Estimation of the Residual Stress in Alkoxide derived PbTiO3 thin film on Si wafer by

Raman and XRD analysis

Tomoya Ohno1,3, Babara Malič1, Hiroaki Fukazawa2, Naoki Wakiya2, Hisao Suzuki2,

Takeshi Matsuda3 and Marija Kosec1

1 Electronic Ceramics Department, Jožef Stefan Institute2 Graduate School of Science and Technology, Shizuoka University3 Department of Materials Science and Engineering, Kitami Institute of Technology

Outline

20 40 600

2000

4000

6000

8000

10000

PZT(0

02)&

(200)

PZT(0

01)&

(100)

PZT(1

11)

Inte

nsi

ty

2θ

Microstructure Crystal Orientation

-400 -200 0 200 400-60-40-20

0204060

Electric Field (kV/cm)

Pola

rizat

ion

(μC

/cm

2 )

103 104 1050

200400600800

10001200

ε"

ε'

diel

ectri

c co

nsta

nt (-

)

Frequency (Hz)-200 -100 0 100 200

-400

-200

0

200

400

Electric Field (kV/cm)

d33

(pm

/V)

Dielectric Property Ferroelectric Property Piezoelectric Property

Residual Stress (Lattice Strain)

PTO/Pt/Si sol-gel Raman analysis Compressive D.S.Fu et.al. Appl. Phys. Lett., 77 (2000) 1532-1534

PZT(MPB)/Pt/Si sol-gel XRD Tensile S. Lu et.al. Matter. Lett., 60 (2006) 255-260

PZT(MPB)/LSCO PLD XRD Tensile K. Fujito et.al., Jpn. J. Appl. Phys., 44 (2005) 6900-6904

PZT(MPB)/Pt/Si sol-gel XRD Tensile R. J. Ong et.al. J. Euro. Ceram. Soc., 25 (2005) 2247-2251

PZT(MPB)/Pt/Si PLD XRD Compressive X. Zheng et.al., Acta Matter., 52 (2004) 3313-3322

PTO/MgO PLD Raman analysis Tensile S-H.Lee et.al., Appl. Phys. Lett., 80 (2002) 3165-3167

PTO/MgO sol-gel Raman analysis Compressive K. Nishida et.al., Appl. Surface Science, 216 (2003) 323-328

PZT(MPB)/Pt/Si sol-gel Raman Analysis Compressive J. Cheng et.al. Appl. Phys. Lett., 88 (2006) 152906

Thin Film ReferencePreparationMethod

MeasurementTechnique

StressDirection

PNZT/MgO CVD Raman Analysis Compressive J. Lappalainen et.al. Appl. Phys. Lett., 88 (2006) 252901(97/2/55/45)

PZT(MPB)/Pt/Si PLD XRD Compressive Y.C.Zhou et.al. Surface and Coatings Technol. 162 (2003) 202-211

PZT(MPB)/Pt/Si sol-gel Curvature Tensile J. Lu et.al. Thin Solid Films 515 (2006) 1506-1510measurement

Introduction

PTO/STO CVD XRD Tensile H. Uchida et.al., Kor. J. Ceram., 6 (2000) 385-389

PTO/STO MOCVD XRD Tensile M. Otsu et.al., Trans. Mat. Res. Soc. Jpn.,

Experimental Procedure

Pb(OCOCH3)2 Absolute Ethanol

Lead Precursor SolutionReflux (80℃ NH3 4hr)

Acetyl acetoneReflux (80℃ 1hr)

Zr-Ti Precursor SolutionReflux (80℃ 4hr)

Ti(iso-OC3H7)4

Absolute Ethanol

Reflux (80℃ 4hr)

Lead Titanate Precursor Solution

Pb(OCOCH3)2・3H2ODehydrate (150℃ 2hr)

Drying at 110℃ 10min

Pre-annealing at 350℃ 10min

Annealing at 600℃ 10min

Film deposition on Si wafer

FE-SEM images

Film Thickness : 480 nm (6 layers) , 80 nm/layerCrystal Size : over 100 nmGranular Structure

20 40 60

Pt (1

11)

PTO

(211

)PT

O (1

12)

PTO

(201

)PT

O (1

02)

PTO

(200

)PT

O (0

02)

PTO

(110

)

PTO

(101

)

PTO

(100

)PT

O (0

01)

240 nm

320 nm

400 nm

480 nm

Inte

nsi

ty

2θ

XRD pattern of the obtained PTO thin film with different thick

45.5 46.0 46.5 47.0 47.5 48.0

PTO(200)

*5

Ψ=15

Ψ=10

Ψ=5

Ψ=0

Inte

nsity

2θ42.0 42.5 43.0 43.5 44.0 44.5 45.0

0

200

400

PTO(002)

Ψ = 15

Ψ = 10

Ψ = 5

Ψ = 0

Inte

nsi

ty

2θ

(a) (002) peak position (b) (200) peak position

Change in the XRD profile of PTO thin film with 150 nm thick as a function of the Ψ angle

Change in the residual stress in PTO thin film with thickness (XRD analysis)

140 160 180 200 220 240 260 280 300 320

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Res

idua

l Com

pres

sive

Stre

ss (G

Pa)

Film Thickness (nm)

⎟⎟⎠

⎞⎜⎜⎝

⎛Ψ∂

∂×⎟⎠⎞

⎜⎝⎛××

+−=

)(sin)2(

180cot

)1(2 20θπθ

νσ E

(a) (002) peak position (b) (200) peak position

0.00 0.02 0.04 0.0643.80

43.85

43.90

43.95

44.00

44.05

44.10

2θ

sin2Ψ

400.3)(sin

)2(2 =⎟⎟

⎠

⎞⎜⎜⎝

⎛Ψ∂

∂ θ

0.00 0.02 0.04 0.06

46.54

46.56

46.58

46.60

46.62

2θ

sin2Ψ

059.1)(sin

)2(2 =⎟⎟

⎠

⎞⎜⎜⎝

⎛Ψ∂

∂ θ

Raman spectrum of PTO thin film with different film thickness

50 100 150 200

300 nm

250 nm

200 nm

150 nm

S.O

.

