The authors characterize a new fiducial grid based on a self-assembled monolayer (SAM) that is well suited to low-energy (≤10 keV) spatial-phase locked electron-beam lithography (SPLEBL). SAMs significantly alter the secondary electron yield of the metal films on which they are formed. In addition, SAMs are not expected to strongly scatter the primary beam, even at low energies, because they are less than 2-nm -thick and are composed of low atomic number elements. In this work the authors evaluate the signal-to-noise ratio (SNR) of SAM grids on gold and copper coated electron-beam resist. 400 nm period octadecanethiol fiducial grids were microcontact printed onto the gold and copper metal layers using polydimethylsiloxane stamps. Gold serves as a model system and provides excellent SNR; however, its strong forward scattering makes it impractical in many applications. Copper offers reduced forward scattering but exhibits inverted secondary electron contrast and greatly reduced SNRs. In all cases, SNR decreases with increasing beam energy as overall secondary electron yield decreases. These results suggest that SAM fiducial grids are promising for low-energy SPLEBL; however, further optimization of the interlayer and SAM composition is warranted.
|Number of pages
|Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
|Published - 2008
Bibliographical noteFunding Information:
This material was based upon work supported by the National Science Foundation under Grant No. CMMI-0609241. Electron-beam lithography and nanofabrication infrastructure was partially supported by the NSF EPSCOR under Award No. EPS-0447479. Experiments at the University of Kentucky were conducted within the Center for Nanoscale Science and Engineering (CeNSE). The authors thank B. Wajdyk, and C. May for valuable technical assistance. Timothy Savas and Thomas O’Reilly from MIT’s Nanostructures Laboratory provided the master fiducial grids used in this work.
ASJC Scopus subject areas
- Condensed Matter Physics
- Electrical and Electronic Engineering