Lead Zirconate Titanate Thick Films Research Articles

Fabrication of Lead Zirconate Titanate Thick Film Disks for Micro Transducer Devices

ABSTRACTA combination of the preparation techniques for the ferroelectric films and the micro machining of Si is considered to be an effective way to fabricate microelectromechanical systems (MEMS), such as piezoelectric micro-transducer devices for the electrical and medical fields. In this study, 10-μm-thick disk shape lead zirconate titanate (PZT) thick films were successfully fabricated using a chemical solution deposition (CSD) process. Pt top electrode and PZT layer were etched by reactive ion etching (RIE) process, and 100 to 500-μm-diameter PZT micro disks were fabricated on Pt/SiO2/Si substrate. The relative dielectric constant, dissipation factor, remnant polarization and coercive field were εr = 1130, tanδ = 0.02, Pr = 14 μC/cm2 and Ec = 25 kV/cm, respectively. This means that the ferroelectric and dielectric properties of the PZT micro disks were comparable with that of the bulk PZT ceramics. The PZT micro disk showed the butterfly-shaped displacement curve, related with piezoelectric response, in the case of bipolar measurement. The piezoelectric constant of the PZT disks poled at 80Vfor 10 min was estimated to be AFM d33 = 221 pm/V. A resonance frequency of the radial oscillation was evaluated to apply for micro transducer devices.

PZT Thick Films Deposited by Improved Hydrothermal Method for Thickness Mode Ultrasonic Transducer

ABSTRACTThe purpose of this study was to improve deposition rate of the hydrothermal method for lead zirconate titanate (PZT) thick film on titanium substrate. We developed a high-speed rotaion substrate holder at a tangential velocity of about 0.8m/s in autoclave. A titanium substrate was fixed by the holder on the surface of a stirring bar. For the film deposition, powder of TiO2 was used instead of the liquid TiCl4. The deposition rate on titanium substrate was improved up to 7μm/24h. Piezoelectric constant d31 of the hydrothermal PZT film was -2.6 × 1011 V/m. This result was lower than that of PZT ceramics. However, this hydrothermal method obtained thick film and this film was confirmed to be polycrystalline PZT analyses of XRD and SEM. In addition, performance of thickness mode vibration of hydrothermal PZT 50μm thick film was investigated by radiating in water. The phase velocity of dilatational wave of the thickness mode vibration of the hydrothermal PZT film was 1800m/s and the electromechanical coupling factor was 47%.

Powder Preparation in Aerosol Deposition Method for Lead Zirconate Titanate Thick Films

The influence of a pre-process for a starting powder in the deposition of ferroelectric thick films using the aerosol deposition method (ADM) was investigated. When a dry-milling procedure was introduced to the preparation of the ferroelectric powder, the deposition rate of ADM increased significantly up to 30-fold and reached 73 µm/min for a 5 mm2 area. However, density and electrical properties of the thick film decreased. If heat treatment at 800°C for 4 h was additionally introduced to the pre-process of the starting powder, the deposition rate increased up to 7–10-fold as compared with that for a starting powder and the electrical properties were improved from Pr=20 µC/cm2 at Ec=50 kV/cm to 32 µC/cm2 at Ec=45 kV/cm.

Low Temperature Processing of Nanocrystalline Lead Zirconate Titanate (PZT) Thick Films and Ceramics by a Modified Sol-Gel Route

Dispersing fine particles into a sol-gel matrix is a promising process to get a thick 0–3 composite coating layer. In this paper, we have further improved this modified sol-gel process by nanocrystalline composite technique to realize the low temperature annealing. Dense Pb(Zr, Ti)O3 (PZT) thick films of 10 to 50 µm in thickness have been obtained on the platinum-coated silicon substrates by spin-coating at sintering temperature of 600–700°C and fully developed submicron-sized grains have been demonstrated in screen-printing piezoelectric films on alumina substrates at sintering temperature of 700–800°C. The dependence of various properties such as microstructure, crystallization, ferroelectric and dielectric properties of such made thick films on the processing parameters have been investigated. For a 10 µm-thick film spin-coated on silicon wafer, the dielectric loss and relative permittivity are 0.010 and 1024, respectively, at 1 kHz. The remanent polarization (Pr) and the coercive field (Ec) are 13.6 µC/cm2 and 34.5 kV/cm, respectively. Obviously, such made thick film has comparable properties with bulk PZT ceramic. This novel technique can be extensively used in sol-gel, screen-printing, tape-casting, even in traditional ceramic process to reduce the process temperature.

