Relationships Between Microstructure and Reliability in Pzt Mems

2001 ◽  
Vol 666 ◽  
Author(s):  
B.W. Olson ◽  
L.M. Randall ◽  
C.D. Richards ◽  
R.F. Richards ◽  
D.F. Bahr
Keyword(s):  
Grain Size ◽  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Electrical Energy ◽  
Lead Zirconate ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Processing Route ◽  
Bulge Testing ◽  
Sol Gel Process

ABSTRACTPiezoelectric oxide films, such as lead zirconate titanate (PZT), are now being integrated into MEMS applications. Many PZT derived systems are deposited using a sol-gel process, which can be used in a microelectronics processing route using spin coating as the deposition method. An application of interest for PZT films is in power generation, where a flexing membrane is used to transform mechanical to electrical energy. The current study was undertaken to identify the relationships between the processing, microstructure, and mechanical reliability of these films. Films were deposited onto both monolithic and bulk micromachined platinized silicon wafers using standard sol-gel chemistries, with roughness and grain size tracked using electron and scanning probe microscopy. Mechanical properties were evaluated in a dynamic bulge testing apparatus. Grain size variations in the Pt film between 35 and 125 nm are shown to have little effect on grain size of the subsequent PZT film and the adhesion of the PZT to the Pt film. Only the Pt film with 125 nm grains was shown to undergo any significant interfacial fracture. Fatigue tests suggest film lifetime is primarily limited by the number of pre- existing flaws in the film from processing. Reducing the microcrack density has been shown to produce films and devices that fail at strains of 1.4% and have mechanical fatigue lifetimes in excess of 100 million cycles at strains simulating the operating conditions.

The crystallization of thin-film ceramics

1992 ◽  
Vol 50 (1) ◽  
pp. 338-339
Author(s):  
J.M. Schwartz ◽  
L.F. Francis ◽  
L.D. Schmidt ◽  
P.S. Schabes-Retchkiman
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Sol Gel ◽  
Processing Route ◽  
Small Areas ◽  
Ceramic Thin Films ◽  
Complex Shapes ◽  
Sol Gel Process ◽  
Ceramic Precursors ◽  
Crystalline Ceramic

Ceramic thin films and coatings are of interest for electrical, optical, magnetic and thermal barrier applications. Critical for improved properties in thin films is the development of specific microstructures during processing. To this end, the sol-gel method is advantageous as a versatile processing route. The sol-gel process involves depositing a solution containing metalorganic or colloidal ceramic precursors onto a substrate and heating the deposited layer to form a crystalline or non-crystalline ceramic coating. This route has several advantages, including the ability to create tailored microstructures and properties, to coat large or small areas, simple or complex shapes, and to more easily prepare multicomponent ceramics. Sol-gel derived coatings are amorphous in the as-deposited state and develop their crystalline structure and microstructure during heat-treatment. We are particularly interested in studying the amorphous to crystalline transformation, because many key features of the microstructure such as grain size and grain size distribution may be linked to this transformation.

Fabrication of Thick, Sol Gel Pzt Films: Applications to Macroscopic Piezoelectric Devices

1994 ◽  
Vol 360 ◽  
Author(s):  
D.A. Barrow ◽  
T.E. Petroff ◽  
M. Sayer
Keyword(s):  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Low Frequency ◽  
Lead Zirconate ◽  
Resonant Vibrations ◽  
Pzt Film ◽  
Sol Gel Process ◽  
Pzt Films ◽  
High Frequency Resonance ◽  
Piezoelectric Devices

AbstractLead zirconate titanate (PZT) films of up to 60 μm in thickness have been fabricated on a wide variety of substrates using a new sol gel process. The dielectric properties (∈ = 900), ferroelectric (Ec = 16 kV/cm and Pr = 35 μC/cm 2) and piezoelectric properties are comparable to bulk values. The characteristic Curie point of these films is at 420 °C. Piezoelectric actuators have been developed by depositing thick PZT films on both planar and coaxial substrates. Stainless steel cantilevers and optical fibres coated with a PZT film exhibit flexure mode resonant vibrations observable with the naked eye. A low frequency in-line fibre optic modulator has been developed using a PZT coated optical fibre. The high frequency resonance of a 60 μm film on a aluminum substrate has been observed.

