Static and Dynamic Techniques for Residual Stress Measurements in Microelectromechanical Systems

2006 ◽  
Author(s):  
Mary Vechery ◽  
Andrew Dick ◽  
Luke Currano ◽  
Madan Dubey ◽  
B. Balachandran
Keyword(s):  
Residual Stress ◽  
Lead Zirconate Titanate ◽  
Microelectromechanical Systems ◽  
Measurement Techniques ◽  
Single Layer ◽  
Lead Zirconate ◽  
Nonlinear Frequency ◽  
Stress Measurements ◽  
Stress Levels ◽  
Dynamic Techniques

A major concern in the development of microelectromechanical systems (MEMS) is the presence of residual stress. Residual stress, which is produced during the fabrication of multi-layer thin-film structures, can significantly affect the performance of microscale devices. Though experimental measurement techniques are accurate, actual stress measurements can vary dramatically from run to run and wafer to wafer. For this reason, modeling of this stress is a challenging task. Past work has focused on experimental, static techniques for determining residual stress levels in single-layer and bi-layer structures. In this effort, two different experimental techniques are used for determining residual stress levels in four-layer piezoelectrically driven cantilever and clamped-clamped structures. One of the techniques is based on wafer bow measurements, and the other technique is a dynamic technique that is based on parameter identification from nonlinear frequency-response data. The devices studied, which consist of a piezoelectric layer or lead zirconate titanate (PZT) layer, are fabricated with varying lengths, widths, and material layer thickness. The results obtained from the static and dynamic techniques are compared and discussed.

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.

Wet-Etch Patterning of Lead Zirconate Titanate (PZT) Thick Films for Microelectromechanical Systems (MEMS) Applications

2000 ◽  
Vol 657 ◽  
Author(s):  
L.-P. Wang ◽  
R. Wolf ◽  
Q. Zhou ◽  
S. Trolier-McKinstry ◽  
R. J. Davis
Keyword(s):  
Lead Zirconate Titanate ◽  
Electromechanical Coupling ◽  
Microelectromechanical Systems ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Metal Fluoride ◽  
Zirconate Titanate ◽  
Pzt Films ◽  
High Etch Rate ◽  
Wet Etch

ABSTRACTLead zirconate titanate (PZT) films are very attractive for microelectromechanical systems (MEMS) applications because of their high piezoelectric coefficients and good electromechanical coupling. In this work, wet-etch patterning of sol-gel PZT films for MEMS applications, typically with film thicknesses ranging from 2 to 10 microns, was studied. A two- step wet-etch process was developed. In the first step, 10:1 buffered HF is used to remove the majority of the film at room temperature. Then a solution of 2HCl:H2O at 45°C is used to remove metal-fluoride residues remaining from the first step. This enabled successful patterning of PZT films up to 8 microns thick. A high etch rate (0.13μm/min), high selectivity with respect to photoresist, and limited undercutting (2:1 lateral:thickness) were obtained. The processed PZT films have a relative permittivity of 1000, dielectric loss of 1.6%, remanent polarization (Pr) of 24μC/cm2, and coercive field (Ec) of 42.1kV/cm, all similar to those of unpatterned films of the same thickness.

Mechanical energy harvesting using polyurethane/lead zirconate titanate composites

2017 ◽  
Vol 52 (9) ◽  
pp. 1171-1182 ◽  
Author(s):  
Abdelkader Rjafallah ◽  
Abdelowahed Hajjaji ◽  
Fouad Belhora ◽  
Daniel Guyomar ◽  
Laurence Seveyrat ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Lead Zirconate Titanate ◽  
Microelectromechanical Systems ◽  
Volume Fraction ◽  
Mechanical Energy ◽  
Mechanical Strain ◽  
Lead Zirconate ◽  
Inorganic Materials ◽  
Zirconate Titanate ◽  
Electromechanical Transduction

The microelectromechanical systems invade gradually the market with applications in many sectors of activity. Developing these micro-systems allows deploying wireless sensor networks that are useful to collect, process and transmit information from their environments without human intervention. In order to keep these micro-devices energetically autonomous without using batteries because they have a limited lifespan, an energy harvesting from ambient vibrations using electrostrictive polymers can be used. These polymers present best features against inorganic materials, as flexibility and low cost. The aims of this paper are manifold. First of all, we made elaboration of the polyurethane/lead zirconate titanate films of 100 µm thickness using a lead zirconate titanate–volume fraction of [Formula: see text]%. Therefore, we did an observation of the lead zirconate titanate grains dispersion and the electrical characterization of the polyurethane–50 vol% lead zirconate titanate composites. Finally, a detailed study of the electromechanical transduction, for the polyurethane–50 vol% lead zirconate titanate unpolarized and polarized composites sustained to the sinusoidal mechanical strain with amplitude of 1.5% and at very low frequencies ( f = 2 [Hz] and f = 4 [Hz]) and static electric field ( Edc = 10 [ V/µm]) or without it ( Edc = 0 [ V/µm]) has been presented.

