Fabrication of multilayered structure of silver nanorod arrays for plasmon memory

In recent years, many devices utilizing plasmon resonance have been studied. Among the various plasmonic devices, the next generation of plasmon memory is expected to be a three-dimensional optical storage media. The plasmon memory is a three-dimensional structure in which a metal nanorod layer and a resin layer are stacked. This is expected to have more capacity than conventional optical storage media. Generally, metal nanostructures can be fabricated by using electron beam lithography, metal deposition, and lift-off processes. By repeating this process, the three-dimensional structure can be fabricated. However, because the electron beam lithography and metal deposition are conducted in a vacuum, the fabrication of plasmon memory requires considerable time. Thus, the productivity of the plasmon memory is very low. In our previous research, we developed a process that can be fabricated in ambient atmosphere by nanoimprint lithography (NIL) and silver ink instead of electron beam lithography and metal deposition. Using NIL, a high throughput nanopattern fabrication method, and silver ink, which can be used in ambient atmosphere, allows for highly efficient production of metal patterns. Thus, this process can shorten the time required compared to the usual process. Additionally, in order to operate as a plasmon memory, it is necessary to align the metal nanostructure for each layer. In this study, we developed an alignment mark suitable for NIL and metal nanostructure fabrication using silver ink. By positioning the alignment mark while looking through an optical microscope, the metal nanostructure was aligned and a three-layer silver patterned nanorod structure was fabricated. The misalignment was suppressed to 230 nm in the vertical direction and 320 nm in the lateral direction.