José Manuel Román Marín

3D Simulation of Nano-Imprint Lithography

A proof of concept study of the feasibility of fully three-dimensional (3D) time-dependent simulation of nano-imprint lithography of polymer melt, where the polymer is treated as a structured liquid, has been presented. Considering the flow physics of the polymer as a structured liquid, we have followed the line initiated by de Gennes, using a Molecular Stress Function model of the Doi and Edwards type. We have used a 3D Lagrangian Galerkin finite element methods implemented on a parallel computer architecture. In a Lagrangian techniques, the node point follows the particle movement, allowing for the movement of free surfaces or interfaces. We have extended the method to handle the dynamic movement of the contact line between the polymer melt and stamp during mold filling.

The dynamics of cylindrical samples in dual wind-up extensional rheometers

Numerical computations of the extension of circular cylindrical shaped samples in a dual wind-up drum rheometer of Sentmanat extensional rheometer type [M. L. Sentmanat, Rheol. Acta 43, 657 (2004); R. Garritano and H. Berting, US Patent No. 7,096,728 (08/29/2006)] are presented. These time-dependent computations are fully three dimensional and based on theoretically ideal configurations. If necking or sample rupture does not occur, the elongation will resemble as ideal uni-axial if the initial sample diameter is decreased sufficiently. An initial diameter larger than 0.5 mm may result in large deviations from ideal uni-axial deformation.

Numerical Modeling of Micro Fluidics of Polymer Melts

A new Galerkin finite element scheme for the numerical simulation of three‐dimensional time‐dependent flow of K‐BKZ fluids has been developed. The scheme was used to model the polymer melt flow in nano imprint lithography (NIL). In NIL a sub micrometer pattern is hot pressed onto a thin polymer film on a hard substrate. The numerical method is based on a Lagrangian kinematics description of the fluid, where the (Cartesian) coordinate system attached to the particles is discretized by ten‐node quadratic tetrahedral elements. The time integral in the K‐BKZ model is discretized by a quadratic interpolation ensuring third order convergence in time. The method has been benchmarked on the free surface problem of a filament stretched between two plates.