Problems of the nanoimprinting technique for nanometer scale pattern definition

We have tested nanoimprint lithography, a new and promising technique for nanometer-scale pattern definition. Preliminary experiments reveal that, besides severe sticking and adhesion problems, the problem of material transport is one inherent to this technique. There are clear indications that most of the effects found may be understood in terms of material transport. We performed experiments within a well defined pressure and temperature window which ranged from 60 to 100 bar and from 50 to 90 degrees C above the glass transition temperature of the poly(methylmethacrylate)-like polymer used. As a result, the quality of imprint is evaluated with respect to full area pattern transfer, based on a qualitative scanning electron microscope investigation of the fully imprinted area of 2 cm x 2 cm patterned with features of different size and shape. Optimum conditions for imprint quality are found around 100 bar and 90 degrees C above T-g for the specific polymer used. Although material transport will limit nanoimprint performance in general, it is found that periodic patterns and isolated or small area negative stamp relief patterns are most suitable for high quality nanoimprinting. (C) 1998 American Vacuum Society. [S0734-211X(98)04006-2].