Extreme ultraviolet photoelectron spectroscopy on fluorinated monolayers
Towards nanolithography on monolayers
Olivier Lugier (Advanced Research Center for Nanolithography)
Alessandro Troglia (Advanced Research Center for Nanolithography)
Najmeh Sadegh (Advanced Research Center for Nanolithography)
Luc van Kessel (TU Delft - ImPhys/Microscopy Instrumentation & Techniques)
Roland Bliem (Advanced Research Center for Nanolithography, Vrije Universiteit Amsterdam)
Nicola Mahne (Istituto officina dei materiali, Consiglio Nazionale Delle Ricerche)
Stefano Nannarone (Istituto officina dei materiali, Consiglio Nazionale Delle Ricerche)
Sonia Castellanos (Advanced Research Center for Nanolithography)
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Abstract
The semiconductor industry plans to keep fabricating integrated circuits, progressively decreasing there features size, by employing extreme ultraviolet lithography (EUVL). With this method, new designs and concepts for photoresist materials need to be conceived. In this work, we explore an alternative concept to the classic photoresist material by using an organic self-assembled monolayer (SAM) on a gold substrate. The monolayer, composed of a richly fluorinated thiol sensitive to low-energy electrons, is adsorbed on the Au substrate which acts as main EUV-absorber and as the source of photoelectrons and secondary electrons. We investigate the stability of the SAM adsorbed on gold towards EUV radiation by means of in-situ photoelectron spectroscopy. The photoelectron spectra indicate that the monolayer attenuates a significant amount of primary electrons generated in the gold layer. The spectral evolution upon EUV irradiation indicates that the SAM loses a significant amount of its initial fluorine content (ca. 40% at 200 mJ/cm2). We attribute these chemical changes mostly to the interaction with the electrons generated in the thiol/Au system.