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PANalytical X'Pert PRO XRD


Donald Savage

High Resolution
Rocking curves
Reciprocal space maps
Six-axis sample stage on high resolution  goniometer.
Absolute angular resolution = 0.0001 degrees.

High Resolution setup for epitaxial layers
Incident beam optics
Hybrid monochromater consisting of closely coupled x-ray mirror and 4 bounce Ge 220 monochromator.
Resolution = 18 arc-seconds.

Diffracted beam optics
1.  Fixed slit        
2.  Three bounce Ge 220 analyzer.  Resolution = 12 arc-seconds

High-resolution diffraction is a collection of application techniques that is applied for the measurements of nearly-perfect materials. Most semiconductor device structures, based on silicon, silicon-germanium, III-V and II-VI compounds, are epitaxially grown from the gas phase onto a substrate. These films are nearly-perfect crystalline films and contain a low dislocation density. Properties of these films are largely determined by their composition and structure. Information from these layers, such as layer thickness, composition, strain and relaxation, can be obtained by measuring rocking curves and reciprocal space maps using high-resolution optics. Defect structures inside the layers can be revealed by X-ray topography.

Solutions for high-resolution diffraction

High-resolution diffraction experiments require a highly monochromatic beam with a well defined wavelength and equatorial divergence. PANalytical X’Pert PRO MRD systems can be configured with a hybrid monochromator or a high-resolution monochromator to fulfil these requirements. With PANalytical’s X’Pert PRO Extended MRD system, an X-ray mirror and a high-resolution monochromator can be placed in line to deliver an incident X-ray beam that is not only highly monochromatic with a low divergence, but also has a high intensity. This high intensity is used to uncover the weakest details in a diffraction experiment.X’Pert Epitaxy and Smoothfit provides functionality to analyze rocking curves, reciprocal space maps and wafer maps. Rocking curves can be simulated and fitted using patented algorithms.

Grazing incidence diffraction                        
Film thickness and structure
Interfacial roughness

Reflectometry setup for thin layers. 
Incident beam optics
X-ray mirror intensifies and collimates line  source beam

Diffracted beam optics
1.  0.27 degree collimator with graphite monochrometer
2.  0.09 degree collimator

Reflectometry is an analytical technique for investigating thin layers using the effect of total external reflection of X-rays.In reflectivity experiments, the X-ray reflection of a sample is measured around the critical angle. Below the critical angle of total external reflection, X-rays penetrate only a few nanometers into the sample. Above this angle the penetration depth increases rapidly. At every interface where the electron density changes, a part of the X-ray beam is reflected. The interference of these partially reflected X-ray beams creates the oscillation pattern observed in reflectivity experiments. From these reflectivity curves, layer parameters such as thickness and density, interface and surface roughness can be determined.Reflectometry is applied to characterize single and multi-layer structures and coatings from amongst many others, magnetic, semiconducting and optical materials.

Solutions for reflectometry.

Experiments can be performed on PANalytical’s X’Pert PRO MRD or X’Pert PRO MPD systems. A “De Wolff’s” beam knife can be applied to reduce the effective reflecting area. A beam knife is advised when curved samples have to be measured.Reflectometry data can be analysed with a choice of automatic fitting procedures implemented in the X’Pert Reflectivity software package.