The measurement of viscosity of thin polymer films

The development of nanotechnology faces many problems, one of which is lack of a fast and cheap method for fabricating structures whose dimensions are less than 0.1 μm. One method to solve this problem is nanoimprint lithography (NIL). The method of fabricating nanometer scale patterns by NIL was first proposed by Chou1,2 in 1995. Nanoimprint lithography creates patterns by the mechanical deformation of imprint resist and has many advantages, such as low cost and high resolution. Unfortunately, in spite of the simplicity of the idea and significant development of the method, there are many problems which must be overcome. One of which is the proper valuer of viscosity. The viscosity is a very important property of resists used in NIL and many methods to measure viscosity in thin films have been developed. In this paper we present the innovative method which allows the measurement of the viscosity of thin film as a function of temperature and indentation depth. It is then possible to investigate the influence of substrate on the rheological properties of thin films. Thickness of the measured films was reduced to 30 nm whereas resolution of the indentation depth was reduced to 5 nm.