Scanning Electron Microscopy (SEM)

Scanning electron microscopy (SEM) provides topographical and elemental information at useful magnifications of 10x to 100,000x, with virtually unlimited depth of field.  Field emission SEM (FESEM) and in-lens FESEM are also available for ultrahigh resolution imaging.

Applications: SEM applications include:

  • Materials evaluation
      • Grain size
      • Surface roughness
      • Porosity
      • Particle size distributions
      • Material homogeneity
      • Intermetallic distribution and diffusion

     

  • Failure analysis
    • Contamination location
    • Mechanical damage assessment
    • Electrostatic discharge effects
    • Micro-crack location

     

  • Quality Control screening
    • “Good-to-bad” sample comparison
    • Film and coating thickness determination
    • Dimension verification
    • Gate width measurement
    • Metallization Inspection

Principle of Operation

A finely focused electron beam scanned across the surface of the sample generates secondary electrons, backscattered electrons, and characteristic X-rays. These signals are collected by detectors to form images of the sample displayed on a cathode ray tube screen.  Features seen in the SEM image may then be immediately analyzed for elemental composition using energy dispersive spectroscopy (EDS) and wavelength dispersive spectroscopy (WDS).

Secondary electron imaging shows the topography of surface features a few nanometers across. Films and stains as thin as 20 nanometers produce adequate-contrast images.  Materials are viewed at useful magnifications up to 100,000x without the need for extensive sample preparation and without damaging the sample.  Even higher magnifications and resolution are routinely obtained by our FESEM.

Backscattered electron imaging shows the spatial distribution of elements or compounds within the top micron of the sample.  Features as small as 10 nanometers are resolved and composition variations of as little as 0.2 percent determined.

Data output is generated in real time on a CRT monitor. Images and spectra can be printed, recorded on CD ROM, and/or emailed for insertion into client reports.