臺灣博碩士論文加值系統

摘要
本論文探討鋯鈦酸鉛（PZT）壓電薄膜於撓性板波（FPW）共振元件之液體感測應用。撓性板波傳遞速度對外界干擾的物理量如應力、質量等，具有相當的敏感度。且當聲波在與液體接觸時，其波傳能量不易散射出去。而撓性板波其背部薄膜孔穴可作為待測溶液的負載區，可精確檢驗出傳遞基材受外界激發所產生的薄板負載質量與應力的變化，故適於液體感測之應用。本研究主要以溶膠-凝膠法製備鋯鈦酸鉛壓電薄膜，來進行撓性板波共振元件製作。元件的材料系統為Pt /Ti /PZT/LSMO /SiNx。在理論分析方面以耦合理論模式來模擬PZT雙埠表面聲波共振器的頻率響應，結合撓性板波的波傳特性來製造撓性板波共振元件。並實際將該元件應用於液體密度感測，結果顯示元件的插入損失和共振頻率會隨著液體負載密度的大小呈線性變化。而該元件的設計比一般撓性板波元件有更低的插入損失值，驗證了本元件於液體感測應用的可行性。

ABSTRACT
This thesis focuses on the development of the Flexure plate wave (FPW) resonator using piezoelectric lead zirconate titanates (PZT) films for liquid sensing. The propagation velocities of the FPW are very sensitive to the stress and the loading mass on the substrate. There is less scattering of the energy from the FPW to the loading liquid due to its low phase velocity. The back cavity of the FPW device can serve as the loading area of the sensing liquid to detect the density of liquid and the stress of the membrane. This research adopts PZT piezoelectric films using Sol-Gel technique to fabricate the FPW resonator. The material system is Pt/Ti /PZT/LSMO /SiNx. This study has presented the simulation model using the COM theory for a two-port SAW resonator over a PZT substrate, which is extended to the design of the FPW resonator. The preliminary measurement results show that the resonant frequency and the liquid density have a good linear correlation, and demonstrate the feasibility of the sensor application using the FPW resonator.

Contents
摘要..................................................................................................................................I
ABSTRACT...................................................................................................................II
誌 謝..............................................................................................................................III
CHAPTER 1 INTRODUCTION..............................................................................1
1.1. BACKGROUND...................................................................................................1
1.2. LITERATURE REVIEW.........................................................................................3
1.3. THE RESEARCH PURPOSE AND PROCEDURES.......................................................8
CHAPTER 2 THE MODELING OF SAW RESONATORS..................................9
2.1. INTRODUCTION..................................................................................................9
2.2. TWO-PORT SAW RESONATOR...........................................................................11
2.2.1. The transmission matrix [T] of IDT.......................................................12
2.2.2. Acoustic transmission line matrix [D]...................................................15
2.2.3. The reflection grating matrix [G]...........................................................15
2.2.4. Overall acoustic matrix [M] for the two-port SAW resonator...............17
2.3. TWO-PORT SAW RESONATOR SIMULATION......................................................19
2.3.1. The number of reflection grating............................................................20
2.3.2. The number of IDT.................................................................................21
2.3.3. The overlap length of IDT......................................................................22
2.3.4. The delay line distance...........................................................................23
CHAPTER 3 THE MODELING OF FPW WAVE SENSORS............................26
3.1. INTRODUCTION................................................................................................26
3.2. THE PHASE VELOCITY OF FPW........................................................................27
3.2.1. Effects of the loading with a non-viscous liquid on the plate.................28
3.2.2. Effects of the loading with a viscous liquid on the plate........................29
3.3. THE ESTIMATE OF THE PHASE VELOCITY OF THE DEVICE..................................30
3.3.1. The phase velocity of the device in air...................................................30
3.3.2. The phase velocity for the device loaded with water..............................31
3.3.3. The phase velocity for the device loaded with glycerol..........................35
CHAPTER 4. THE FABRICATION OF THE FPW RESONATOR...................37
4.1. THE FABRICATION FLOWCHART........................................................................37
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4.2. THE MASK DESIGN...........................................................................................39
4.3. THE COATING OF THE PIEZOELECTRIC FILM......................................................43
4.3.1. Sol Gel prepared PZT thin film...............................................................43
4.3.2. The Coating of PZT over a metal layer..................................................44
