Development of an experimental technique for testing rheological properties of ultrathin polymer films used in nanoimprint lithography

Abstract

A new method for the measurement of rheological properties (complex viscosity, viscosity and elasticity) of thin polymeric films is presented. The probe, which is placed on the end of an arm of a mini tuning fork, is caused to oscillate and then is put into poly(methyl methacrylate) films, whose thickness ranges from 30 nm to 1080 nm. All measured properties depend on temperature, thickness of the films, indentation depth and the molecular weight of PMMA. Complex viscosity, viscosity and elasticity are found to be lower at higher temperatures and higher with greater molecular weight. They are also lower for thicker films. The results gained from this experiment may be useful in the development of nanoimprint lithography and many other branches of nanotechnology. Furthermore, the method allows for the measurement of the rheological properties of many different thin films (nanoimprint polymers, oils, lubricants) at different temperatures.