Specular X-ray Reflectivity (XRR)

Specular X-ray Reflectivity (XRR)

Specular X-Ray Reflectivity (XRR) is a surface sensitive analytical technique that utilizes monochromatic X-ray beam reflection at a specular angle, to study material surfaces, ultra-thin films and multilayered structures. The term specular reflection means that the reflected angle of the X-ray beam is equal to its incident angle. The intensity of the reflected X-ray wave is correlated with the angle of incidence of the X-ray beam, its wavelength and properties of the reflecting layer such as refractive index, roughness, thickness and density. The mathematical analysis involves matching measured X-Ray intensity data with computer simulations. The angle of incidence is maintained at grazing angle around the critical angle, to investigate thin layers. The reflecting layer may be a single thin layer at the surface or an in-depth interlayer in a multi-layer structure. XRR is used to characterize single and multi-layer structures, thin films, optical coatings and catalyst surfaces.

Common Uses of Specular X-ray Reflectivity (XRR)

• Determining thickness, density and roughness of ultra-thin films, single and multilayer stacks in semiconductors
• Quality control of reflectance and resolution of optical coatings
• Research and development of specialized coatings for optical devices
• High throughput quality control of semiconductor wafer manufacturing

Advantages of Specular X-ray Reflectivity (XRR)

• High resolution and precision covering thicknesses from Ångstroms to microns
• Crystalline or amorphous materials can be characterized
• Conductors or insulators can be analyzed
• Measurements at ambient conditions 

Limitations of Specular X-ray Reflectivity (XRR)

• Interpretation is based upon mathematical analysis and simulation
• Film thickness upper limit is around 200 nm

 Industrial Applications of Specular X-ray Reflectivity (XRR)

• Semiconductors
• Optical coatings
• Materials science research