Lead Zirconate Titanate Thick Film Prepared by Electrophoretic Deposition from Oxide Mixture

Lead zirconate titanate (PbZr0.52Ti0.48O3; PZT) thick film with a thickness of 70 µm was prepared by the electrophoretic deposition method from a raw oxide mixture of PbO, ZrO2, and TiO2. X-ray diffraction and scanning electron microscopy were used to characterize the sintered PZT thick film. Single phase PZT was observed in the films sintered at 900 °C and above. The film sintered at 1000 °C for 30 min exhibited a dielectric constant of 1050 with a dielectric loss of about 0.05 measured at 1 kHz, a maximum polarization of 29 µC/cm2, a remnant polarization of 19 µC/cm2, and a coercive field of 21 kV/cm. This simple process to form PZT thick films may also be applied to the preparation of other multicomponent ceramics and ceramic films.

Microelectromechanical systems (MEMS) accelerometers using lead zirconate titanate thick films

MEMS accelerometers based on piezoelectric lead zirconate titanate (PZT) thick films with annular diaphragm sensing structures were designed, fabricated, and tested. Theoretical and numerical models for this new inertial sensing structure are presented. The design provides good sensitivity along one axis, with low transverse sensitivity and good temperature stability. Test results show high sensitivities and broad usable frequency ranges. Measured sensitivities range from 0.77 to 7.6 pC/g for resonant frequencies from 35.3 kHz to 3.7 kHz. Reasonable agreement with theoretical values was obtained.

PZT THICK FILMS FABRICATION USING A SOL-GEL BASED 0-3 COMPOSITE PROCESSING

A sol-gel based 0-3 ceramic-ceramic composite processing has been applied to fabricate lead zirconate titanate thick films with a composition near the morphotropic phase boundary, PZT53/47. In order to eliminate the effects of humidity on the stability of the sols, solid PZT precursors are prepared from partially stabilized titanium isopropoxide, lead acetate trihydrate and zirconium acetylacetonate without any solvent. Then the solid precursors were dissolved in 2-methoxythanol to form sols. Certain quantum modified PZT ceramic powder was dispersed into this obtained solution. Crack-free thick films with series thickness of 5 ~ 20-μm were fabricated using spin-coating method. The surface morphology and structural properties of the films were studied with Field Emission-SEM and X-ray diffraction techniques respectively. Electrical properties were compared with those of thin films. Thick PZT films should have good perspective in the application of new piezoelectric devices that cannot be achieved using conventional thin film or bulk techniques.

Lead Zirconate Titanate Thick Films Fabricated from Sols with and without Its Powder

Sol modified with diethanolamine was used for the preparation of thick lead zirconate titanate (PZT) films. The deposited films crystallized in the perovskite structure by heating above 600°C. Thick film with 3 µm single-coating thickness was obtained using a dip-coating of sol containing PZT powder. The resultant thick films were porous and the pores could not be filled with a cover coating of powder-free sol. The dielectric properties of the thick and porous films prepared using powder-containing sols were poor, although they exhibited ferroelectric polarization–electric field (P–E) hysteresis. Using the powder-free sol, a film with thickness >1 µm was realized on the Sn-doped In2O3(ITO)/glass substrate by a single deposition. The resultant film was dense and about 5.6 µm thick after five depositions. The film showed a saturated ferroelectric P–E hysteresis curve and the dielectric constant, loss tangent, and remanent polarization were 840, 0.03, and 34 µC/cm2, respectively.

Effects of annealing and poling conditions on piezoelectric properties of Pb(Zr 0.52,Ti 0.48)O 3 thick films formed by aerosol deposition method

Lead zirconate titanate (PZT) thick films were formed on several kinds of substrates by impact consolidation of PZT ultrafine particles through an aerosol deposition method. The PZT layers were shown to have a high breakdown voltage of about 700 kV/cm after annealing at temperatures from room temperature to 1000°C. After annealing at 600–1000°C for 1 h in air and poling at 250°C 40 kV/cm for 30 min, the layers had good piezoelectric properties: – d 31∼100 pm/V, which did not change with fatigue testing up to 10 9 cycles.

Fabrication and electrical properties of lead zirconate titanate thick films by the new sol–gel method

Lead zirconate titanate (Pb(Zr 0.53Ti 0.47)O 3, PZT) ferroelectric films with 2–60 μm in thickness have been successfully fabricated on Pt-coated oxidized Si substrates(Pt/Ti/SiO 2/Si) by a new sol–gel based 0-3 method. The films consisted of 0-3 ceramic/ceramic composites formed by dispersing nanopowders in a PZT solution. The precursor solution for spin coating was prepared from lead acetate, tetrabutyl titanate, and zirconium nitrate. The microstructure and morphology of the prepared PZT thick films were investigated by X-ray diffractometry and scanning electron microscopy techniques. The XRD analysis indicates that the thick films possess single-phase perovskite type structure and no pyrochlore phase exists. The SEM micrograph shows that the PZT thick films were of uniformity, density and crack-free. Dielectric constant of 860, loss tangent of 0.03, remnant polarization of 25 μC cm −2, a coercive field of 40 kV cm −1 were obtained on 50 μm thick films annealed at 700 °C.

