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Pushing the capabilities of electron-beam lithography to the sub-10-nanometer domain has required more than 30 years of research by many researchers. We are just now achieving robust fabrication of sub-10-nanometer-period dense structures. We recently used Raith's 150TWO electron-beam lithography system, and MIT's new salty-development process (the details of which are described in the paper below). This work will enable top-down lithography to finally make contact to the molecular scale, which traditionally only self-assembled systems have been able to access. |
Some Relevant Publications
Using high-contrast salty development of hydrogen silsesquioxane for sub-10-nm half-pitch lithography
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Hydrogen silsesquioxane (HSQ) is a negative electron resist, but it is notorious for its low resist contrast, resulting in problems when writing complex, dense, high-resolution structures. We observed a marked increase in resist contrast when salt was added to an acqueous basic developer. Higher contrast performance enabled high-resolution electron-beam patterning of sub-10-nanometer dense and isolated structures. When used in this way, HSQ becomes a near-ideal material for electron-beam lithography. |
Graph showing impact of added salt in resist development. Steeper slope indicates improved resist contrast.
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Joel K.W. Yang and Karl K. Berggren
Journal of Vacuum Science and Technology B, vol. 25, 2025 (2007)
[abstract],[pdf].
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Robust Shadow-Mask Evaporation via Lithographically-Controlled Undercut
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Resist undercuts are necessary for nanofabrication of Josephson junctions. They also permit high-quality evaporation and liftoff patterning in certain cases, where evaporator-source columnarity is poor, or where metal diffusion occurs. Typically, however, the undercut dimension is poorly controlled by timing a development step. In this paper, we demonstrate a way to define an undercut using lithography, achieving large, highly controlled undercuts, and demonstrating ultra-high-resolution pattern transfer and liftoff. |
Scanning-electron micrograph cross-section of lithographically defined resist-undercut structures. |
Bryan Cord, Chris Dames, Jose Aumentado, Karl K. Berggren
Journal of Vacuum Science and Technology B, vol. 24, 3139 (2006)
[abstract], [pdf].
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Collaborators
- Dr. M. Rooks (Yale University)
- Dr. J. Aumentado (NIST, Boulder)
- Dr. C. Dames (MIT, Dept. of Mechanical Engineering, currently at UC Irvine)
Sponsors
- Air Force Office of Scientific Research (AFOSR)
- Army Research Office (ARO)
- King Abdulaziz City for Science and Technology (KACST) and Al'Faisal University
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