As discussed in Chapter 1, imprint lithography involves a mechanical
replication process where surface reliefs from the template/stamp are embossed into a thin layer of polymeric fluid or liquid monomer with crosslinking agents on the substrate. Two versions of imprint lithography are currently practiced. One version is based on the thermal embossing of a thermoplastic polymer and is called thermal imprint lithography (TIL). The other version is based on embossing of photocurable monomers and oligomers with crosslinking agents and is called photoimprint lithography (PIL).
The components of a given imprint resist are chosen consistent with the type of imprint process for which the resist in question will be used. TIL resist comprises basically the thermoplastic resin that is chosen to have a glass transition temperature that is within the desired operating temperature, sufficient adhesion to the substrate, and sufficient mechanical strength to withstand post-imprint processes such as reactive ion etching. Popular TIL imprint resist polymers include dielectrics such as poly(methyl methacrylate),1 polynorbornene, poly(tetrafluoro ethylene), polystyrene, polyurethane, etc., as well as conducting polymers such as poly(hexylthiophene).
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