• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.2
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• pp.18-22
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• 2001

The thin films of high permitivity in ferroelectric materials using a capacitor are applied to DRAMs and FRAMs. (Ba, Sr)TiO$_3$ thin as ferroelectric materials were prepared by the sol-gel method and made by spin-coating on the Pt/Sio$_2$/Si substrate at 4,000 [rpm] for 10 seconds. The structural characteristics of the surface were analyzed by fractal dimension. The thickness of BST ceramics thin films was about 260∼280 [nm]. The property of the leakage current was stable with 10-9∼10-11[A] when the applied voltage was 0∼3[V]. BST thin films ha low leakage current properties when fractal dimension was low and a coating area was high.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.130-133
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• 2002

Solder leaching resistance of the metal electrode is an important factor with regard to adhesion properties of ceramic substrate. In the Low Temperature Co-fired Ceramics (LTCC), Ag-Pd or Ag-Pt pastes are used instead of pure Ag paste to prevent leaching. Solder leaching behavior of the Ag-Pd paste in relation to LTCC raw material powder size was investigated. First fabrication of LTCC green tape with different particle size was done. LTCC substrates with Ag-Pd electrode were prepared using conventional multilayer ceramic process. Dipping test was performed to test solder leaching behavior of the electrode. Ag-Pd electrode on LTCC substrate with smaller particle size achieved higher solder leaching resistance.

• Transactions on Electrical and Electronic Materials
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• v.6 no.2
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• pp.35-38
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• 2005

Pb(Zr$_{0.8}$Ti$_{0.2}$)O$_{3}$ powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT thick films were fabricated by the screen-printing techniques on Pt/Ah03 substrates. The structural properties were examined as a function of sintering temperature. The particle size distribution of the PZT powder derived from the sol-gel process is uniform with the mean particle size of about 2.6 m. As a result of the DTA, the formation of the polycrystalline perovskite phase was observed at around $890^{circ}$CC. In the X-ray diffraction analysis, all PZT thick films showed a perovskite polycrystalline structure without a pyrochlore phase. The perovskite crystallization temperature of PZT thick films was about $890^{circ}$C. The average thickness of the PZT thick films was approximately 80-90 m.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1586-1588
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• 2003

The Pb$(Zr{_{0.7}}Ti_{0.3})O_3$[PZT(70/30)] thin films were fabricated on Pt/$TiO_2/SiO_2$/Si substrate by RF sputtering method. The effects of Ar/$O_2$ ratio on the structural and dielectric properties of PZT thin fillms were investigated. In the case of the PZT thin films deposited with condition of 50/50$(Ar/O_2) $ ratio, the grain of the PZT thin films were fine and uniform. Increasing of $O_2$ ratio, the dielectric constant was increased. In this case the dielectirc constant and dielectric loss of PZT thin fims were about 627 and 0.010, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.209-210
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• 2006

Organic binders are usually pre-mixed with ceramic powders to enhance the formability during the shape forming process. These binders, however, must be eliminated before sintering in order to avoid pore formation and unusual grain growth during sintering. The present work was performed to investigate the effects of residual binder on grain growth behavior during sintering of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ piezoelectric ceramics. The microstructures of sintered samples were examined for various thermal processes and atmosphere at debinding. Addition of binder seems to promote abnormal grain growth especially in incompletely debinded regions and to make the grain shape change from corner-rounded to faceted.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.594-597
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• 2003

In the present study, the piezoelectricity and polarization of multilayer ceramic actuator, being designed to stack PMN-PZ-PT ceramic layers and Ag-Pd electrode layers alternatively, were investigated under a consideration of geometric factor, the volume ratio of the ceramic to the electrode layers. The actuators were fabricated by tape casting of 0.2Pb(Mg1/3Nb2/3)O3-0.38PbZrO3-0.42PbTiO3 followed by lamination and burnout & co-firing processes. The actuators of 10 10 0.62 nm3 in size were formed in a way that 60 200 m thick ceramics were stacked alternatively with 5 m thick electrode layer. Increases in polarization and electric field-induced displacement with thickness of the ceramic layer were attributed to change of 90o/180o domain ratio, which was affected by interlayer internal stress. The piezoelectricity and actuation behaviors were found to depend upon the volume ratio (or thickness ratio) of ceramic to electrode layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.359-360
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• 2005

