A self-assembled monolayer-assisted surface microfabrication and release technique

This paper describes a method of thin film and MEMS processing which uses s elf-assembled monolayers as ultra-thin organic surface coating to enable a simple removal of microfabricated devices off the surface without wet chemi cal etching. A 1.5-nm thick self-assembled monolayer of dodecyltrichlorosil ane reduces the adhesion between the SiO2 substrate surface and a 100-nm th ick evaporated aluminum film. A 100-mum thick layer of photoplastic SU-8, w hich is spun and structured by lithography and development on top of the mo nolayer/aluminum. sandwich layer, can be mechanically lifted off the surfac e with the aluminum layer. The organic monolayer provides enough stability for the microfabrication process including photoresist spinning and thermal steps. The aluminum film has a surface roughness of less than I mn rms as measured by AFM. Photolithographic microstructuring of the aluminum film pr ior to the photoplastic process allows for transparent embedded bottom-side metal electrodes. As first application example, molded nanoprobes for scan ning near-field optical microscopy, has been demonstrated using this techni que. (C) 2001 Elsevier Science BY All rights reserved.