Use of controlled reactive spreading of liquid alkanethiol on the surface of gold to modify the size of features produced by microcontact Printing

TLDR: In this paper, the authors describe a procedure that uses the controlled reactive spreading of a liquid on a solid surf-ace to reduce the size of features produced by microcontact printing (rCP).

Abstract: This paper describes a procedure that uses the controlled reactive spreadingl 2 of a liquid on a solid surf'ace to reduce the size of features produced by microcontact printing (rCP).r It suggests a strategy for generating small f-eatures ( 100-500 nrnt in patterns on surfaces that relies on a physical process occuming on a surf-ace-lateral reactive spreading of a liquid-rather than on exposure to short-wavelength radiation or electrons. 4CP prints the patterned self-assembled monolayer' (SAM)r on the surface of gold, using an elastomeric stamp whose surface has itself been patterned in an appropriate relief structure. The stamp is wetted with an alkanethiol (typically hexadecanethiol, CH3(CH2)rsSH) and brought into contact with the gold in air for 10-20 s. I t is a very convenient technique for fornring patterned SAMs with features having dintensions of -2 lm or larger. The photolithography required to make the ntasters used to mold the e lastomer ic s tamps is s t ra ight lbrward ar th is sca le .5 and the edge resolution that can be obtained presentl)' using this method (about 50 nm)2 does not limit the resolutton of the overall pattern. It is more difficult to make t'eatures smaller than 2 ltmby pCP, primarily because fabricating the required stamps requires more complex photolithography. Features as small as 200 nm have, however, been made using masters prepared (with difficulty) by X-ray lithography.5-7 We are developing procedures that extend the capabilities of 4CP into the submicrometer range and that do not require highresolut ion photol i thography.8'e In part icular. we wish to f ind methods that start with an elastomeric stamp having features with dimensions of -2 pm or larger (that is, in the range that is easily prepared by routine photolithographic methods) and