• Journal of the Korean Vacuum Society
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• v.8 no.2
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• pp.111-115
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• 1999

The structural characteristics of an epitaxial $BaTiO_3$ film on MgO(001) grown by sputtering were studied as a function of temperature using in-situ, real time synchrotron x-ray scattering experiments. We found that the as-grown film was single c-domain but strained at room temperature and tetragonally distorted with the c-axis normal to the film surface. Interestingly, its lattice parameters were found to be expanded in both the in-plane and the out-of -plane directions, i.e. biaxially, comparing with those of a bulk $BaTiO_3$ . More importantly, as it was heated up to $600^{\circ}C$, the tetragonal structure was kept up through without and any phase transition, which is usually observed in other epitaxial ferroelectric thin films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.339-342
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• 1998

Ferroelectric L $a_2$ $Ti_2$ $O_{7}$(LTO) thin films were prepared by chemical solution deposition processes. Acetylacetone was used as chelating agent and nitric acid was added in the stock solution to control hydrolysis and condensation reaction rate. The LTO thin films were spin-coated on Pt/Ti/ $SiO_2$/(100)Si and Pt/Zr $O_2$/ $SiO_2$/(100)Si substrates. After multiple coating, dried thin films were heat-treated for decomposition of residual organics and crystallization. The role of acetylacetone in Ti iso-propoxide stabilization by possibly substituting $O^{i}$Pr ligand was studied by H-NMR. B site-rich impurity phase, i.e. L $a_4$ $Ti_{9}$ $O_{24}$, was found after annealing, where its appearance was dependent on process temperature indicating the possible reaction with substrate. Dielectric and other relevant electrical properties were measured and the results were compared between modified sol-gel and MOD processes.s.s.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.261-266
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• 1995

In this study, PZT solutions added impurities of Yttrium acetate were prepared by sol-gel processing and were deposited on Pt/ $SiO_{2}$/Si substrates at 5000 rpm for 20 sec. using spin-coating method. Coated films were annealed at 700-750.deg. C for 30 min. using conventional furnace method. Variations of the crystallographic structure and microstructure of PZT thin films with adding impurities were observed using XRD and SEM, and the electrical properties, such as relative permittivity, tan .delta., hysteresis curves and leakage currents, were measured. As the yttrium contents were increased, the remanent polarization and coercive field were decreased. Variations of remanent polarizations and coercive fields of pure and yttrium doped specimens according to polarization reversal cycles were observed using hysteresis measurement. PZT thin films added $Y^{3+}$ ions were completely crystallized at 750.deg. C. $Y^{3+}$ ions, as donor impurity, substituted Pb.sup 2+/ ions located at A-site of perovskite structure. By substitution of $Y^{3+}$ ions, leakage currents became less by decreasing the space charges. Degradation of remanent polarizations of Yttrium added specimens after fatigue was not observed and coercive fields increased more than those of pure PZT thin films.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.17-22
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• 2006

Ferroelectric PZT thin films were formed by 2-step sputtering and their dielectric properties and conduction mechanisms were investigated. Also. donor impurity doping was tried to compensate the carriers in PZT thin films. The leakage current density was able to reduce to $10^{-7}A/cm^2$ order by 2-step sputtering with thickness control of room temp.-layer. The conduction mechanism was confirmed as bulk-limited, and optimum donor impurities on PZT thin film were taken. Especially, leakage current characteristics was improved to $10^{-8}A/cm^2$ order in donor-doped PZT thin films formed by 2-step sputtering.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.13-17
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• 2004

The PZT thin films are well-known material that has been widely studied for ferroelectric random access memory (FRAM). We etched the PZT thin films by $CF_4/(Cl_2+Ar)$ plasma and investigated improvement in etching damage by $O_2$ annealing. PZT thin films were etched for 1 min in an ICP using a gas mixture of $Cl_2$(80%)/Ar (20%) with 30% $CF_4$ addition. The etching conditions were fixed at a substrate temperature of $30^{\circ}C$, an rf power of 700 W, a dc-bias voltage of -200 V and a chamber pressure of 2 Pa. To improve the ferroelectric properties of PZT thin films after etching, the samples were annealed for 10 min at various temperatures in $O_2$ atmosphere. After $O_2$ annealing, the remanent polarization, fatigue, and the leakage current were gradually recovered to the characteristics of the as-deposited film, according as the temperature increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.168-170
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• 1994

Pb($Zr_{0.52}$$Ti_{0.48}$)$O_3$ ceramic thin films were fabricated from an alkoxide-based solution by Sol-Gel method. Pb($Zr_{0.52}$$Ti_{0.48}$)$O_3$ ceramic thin films were formed by spin coating method on Pt/$SiO_2$Si substrate at 4000ppm for 30 seconds. The coating process was repeated 6 times and then heat-treated at temperature between 500∼800[$^{\circ}C$] for 1 hour. The final thickness of the thin films were about 4800[A]. The ferroelectric perovskite phases precipitated under the heat-treated at 700[$^{\circ}C$] for 1 hour. Pb($Zr_{0.52}$$Ti_{0.48}$)$O_3$ thin films heat-treated at 700[$^{\circ}C$] for 1 hour showed good dielectric and ferroclectric properties.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.72-72
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• 1999

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.05a
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• pp.110-110
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• 2001

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.153.1-153.1
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2004.04b
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• pp.40.3-40.3
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• 2004