Preparation of Lead Zirconate Titanate Thick Films by Arc-Discharged Reactive Ion-Plating Method

Lead zirconate titanate (PZT) thick films of 1 to 3 µm thickness were prepared by an arc-discharged reactive ion-plating (ADRIP) method. Each PZT thick film had a columnar dense structure. The films showed a perovskite single phase without any thermal treatment after deposition. A high plasma density of the arc discharge enabled a high deposition rate of more than 3 µm/h. The relative dielectric constant (εr) of the PZT thick films with the Zr/Ti=53/47 composition was about 2000. This value was almost equivalent to that of PZT bulk ceramics. The films typically showed well-saturated P-E hysteresis curves with the remanent polarization (Pr) of 44 µC/cm2 and the coercive field (Ec) of 39 kV/cm. The butterfly-shaped property of the displacement curve, which is caused by the bending motion in the vertical direction on the film surface, was also observed. Furthermore, the PZT thick films with the (100)-dominant orientation could be obtained by depositing them onto (100)-preferred PZT thin layers which were prepared by a chemical solution deposition (CSD) process.

Ferroelectric and Displacement Properties of Lead Zirconate Titanate Thick Films Prepared by Chemical Solution Deposition Process

AbstractCrack free 10-μm-thick Pb1.1(Zr0.53Ti0.47)O3 (PZT) films were successfully fabricated using a chemical solution deposition process, and the ferroelectric and displacement properties were evaluated. A 0.5 M PZT precursor solution was prepared from trihydrated lead acetate, titanium iso-propoxide, zirconium n-propoxide, and 2-methoxyethanol as the solvent. The process of spin coating and pyrolysis at 500 °C was repeated five times, and then the precursor films were fired at 700 °C for 5 min. This sequence was repeated 30 times. Finally, the films were fired at 700 °C for 10 min. The fabricated crack-free PZT thick films showed (100) preferred orientation. A flat surface and dense microstructure was observed. The electrical properties were comparable with the bulk PZT ceramics. The dielectric constant and dissipation factor were εr = 1453 and tan δ = 0.039, and the remnant polarization and coercive field were Pr = 25 μC/cm2 and Ec = 30 kV/cm, respectively. Field-induced displacement of the films was measured using an atomic force microscope (AFM) with and without a top electrode using a contact mode.

Fabrication and electrical properties of lead zirconate titanate thick films using a new sol-gel processing technique

Lead zirconate titanate (Pb (\( \left( {Zr_{0.53} Ti_{0.47} } \right)O_3 \), PZT) ferroelectric films 2–60 μm in thickness have been successfully fabricated on Pt-coated oxidized Si substrates \( \left( {Pt/Ti/SiO_2 /Si} \right) \) by a new sol-gel-based process. The films are a 0-3 ceramic–ceramic composite formed by dispersing ceramic powders in a sol-gel solution. The precursor solution for spin coating was prepared from lead acetate, tetrabutyl titanate, and zirconium nitrate. The microstructure and morphology of the prepared PZT thick films were investigated via X-ray diffractometry (XRD) and scanning electron microscopy techniques. XRD analysis shows that the thick films possess single-phase perovskite-type structure, no pyrochlore phase exists in thick films, and SEM micrographs suggest that the PZT thick films were uniform, dense, and crack free. A dielectric constant of 860, loss tangent of 0.03, remanent polarization of \( 25\mu Ccm^{ - 2} \), and a coercive field of \( 40kVcm^{ - 1} \) were measured on 50 μm thick films.

