Transcript Applying X-rays in Material Analysis

Applying X-Rays in Material Analysis
Vladimir Kogan
Philips Analytical and DANNALAB
The Netherlands
X-Ray Diffraction Analysis
q
d
Bragg's Law
l = 2d sin q
• Based on measuring the intensity
of the x-rays diffracted by the
sample at different angles
• Delivers information about the
structure and composition of
material at different scales
• This information is used to
explain or predict the properties of
a sample
Classification of Samples
Amorphous
Polycrystalline
Monocrystalline
Bulks
Powders and Foams
Thin Films
XRD for Amorphous Materials
SAXS Analysis of Human Serum Albumin (HSA)
in the Monodisperse Solution and in the Native Serum
An understanding of the structural properties of serum albumin is extremely important in the development of new human
pharmaceuticals. HSA contributes to many transport and regulatory processes in the body. Distribution, free concentration and
metabolism of verious pharmaceuticals can be significantly influenced depending from the binding with HSA.
From the monodisperse curve of HSA we have determined the average parameters of the molecule - axes of ellipsoid, suface,
volume, radius of gyration etc. From the polydisperse curve (native serum) we have derived the histogram of particles
distribution by average radius.
DANNALAB, 2002
XRD for Polycrystalline Materials
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•
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Crystallography - type and dimensions
of unit cell
Atomic structure - atom’s coordinates
Grain’s size and shape
Micro and macro strain
Phase composition - presence and
concentration of different phases
File name: org2_cap.IDF, date and time: 25/08/00 10:44:22
Counts
2000
1500
1000
500
0
300
200
100
0
-100
D-Mannitol (beta form) HOCH2(CHOH)4CH2OH
-200
-300
10
20
30
40
50
º2Theta
60
70
Si Detector for XRD Applications
• 0.07mm pitch
• No cooling required
• Efficiency: > 94 % for 8KeV
• Maximum 4mln cps in the
complete detector
• Background: < 0.1 cps
Specific of Thin Layers
ct > a L
at = a S
mismatch
Layer = aL
m
a L  a S 
aS
ct
Substrate = aS
Strained layer
Relaxed layer
Different Types of Thin Films
Pseudomorphic epitaxial layers. “No” defects. Strain may be present
Example :
AlGaAs/GaAs, SiGe/Si
Applications: Lasers, High-frequency IC’s
Lattice mismatched epitaxial layers. Layers are partly (or fully) relaxed
Example:
ZnSe/GaAs, InAsSb/GaSb
Applications: Blue LED’s, IR optopelectronic
Layers with large lattice mismatch and/or dissimilar crystal structures
Example:
GaN/Sapphire, YBaCuO/SrTiO3, BST, PZT
Applications: Blue Lasers and LED’s, High Tc Superconductors,
Ferro electrics
Layers where the epitaxial relationship is weak. Highly textured.
Example:
AuCo multilayers on Si
Applications: Thin film media, heads
XRD for Thin Films and Layers
Reflectivity Measurements
• Thickness, Density, Surface Roughness
• Lateral and Depth Correlation
• Curvature
High Resolution Diffraction
• Orientation
• Quality of Epitaxy, Lattice Mismatch
• Phase Composition
• Thickness, Density, Surface Roughness
In-plane Scattering
• Nano-layers
• Nano-structures
• In-plane properties
Typical Setup for Reflectivity Measurements
Detector
Divergence
slit
Attenuator
Beam
knife
Sample
Anti-scatter
slit
Receiving
slit
Graphite
monochromator
q
2q
The Information that can be Derived from a Reflectivity Curve
Reflectivity
XRD Study of Self-Assembled Monolayers C18H37SH on Gold
Specular Reflectivity Curve
Determined thickness of the layers:
C18H37SH
- 1.6nm
Au1
- 0.6nm
Au2
- 19.0nm
Si
> 100000nm
Reflectivity Map, Diffuse Scattering
Determined Average Lateral
Correlation Length: 2.5nm
DANNALAB, 2002
Modern High Resolution Diffractometer
(Perfect) epitaxial layer,
stressed and textured samples
highly textured layers
Detector 1
Ge[220] 4 - Crystal
monochromator Symm.
or Asymm.
