Extreme ultraviolet patterning of tin-oxo cages
We report on the extreme ultraviolet (EUV) patterning performance of tin-oxo cages: molecular building blocks that are known to turn insoluble upon EUV exposure, thus having the properties of a negative tone photoresist. In this work, we focus on contrast curves of the materials using open-frame EUV exposures and their patterning capabilities using EUV interference lithography. It is shown that baking steps, such as post-exposure baking (PEB) can significantly affect both the sensitivity and contrast in the open-frame experiments as well as the patterning experiments. In addition, we show that the exchange of the anions of the cage can make a difference in terms of their physical properties. Our results demonstrate the significance of process optimization while evaluating the resist performance of novel molecular materials.