Integration of ferroelectric thin films into silicon based microsystems [Elektronische Ressource] / vorgelegt von Carsten Kügeler

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2006
• Nombre de lectures: 8
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

Integration of Ferroelectric Thin Films
into Silicon Based Microsystems
Von der Fakultät für Elektrotechnik und Informationstechnik
der Rheinisch-Westfälischen Technischen Hochschule Aachen
zur Erlangung des akademischen Grades eines Doktors der
Ingenieurwissenschaften genehmigte Dissertation
vorgelegt von
Diplom-Ingenieur
Carsten Kügeler
aus Rheda-Wiedenbrück
Berichter: Univ.-Prof. Dr.-Ing. Rainer Waser
Univ Dr. rer. nat. Wilfried Mokwa
Tag der mündlichen Prüfung: 13.07.2006
Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.III
Preface
This dissertation was written during my Ph.D.-studies at the Institut für Werkstoffe der Elek-
trotechnik of the Rheinisch-Westfälische Technische Hochschule Aachen, Germany (RWTH
Aachen).
I would like to express my gratitude to Prof. R. Waser for giving me the opportunity to do re-
search at the Institut für Werkstoffe der Elektrotechnik in the exciting field of ferroelectric based
MEMS and for providing an excellent working and learning environment. I highly appreciate
his advice and support.
I am also indebted to Prof. W. Mokwa who kindly agreed to be the co-examiner in the jury.
Many thanks also to: Dr. U. Böttger for his support and stimulating discussions; S. Tappe and
R. Plonka for the fruitful discussions, careful proof-reading and being great office mates; D.
Bräuhaus, C. Dehoff and K. Herbertz for their dedicated work during the diploma thesis; Dr. T.
Schneller and R. Thelen for preparing the precursor solutions and the help regarding questions
of chemistry; D. Erdoglija for Pt electrodes and for performing lithography so many
times; G. Wasse for taking SEM pictures.
Last but not least I would like to thank all colleagues and all the students at the Institut für
Werkstoffe der Elektrotechnik and at the Forschungszentrum Jülich for their valuable support
and many great moments spent together.IVV
Contents
1 Introduction 1
1.1 Motivation . . . . . ............................... 1
1.2 State of the Art . . ............................... 2
1.2.1 Piezoelectric Cantilever Structures on Silicon Substrates . ...... 2
1.2.2 Cantilever on Metal . . ...... 2
1.2.3 Integrated Piezoelectric Driven Micro-Relays ............. 2
1.2.4 Piezoelectric Driven Microwave Switches . . ............. 3
1.2.5 Thin Film Bulk Acoustic Resonators for High Frequency Applications 3
1.2.6 Dielectric Bolometers . ........................ 4
1.3 Objectives . . . . . ............................... 5
2 Ferroelectric Materials 7
2.1 Spontaneous Polarization . . . . ........................ 7
2.2 Piezoelectric Effect and Electrostriction . . . ................. 10
2.3 Lead Zirconate Titanate (PZT) . ........................ 12
2.4 Lanthanum doped Lead Hafnate Titanate (PLHT) . . ............. 13
2.5 Barium Strontium Titanate (BST) . . . . . . ................. 14
3 Thin Film Deposition 17
3.1 Chemical Solution Deposition . ........................ 18
3.2 Microstructural Analysis . . . . ........................ 19
3.2.1 Lead Zirconate Titanate (PZT) . . . . ................. 20
3.2.2 Lanthanum doped Lead Hafnate Titanate (PLHT) . . . . . ...... 23
3.2.3 Barium Strontium Titanate (BST) . . ................. 27
4 Material Characterization with Respect to MEMS Devices 29
4.1 Electrical Methods . . . . . ................. 29
4.2 Electromechanical Characterization Methods ................. 30
4.3 Lead Zirconate Titanate (PZT) . ........................ 31
4.3.1 Electromechanical Fatigue . . . . . . ................. 35VI
4.4 Lanthanum doped Lead Hafnate Titanate (PLHT) . . ............. 38
4.5 Barium Strontium Titanate (BST) . . . . . . ................. 42
5 Technology 45
5.1 Photolithography . ............................... 45
5.2 Silicon Bulk Micromachining . . ........................ 47
5.3 Surface . . . . ........................ 49
5.3.1 Plasma Etching of Pt and BST . . . . ................. 52
5.3.2 Plasma Etching of PZT . ........................ 53
