Confocal laser optical profilometry

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Confocal laser optical profilometry
LEXT confocal.jpg
Technology Details
Technology Metrology
Equipment Olympus OLS 4000 LEXT

Confocal laser optical profilometry is an optical 3D surface profiling technology.


Olympus OLS 4000 LEXT

Main article: Olympus OLS 4000 LEXT

Method of operation

  • This technique is based on confocal microscope configuration using high numerical aperture objectives which have a very narrow depth of focus. Only the "in focus" reflected light passes through the confocal pinhole.
  • A laser is scanned in X/Y across field of view on the sample surface.
  • Reflected intensity data is collected as focus (Z) is scanned with the peak intensity corresponding to feature height.


  • Confocal laser optical profilometry can be used for measuring surface roughness, sample topography, etched pattern step heights, and feature sizes.
  • This technique and scanning white light interferometry (SWLI) are particularly useful for characterizing the depth of high aspect ratio trench features which can not be measured using stylus profilometry. [Stylus profilometry] is only capable of a maximum aspect ratio of ~1 (or less depending on feature size) and a maximum step height of 150um due to physical dimensions and limitations of the stylus.
  • Our LEXT confocal laser optical profiler has better lateral resolution (0.12 μm) than our Zygo SWLI profiler (0.64 μm at maximum magnification).
  • Optical profilometry is also useful for measuring sample surface roughness. This technique is preferred to stylus profilometry for surface roughness analysis since the physical dimensions of the stylus (25 μm tip radius) can limit accuracy of the measurement.

See also


Further reading