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Rigakuigaku Corporationorporation pplication Laboratorypplication Laboratory
Takayuki Konyaakayuki Konya
X-ray diffraction techniques
for thin films
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Todays contents (PM)
Introduction
X-ray diffraction method
Out-of-Plane
In-Plane
Pole figure
Reciprocal space mapping
High resolution rocking curve
X-ray reflectivity
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spread of
reciprocal lattice points
Position and coordinate
of reciprocal lattice points
Shape of a reciprocal latticedistribution
crystal perfection
defects
mosaicity
lattice constant
crystal orientation
lattice distortion
degree of preferred
orientation
What XRD reveals
K
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Structure parameters
Order Analysis Method
Thickness1~10
3nm
Precision :~several %Xray Reflectivity
Density H2O~Heavy Metals Xray Reflectivity
Roughness 0.2~several nm Xray Reflectivity
Phase ID -In-Plane XRD
Out-of-Plane XRD etc
Crystal System -In-Plane XRD
Out-of-Plane XRD etc
Lattice
Constant
~several nm
Precision : 0.05~0.00005nm
In-Plane XRD
Out-of-Plane XRD etc
Crystal qualityPoly~Single, Perfect
Crystals
In-Plane XRD
Out-of-Plane XRD etc
Preferred
Orientation
Random~Preferred Orientation
~Single CrystalPole Figure ect
Orientation
Relation
Relation between
Film & Substrate
Rocking Curve
Reciprocal Space Map etc
Structure Parameter
Layer
Structure
Crystal
Structure
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Todays contents (PM) Introduction
X-ray diffraction method
Out-of-Plane
In-Plane
Pole figure
Reciprocal space mapping
High resolution rocking curve
X-ray reflectivity
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Todays contents (PM)
Introduction
X-ray diffraction method
Out-of-Plane
In-Plane Pole figure
Reciprocal space mapping
High resolution rocking curve
X-ray reflectivity
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Difference between Scan Modes
The orientation of observed crystal plane
depends on scanning mode.
Observed plane is..parallel to the surface
In-Plane scan
perpendicular
to the surface
Film scan
tilting
(changing during a scan)
Out-of-Plane scan
Observed plane is..
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What is In-Plane XRD?
Diffraction angle 2B
Incident x-ray Reflected x-ray
Diffracted x-ray
The detector moves parallel to
the surface.
Observing planes are
perpendicular to the surface.
Grazing incidence
(fixed angle)
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Outward of In-Plane Attachment Scanning motion is completely
perpendicular to /2 scan.
/2 scan
In-Plane measurement
(2/ scan)
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In-plane effect
1400
1200
1000
800
600
400
200
0
Intensity(cps)
9080706050403020
2/ (degree)
Out of Plane111
220 113 004 331 224
100
80
60
40
20
0
Intensity(cps)
9080706050403020
2/ (degree)
In Plane
111
022
311400133
422
111
220
poly-Si
Glass
In-PlaneInIn--PlanePlane Out-of-planeOutOut--ofof--planeplane
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10
100
1000
extinctiondistance(nm)
1.00.80.60.40.20.0
incident angle (degree)
0.0001
0.001
0.01
0.1
1
Probed depth control ?
Sample:Al Wavelength:1.54056CuK1
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Surface & Interface Structure
250
200
150
100
50
0
Intensity
(cps)
807060504030
2/(degree)
Incident angle0.2 deg.0.5 deg.
Al+Cu
Al+Cu
Cu(111)Cu(200)
Cu(220)
Al(111)
Al(220)
Al(311)
Al(222)
AlTransition layer
Al+Cu
Cu
TaSiO2
~300nm
Si (substrate)
In-Plane XRDIn-Plane XRD
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Todays contents (PM) Introduction
Advantage of reciprocal lattice vector
X-ray diffraction method
Out-of-Plane
In-Plane
Pole figure
Reciprocal space mapping High resolution rocking curve
X-ray reflectivity
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Single crystal and random orientation
Single crystal Fiber orientation Random orientation
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Orientation conditions and pole figure
=90=0
=90 =270
=180
=90=0
=90 =270
=180
Random orientation
=90=0
=90 =270
=180
=90=0
=90 =270
=180
=70.5 =35.3
{111} fiber orientation
=90=0
=90 =270
=180
=90=0
=90 =270
=180
(111) single crystal
(111) pole figure (220) pole figure
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Todays contents (PM)
Introduction
Advantage of reciprocal lattice vector
X-ray diffraction method
Out-of-Plane In-Plane
Pole figure
Reciprocal space mapping
High resolution rocking curve
X-ray reflectivity
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Reciprocal space mapping Diffraction intensity distribution is plotted
on reciprocal space.
