Electron beam and soft X-ray lithography with a monomolecular resist

This contribution reviews current state of electron beam and soft X-ray lithography with a monomolecular resist. Self-assembled monolayers (SAMs) represent versatile resist materials for such a lithography. Depending on the architecture of the SAM constituents, they can serve as both positive and negative resists within framework of conventional lithography, but also be used as multi-purpose templates for Chemical Lithography. The latter technique exploits either selective modification of specific tail groups at the SAM-ambient interface (in the case of aromatic backbone) or irradiation-promoted exchange reaction between the primary SAM and potential molecular substituents (in the case of aliphatic backbone). Due to the monolayer thickness of SAM resists and molecular size of their structural building blocks, patterning down to few nanometers is in principle possible. Currently, the lateral resolution is limited by the grain character of the SAM substrates and parameters of the lithographic setup, with the latter being especially important in the case of soft X-ray lithography.