• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.12
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• pp.1054-1059
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• 2002

A great deal of research has been done in the field of characterization for piezoelectric thin films after the first report on the measurement for the piezoelectric coefficient of thin films in 1990. The main idea of this research is to provide a distinctive solution for the measurement and standardization of both the longitudinal and the transverse piezoelectric d-coefficients, d33 and d31, of ferroelectric thin films. In general, to get these two coefficients of thin films, two different measuring systems are required. Here, we propose the improved method for the evaluation of these two coefficients with single equipment and with the relatively convenient procedure. The two-step loading process of applying the both positive and the negative pressure has been introduced to acquire the piezoelectric coefficients. These results have been calibrated for both the longitudinal and 4he transverse piezoelectric d-coefficients, d33 and 431, of thin films by comparison with the virtual standard created from FEM. In this experiments, we have obtained d33 of 331pC/N and 031 of -92.2pC/N for the PZT thin films.

• 한국가시화정보학회:학술대회논문집
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• 2002.04a
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• pp.1-7
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• 2002

This papers describes the preparation and experimental results of a micro mass detection devices based on cantilever and a diffuser-type micro pump using screen printing thick-film technologies and Si micro-machining. PZT-PCW thick films were prepared by new hybrid method based on the screen printing. By applying these PZT-PCW piezoelectric thick films on actuator, a cantilever for mass detection sensor and a micropump for microfluidic element are successfully fabricated. Resonant frequency and displacement of PZT-PCW thick film actuator in air and in liquid are measured by laser vibrometer system as a function of actuator size. The resonant frequency of PZT-PCW thick film actuator in liquid decreases order of 1/2-1/4 due to damping effect. The sensitivity of cantilever is characterized by Au deposition method which has the mass loading effect such as adsorption of protein. The Sensitivity of PZT-0.12PCW thick film cantilever is proportional to detecting area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.921-925
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• 2000

Characteristics of Pb(Mg, Nb)O$_3$-Pb(Zr, Ti)O$_3$system thick films fabricated by a screen printing method were investigated. The buffer layer were coated with various thickness of Ag-Pd by screen printing to investigate the effect as a diffusion barrier and deposited Pt as a electrode by sputtering on Ag-Pb layer. The printed thick films were burned out at 650$\^{C}$ and sintered at 950$\^{C}$ in O$_2$condition for each 20, 60min after printing with 350mesh screen. The thickness of piezoelectric thick film was 15∼20㎛ and Ag-Pb layer acted as a diffusion barrier above 3㎛ thickness. The PMN-PZT thick films were screen printed on Pt/Ag-Pb(6m) and sintered by 2nd step (650$\^{C}$/20min and 950$\^{C}$/1h) using paste mixed PMN-PZT and binder in the ratio of 70:30, and the remnant polarization of thick film was 9.1$\mu$C/㎠ in this conditions.

• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.1-4
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• 2004

Fabrication and electrical and mechanical properties of piezoelectric micro bending actuators (PMBA) using sol-gel-multi-coated thick PZT films and MEMS processes were investigated. PMBA could be used for design and fabrication of micro fluidic devices, for example, micro-pumps, micro dispensers, and so on. PMBA were fabricated using 2 um thick PZT films on Pt (350 nm)/$SiO_2$ (500 nm)/Si ($300\mu\textrm{m}$) substrates and MEMS processes. 7 types of PMBA were fabricated with areas of silicon diaphragms, PZT films and top electrodes. When the sizes of silicon diaphragms, PZT films and Pt top electrodes were reduced from 3000$\times$$1389\mu\textrm{m}$, 4000$\times$$1000\mu\textrm{m}$ and 4000$\times$$900\mu\textrm{m}$ down to 14%, 14% and 11 % of them, respectively, the center displacements of PMBA were decreased from 0.68 um to 0.10 um at 5 Hz and 12 Vpp. So, PMBA with large areas showed larger displacements than PMBA with small areas and experimental results were also good agreement with the plate and shell theory.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.966-970
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• 2006

We reported on characteristics of the piezoelectric ceramic-polymer composite for the application of the thick-film speaker. The PVDF-PZT composites were fabricated to incorporate the advantages of both ceramic and polymer with various mixing ratios by 3-roll mill mixer. The composite solutions were coated by the conventional screen-printing method on ITO electrode coated PET (Polyethylene terephthalate) polymer film. After depositing the top-electrode of silver-paste, 4 kV/mm of DC field was applied at $120^{\circ}C$ for 30 min to poling the composite films. The value of $d_{33}$ (piezoelectric charge constant) was increased when the PZT weight percent was increased. The maximum value of the $d_{33}$ was 24 pC/N at 70 wt% PZT. But the $g{33}$ (piezoelectric voltage constant) showed the maximum value of $32mV{\cdot}m/N$ at 65 wt% of PZT powder. The SPL (sound pressure level) of the speaker fabricated with the 65:35 composite film was about 68 dB at 1 kHz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.601-607
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• 2016

Piezoelectric thick films of soft $Pb(Zr,Ti)O_3$ (PZT) based commercial material (S55) were fabricated using a conventional tape casting method. Ag-Pd electrodes were printed on the piezoelectric film at room temperature and all 5 layered films with a dimension of $12mm{\times}16mm$ were successfully laminated for a multi-layered piezoelectric ceramic actuator. The laminated specimens were co-fired at $1,100^{\circ}C$ for 1 h. A flat layered and dense microstructure was obtained for the $112{\mu}m$ thick piezoelectric actuator after sintering process. Thereafter, a prototype piezoelectric speaker was fabricated using the multi-layered piezoelectric ceramic actuator which can operate as a bimorph. Its SPL (sound pressure level) characteristic was also evaluated for speaker application. Frequency response revealed that the output SPL with a root mean square voltage of 10 V increased gradually to the highest peak of 87.5 dB for 1.5 kHz and exhibited a relatively stable behavior over the measured frequency range (${\leq}20kHz$) at a distance of 10 cm, implying that the fabricated piezoelectric speaker is potential for speaker applications.

