Film Thickness Determination by X-ray Reflectivity/Interference
- Practical Electron Microscopy and Database -
- An Online Book -

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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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X-ray reflectivity can be employed to measure the thickness of films, e.g. ALD and MBE-deposited layers, in order to adjust growth rates. In this technique, monochromatic X-rays reflected from the sample surface at low incident angles are measured and analyzed with a typical accuracy of ≤1 nm for layer thicknesses between ~2 and 500 nm. To obtain the thickness of a layer, the interference of the X-rays reflected from the surface of the layer and the X-rays reflected from the interface between the layer and substrate is measured in the form of intensity oscillations. The oscillation separation (Δθ) is given by,

         Film Thickness Determination by X-ray Reflectivity/Interference -------------------------------------- [2480]

where,
         λ -- The X-rays' wavelength,
         t -- The thickness of the layer.

An example of such instruments is GE Inspection technology high-resolution X-ray diffractometer. However, to obtain the thicknesses, the measured data needs to be analyzed with software, e.g. Parratt 32. Most tool and software combinations can extract not only the film thicknesses but also the surface roughness and the number of layers.

 

 

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