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Scanning Electron Microscope

Scanning Electron Microscope. An introduction video: http://virtual.itg.uiuc.edu/training/EM_tutorial/. A short history. TEM constructed in 1931 Von Ardenne first STEM in 1938 by rastering the electron beam in a TEM Zworykin et al. 1942, first SEM for bulk samples

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Scanning Electron Microscope

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  1. Scanning Electron Microscope An introduction video: http://virtual.itg.uiuc.edu/training/EM_tutorial/

  2. A short history • TEM constructed in 1931 • Von Ardenne first STEM in 1938 by rastering the electron beam in a TEM • Zworykin et al. 1942, first SEM for bulk samples • 1965 first commercial SEM by Cambridge Scientific Instruments Resolution at that time ~ 50 nm <-> Today < 1 nm Morphology only at that time <-> Today analytical instrument

  3. SEM features

  4. Principles of SEM Magnification? Resolution?

  5. SEM components

  6. Cathode Ray Tube(CRT) accelerates electrons towards the phosphor coated screen where they produce flashes of light upon hitting the phosphor. Deflection coils create a scan pattern forming an image in a point by point manner

  7. Color CRT?

  8. The objective lens

  9. The objective lens aperture Aperture in SEM: either to limit the amount of electrons or enhance contrast

  10. Depth of Field

  11. Resolution

  12. Resolution Can increase the resolution by: How these changes affect the depth of field?

  13. Detector and sample stage

  14. LEO Gemini Column A detector placed within the column is known as an “in-lens” detector and produces a very different image compared to a conventionally located detector

  15. Secondary Electron Detector Side Mounted In-Lens

  16. Secondary Electron Detector In-Lens Side Mounted

  17. Beam deceleration FEI Magellan™ extreme-high-resolution (XHR) SEM

  18. STEM in SEM Oliver Guise et al.

  19. SEM artifacts

  20. E-beam lithography • High resolution (defined by the beam) • No mask requirement (diverse patterns designed by software) • A variety of resists for choice • Slow compare to photolithography

  21. Nano Arch by e-beam lithography

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