Fluorescence microscopy for quality control in nanoimprint lithography

Fluorescence microscopy is introduced as a low cost quality control process for nanoimprint lithography. To depict imprinted structures down to 1 μm lateral size and to detect residues down to 100 nm lateral size, the standard printable polymer mr-I8000 is labelled with less than 0.1 wt.% fluorescent dye. Three different types of stamps are used to determine the dependence of the shape and size of stamp features in a series of imprints. The quality of a stamp is given by the sticking polymer residues per unit area. Fluorescence light images as well as visible light images are analysed. Changes in the area of the stamp covered with polymer as a function of the number of imprints is summarised in a statistical process chart. Adhesion was artificially induced in order to observe self cleaning of virgin stamps. They were detected and monitored, suggesting that this method is a suitable technique for quality control and that it could be easily adapted to the nanoimprint process.