Residual Stress Control to Optimize Pzt Mems Performance

2002 ◽  
Vol 741 ◽  
Author(s):  
M.S. Kennedy ◽  
D.F. Bahr ◽  
C.D. Richards ◽  
R.F. Richards
Keyword(s):  
Residual Stress ◽  
Lead Zirconate Titanate ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Lead Zirconate ◽  
X Ray Diffraction ◽  
Membrane Performance ◽  
Boron Doped ◽  
Pzt Film ◽  
Bulge Testing

ABSTRACTFlexing piezoelectric membranes can be used to convert mechanical energy to electrical energy. The overall deflection of individual membranes is impacted by the residual stress in the system. Membranes comprised of silicon dioxide, Ti/Pt, lead- zirconate- titanate (PZT), and TiW/Au layers deposited on a micromachined boron doped silicon wafer were examined for both morphology and residual stress. By characterizing the membrane residual stress induced during processing with x-ray diffraction, wafer curvature, and bulge testing and identifying methods to reduce stress, the membrane performance and reliability can be optimized. For Zr:Ti ratios of 52:48, the residual stress in the PZT was 350 MPa tensile, with an overall effective stress in the composite membrane of 150 MPa. A reduction of stress was accomplished by changing the PZT chemistry to 40:60 Zr:Ti in the PZT to obtain a stress in the PZT of 160 MPa tensile and an overall effective membrane stress of 100 MPa. The crystallization of the 52:48 PZT film at 700 °C causes a 28% reduction in the thickness of the film.

Lead Zirconate Titanate Nanowire Growth Via Spin Coating in Conjunction with Sol-Gel Process

2007 ◽  
Vol 356 (1) ◽  
pp. 230-235 ◽  
Author(s):  
Jongok Kim ◽  
Yong Chan Choi ◽  
Ki-Seog Chang ◽  
Sang Don Bu
Keyword(s):  
Lead Zirconate Titanate ◽  
Spin Coating ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Nanowire Growth ◽  
Zirconate Titanate ◽  
Sol Gel Process

A novel route to perovskite lead zirconate titanate from glycolate precursors via the sol–gel process

2008 ◽  
Vol 22 (2) ◽  
pp. 104-113 ◽  
Author(s):  
N. Tangboriboon ◽  
A. Jamieson ◽  
A. Sirivat ◽  
S. Wongkasemjit
Keyword(s):  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Zirconate Titanate ◽  
Sol Gel Process

Synthesis of Phase Pure Strontium Doped Lead Zirconate Titanate Nano Crystalline Powder by Sol-Gel Approach

2012 ◽  
Vol 510-511 ◽  
pp. 454-460 ◽  
Author(s):  
H. Nawaz ◽  
S. Aftab ◽  
M. Shoaib ◽  
M. Siddiq
Keyword(s):  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Titanium Alkoxides ◽  
Crystalline Powder ◽  
Acetate Trihydrate ◽  
Nano Crystalline ◽  
Sol Gel Process ◽  
Phase Pure ◽  
Different Temperatures

Phase pure Strontium doped PZT (Pb0.96Sr0.04Zr0.53Ti0.47O3) was synthesized by sol gel process. Zirconium and Titanium alkoxides were used as starting materials and Lead (II) Acetate trihydrate was used as Pb source. The alkoxides mixture was stabilized by acetylacetonate. The vacuum dried gel was calcined at different temperatures to study the calcination temperature and the resulting samples were analyzed by DSC, TG and XRD. The powder remained amorphous until a temperature of 550°C. The morphology and composition of the powder was studied using EDX, stereomicroscope and high resolution SEM.

Effect of Processing Conditions on the Piezoelectric Properties of Sol-gel Derived Pb(Zr,Ti)O3 Films for Micromechanical Applications

2005 ◽  
Vol 20 (6) ◽  
pp. 1428-1435 ◽  
Author(s):  
J. Pérez ◽  
P.M. Vilarinho ◽  
A.L. Kholkin ◽  
J. Manuel Herrero ◽  
C. Zaldo
Keyword(s):  
Lead Zirconate Titanate ◽  
Annealing Temperature ◽  
Piezoelectric Properties ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Piezoelectric Response ◽  
Preparation Conditions ◽  
Sol Gel Process ◽  
Pzt Films ◽  
Interface Effects

Lead zirconate titanate (PZT) films of composition close to the morphotropic phase boundary were deposited onto standard Si/SiO2/Ti/Pt substrates using a modified sol-gel process. The preparation conditions were optimized to obtain high-quality films at sufficiently low temperature (Ta - 500 °C). The dielectric, ferroelectric, and piezoelectric properties of the films were then measured as a function of the annealing temperature and the number of distillations to evaluate their suitability for micromechanical applications. The maximum values of the longitudinal charge and voltage piezoelectric coefficients were d33 ∼ 65 pm/V and g33 ∼ 4 × 10−3 Vm/N, respectively. The results indicate that the piezoelectric properties improved and became saturated with increasing number of distillations and are almost independent on Ta. Only moderate decrease of the piezoelectric response with frequency suggests that the investigated PZT films can be used in high-frequency piezoelectric applications. The results are discussed in terms of the microstructure and interface effects on the piezoelectric deformation in ferroelectric thin films.

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