Analysis of the nanoimprint lithography with a viscous model

Limitations of Simple Flow Models for the Simulation of Nanoimprint

“…(2007) or Jeong et al (2002), although power-law viscous fluids were considered in the finite element simulations of Rowland et al (2005) and in the analytical approach of Hsin and Young (2008), among others. Actually, as shown 4 by Schultz et al (2006), for instance, the polymer exhibits shear-thinning above a transition shear rate, but the limitation to a linear behavior may be acceptable for low strain rates. Moreover, the purpose of the present study is to explore the applicability of simple models, and this can be limited to simple behaviors in a first stage.…”

“…Nanoimprint lithography can be used to reproduce a variety of patterns, like periodic arrays of pillars or holes with circular or square cross-sections, among others (see Guo, 2004, for examples), but simple lines are very frequently used to demonstrate the technique, as in the pioneering papers by Chou et al (1995Chou et al ( , 1996, and to test models (Jeong et al, 2002;Rowland et al, 2005;Young, 2005, for instance). One advantage of line patterns is the two-dimensional flow involved, which allows the study of a mere cross section.…”

“…Basically, results taken from the lubrication theory are employed in this context. For instance, Schultz et al (2006) adapted this theory to model the flow below an elementary periodic pattern, and Leveder et al (2007) used it in a reverse manner to deduce the polymer viscosity from the applied force. The other approach, which allows especially to overcome the limitation of the lubrication theory to small thickness-to-width aspect ratios below patterns, performs a full numerical simulation of the polymer flow like in Jeong et al (2002), or Rowland et al (2005), for example.…”

“…The other approach, which allows especially to overcome the limitation of the lubrication theory to small thickness-to-width aspect ratios below patterns, performs a full numerical simulation of the polymer flow like in Jeong et al (2002), or Rowland et al (2005), for example. These authors put emphasis on polymer flow but did not provide the corresponding imprint force, though, whereas Young (2005) did compute it. Of course, this type of approach gives a precise solution to a given flow problem, provided the discretization is fine enough, but it requires the availability of a simulation code and involves much longer computation times than using analytical estimates.…”

A novel process for continuous thermal embossing of large‐area nanopatterns onto polymer films

“…process is shown in Figure 1 [ 34,35] Temperatures in the holding regime of the embossing step will typically be just around the glass temperature of the material (orange, top roll). This holding stage is an important part of the embossing process, especially when using thermoplastic materials, as relaxation effects can become a problem.…”