The secondary-electron signal levels of eight thiophenol-based self-assembled monolayers (SAMs) on gold (Au) are measured and compared against the signal level from bare gold between energies 1 and 2 keV. To enable accurate comparison, scanning electron micrographs of SAMs are taken with a Faraday cup and a reference sample. Most SAMs-on-gold produce a lower signal level than that from bare gold, with the exception of 3-methylthiophenol. Highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the thiophenol derivatives are calculated and compared against the signal levels. Signal levels from bis[3-(triethoxysilyl)propyl]tetrasulfide, (4-chlorophenyl)-triethoxysilane, and amino-propyl-triethoxy-silane on titanium (Ti) and aluminum (Al) are also measured. All three SAMs on aluminum have lower signal levels than bare Al but this effect is reversed for the case of Ti, where SAMs deposited on Ti result in a higher signal level. A hybrid Ti/Al fiducial grid is fabricated and the point-spread function at 2 keV in the underlying resist is investigated.
|Journal||Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics|
|State||Published - Nov 2011|
Bibliographical noteFunding Information:
The authors would like to thank Tim Savas for providing the silicon nitride masks used in the shadow evaporation, and Tim Swager, David Joy, John Notte, Jim Daley, and Mark Mondol for helpful discussions. The authors would also like to thank Olesya Haze for her help with HOMO and LUMO calculations. Imaging was performed in MIT’s Scanning Electron Beam Lithography (SEBL) facility. This material is based upon work supported by the National Science Foundation under Grant No. CMMI-0609241.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Electrical and Electronic Engineering
- Materials Chemistry