E(1

LO

)

A(1

TO

)

E(1

TO

)

Inte

nsity

(CPS

)

Raman shift (cm-1)

Change in the E(1TO) fitted curves as a function of the film thickness

Raman Spectrum

0 20 40 60 80 100 120 140

E(1TO)

300 nm

250 nm

200 nm

150 nm

Inte

nsity

Raman Shift (cm-1)

Change in the residual stress in PTO thin film

GPa29.0=

140 160 180 200 220 240 260 280 300 320

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

PTO/Pt/Ti/SiO2/Si

Res

idua

l Com

pres

sive

Stre

ss (G

Pa)

Film Thickness (nm)

Raman Analysis (from E(1TO)) Raman Analysis (from E(3TO)) XRD Analysis (sin2Ψ method)

dTE T

T sff

fthernal ∫ −

−=

0

)()1(

ααν

σ

σtotal = σepitaxial+σthermal+σtransition

0=epitaxialσ (because of film thickness)

T. Tybell et.al., Appl. Phys. Lett., 75 (1999) 856

(tensile)

Phase transition stress should be compressive component

Y. C. Zhou et.al. Surface and Coating Technol., 162 (2003) 202

PbTiO3

S. Shirasaki et.al. J. Am. Ceram. Soc., 56(8) (1973) pp.430-435

Unit-cell parameters as a functions of temperature for typical specimens

Tetragonal distortion and unit-cell volume as a functions of temperature for typical specimens

The origin of the Phase Transition Stress

What is the Phase Transition Stress ??

Model (1)

a0=3.950 a=3.940c=4.020

Tensile

c-oriented lattice

Compressive

a-oriented lattice

Phase Transition

Cubic Structure * Tetragonal Structure (Near the Curie Temp.) *

x

y

*S. Shirasaki et.al. J. Am. Ceram. Soc., 56(8) (1973) pp.430-435

σa

σa

σa

σa

σaσa

σc

σc

In plane In plane

In plane

Tetragonal

Cubic

(100) (110)(100)(001) (110)(101)

a0=3.95

a=3.94c=4.02

σa0

σa0

σa0

σa0 σa σa

σc

σc

σa*

σacσac

σa*

σabσab

σc*

σc*

)()1( 20 aaa

E νεεν

σ +−

=)(

)1( 2 accE νεεν

σ +−

=

)()()(

)101(

)101()101()( Cd

TdCdac

−=ε

0

0

aaa

a−

=ε )()()(

)110(

)110()110()( Cd

TdCdab

−=ε

0

0

aca

c−

=ε

)()1( 2* acaa

E νεεν

σ +−

=

)()1( )(2 aacac

E νεεν

σ +−

=

)()1( 2* abac

E νεεν

σ +−

=

)()1( 2 cabab

E νεεν

σ +−

=

0)001( aσσ =2)100(

ca σσσ +=

2*

)101(aca σσσ +

=2

*)110(

abc σσσ +=

Model (2)

x

y

)()1( 2 caa

E νεεν

σ +−

=

)110()110()101()101()100()100()001()001( σασασασασ ×+×+×+×=transition

⎟⎟⎠

⎞⎜⎜⎝

⎛ −+

−−

+−

×−

=0

0

0

0)100(

0

0)001( )1(21 a

caa

aaEa

aaEν

αν

α

⎟⎟⎠

⎞⎜⎜⎝

⎛ −+

−−

+⎟⎟⎠

⎞⎜⎜⎝

⎛ −+

−×

−+

)()()(

)1(2)()()(

)1(2 )110(

)110()110(

0

0)110(

)101(

)101()101(

0

0)101( Cd

TdCda

caECd

TdCda

aaEν

αν

α

20 40 60

0

500

1000

1500

PTO

(110

)

PTO

(101

)

PTO

(100

)PT

O(0

01)

Inte

nsi

ty

2θ

ex) PTO(300nm)/Pt/Ti/SiO2/Si %5.6:)001(α

%7.69:)101(α%5.6:)100(α

%3.17:)110(α

)110()101()100()001( 173.0697.0065.0065.0 σσσσσ ×+×+×+×=transition

GPa410.0)001( +=σ

GPa232.1)100( −=σ

GPa234.1)110( −=σ

GPa419.0)101( −=σ

GPatransition 56.0−=σGPathermal 29.0=σ

To be Compressive stress

New Equation for the random oriented film

(tensile factor)

(compressive factor)

(compressive factor)

(compressive factor)

Conclusions

2. The residual stress in PTO film was calculated by Raman and XRD analysis.

1. The PTO film was deposited on Si wafer by CSD.

3. The obtained stress direction and the value was almost the same between Raman and XRD analysis

4. In the case of Random oriented film, the compressive residual stress is also reasonable result, since the large compressive phase transition stress cancel the tensile thermal stress