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Secondary Electron Detection

Secondary Electron Detection. CAMTECH 2011 Regi. INTRO. High energy e - beam scans sample surface ( Raster - line by line). Provides information about surface and near-surface atoms – topography and chemical composition. Stereoscopic images (3D perspective). BEAM-SAMPLE INTERACTIONS.

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Secondary Electron Detection

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  1. Secondary Electron Detection CAMTECH 2011 Regi

  2. INTRO • High energy e- beam scans sample surface (Raster - line by line). • Provides information about surface and near-surface atoms – topography and chemical composition. • Stereoscopic images (3D perspective)

  3. BEAM-SAMPLE INTERACTIONS Incident beam BSE Emissions of SE Electrostatic force 10nm Constituent atoms

  4. BEAM-SAMPLE INTERACTIONS • Backscattered Electrons (BSE) increase in reflectivity with growth in atomic number • Secondary electrons (SE) predominantly produced by the interactions between highly energetic beam electrons and weakly bonded. • Only SE produced within a depth of 10 nm can escape the sample

  5. Secondary Electrons • Energy below 50 eV • Electron Emission Yield • The bigger the yield the bigger the signal intensity - varies from material to material - increases with e--beam incident angle SE BSE Relative count of emitted e- 1 10 100 1k 10k 20k Energy of e- emitted from specimen (log eV)

  6. SE Images • Carry information about topography and defects adjacent to surface (depth) – 10 nm BSE SE

  7. SE Detection • Distinguished SE1, SE2 and SE3 SE1: emitted from the e--beam irradiation point SE2: emitted along with the springing-out process of BSE SE3: due to BSE collisions with Parts other than the specimen

  8. SE Detection Everhart and Thornley Detector: designed in 1960 to collect and amplify the signal provenient from SE Dynode Collecting electrode Scintillator SE Light guide Photoelectric conversion face

  9. Thanks!

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