Room-temperature imprint lithography by solvent vapor treatment

We demonstrate room-temperature nanoimprint lithography using solvent vapor treatment of the polymer film on a substrate. In this method, the film treated with the solvent vapor is pressed with a mold at room temperature, requiring no heating that has been needed for the lithography. We show that the mold or mask patterns down to 60 nm can well be transferred onto the polymer film without any problem of the polymer adhering to the mold. The vapor treatment of the dried polymer film results in lowering both the viscosity and the glass transition temperature, thereby allowing for the room-temperature lithography. This room-temperature imprinting should make the imprint lithography more valuable for practical applications.