X-ray Reflectivity (XRR)

XRR is used for the characterization of mulilayer samples.  It can measure film thickness and density of multilayer samples.

How it works — an X-ray beam is reflected off of a sample at very small diffraction angles generating a reflectivity pattern.  A simulation of the reflectivity pattern gives an accurate measurement of thickness, interface roughness, and layer density for either crystalline or amorphous thin films.

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Instrumentation Available

Key Attributes

  • Signal Detected: Reflected X-rays
  • Detection Limits: 1.5-10nm minimum layer thickness
  • Thickness Resolution: ~1% of measured thickness
  • Imaging available
  • Probe Size: ~1cm

Strengths

  • Analysis of large areas (>300 mm)
  • Can analyze both conductive and insulating
  • No prior knowledge of the optical properties of the film is required
  • Minimal or no sample preparation required
  • No vacuum required

Limitations

  • Knowledge of the basic layer structure is required for the simulation
  • Maximum film thickness ~300nm

Applications

  • Measurement of film thickness and density on multilayer samples
  • Measurement of interface roughness
  • Thickness uniformity measurements

Additional Reading