scholarly journals PZT/PZT and PZT/BiT Composite Piezo-Sensors in Aerospace SHM Applications: Photochemical Metal Organic+Infiltration Deposition and Characterization

2018 ◽  
Author(s):  
Hamidreza Hoshyarmanesh ◽  
Nafiseh Ebrahimi ◽  
Amir Jafari ◽  
Parisa Hoshyarmanesh ◽  
Hyung-Ho Park
Keyword(s):  
Lead Zirconate Titanate ◽  
Thick Films ◽  
Composite Films ◽  
Single Layer ◽  
Deposition Process ◽  
Lead Zirconate ◽  
Phase Development ◽  
Metal Organic ◽  
Microstructure Morphology ◽  
Uv Lamp

The composition of fine-ground lead zirconate-titanate powder Pb(Zr0.52Ti0.48)O3, suspended in PZT and bismuth titanate (BiT) solutions, is deposited on the curved surface of IN718 and IN738 nickel-based supper alloy substrates up to 100 µm thickness. Photochemical metal organic and infiltration techniques are implemented to produce smooth, semi-dense, and crack-free random orientated thick piezoelectric films as piezo-sensors, free of any dopants or thickening polymers. Every single layer of the deposited films is heated at 200 °C with 10 wt.% excess PbO, irradiated by UV lamp (365 nm, 6 watt) for 10 minutes, pyrolyzed at 400 °C, and subsequently annealed at 700 °C for one hour. This process is repeated successively until reaching the desired thickness. Au and Pt thin films are deposited as the bottom and top electrodes using evaporation and sputtering methods, respectively. PZT/PZT and PZT/BiT composite films are then characterized and compared to similar PZT and BiT thick films deposited on the similar substrates. The effect of composition and deposition process is also investigated on the crystalline phase development and microstructure morphology as well as dielectric, ferroelectric and piezoelectric properties of piezo-films. The maximum remnant polarization of Pr = 22.37 ± 0.01, 30.01 ± 0.01 µC/cm2, the permittivity of εr = 298 ± 3, 566 ± 5 and piezoelectric charge coefficient of d33 = 126, 148 m/V were measured versus the minimum coercive field of Ec = 50, 20 kV/cm for the PZT/PZT and PZT/Bit thick films, respectively. The thick film piezo-sensors are developed to be potentially used at frequency bandwidth of 1–5 MHz for rotary structural health monitoring and also in other industrial or medical applications as a transceiver.

Design and Fabrication of a Functionally Modified Bimorph Actuator

2014 ◽  
Author(s):  
Johnson Fujamade ◽  
Frances Williams ◽  
Oliver Myers ◽  
Brandon Plastied ◽  
Messaoud Bahoura ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Microelectromechanical Systems ◽  
Lead Zirconate ◽  
Linear Displacement ◽  
Design Parameters ◽  
Platinum Electrodes ◽  
Mems Devices ◽  
Device Design ◽  
High Performing ◽  
Mems Technology

In recent years, the use of microelectromechanical systems (MEMS) devices has led to high performing actuators for various applications, including unmanned air vehicles (UAVs) for defense applications. The incorporation of MEMS technology in this field has resulted in miniaturized UAVs with the capability of carrying out sophisticated reconnaissance and relaying real time information remotely; however, maneuverability of these devices around obstacles is still a challenge. This paper presents the design and fabrication of a functionally modified bimorph actuator with enhanced UAV aerodynamics and maneuverability. The actuator is a metal-based MEMS device consisting of stainless steel, lead zirconate titanate (PZT), and titanium/platinum electrodes. COMSOL analysis was performed to examine optimal device design parameters and is presented in this paper. The design consists of off-axis PZT segments on a bimorph PZT layer which results in bend twist coupling. A detailed description of the fabrication process flow developed based on the optimization of the device design is also given. MEMS processing technology was incorporated to produce a torsional cantilever beam that produces angular and linear displacement for superior UAV maneuverability and its performance is also presented in this paper.

scholarly journals Anisotropic Magnetoelectric Effect in a Planar Heterostructure Comprising Piezoelectric Ceramics and Magnetostrictive Fibrous Composite

