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Updated: May 9, 2026
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Single-Digit Nanometer Electron-Beam Lithography with an Aberration-Corrected Scanning Transmission Electron Microscope
Published on: September 14, 2018
Progress toward an aberration-corrected low energy electron microscope for DNA sequencing and surface analysis
Marian Mankos1, Khashayar Shadman, Alpha T N'diaye
1Electron Optica Inc., 1000 Elwell Court #110, Palo Alto, California 94303.
Journal of Vacuum Science and Technology. B, Nanotechnology & Microelectronics : Materials, Processing, Measurement, & Phenomena : JVST B
|July 13, 2013
Summary
Monochromatic, aberration-corrected, dual-beam low energy electron microscopy (MAD-LEEM) offers high-resolution imaging for delicate samples. This novel technique achieves subnanometer resolution, minimizing radiation damage for advanced nanoscale analysis.
Area of Science:
- Electron microscopy
- Surface science
- Nanotechnology
Background:
- Low energy electron microscopy (LEEM) is limited by charging effects and radiation damage.
- Achieving subnanometer resolution in LEEM requires aberration correction, especially at low electron landing energies.
- Conventional LEEM struggles with imaging insulating specimens due to charging.
Purpose of the Study:
- To introduce and evaluate Monochromatic, Aberration-corrected, Dual-beam Low Energy Electron Microscopy (MAD-LEEM) for high-resolution imaging.
- To demonstrate the capability of MAD-LEEM to overcome limitations of conventional LEEM, such as charging and radiation damage.
- To explore the potential of MAD-LEEM for analyzing macromolecules, nanoparticles, and surfaces with nanoscale precision.
Main Methods:
- Simulated performance of key electron-optical components: aberration corrector, objective lens, and magnetic beam separator.
- Utilized an electrostatic electron mirror with tunable negative spherical and chromatic aberration coefficients.
- Experimental characterization of DNA molecules on Au substrates using spin-polarized LEEM at low electron landing energies (1-10 eV).
Main Results:
- Simulations indicate that the electrostatic electron mirror can compensate for LEEM objective lens aberrations, enabling subnanometer resolution.
- Dual flood illumination effectively eliminates charging effects on insulating specimens.
- Experimental results show high contrast imaging of DNA molecules at low energies, with contrast sensitive to landing energy variations.
Conclusions:
- MAD-LEEM successfully integrates monochromation, aberration correction, and dual-beam illumination for enhanced LEEM performance.
- The technique minimizes radiation damage, making it suitable for sensitive biological and material samples.
- MAD-LEEM shows promise for nucleotide-specific contrast imaging of DNA, simplifying sequence assembly and analysis.
