Patterning by etching at the nanoscale

The channel in the stamp can be enlarged in the order of tens of nanometers to several micrometres.

PDMS contains polymer chains of silicon-oxygen bonds, these bonds can be broken by fluoride containing species, in the same way that silicon wafers are prepared by etching with hydrofluoric acid, ammonium fluoride and related compounds.

By then running an etching solution through the channel, part of the PDMS will be removed.

The width of feature produced is controlled by etchant and time.

To apply this technique for the production of small patterned features it is necessary that the surface can be reacted to passivate it in the area exposed by the channel, followed by etching and then reacted in away that will only occur in the newly exposed area.