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3228 ◽  
Author(s):  
Yuri Fetisov ◽  
Dmitri Chashin ◽  
Dmitri Saveliev ◽  
Leonid Fetisov ◽  
Mikhail Shamonin
Keyword(s):  
Lead Zirconate Titanate ◽  
Magnetoelectric Effect ◽  
Fibrous Composite ◽  
Frequency Doubling ◽  
Single Layer ◽  
Piezoelectric Ceramics ◽  
Lead Zirconate ◽  
Field Amplitude ◽  
Constant Field ◽  
Excitation Field

The direct magnetoelectric (ME) effect is investigated in a planar structure comprising mechanically coupled layers of a magnetostrictive fibrous composite (MFC) and a piezoelectric ceramics (lead zirconate titanate, PZT). The MFC is an array of Ni-wires with a diameter of 200 μm that are aligned parallel to each other in a single layer. The wires are separated by a distance of 250 or 500 μm and fixed in a polyamide matrix. The structure was placed in a tangential constant field H and was excited by an alternating magnetic field h parallel to H, while the voltage generated by the PZT layer was measured. The resulting field dependences of the magnetization M(H) and the magnetostriction λ(H) were determined by the orientation of the field H in the plane of the structure and the distance between the Ni-wires. The ME coupling coefficient of the structure decreased from 4.8 to 0.25 V/A when the orientation of H was changed from parallel to perpendicular to Ni-wires. With an increase in the excitation field amplitude h, a nonlinear ME effect in the output voltage, namely frequency doubling, was observed. The frequency and field dependences of the efficiency of the ME transduction in the MFC-piezoelectric heterostructure are well described by the existing theory.

Modeling and Analysis the Effect of PZT Area on Square Shaped Substrate for Power Enhancement in MEMS Piezoelectric Energy Harvester

2017 ◽  
Vol 26 (09) ◽  
pp. 1750128 ◽  
Author(s):  
Babak Montazer ◽  
Utpal Sarma
Keyword(s):  
Lead Zirconate Titanate ◽  
Power Output ◽  
Energy Harvester ◽  
Single Layer ◽  
Beam Theory ◽  
Lead Zirconate ◽  
Modeling And Analysis ◽  
Piezoelectric Energy ◽  
Resonance Frequencies ◽  
Array Structure

Modeling and analysis of a MEMS piezoelectric (PZT-Lead Zirconate Titanate) unimorph cantilever with different substrates are presented in this paper. Stainless steel and Silicon [Formula: see text] are considered as substrate. The design is intended for energy harvesting from ambient vibrations. The cantilever model is based on Euler–Bernoulli beam theory. The generated voltage and power, the current density, resonance frequencies and tip displacement for different geometry (single layer and array structure) have been analyzed using finite element method. Variation of output power and resonant frequency for array structure with array elements connected in parallel have been studied. Strain distribution is studied for external vibrations with different frequencies. The geometry of the piezoelectric layer as well as the substrate has been optimized for maximum power output. The variation of generated power output with frequency and load has also been presented. Finally, several models are introduced and compared with traditional array MEMS energy harvester.

Multilayer Lead Zirconate Titanate and Barium Titanate Ferroelectric Capacitors

1996 ◽  
Vol 433 ◽  
Author(s):  
L.H. Chang ◽  
W.A. Anderson
Keyword(s):  
Dielectric Constant ◽  
Lead Zirconate Titanate ◽  
Multilayer Structure ◽  
Layer Structure ◽  
Perovskite Phase ◽  
Processing Condition ◽  
Single Layer ◽  
Relative Dielectric Constant ◽  
Lead Zirconate ◽  
Effective Dielectric Constant

AbstractFerroelectric PbZrxT1−xO3 (PZT) thin films have been deposited on Pt coated Si substrates by if magnetron sputtering. The optimized processing condition to obtain proper stoichiometric PZT, the desired ferroelectric perovskite phase, and better dielectric properties was demonstrated using a PZT target with Pb(Zr+Ti) ratio of 1.2 and depositing at 350°C, followed by thermal treatment at 620°C for 30 min. The structural and electrical properties of the PZT layer were further improved by fabricating a novel multilayer structure which combined the PZT with the nanolayer BaTiO3. The leakage current density was reduced from 2×10−7 A/cm2 for the single layer structure to 2×10−9 A/cm2 for the multilayer structure at a field of 4×105 V/cm, while maintaining a high relative effective dielectric constant of 442. The relative dielectric constant of the PZT film in the multilayer structure was calculated to be about 880.

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