Research on the Filling Process of Ultraviolet Nanoimprint Lithography with High-Resolution Stamps

With the rapid development of the semiconductor industry, the feature size of integrated circuits (ICs) is continuously getting smaller and smaller. Although traditional optical lithography and extreme ultraviolet (EUV) lithography can fabricate products with 5-nm feature size, the production cost is quite high. As a candidate of next-generation lithography, ultraviolet nanoimprint lithography (UV-NIL) can also achieve high-resolution imprints at a lower cost. Based on contact mechanics, the filling mechanism and imprint quality of UV-NIL were examined using high-resolution stamps with different feature sizes of 3 nm, 4 nm, and 5 nm. It was found that UV-NIL could successfully replicate patterns with feature sizes down to 3 nm; however, the imprinting process was more complicated. Among the selected nine stamps, the replications of 4-nm and 5-nm feature sizes had a relatively uniform residual layer and a symmetric contact pressure, whereas the replications of 3-nm feature size had an asymmetric contact pressure, resulting in an asymmetric residual layer. In order to obtain a more uniform residual layer with higher-quality imprinting, the pressure applied to the left and right sides of a stamp should be appropriately changed. The pattern density of a stamp had a certain influence on the contact pressure. As the pattern density increased, the contact pressure tended to be uniform; however, when the pattern density exceeded 0.5, the situation became worse. This research can provide guidance for promoting the development of UV-NIL in the direction of high-resolution pattern replication.