5.3.3 Plasma Etching of SiO and Si N ................... 542 3 4
5.3.4 Anisotropic Silicon Etching . . . . . ................. 5
5.3.5 Isotropic Silicon Etching ........................ 56
5.4 HF-Vapor Etching . ............................... 59
5.5 Stress Compensation . . . . . . ........................ 63
5.6 Electroplating of Freestanding Copper Contacts . . . ............. 6
6 Piezoelectric Cantilever Structures on Silicon Substrates 69
6.1 Cantilevers Fabricated by Silicon Bulk Micromachining . . . . . . ...... 69
6.2 Cantilevers F by Silicon Surface . . . . ...... 76
6.3 Cantilevers Fabricated on Silicon On Insulator Substrates . . . . . ...... 79
7 Devices 85
7.1 Integrated Piezoelectric Driven Micro-Relays ................. 85
7.2 Piezoelectric Driven Microwave Switches . . ................. 91
7.3 Thin Film Bulk Acoustic Wave Resonators . . ................. 97
7.4 Dielectric Bolometers for Infrared Detection . ................. 103
7.5 Piezoelectric Cantilevers on Metal Foil Substrates . . ............. 10
8 Conclusions 117
8.1 Summary . . . . . ............................... 117
8.2 Outlook . . . . . . ............................... 120
References 121VII
Used Symbols and Abbreviations
Symbols
A Area
C Capacitance
C on membranef
C on bulkref
C Curie-Weiss constantCurie
d Tensor of the piezoelectric coefficientsij
D Dielectric displacement
D Components of the dielectric displacement vectori
e ij-th component of transversal piezoelectric charge coefficientij
E Electric field
E Coercive field
C
E Young’s modulus of siliconSi
f Frequency
f Large signal frequencybias
f Small signal frequencyosc
h displacement
I Electric current
−23 −1k Boltzmann’s constant k = 1.38066·10 JKB B
k Electromechanical coupling constantt
l Length
L Power density
P Polarization or Power
P Remanent polarizationr
P SaturationS
Q ij-th component of electrostriction tensorij
r radius
r initial radius0
S Mechanical strain or microwave measurement parameter
s ij-th component of the elastic compliance tensorij
t Time or thickness
T Temperature
T Intrinsic stressint
T Extrinsic stressext
T Thermal stresstherm
T Curie-Weiss temperature0
T TransitionC
T k-th component of the mechanical stress tensork
v sound velocity
V Voltage
V Small signal voltageosc
V Coercive voltageC
z Normalized acoustic impedanceiVIII
Z Acoustic impedance0
Greek Symbols
γ phase delay
12ε Permittivity of free space (8.854·10 As/Vm)0
ε,ε ,εvity, relative and reversible permittivityr rev
ε Total permittivitytotal
ε Intrinsic permittivityintrinsic
ε Extrinsicvityextrinsic
ε Components of the permittivity tensorij
ν Poisson ratio of siliconSi
ρ Mass density
ω Angular frequency
σ electric conductance
Abbreviations
AFM Atomic Force Microscopy
AlN Aluminum Nitride
BAW Bulk Acoustic Resonator
BS Beam Splitter
BST Barium Strontium Titanate
BTO Titanate
BOX Buried oxide
CH COOH Acetic acid3
CHF Trifluoromethane3
CF Tetrafluoromethane4
CMOS Complementary Metal Oxide Semiconductor
CSD Chemical Solution Deposition
CuSO · 5H O Coppersulphatepentahydrate4 2
CVD Chemical Vapor Deposition
ECR Electro cyclotron resonance plasma source
FeRAM Ferroelectric Random Access Memory
FEM Finite Element Method
HF Hydrofluoric Acid
H SO Sulfuric acid2 4
IR Infra red
KOH Potassium Hydroxide
LPCVD Low Pressure Chemical Vapor Deposition
L Lens
LNO Lanthanum Nickel Oxide
M Mirror
MBE Molecular Beam Epitaxy
MEMS Microelectromechanical SystemsIX
MOCVD Metal-Organic Chemical Vapor Deposition
MODganic Decompostion
MPB Morphotropic Phase Boundary
MW MEMS Microwave Microelectromechanical Systems
HNO Nitric acid3
PBS Polarizing Beam Splitter
PLD Pulsed Laser Deposition
PLHT Lanthanum doped Lead Hafnate Titanate
PLZT Lead Zirconate Titanate
PHT Lead Hafnate Titanate
PZT Lead Zirconate Titanate
PVD Physical Vapor Deposition
RF MEMS Radio Frequency Microelectromechanical Systems
RTA Rapid Thermal Annealing
SEM Scanning Electron Microscope
SF Sulfur hexafluoride6
SiO Silicon dioxide2
Si N Silicon nitride3 4
STO Strontium Titanate
TFBAR Thin Film Bulk Acoustic Resonator
TMAH Tetramethylammonium Hydroxide
UMTS Universal Mobile Telecommunication System
WLAN Wireless Local Area Network
XRD X-Ray DiffractionX