• Korean Journal of Materials Research
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• v.12 no.3
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• pp.211-214
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• 2002

Properties of 52/48 PZT films with various thicknesses for piezoelectric micro-electro mechanical systems (MEMS) devices fabricated by multi-coating method on $Pt(3500{\AA})/Ti(400{\AA})/SiO_2(3000{\AA})/Si$(525$\mu\textrm{m}$) substrates were investigated. PZT films were deposited by spin-coating process at 3500 rpm for 30 sec, followed by pyrolysis at 45$0^{\circ}C$ for 10 min producing the thickness of about 120nm. These processes were repeated 4, 8, 12, 16 and 20 times in order to have various thicknesses, respectively. Finally, they were crystallized at $650^{\circ}C$ for 30 min. All thick PZT films showed dense and homogeneous surface microstructures. Thick PZT films showed crystalline structures of random orientations with increasing thickness. Dielectric constants of thick PZT films were increased with increasing film thickness and reached 800 at 100kHz for 2.3$\mu\textrm{m}$ thick PZT film. $P_r\; and\; E_c$ of 2.3$\mu\textrm{m}$ thick PZT films were about 20$\mu$C/$\textrm{cm}^2$ and 63kV/cm. Depth profile analysis by Auger Electron Spectroscopy (AES) of 4800 $\AA$ thick PZT film showed the formation of the perovskite phase on Pt layer by Pb diffusion behavior. It was considered that Pb-Pt intermediate layer promoted PZT (111) columnar structures.

• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.418-424
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• 2008

The PZT based piezoelectric thick films prepared by screen printing method have been mainly used as a functional material for MEMS applications due to their compatibility of MEMS process. However the screen printed thick films generally reveal poor electrical and mechanical properties because of their porous microstructure. To improve microstructure we mixed attrition milled powder with ball milled powder of 0.01Pb$(Mg_{1/2}W_{1/2})O_3$-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3$-$0.35PbTiO_3$-$0.23PbZrO_3$+0.1 wt% ${Y_2}{O_3}$+1.5 wt% ZnO composition. By mixing 25 % of attrition milled powder and 75 % of ball milled powder, the broadest particle size distribution was obtained, leading to a dense thick film with crack-free microstructure and improved dielectric properties. The X-ray diffraction analysis revealed that the film was in wellcrystallized perovskite phase. The remanent polarization was increased from $13.7{\mu}C/cm^2$ to $23.3{\mu}C/cm^2$ at the addition of 25 % attrition milled powder.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.177-180
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• 2002

Thickness dependence of crystallographic orientation of diol based sol-gel derived PZT(52/48) films on dielectric and piezoelectric properties was investigated The thickness of each layer by one time spinning was about 0.2 $\mu\textrm{m}$, and crack-free films was successfully deposited on 4 inches Pt/Ti/SiO$_2$/Si substrates by 0.5 mol solutions in the range from 0.2 $\mu\textrm{m}$ to 3.8 $\mu\textrm{m}$. Excellent P-E hysteresis curves were achieved without pores or any defects between interlayers. As the thickness increased , the (111) preferred orientation disappeared from 1$\mu\textrm{m}$ to 3 $\mu\textrm{m}$ region, and the orientation of films became random above 3 $\mu\textrm{m}$. Dielectric constants and longitudinal piezoelectric coefficient d$\_$33/, measured by pneumatic method were saturated around the value of about 1400 and 300 pC/N respectively above the thickness of 0.8 7m. A micromachined piezoelectric cantilever have been fabricated using 0.8 $\mu\textrm{m}$ thickness PZT (52/48) films. PZT films were prepared on Si/SiN$\_$x/SiO$_2$/Ta/Pt substrate and fabricated unimorph cantilever consist of a 0.8 fm thick PZT layer on a SiNx elastic supporting layer, which becomes vibration when ac voltage is applied to the piezoelectric layer. The dielectric constant (at 100 kHz) and remanent polarization of PZT films were 1050 and 25 ${\mu}$C/$\textrm{cm}^2$, respectively. Electromechanical characteristics of the micromachined PZT cantilever in air with 200-600 $\mu\textrm{m}$ lengths are discussed in this presentation.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.83-89
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• 2015

In this paper, we propose a fabrication technique for enhanced electrical properties of piezoelectric thick films with excellent patterning property using sol-infiltration and a direct-patterning process. To achieve the needs of high-density and direct-patterning at a low sintering temperature (< $850^{\circ}C$), a photosensitive lead zirconate titanate (PZT) solution was infiltrated into a screen-printed thick film. The direct-patterned PZT films were clearly formed on a locally screen-printed thick film, using a photomask and UV light. Because UV light is scattered in the screen-printed thick film of a porous powder-based structure, there are needs to optimize the photosensitive PZT sol infiltration process for obtaining the enhanced properties of PZT thick film. By optimizing the concentration of the photosensitive PZT sol, UV irradiation time, and solvent developing time, the hybrid films prepared with 0.35 M of PZT sol, 4 min of UV irradiation and 15 sec solvent developing time, showed a very dense with a large grain size at a low sintering temperature of $800^{\circ}C$. It also illustrated enhanced electrical properties (remnant polarization, $P_r$, and coercive field, $E_c$). The $P_r$ value was over four times higher than those of the screen-printed films. These films integrated on silicon wafer substrate could give a potential of applications in micro-sensors and -actuators.