• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1048-1054
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• 1998

The effects of deposition temperature of Pt top electrodes on the electrical properties of Pb(Zr,Ti))$O_3$, (PZT) thin film were investigated. When the Pt top electrodes were deposited at substrate temperatures of $200^{\circ}C$ or above,the ferroelectric properties of the PZT thin film under the Pt electrode were severely degraded. Whereas those of the PZT film where the Pt electrodes were not deposited were not degraded. Water vapors which remained in the vacuum chamber were dissociated into hydrogen atoms by the catalysis of Pt top electrode, and those hydrogen atoms diffused into the PZT film and produced oxygen vacancies at high substrate temperature, resulting in the degradation of the ferroelectric properties of the PZT film located under the Pt electrode. Since the water vapors could not be dissociated into hydrogen atoms without the catalysis of Pt. the degradation of the PZT film did not take place where the Pt electrode were not deposited. The degraded feroelectric properties could be recovered by rapid thermal annealing (RTA) treatment. On the other hand. leakage current characteristics were improved with increasing the deposition temperature of Pt top electrodes.

• Journal of the Korean Ceramic Society
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• v.30 no.4
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• pp.332-338
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• 1993

TiN/Ti is the best buffer layer between PZT thin film and si substrate among the Ti, TiN, ZrN, TiN/Ti, ZrN/Ti. The amorphous PZT films deposited on TiN/Ti buffer layer directly transform into perovskite phase when rapid thermal annealed for 30sec above 55$0^{\circ}C$. As Rapid Thermal Annealing(RTA) temperature increased, the remanent polarization(Pr) and dielectric constant($\varepsilon$r) increased and then showed Pr=21 $\varepsilon$r=593 when rapid thermal annealed 80$0^{\circ}C$ for 30sec. On the contrary the leakage current increased with increasing RTA temperature due to the formation of void made by Pb evaporationand grain cohesion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.24-27
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• 1994

Variations with structural and electrical properties of Yttrium added PZT thin films were observed and measured respectively. Area of rosette was increased by Yttrium added and shapes of hysteresis curves were changed to slim type. $Y^{3+}$ ion substituted $Pb^{2+}$ ion and played the role of doner. Because the creation of space charges was restricted by Yttrium, degradation of remanent polarizations by cumutation of polarization reversals of PZT was protected. But coercive field was increased because of vacancies generated Yttrium added.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.641-643
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• 2003

The ferroelectric properties of PZT(53/47) thin film was investigated by methoxy enthanol solution based on sol-gel method. The thickness of each layer by spincoating 0.25M sol at one time was $0.1{\mu}m$ and crack-free film was formed. $LaNiO_3/Si(100)$ electrode and $Pt/Ti/SiO_2/Si(100)$ electrode was coated by PZT sol at several times. PZT orientation was confirmed as a method of XRD and coercive field(Ec) as well as remnant polarization(Pr) was investigated from hysterisis curve. As a result of XRD analysis, we can know that the orientation of on PZT/LNO/Si(100) is better than on $Pt/Ti/SiO_2/Si(100)$. The remnant polarization(Pr) in LNO electrode was $87.5{\mu}C/cm^2$ and $39.8{\mu}C/cm^2$ in Pt. From this figures, it is investigated that the Pr in LNO electrode was better than in Pt.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.47-52
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• 2002

A processing method is developed for preparing sol-gel derived $Pb(Zr_{1-x}Ti_x)O_3$ (x=0.5) thin films on Pt-Ir($Pt_{80}Ir_{20}$)-alloy substrates. The as-deposited layer was dried on a plate in air at $70^{\circ}C$. And then it was baked at $1500^{\circ}C$, annealed at $450^{\circ}C$ and finally annealed for crystallization at various temperatures ranging from $580^{\circ}C$ to $700^{\circ}C$ for 1hour in a tube furnace. The thickness of the annealed film with three layers was $0.3{\mu}m$. Crystalline properties and surface morphology were examined using X-ray diffractometer (XRD). Electrical properties of the films such as dielectric constant, C-V, leakage current density were measured under different annealing temperature. The PZT thin film which was crystallized at $600^{\circ}C$ for 60minutes showed the best structural and electrical dielectric constant is 577. C-V measurement show that $700^{\circ}C$ sample has window memory volt of 2.5V and good capacitance for bias volts. Leakage current density of every sample show $10^{-8}A/cm^2$ r below and breakdown voltage(Vb) is that 25volts.

• Transactions on Electrical and Electronic Materials
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• v.11 no.4
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• pp.182-185
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• 2010

$Pb_{0.99}[(Zr_{0.6}Sn_{0.4})_{0.9}Ti_{0.1}]_{0.98}Nb_{0.02}O_3$ (PNZST) thin films were deposited by radio frequency magnetron sputtering on a $(La_{0.5}Sr_{0.5})CoO_3$ (LSCO)/Pt/Ti/$SiO_2$/Si substrate using a PNZST target with an excess PbO of 10 mole%. The thin films deposited at the substrate temperature of $500^{\circ}C$ crystallized to a perovskite phase after rapid thermal annealing (RTA). The thin films, which annealed at $650^{\circ}C$ for 10 seconds in air, exhibited good crystal structures and ferroelectric properties. The remanent polarization and coercive field of the fabricated PNZST capacitor were approximately $20uC/cm^2$ and 50 kV/cm, respectively. The reduction of the polarization after $2.2\;{\times}\;10^9$ switching cycles was less than 10%.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1181-1187
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• 1999

PZT(53/47) precursor 1M sols were prepared using a diol based Sol-Gel process, and thin films were deposited by spin coating onto Pt/Ti/$SiO_2$/Si substrates. With a single coating, final film thickness of aproximately 0.9${\mu}m $ was achieved from diol-based PZT sol. Since PZT crystallized in a ferroelectric perovskite phase from an intermediate nonferroelectric pyrochlore phase, the effects of the presence of perovskite PZT seeds on the phase transformation of PZT were investigated. Seeded PZT films were prepared from the seeded PZT 1M sols in which seeds with less than 0.2${\mu}m $ in size and 1wt% were dispersed in n-propanol before mixing with the PZT stock solution. The seeding effects were confirmed by the fact that the formation temperature of perovskite phase decreased by 50$^{\circ}C$ with less than 1wt% seeds.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.3
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• pp.128-132
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• 2004

The perovskite ferroelectric materials of the PZT, SBT and BST series will attract much attention for application to ULSI devices. Among these materials, the BST ($Ba_0.6$$Sr_0.4$/$TiO_3$) is widely considered the most promising for use as an insulator in the capacitors of DRAMS beyond 1 Gbit and high density FRAMS. Especially, BST thin films have a good thermal-chemical stability, insulating effect and variety of Phases. However, BST thin films have problems of the aging effect and mismatch between the BST thin film and electrode. Also, due to the high defect density and surface roughness at grain boundarys and in the grains, which degrades the device performances. In order to overcome these weakness, we first applied the chemical mechanical polishing (CMP) process to the polishing of ferroelectric film in order to obtain a good planarity of electrode/ferroelectric film interface. BST ferroelectric film was fabricated by the sol-gel method. And then, we compared the surface characteristics before and after CMP process of BST films. We expect that our results will be useful promise of global planarization for FRAM application in the near future.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.36-36
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.05a
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• pp.25-25
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• 2001