X-ray mirror
Triple Axis
Section
X-ray tube
(line focus)
Soller slits
(optional)
Optical slit
Detector 2
The highly parallel monochromatic beam
should be used to study perfect layers
Divergence slit
High Resolution Diffraction
Analysis of SiGe HBT Structure
The introduction of a SiGe epitaxial layer in the bipolar transistor (HBT) brings significant gains in speed,
challenging GaAs in its traditional application fields. New technological step of introducing Ge requires
also an accurate method for the characterization of Ge content and gradients.
Automatic simulation and refinement of a measured rocking curve helps to identify parameters of
individual layers. Method delivers 1 % accuracy for composition and 3 % accuracy for SiGe thickness.
DANNALAB, 2002
High Resolution Diffraction
GaN/InGaN (Blue Laser Structure)
Reciprocal Space Map
Relaxed GaInAs/GaAs (224)
S
L
Orientation and Domain Structure
Transition in YBa2Cu3O8-x Film on SrTiO3 Substrate XRD Measurements
{304} Reciprocal Space Maps
20nm tetragonal
(nonsuperconducting) phase
100nm orthorhombic
(superconducting) phase
With the increase of the thickness of the YBa2Cu3O8-x layer, the dependence of the structure from the
SrTiO3 substrate is declining. This results in the appearance of the orthorhombic superconducting phase.
DANNALAB, 2002
High Resolution Diffraction
Strain Fields in Boron-implanted Silicon
DANNALAB, 2002
Devices and Structures
Stresses due to adhesive bonding
Different methods has been tested to make stress-free bonding of Si with steel. One of the methods
(s41 and s42) delivers quality, comparable with the stress free samples (Test1 and Test2)
800
s11
s12
s21
s22
s31
s32
s41
s42
Test1
Test2
700
S value
600
500
400
300
200
100
0
1st
batch
2nd
batch
3rd
batch
IC Chip Glued on the Ceramic Substrate
Surface Mapping by Measuring Rocking Curves
Method 1
Method 2
chip16
ch ip 60
( X  Y  Int ensi ty)
( X  Y  Intensit y )
ch ip 16
ch ip 60
( X  Y  Int ensi ty)
( X  Y  Int ensi ty)
DANNALAB, 2002
Sensor on Chip Assembly
Surface Mapping by Measuring Rocking Curves
Mapping of free standing Si sensor
Mapping of sensor bump-bonded to chip
sen sor63
Wire bonding side
( X  Y  Int ensi ty)
sen sor63
( X  Y  Int ensi ty)
DANNALAB, 2002
Roadmaps for new XRD detectors
Amorphous
Materials
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0D, 1D and 2D
Flat shape
Dynamical range 107
Counting speed up
to 107c/s/mm2 useful
energy and 109 total
Energy resolution
<250 eV
Polycrystalline
Materials
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0D, 1D and 2D
Different shapes
Very low noise
Pixel size down
to 0.05 mm
Counting speed up
to 105c/s/mm2
Energy resolution
<250 eV
Monocrystalline
Materials
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0D, 2D
Flat shape
Dynamical range 107
Counting speed up
to the 107c/s/mm2
Conclusions
• Appearance of new technologies for x-ray detectors considered to be one of the
key factors for the advances in XRD instrumentation.
• The applications of XRD actively shifting nowadays to the field of high-tech
materials an devices, including advanced x-ray detectors.
• Both fields have a lot of synergy and may benefit from each other.
Special thanks to
J. Visschers, for inviting me to this conference
J. Woitok, M. Fransen, K. Bethke, R. de Vries for useful comments