Durability Test of Replica Mold in UV Nanoimprinting and Enlargement of Mold Patterned Area by Mold Stitching

UV nanoimprint lithography (UV-NIL) is a powerful tool for replicating nanoscale patterns. To preserve the master mold, it is effective to use a replica mold that is replicated from the master mold by UV-NIL. To avoid a release coating treatment, an acrylic-type UV-curable resin with fluorinated materials has been developed. The molds of these materials can be transferred without a release coating because of the fluorinated material. The durability of the replica mold is very important for mass production; thus, a durability test, which is a repetitive transfer in UV-NIL, was performed. A hole-shaped replica mold was transferred more than 10,000 times, and the transferred pattern error did not increase. Thus, the replica mold had very high durability and fidelity in UV-NIL. The master mold tends to have a small area; therefore, an enlargement of the patterned area is desired. The developed UV-curable resin can also increase the patterned area. In addition, we have developed a stitching substrate method to enlarge the patterned area. The concept of this method is hard substrates, such as silicon, can clean the edge face more easily than soft film substrates. In addition, the shape of hard substrates is uniform; therefore, the stitching of hard substrates is easier. Using this method and developed UV-curable resin, a double-area replica mold was obtained. This method is simple and inexpensive; however, only a 1.7 µm step height of the stitched region was obtained.