Advanced step and flash nanoimprint lithography using UV-sensitive hard mask underlayer material

Step and flash nanoimprint lithography has many advantages such as high resolution, low line edge roughness and easy operation. However, resist peeling and defects present challenges that must be resolved in order to mass-produce advanced devices. A new approach using a spin-on UV-sensitive hard mask underlayer material with terminal methacrylate groups has been developed successfully, in order to obtain high adhesion by radical polymerisation between acrylate groups of the resist material and methacrylate groups of the underlayer during UV irradiation. The obtained high adhesion between the resist and underlayer was acceptable to improve the generated resist peeling and contamination problem when the template was removed from the resist after UV irradiation. The first demonstrated underlayer material indicated great properties, such as 80 nm straight profiles on 20 nm thin residual thickness and nanoimprint patterning replication on 200 mm wafer.