cyclo-olefin-polymer (COP). We also carried out a series of experiments and numerical simulations of an intermittent line-and-space patterning at various pressure-holding times. Both experiments and simulations presented characteristic polymer deformation which never appear in continuous line-and-space patterning. The numerical simulation well agreed with experiments and revealed complicated distributions of stress and pressure during the imprinting that were difficult to be directly observed in thermal nanoimprint experiments.

Mold releasing forces are experimentally measured in various exposure dosages for UV nanoimprint resist. PAK01 resist is examined to evaluate the chemical conversion by FTIR. Time dependent conversion ratio is measured under UV exposure and the conversion ratio of the UV resin versus exposed dosages is verified. Also, releasing forces for various exposure dosages are mechanically measured for flat mold. The results show the measured releasing force is not stabilized until the conversion is completed up to over around 90 %. Based on these results, the minimums exposure dosage is known for successful releasing.

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