4.4. THE CHARACTERISTICS OF THE PIEZOELECTRIC THIN FILM...............................45
4.4.1. XRD analysis..........................................................................................45
4.4.2. P-E curve analysis..................................................................................48
4.4.3. SEM analysis..........................................................................................49
4.4.4. AFM analysis..........................................................................................51
4.5. THE FABRICATION OF THE SAW RESONATOR AND THE FPW RESONATOR........52
4.5.1. The patterning of the IDT.......................................................................52
4.5.2. Anisotropic etching of the silicon substrate............................................55
CHAPTER 5 THE MEASUREMENT RESULT AND DISCUSSION...............57
5.1. THE MEASUREMENT OF S-PARAMETERS...........................................................57
5.2. THE SAW DELAY LINE AND THE SAW RESONATOR SIGNALS...........................60
5.2.1. Comparing the different delay line distances between the gratings and adjacent IDTs for SAW resonators..........................................................................62
5.3. THE FPW DELAY LINE AND THE FPW RESONATOR SIGNALS............................63
5.4. LIQUID SENSING USING THE FPW DELAY LINE AND THE FPW RESONATOR......65
5.4.1. The frequency deviations due to the loading of liquid............................65
5.4.2. The density sensing for non-viscous liquids...........................................67
5.4.3. The frequency deviation due to liquid viscosity......................................69
CHAPTER 6 CONCLUSIONS AND FUTURE WORKS....................................72
6.1. CONCLUSIONS.................................................................................................72
6.2. FUTURE WORKS...............................................................................................73
REFERENCE...............................................................................................................75
v
List of Figures
FIG 1-1 THE SAW DEVICE CONFIGURATION.................................................................2
FIG 1-2 LAMB WAVE STRUCTURE..................................................................................3
FIG 1-3 (A) BEFORE POLING (B) DURING POLING (C) AFTER POLING............................5
FIG 1-4 FPW RESONATOR STRUCTURE.........................................................................8
FIG 2-1 ONE-PORT SAW RESONATORS STRUCTURE....................................................10
FIG 2-2 TWO-PORT SAW RESONATORS STRUCTURE...................................................10
FIG 2-3 THE NOTATIONS FOR THE SIGNALS AND THE REFERENCE PLANES OF THE IDT12
FIG 2-4 THE SAW REFERENCE PLANE OF REFLECTION GRATING................................15
FIG 2-5 REPRESENTATION OF TWO-PORT RESONATOR BUILDING BLOCKS....................17
FIG 2-6 THE SIMULATIONS FOR THE RESONATOR WITH DIFFERENT NUMBERS OF REFLECTION GRATINGS (NT=20).......................................................................21
FIG 2-7 THE SIMULATIONS FOR THE RESONATOR WITH DIFFERENT NUMBERS OF ELECTRODES OF IDT (NG = 40)........................................................................22
FIG 2-8 THE SIMULATION FOR THE RESONATOR WITH DIFFERENT OVERLAP LENGTHS OF IDT (NG=40, NT =20)......................................................................................23
FIG 2-9 THE SIMULATION FOR THE RESONATOR WITH DIFFERENT DELAY LINE (D2 AND D6) DISTANCES................................................................................................24
FIG 2-10 TWO-PORT SAW RESONATOR FREQUENCY RESPONSE......................................25
FIG 3-1 THE WAVE MOTION OF LAMB WAVES..............................................................26
FIG 3-2 FPW STRUCTURE...........................................................................................27
FIG 3-3 THE EVANESCENT DECAY LENGTH FOR THE LIQUID LOADING IN A FPW DEVICE 29
FIG 4-1 A SCHEMATIC VIEW OF THE FABRICATING PROCESS........................................38
FIG 4-2 THE IDT MASK OF THE TWO-PORT RESONATOR..............................................40
FIG 4-3 THE IDT MASK OF THE SAW DELAY LINE......................................................41
FIG 4-4 THE BACK SIDE MASK....................................................................................41
FIG 4-5 THE FPW RESONATOR DESIGN.......................................................................42
FIG 4-6 THE GEOMETRICAL DESIGN OF TWO-PORT RESONATOR..................................43
FIG 4-7 THE PZT/LSMO/PT/TI SCALED OFF THE SUBSTRATE OF SINX/SI...................45
FIG 4-8 X-RAY OF LSMO (2L) / PT/TI /SI AT 650 °C FOR 30 MIN..............................46
FIG 4-9 X-RAY OF PZT (5L)/LSMO (3L) / SI AT 650 °C FOR 30 MIN.........................47
FIG 4-10 P-E CURVE MEASURING RESULT.....................................................................49
