X-ray Reflectivity (XRR)

Specular X-ray Reflectivity (XRR), a technique parallel to X-ray Diffraction (XRD), is now becoming a widely used tool for the characterization of thin-film and multilayer structures. X-ray scattering at very small diffraction angles allows characterization of the electron density profiles of thin films down to a few tens of angstroms. Using a simulation or the least-squared fit of the reflectivity pattern, one can obtain highly accurate measurements of thickness, interface roughness, and layer density for either crystalline or amorphous thin films and multilayers.

Main Applications

Determination of thickness, interface roughness, and density for thin films and multi-layers

Ideal Uses for XRR Analysis		Relevant Industries for XRR Analysis
Highly accurate film thickness and density measurement Measuring film or interface roughness Measuring film uniformity across wafers Measuring pore density and pore size of low-k films		Compound Semiconductor Data Storage Defense Displays Electronics Photonics Semiconductor Solar Photovoltaics Telecommunication

Strengths of XRR Analysis		Limitations of XRR Analysis
Non-destructive Whole wafer analysis (150, 200, 300 mm) as well as irregular and large samples Mapping of full wafers Conductor and insulator analysis Minimal or no sample preparation requirements Ambient conditions for all analysis		A priori knowledge of the basic sample structure (the order of layers and their compositions) is needed in order to provide accurate density results

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XRR Technical Capabilities

Signal Detected:
Reflected X-rays

Elements Detected:
No elements are specifically detected, rather the electron density of the layers is measured. This, combined with knowledge of the layer composition, allows an exact determination of layer thickness and density.

Detection Limits:
30-100 Angstroms minimum layer thickness

Depth Resolution:
~1% of measured thickness

Imaging/Mapping:
Yes

Lateral Resolution/Probe Size:
~1 cm