Numerical and experimental analysis of intermittent line-and-space patterns in thermal nanoimprint

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.