8/12/2019 X-Ray Diffraction Techniques for Thin Films

1/15

1

1

Rigakuigaku Corporationorporation pplication Laboratorypplication Laboratory

Takayuki Konyaakayuki Konya

X-ray diffraction techniques

for thin films

2

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

2/15

8/12/2019 X-Ray Diffraction Techniques for Thin Films

3/15

3

5

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

6

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

4/15

4

7

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

8

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

5/15

5

9

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..

10

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)

8/12/2019 X-Ray Diffraction Techniques for Thin Films

6/15

6

11

Outward of In-Plane Attachment Scanning motion is completely

perpendicular to /2 scan.

/2 scan

In-Plane measurement

(2/ scan)

12

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

7/15

7

13

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

14

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

8/15

8

15

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

16

Single crystal and random orientation

Single crystal Fiber orientation Random orientation

8/12/2019 X-Ray Diffraction Techniques for Thin Films

9/15

9

17

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

18

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

10/15

10

19

Reciprocal space mapping Diffraction intensity distribution is plotted

on reciprocal space.

o

ghkl2/

2/

20

Epitaxial layer structures

00lcubic[112]

hh0

00l cubic[112]

hh0

tetragonal[112]

00lfilm[001]

hh0

substrate[001]

Relaxation Strain Misorientation

8/12/2019 X-Ray Diffraction Techniques for Thin Films

11/15

11

21

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

22

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

12/15

12

23

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

24

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

13/15

13

25

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

26

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

14/15

14

27

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

28

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

8/12/2019 X-Ray Diffraction Techniques for Thin Films

15/15

29

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

30

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