. I . Am. Chem. Soc. 1995, 117. 5875-5876
Polymeric Self-Assemhled Monolayers. 3. Pattern Transfer by Use of Photolithography, Electrochemical Methods, and an Ultrathin, Self-Assemhled Diacetylenic Resist
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Scheme 1
Kwok C. Chan. Taisun Kim, Jonathan K. Schoer, and Richard M. Crooks* Dqxtrrnieitr of Chenntism~.Texos A&M Universiry College Smtion. Texns 77843-3255 Received Fehrtrury 6. 1995
W e report herein that a substrate can he patterned using a diacetylenic. self-assembled monolayer (SAM) resist and photolithographic and electrochemical methods. Our proof-ofconcept experiments result in micron-scale pattern transfer onto Au substrates. but extension to other materials, including Si,' AI.' and GaAs,' and nanometer-scale patterning will he straightforward, For a number of reasons there has been considerable recent interest in using ultrathin SAM resists for patterning surfaces. First. since such resists consist of single, small molecules, the theoretical resolution of lithographically defined features can he as small as a few nanometers if the resist is patterned with an appropriate tool. such as the tip of a scanning tunneling microscope (STM).I-" Second, SAMs are extremely dense and in some cases their structure approaches that of a twodimensional crystal even when the SAM is formed by vaporphase dosing.'-" This insures low defect density and simplified resist application and stripping (vide infro). Finally, the terminal proups of the SAMs can he vxied to enhance selective chemical or physical vapor deposition of materials?."' Prior to the work discu .ed here, several reports had appeared that illustrate the viab ity of SAMs as resist materials. Examples of patterning based on the removal or the application of SAMs by photo-oxidation."~'Z stamping.l4-lx STM,I-" electron beam.l'.''' and physical abrasion'"-'' have been illustrated.
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