Nano Imprint Lithography

Nano-imprint lithography (NIL) is a lithography technique that combines the speed of optical lithography with the resolution of EBL. It creates patterns by mechanical deformation of imprint resist and subsequent processes. It has many applications and is an important technology for further development in the nanotechnology area. There are many different types of nanoimprint lithography, but two of them are most important: thermoplastic nanoimprint lithography (where the polymer is cured by a change in temperature) and photo nanoimprint lithography (where the polymer is cured by exposure to UV light). The facility available at NanoSYD cleanroom consists of photo nanoimprint lithography. (Company link)

The general process for photo NIL is described in the figure bellow. Special stamps contain the nanoscale patterns to be defined on the substrate. The stamps are pressed into a polymeric material (resist) that was previously deposited on the substrate (figure 1a). When the stamp is filled with polymer, it is cured by UV light through the stamp, obtaining the stamps shape (figure1b). A residual layer of resist is left and has to be removed (figure1c).

Nanoimprint lithography is a simple pattern transfer process that is neither limited by diffraction nor scattering effects nor secondary electrons. It is also a potentially simple and inexpensive technique. However, there are some concerns about using this technique, as defects (any resist droplets or trapped air if the sample is not flat can result in defects on the substrate), template patterning and template wear (the use of substantial pressure to not only contact but also penetrate a layer during imprinting accelerates the wear of imprint templates compared to other types of lithographic masks).

Further reading