o
ghkl2/
2/
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Epitaxial layer structures
00lcubic[112]
hh0
00l cubic[112]
hh0
tetragonal[112]
00lfilm[001]
hh0
substrate[001]
Relaxation Strain Misorientation
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Reciprocal space mapping
GaAs115
AlGaAs115
qx/-1
qy
/-1
Mosaic spread
Mismatch (strained)
Broadening in direction
of sample rotation
Broadening in direction
of radial scan
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Todays contents (PM)
Introduction
Advantage of reciprocal lattice vector
X-ray diffraction method
Out-of-Plane In-Plane
Pole figure
Reciprocal space mapping
High resolution rocking curve
X-ray reflectivity
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High- resolution rocking curve
The differences of lattice spacing between the substrate
and epitaxial films are observed.
Thickness and composition ratio of epitaxial films
(when the degree of relaxation is known. )
ko
kgghkl
2/
2/
log(I )K
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When the sample has multilayer structure
Complicated oscillation composed of oscillation from
each layer is observed.
10-7
10-6
10-5
10-4
10-3
10-2
10-1
Reflectivity
-2000 -1000 0 1000
Deviation Angle (arcseconds)
Si
GeSiGeSi
(004)
GexSi(1-x) 50nm
GexSi(1-x)300nmx=0.015Si substrate
x=0.050 x=0.015
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When the sample has superlattice structure
Satellite peaks are observed.
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
Reflectivity
-8000 -4000 0 4000 8000
Deviation Angle (arcseconds)
GaAs0
1
2 34
-1
-2-3
(004)
InxGa(1-x)As 5nmGaAs 5nm
10L
GaAs substrate
x=0.200
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How to interpret the profile
10-7
10-6
10-5
10-4
10-3
10-2
10-1
Reflectivity
-2000 -1000 0 1000
Deviation Ang le (arcseconds )diffraction angle (arcsec.)
Intensity
(004)
Si substrate
GexSi(1-x)300nm x=0.015
GexSi(1-x) 50nm x=0.050
Si substrate
SiGe mismatch
SiGe mismatch
Oscillation period
SiGe thickness
Oscillation period
SiGe thickness
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Todays contents (PM) Introduction
X-ray diffraction method
Out-of-Plane
In-Plane
Pole figure
Reciprocal space mapping
High resolution rocking curve
X-ray reflectivity
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What reflectivity reveals
density
Interface roughness
thickness
thickness
X-ray reflectivity nondestructively reveals
- layer structure of multi layers
- thickness (1 to 1000nm)
- density as an absolute value
- surface and interface roughness
substrate
layer 1
layer 2
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How to interpret the profile
10-5
10-4
10-3
10-2
10-1
100
Reflectivity
86420
2/(degree)
Decay of reflectivity
Surface roughness
Decay of amplitude
Interface roughness
Period of oscillation
Thickness
Amplitude ofoscillation
Contrast of density
Critical anglec
Density density 1density 2
density 3
thickness1thickness2
roughness 1
roughness 2roughness 3
layer 1
layer 2
substrate
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X-ray reflectivity measurement of TiN film
Coating layerCoating layer
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
Reflectivity
2.01.51.00.50.0
Grancing angle (degree)
Simulation
Experimental
Layer
density
(g/cm 3)
Thickness
(nm)
Roughness
(nm)
TiN 3.680 1.230 1.420
TiN 2.900 8.400 1.000
SiO2 2.260 127.700 0.220Si substrate
SiO2Si
TiN