In technology, soft lithography refers to a set of methods for fabricating or replicating structures using "elastomeric stamps, molds, and conformable photomasks" (in the words of Rogers and Nuzzo, p. 50, as cited in "References"). It is called "soft" because it uses elastomeric materials most notably PDMS. Soft lithography is generally used to construct features measured on the nanometer scale. According to Rogers and Nuzzo (2005), development of soft lithography expanded rapidly during the period 1995 to 2005.
Soft lithography includes the technologies of Micro Contact Printing (µCP), replica molding (REM), microtransfer molding (µTM), micromolding in capillaries (MIMIC) and solvent-assisted micromolding (SAMIM) (From Xia et al.) Patterning by etching at the nanoscale (PENs) One of the soft lithography procedures, Micro contact printing as discussed by Xia and Whitesides, is as follows:
Next, the stamp is created by pouring a degassed resin overtop of the etched wafer. Common resins include PDMS and Fluorosilicone.
Removing the cured resin from the substrate, a stamp contoured to your pattern is acquired.
The stamp is then "inked" by placing it, pattern-up, in a bath of inking solution (for example, ODT in ethanol) for a short period of time(Figure 1). The ink molecules will fall and adhere to the surface of the stamp (Figure 2) creating a single-molecule layer of the ink on the stamp.
The inked stamp is then pressed on the substrate and removed, leaving the desired single-molecule thick pattern on the substrate (Figure 3)
Steps 4 and 5 are repeated for each substrate on which the pattern is desired