Elastomeric stamps produced by soft lithographic techniques67 can be used as phase masks for near-field, contact-mode photolithography.1 The technique relies on the phenomenon of significant reduction in intensity of light around the perimeters of relief structures on a phase mask in contact with a substrate bearing a film of photoresist.

Irradiation of the mask in contact with the substrate produces lines in positive photoresist and trenches in negative photoresist that can be significantly thinner than the broadband, incoherent light source used for irradiation. Resolution of 50 nm has been demonstrated.174,175 For a detailed quantitative description of the mechanism of the process, see the work by Li et al.,30 Rogers et al.,33 and Paul et al.173