PZT(20/80) and PZT(80/20) powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT(20/80)/PZT(80/20) heterolayered thick films were fabricated by the screen-printing method on Pt/$Al_2O_3$ substrates. The structural properties such as DTA, X-ray diffraction and microstructure, were examined as a amount of the excess PbO. In the DTA analysis, the formation of the polycrystalline perovskite phase was observed at around $880^{\circ}C$. The average thickness of the PZT heterolayered thick films was approximately $80{\mu}m$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.5
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• pp.259-264
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• 2000

In this paper, the characteristics of piezoelectric transformer is studied for driving CCFL(Cold Cathode Fluorescent Lamp). In order to investigate the effects of geometrical dimensions, λvibration-mode type piezoelectric transformers with different sizes in the length(l), width$(\omega)$ and thickness(t) are made of ceramics with PZT-PMWS compositions. The increases in temperature and aging effect are also measured in the transformer of PT-3 sample under the condition of operation continuously for 10 hrs. As the results of dimensional effects, the output power and voltage step-up ratio are largely affected by the ratio of length to thickness(l/t) rather than that of length to $width(l/\omega)$. The output power and step-up ratio are increased with increasing l/t. On case of PT-3, the output voltages are 510[Vrms] at 36[Vrms] in input voltage, $100[k\Omega]$ in load resistance. Temperature increases and variation of output voltages are $10[^{\circ}C]$ and less than 5[%], respectively.

• The Korean Journal of Ceramics
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• v.7 no.1
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• pp.20-25
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• 2001

PbTiO$_3$ thin films were prepared by low-pressure thermal plasma deposition on (100)Pt/(100)MgO substrates. Mist of source material in which metal alkoxides are dissolved in 2-methoxyethanol was introduced into plasma through heating furnace and deposited onto substrates at $600^{\circ}C$. As-deposited PbTiO$_3$/Pt/MgO thin film prepared at 1.33$\times$10$^4$ Pa was grown epitaxially, but was consisted of many rectangular shaped grains, with many grain boundaries and it was impossible to measure electric properties. As-deposited film prepared at 1.00$\times$10$^4$ Pa showed weak peaks of X-ray diffraction and the film was not grown epitaxially. On the other hand, the film after annealed at $700^{\circ}C$ showed strong diffraction peaks and epitaxial growth was also observed. For annealed film, moreover, no clear grain boundaries were observed. The value of ${\varepsilon}_r$, tan${\delta}$, Pr and Ec of annealed film were 160, 3.2%, 10.4${\mu}$C.cm$^-2$ and 51.2kV.cm$^-1$, respectively. Since the composition, Pb/Ti, measured by EDS attaching to SEM changed point by point, the distribution of composition in annealed film was investigated and found out several relations between composition and electric properties. At stoichiometric composition, Pr and Ec showed the lowest value and they gradually became large as composition deviated from stoichiometric one. Moreover, the value of ${\varepsilon}_r$ became gradually large as the ratio of Ti became high.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.195-201
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• 2003

The (Ba,Bi,Sr)TiO$_3$[BBST] thin films were fabricated on Pt/Ti/SiO$_2$ /Si substrate by RF sputtering method. The effects of Ar/O$_2$ ratio on the structural and dielectric properties of BBST thin films were investigated. Increasing the Ar/O$_2$ ratio, the intensity of BaBi$_4$Ti$_4$O$_{15}$ and Bi$_4$Ti$_3$O$_{12}$ peaks were increased but (Ba$_{0.5}$Sr$_{0.5}$)TiO$_3$ peak was decreased. In the BBST thin films deposited with condition of Ar/O$_2$(90/10) ratio, the composition ratio of the Ba, Bi and Sr atoms were 0.35, 0.25 and 0.4 respectively. The Bi and Ti atoms were diffused into the Pt layers. Increasing the Ar/O$_2$ ratio, the dielectric constant of the BBST thin films were increased but the dielectric loss of the BBST thin films were decreased. The dielectric constant and dielectric loss of the BBST deposited at 90/10 of Ar/O$_2$ ratio were 319 and 2.2%. respectively . Increasing the applied voltage, the capacitance of the BBST thin films were decreased.reased.