Fabrication of MEMS Tonpilz Transducers

AbstractTonpilz transducers consist of a heavy tail mass, a piezoelectric spring, and a light head mass. Miniaturized tonpilz transducers are potentially interesting for the 10 to100 MHz frequency range in imaging transducers due to their high efficiency and output capabilities. Piezoelectric thin films can be used as the active element in the construction of miniaturized tonpilz structures. A 4-10 νm film is necessary for the mass-spring-mass system to resonate at these high frequencies. In this work, fabrication and characterization of lead zirconate titanate (PZT) thick films on conductive oxide LaNiO3 (LNO) coated silicon on insulator (SOI) substrates will be reported for this application. First, conductive LNO thin films, approximately 300 nm in thickness, were grown on SOI substrates by a metal-organic decomposition (MOD) method. The room temperature resistivity of the LNO was 6.5×10-4 ωcm. Randomly oriented PZT (52/48) films up to 7 νm thick were then deposited using a sol-gel process on the LNO coated SOI substrates. 20 mol.% excess lead was added to the solutions to compensate for lead volatilization during film heat treatments. PZT films with LNO bottom electrodes showed good dielectric and ferroelectric properties. The dielectric permittivity (at 1 kHz) was over 1000. The remanent polarization of PZT films was larger than 26 νC/cm2. The e31,f coefficient of PZT thick films was larger than –6.5 C/m2 when poled at -75 kV/cm for 15 minutes. A silver layer approximately 40 νm thick was screen- printed onto the PZT film to form the tail mass of the tonpilz structure. Elements were diced and the bulk silicon was removed by dry and wet-etching methods to leave the p-type silicon layer as tonpilz head mass. Fabrication of MEMS tonpilz microstructures will also be presented.

Microstereolithography of lead zirconate titanate thick film on silicon substrate

The microstereolithography (μSL) of lead zirconate titanate (PZT) thick films on platinum-buffered silicon substrates is reported for the first time in this paper. Crack-free PZT thick films (80–130 μm thick) have been fabricated by laser direct-write UV polymerization from the HDDA-based UV curable PZT suspensions. The characterization of the fired films shows dielectric permittivities of 120–200, tangent loss of 0.92–2.5% and remnant polarization of 0.9–1.7 μC/cm 2. The field-induced longitudinal piezoelectric coefficient ( d 33) of an 84-μm thick film is 100 pC/N and the piezoelectric voltage coefficient ( g 33) is about 59.5×10 −3 V m/N. These results demonstrated the potential for μSL of advanced piezoelectric microsensors and microactuators.

Actuation Properties of Lead Zirconate Titanate Thick Films Structured on Si Membrane by the Aerosol Deposition Method

The results of the direct deposition of lead zirconate titanate [Pb(Zr0.52, Ti0.48)O3] (PZT) thick film on a Si-based structure are presented. The construction of a bottom electrode is very important for successful deposition. The actuation properties of PZT on the Si membrane were investigated. For a 6.2×6.1 mm2, 65-µm-thick Si membrane driven by a 4.7×4.3 mm2, 13-µm-thick PZT layer, the deflections, which were 1.5 µm upon applying 52 V at nonresonance frequency and 22 µm upon applying 8 V at resonance frequency, were measured.

Residual Stress Analysis of Pt Bottom Electrodes on ZrO2/SiO2/Si and SiO2/Si Substrates for Pb(ZrTi)O3 Thick Films

We fabricated Pt bottom electrodes on SiO2/Si and ZrO2/SiO2/Si substrates by DC magnetron sputtering. The residual stress of the Pt layers deposited on SiO2 and ZrO2/SiO2 diffusion barrier layers was measured by an X-ray diffractometer (XRD). The Pt layers deposited at 400°C exhibited tensile residual stress, but the Pt layers deposited at room temperature exhibited compressive residual stress. Lead zirconate titanate (PZT) thick films were fabricated on the Pt electrodes by a screen printing method. The dielectric permittivity, tan δ, P–E hysteresis loop, breakdown field, coercive field and piezoelectric constant were measured for the PZT thick films. A PZT thick film on Pt/ZrO2/SiO2/Si displaying a low tensile residual stress exhibited the remanent polarization, coercive field, dielectric permittivity (εr), dissipation factor (tan δ), breakdown field and piezoelectric constant (d33) of 13 µC/cm2, 8.5 kV/cm, 800, 0.015, 12 MV/m and 343 µC/N, respectively.

Patterning Properties of Lead Zirconate Titanate (PZT) Thick Films Made by Aerosol Deposition

Factors responsible for a sidewall formation of thick PZT films prepared by impact based deposition technique were experimentally investigated. An inclination of patterns sidewall is mainly determined by velocity of the impacted particles. For 100μm film obtained by aerosol deposition method a pattern with the sidewall angle 600 was achieved.

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

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.

Fabrication of PZT Thick Films on Silicon Substrates for Piezoelectric Actuator

In recent years, there has been an increased interest in ferroelectric lead zirconate titanate (PZT) films for applications in piezoelectric devices. Many potential applications require a film thickness of about 10 μm for higher force, better sensitivity and stability. In this study we fabricate lead zirconate titanate (PZT) thick films by screen printing on silicon substrates with a platinum bottom electrode. Various substrates were studied. The longitudinal piezoelectric coefficient, d33, was measured by the normal load testing method. Breakdown voltage, tan δ, P-E hysteresis loop and permittivity were measured on the PZT thick films. The results are promising for the use of PZT thick films in various applications, for example, in silicon micromachined micro-pump.