FIG 4-11 SEM OF PZT (5L)/LSMO (2L)/PT/TI/ /SI.....................................................50
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FIG 4-12 THE SEM OF THE LSMO SURFACE................................................................50
FIG 4-13 THE SEM OF THE PZT SURFACE....................................................................51
FIG 4-14 THE AFM ANALYSIS OF THE LSMO SURFACE...............................................52
FIG 4-15 THE AFM ANALYSIS OF THE PZT SURFACE...................................................52
FIG 4-16 SAW RESONATOR DEVICE..............................................................................53
FIG 4-17 SAW DELAY LINE DEVICES............................................................................54
FIG 4-18 THE LIFT-OFF OF THE IDTS (ELECTRODE WIDTH = 10μM).............................54
FIG 4-19 THE LIFT-OFF OF THE REFLECTION GRATINGS (ELECTRODE WIDTH = 10μM)..55
FIG 4-20 FPW DEVICE.................................................................................................56
FIG 5-1 THE INSTRUMENT OF NETWORK ANALYZER (HP8753 ES).............................57
FIG 5-2 S-PARAMETERS ARE DEFINED BY TWO-PORT NETWORK..................................58
FIG 5-3 CALIBRATION STEPS OF NETWORK ANALYZERS.............................................59
FIG 5-4 THE LAYOUT OF THE DEVICE..........................................................................59
FIG 5-5 THE SAW DELAY LINE SIGNAL......................................................................61
FIG 5-6 THE SAW RESONATOR SIGNALS....................................................................61
FIG 5-7 THE PERTURBATION OF MECHANICAL DISPLACEMENT DUE TO RAYLEIGH WAVES 62
FIG 5-8 THE COMPARISON OF DIFFERENCE DELAY LINE DISTANCES BETWEEN THE GRATINGS AND ADJACENT IDTS.......................................................................63
FIG 5-9 THE FPW DELAY LINE SIGNAL (F = 5.47MHZ)..............................................64
FIG 5-10 THE FPW RESONATOR SIGNAL (F = 5.53MHZ)..............................................64
FIG 5-11 THE COMPARISON OF DIFFERENT FREQUENCY RESPONSES OF THE FPW DELAY LINE LOADED WITH LIQUID..............................................................................66
FIG 5-12 THE COMPARISON OF DIFFERENT FREQUENCY RESPONSES OF THE FPW RESONATOR LOADED WITH LIQUID...................................................................66
FIG 5-13 THE COMPARISON OF DIFFERENT FREQUENCY RESPONSES OF THE FPW DELAY LINE LOADED WITH NON-VISCOUS LIQUIDS......................................................68
FIG 5-14 THE COMPARISON OF DIFFERENT FREQUENCY RESPONSES OF THE FPW RESONATOR LOADED WITH NON-VISCOUS LIQUIDS...........................................68
FIG 5-15 THE SENSITIVITY ANALYSIS BETWEEN THE RESONANT FREQUENCY AND THE DENSITY FOR NON-VISCOUS LIQUIDS................................................................69
FIG 5-16 THE COMPARISON OF DIFFERENT FREQUENCY RESPONSES OF THE FPW DELAY LINE FOR SALINE WATER AND GLYCEROL..........................................................70
FIG 5-17 THE COMPARISON OF DIFFERENT FREQUENCY RESPONSES OF THE FPW RESONATOR FOR SALINE WATER AND GLYCEROL..............................................71
vii
List of Tables
TABLE 2-1 THE REFERENCE MATERIAL PROPERTIES OF PZT..........................................20
TABLE 3-1 THE MATERIAL PROPERTIES OF THE COMPOSITE PLATE.................................30
TABLE 3-2 THE LIQUID PROPERTIES..............................................................................32
TABLE 3-3 ESTIMATED RESONANT FREQUENCY OF THE FPW DEVICE LOADED WITH NON-VISCOUS LIQUIDS.................................................................................33
TABLE 3-4 THE RESONANT FREQUENCIES OF THE GLYCEROL AND THE SALINE SOLUTION WITH THE SAME DENSITY.............................................................................36
TABLE 4-1 THE PARAMETERS OF THE TWO-PORT DELAY LINE DEVICE............................39
TABLE 4-2 THE PARAMETERS OF THE TWO-PORT RESONATOR........................................40
TABLE 4-3 THERMAL EXPANSION COEFFICIENTS OF MATERIALS....................................44
TABLE 4-4 JCPDS CARD OF LA0.7SR0.3MNO3...............................................................47
TABLE 4-5 JCPDS OF PB（ZR0.52TI0.48）O3................................................................48
TABLE 5-1 THE RESONANT FREQUENCY AND INSERTION LOSS OF THE DEVICES LOADED WITH LIQUID................................................................................................67
TABLE 5-2 THE RESONANT FREQUENCY AND INSERTION LOSS OF THE DEVICES LOADED WITH NON-VISCOUS LIQUIDS........................................................................69
TABLE 5-3 THE COMPARISON BETWEEN VISCOUS AND NON-VISCOUS LIQUIDS WITH THE SAME DENSITY.............................................................................................71

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