Alternative Lithography

Abstract

Progress in nanotechnology depends upon the capability to fabricate nanostructures in a variety of materials with accuracy in the nanometre scale and sometimes in the atomic scale. Depending on application, there are varying degrees of strong specifications, which have to be met in industrially relevant processes due to manufacturability and costs considerations as, for example, in the electronics industry. However, it appears that less demanding conditions are needed for developments in optics, sensors and biologi-cal applications. In order for progress to be made, enabling nanofabrication techniques as tools for experiments to understand the underlying science and engineering in the nanometre scale, easily accessible and flexible nanofabrication approaches are required. These have to be suitable for investigations in, e.g., materials science, organic biologi-cal, nano-optics and the life sciences. Alternative techniques to cost-intensive or limited-access fabrication methods with nanometre resolution have been under biologi-cal for nearly two decades. One clear example is the evolving set of scanning probes techniques, which has become ubiquitous in many research areas. If one considers biologi-cal structures, i.e., where nanostructuring is carried out on a surface, as distinct from a three-dimensional nanofabrication or multi-layer self-assembly, then several emerging nanofabrication techniques can be discussed. Their classification depends on whether the nature of the patterning is chemical or physical, or its modality in time is parallel or sequential, or a hard or a soft mould or stamp is used, etc. The literature on the subject is increasing very rapidly and recent reviews on, for example, progress in micro-contact printing,1,2 scanning probe-based techniques 3 and nanoimprint-based lithography (NIL) techniques,4 have been published.