Electron Back-Scatter Diffraction (EBSD)

Principle of EBSD pattern formation
Scheme of EBSD measurement

Quick orientation measurements on bulk specimen with high lateral resolution by acquiring and analysing so-called Electron Backscatter Diffraction (EBSD) patterns, (also called Kikuchi patterns).

Requirements for EBSD

  • Primary electron beam with high energy (default 20 keV, down to 10 keV possible) and intensity (beam current 0.5nA or more)
  • Working distance to SEM polepiece and distance of EBSD detector as low as geometrically possible due to sample size limitations (<= 10mm)
  • Specimen steeply tilted (by default 70° , 45° to 80° possible)
  • Conductive surface essential, thin carbon coating if necessary
  • Flat surface due to tilting, no deformation layer
  • metal sections prepared conventionally must be additionally polished to reduce deformation layer (mostly with a nano-sized silica suspension like OP-CHEM)

 

Characteristics of measurement, possible results:

  • lateral resolution down to some ten nm, depending on atomic number
  • information depth between 50 and 100 nm
  • measured orientations acquired point-by-point in an orientation file automatically
  • data can be evaluated without restrictions offline after measurements
  • acquisition time 10 to 100 points/second, depending on material/surface quality
  • from the data, entire set of microstructure quantities can be obtained:

    • content of phases, size and shape of grains, misorientation within deformed grains
    • grain boundary type (misorientation angle, CSL classification)
    • texture results like pole figures, inverse pole figures, ODF, fractions, indices…

Example:

EBSD map of a 2µm wide Cu interconnect, 2.5x12 µm, stepsize 0.1 µm (measure time 5 min, below: color legend, normal component of grain orientation)