Imprint lithography using thermo-polymerisation of MMA

We investigate a new approach for imprint lithography which consists in using a thermo-polymerisation reaction under the mold rather than the softening of a polymerised thermoplastic resist. We use as a demonstrator, methylmethacrylate (MMA) monomers. We show that the major problem of this technique is to keep a reasonable amount of the solution containing the monomer species in between the sample and the mold; this is due to its extreme fluidity and high evaporation rate. However, we demonstrate that the use of various silane molecular layers deposited on both the sample and the mold enables the achievement of the imprinting process. We found that under appropriate conditions, no residual layer of polymer is left under the imprinted features, due to the concept of a minimum activation volume allowing the polymerisation reaction to occur. This result opened the possibility to directly perform a transfer procedure like lift-off, without any need for a dry etching process.