Extending microcontact printing as a microlithographic technique

This paper describes a number of approaches that have been employed to reduce the size of features of self-assembled monolayers (SAMs) generated using microcontact printing (mu CP). In mu CP, an elastomeric stamp is used to print patterned SAMs of alkanethiolates on the surfaces of coinage metals and SAMs of alkylsiloxanes on Si/SiO2. It is a convenient technique for generating patterned microstructures with feature sizes greater than or equal to 500 nm. The capability of this technique could be extended to produce features smaller than 500 nm using the following approaches:. (1) mu CP with mechanical deformation of the elastomeric stamp--that is, with lateral compression or uniaxial stretching in the plane of the stamp and with pressure perpendicular to the plane of the stamp; (2) mu CP with physical alternation of the elastomeric stamp--that is, with a stamp that has been swelled with a solvent or a stamp whose dimensions have been reduced by extraction of an inert filler; (3) mu CP with reduction in the size of features resulting from processes taking place on the surface--that is, lateral reactive spreading of hexadecanethiol on gold; and (4) mu CP with multiple impressions on the same surface. The advantages and disadvantages of each approach are evaluated and compared in this paper.