X-ray Diffraction/ X-ray Reflectivity (XRD/XRR)
What is XRD / XRR?
X-ray Diffraction (XRD) is a powerful non-destructive technique for characterizing
crystalline materials. It provides information on structures, phases, preferred
crystal orientations (texture) and other structural parameters such as average
grain size, crystallinity, strain and crystal defects. X-ray diffraction peaks
are produced by constructive interference of monochromatic beam scattered from
each set of lattice planes at specific angles. The peak intensities are determined
by the atomic decoration within the lattice planes. Consequently, the X-ray diffraction
pattern is the fingerprint of periodic atomic arrangements in a given material.
An on-line search of a standard database for X-ray powder diffraction pattern
enables quick phase identification for a large variety of crystalline samples.
Specular X-ray Reflectivity (XRR), a technique parallel to X-ray diffraction,
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 electron density profiles of thin film down to a few tens
of angstroms. Using a simulation or the least-squared fit of the reflectivity
pattern, one can obtain accurate measurements of thickness, interface roughness
and layer density for either crystalline or amorphous thin films and multilayers.
XRD / XRR at Santa Clara
Our Philips X’Pert –MRD x-ray diffractometer is equipped with PREFIX
optical modules that can be exchanged depending on the analysis requirement without
affecting the accuracy of positioning. It is simple to switch between line and
point focus of the x-ray tube, enabling simple switching from a regular XRD configuration
to a High-resolution XRD configuration. Different combinations of PREFIX optical
modules enable us to analyze powder samples, thin films, bulk polycrystalline
samples exhibiting texture or stress, disks and ICs. An on-line search of the
JCPDS database provides fast phase identification as well as qualitative measurements
for texture, crystal mis-orientation and strain in specimens. Accurate sample
alignment tools also enable highly reproducible data collection for thin-film
diffraction and reflectivity measurements.
Main Applications
| • |
Determination of phase contents of reaction
products |
| • |
Measurement of average crystallite size, strain or
micro-strain effects in bulk and thin-film samples. |
| • |
Quantification of preferred orientation (texture) in
thin films and multi-layers. |
| • |
Refinement of lattice parameters. |
| • |
Measurement of residue stress in blank film stack and
patterned wafers. |
| • |
Determination of thickness, interface roughness and
density for thin films and multi-layers. |
Specifications
| • |
Phase identification of a large variety
of bulk and thin-film samples using JCPDS database, detection
of crystalline minority phases of greater than ~1%. |
| • |
Variable penetrating depth between thousandth to tens
of microns depending on material properties and X-ray
incidence angles, and adjustable probe area of centimeter
square to millimeter square based on analysis needs. |
| • |
Films as thin as 50 angstroms could be analyzed for
texture and phase behaviors. |
| • |
Measuring X-ray reflectivity of thin film (40-2000 Å)
for thickness, interface roughness down to a few angstroms
of resolution, and layer density within a few percent
accuracy. |
| • |
Measuring sub-milligram loose powder or dried solution
samples for phase identification. |
Advantages
| |
Completely non-destructive analysis. |
| |
Quantitative measurement of phase contents and texture
orientation. |
| |
Minimal or no sample preparation requirements. |
| |
Ambient conditions for all analysis. |
|
Table
of Figures:
(click thumbnail for
larger display) |
XRD Figure 1 |
XRD Figure 2:
Powder X-ray Diffraction of AlF 3·3H 2O mineral.
The vertical lines indicate the positions and peak intensities
of the powder diffraction standard from JCPDS database |
Figure 3:
X-ray Diffraction patterns of two Cu films that show
complete (111) orientation normal to the surface (blue
line), and both (111) and (200) orientations along the
surface normal (red line). |
Figure 4:
X-ray rocking curves for the two Cu films on the left
that show uni-modal (blue line) and bimodal (red line)
mosaic distributions of Cu (111) |
AFM Figure 5:
X-ray Reflectivity interference fringes for a Ta 2O 5 film
of 165 angstroms.
|
|
