• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1986-1988
• /
• 1999

Ferroelectric lead zirconate titanate(PZT) thin films were prepared on various bottom electrodes by rf magnetron sputtering methode. The structural phase and surface morphology of the PZT thin films were largely affected by the bottom electrodes. P-E curves of PZT thin films deposited on Pt. $RuO_2$ and Ru/$RuO_2$ bottom electrode showed typical P-E hysteresis loop. The measure values of $P_r,\;E_c$ of the Ru/PZT/Ru/$RuO_2$ capacitor were $16.9{\mu}C/Cm^2$, 140kV/ cm, respectively. The Ru/PZT/Ru/$RuO_2$ capacitors were fatigue free uP to nearly $10^9$ switching cycle but Pt/PZT/Pt capacitor showed 34% degradation uP to $10^9$ switching cycle.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.341-344
• /
• 1999

The effects of post annealing treatments of ferroelectrlclty in PZT(P $b_{1.05}$(Z $r_{0.52}$, $Ti_{0.48}$) $O_3$ thin film deposited on Pt/ $SiO_2$/Si substrate by RF-Magnetron sputtering methode was Investigated. Analyses by RTA(Rapid Thermal Annealing) treatments reveled that the crystallization process strongly depend on the healing temperature. The Perovskite structure with strong PZT (101) plan was obtained by RTA treatments at 75$0^{\circ}C$ With increasing RTA temperature of PZI thin films, the coercive field and remanent Polarization decreased, while saturation polarization( $P_{r}$) was decreased. P-E curves of Pt/PZT/Pt capacitor structures demonstrate typical hysteresiss loops. The measure values of $P_{r}$,. $E_{c}$ and dielectric constants by post annealed at 75$0^{\circ}C$ were 38 $\mu$C/$\textrm{cm}^2$ 35KV/cm and 974, respectively. Switching polarization versus fatigue characteristic showed 12% degradation up to 10$^{7}$ cycles.s.s.s.s.s.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.93-96
• /
• 2002

In this study, PZT thin films were fabricated using sol-gel processing onto Si/$SiO_2$/Ti/Pt substrates. PZT sol with different Zr/Ti ratio(20/80, 30/70, 40/60, 52/48) were prepared, respectively. The films were fabricated by using the spin-coating method on substrates. The films were heat treated at $450^{\circ}C$, $650^{\circ}C$ by rapid thermal annealing(RTA). The preferred orientation of the PZT thin films were observed by X-ray diffraction(XRD), and Scanning electron microscopy(SEM). All of the resulting PZT thin films were crystallized with perovskite phase. The fine crystallinity of the films were fabricated. Also, we found that the ferroelectric properties from the dielectric constant of the PZT thin films were over 600 degrees, P-E hysteresis constant. And the leakage current densities of films were lower than $10^{-8}A/cm^2$. It is concluded that the PZT thin films by sol-gel process to be convinced of application for ferroelectric memory device.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.4
• /
• pp.269-273
• /
• 2001

W fabricated thin film using Na$_{0.5}$K$_{0.5}$NbO$_3$ volatile material by pulsed laser deposition (PLD) and studied characterization from EM, XRD, P-E. The density and scale of droplet, which is the defect of PLD, was investigated by SEM but large droplet was not found. The degree of assemble oriented C-axis measured with X-ray diffraction suggests that this film oriented C-axis achieved by $\theta$-2$\theta$ scan and rocking curves shows good self-assemble phenomenon, finally $\phi$-scan does that all of the four directions of the lattice in film equals to those of substrate. P-E hysteresis loop shows residual remnant polarization or saturation polarization value, but it is applicable to memories.ies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.118-121
• /
• 1999

PLZT thin films were fabricated with different energy density by pulsed laser deposition. PLZT films deposited on Pt/Ti/SiO$_2$/Sr substrate. This PLZT thin films of 5000$\AA$ thickness were crystallized at $600^{\circ}C$, 200mTorr $O_2$ pressure for 2 J/$\textrm{cm}^2$ laser energy density. 14/50/50 PLZT thin film showed a maximum dielectric constant value of $\varepsilon$$_{r}$=1289.9 P-E hysteresis loop of 14/ 50/50 PLZT thin film was slim ferroelectric. Leakage current density of 14/50/50 PLZT thin film was 10/ sup -7/=A/$\textrm{cm}^2$.>.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1424-1426
• /
• 2003

PMN-PZT 적충형 세라믹 액츄에이터 소자를 제작한후 그 열화 특성을 조사하였다. 액츄에이터는 tape casting 방법으로 green sheet를 제작한후, screen printing방법을 이용하여 전극형상을 만들고, lamination과 cutting공정을 통하여 소자를 제작하였다. 작된 소자의 구조적인 특성을 분석하기 위하여 X-ray diffractometer를 사용하였으며, Doppler effect를 사용하는 laser vibrometer를 이용하여 전압에 따른 변위량을 측정하였다. 제작된 소자의 열화 특성을 알아보기 위하여 60 Hz의 triangular 교류 파형을 적충형 세라믹 액츄에이터에 인가하여 열화전과 후의 P-E hysteresis loop의 변화를 살펴보았으며, unipolar AC 전압을 지속적으로 인가하여 소자를 depling 시킴으로써 열화현상을 관찰하였다. 파단면에 대한 SEM 분석을 통하여 소자의 파괴 메카니즘을 알아 보도록 하였다. 이로부터 전기적, 기계적 열화가 소자의 동작에 미치는 영향에 대해서 알아 보았다.

• Journal of the Korean Ceramic Society
• /
• v.37 no.7
• /
• pp.665-672
• /
• 2000

The ferroelectric YMnO3 thin films were prepared by MOD(metal-organic decomposition) method with Y- and Mn-acetylacetonate as starting materials. Thin films were grown on various substrates by spin-coating technique. The crystalline phases of the thin films were identified by X-ray diffractometer as a function of heat-treatment temperature, pH of coating solution and substrate. In addition, the effect of Mn/Y molar ratio(0.8~1.2) on the formation of hexagonal-YMnO3 phase was investigated. In forming highly c-axisoriented hexagonal-YMnO3 single phase, the Pt coated Si substrate was more effective than the bare Si substrate, and the optimum heat-treatment condition was at 82$0^{\circ}C$ for 30 min. Higher Mn/Y molar ratio within 0.8~1.2 and pH of YMnO3 precursor solution within 0.5~2.5 favored formation of ferroelectric hexagonal phase rather than orthorhombic phase. Leakage current density of the hexagonal-YMnO3 thin film formed on Pt(111)/TiO2/SiO2/Si substrate was low enough as 0.4~4.0$\times$10-8(A/$\textrm{cm}^2$) at 5 V and its remanent polarization(Pr), calculated from the P-E hysteresis loop, was 3 nC/$\textrm{cm}^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.236-236
• /
• 2008

(Bi,La)$Ti_3O_{12}$(BLT) thin film is one of the most attractive materials for ferroelectric random access memory (FRAM) applications due to its some excellent properties such as high fatigue endurance, low processing temperature, and large remanent polarization [1-2]. The authors firstly investigated and reported the damascene process of chemical mechanical polishing (CMP) for BLT thin film capacitor on behalf of plasma etching process for fabrication of FRAM [3]. CMP process could prepare the BLT capacitors with the superior process efficiency to the plasma etching process without the well-known problems such as plasma damages and sloped sidewall, which was enough to apply to the fabrication of FRAM [2]. BLT-CMP characteristics showed the typical oxide-CMP characteristics which were related in both pressure and velocity according to Preston's equation and Hernandez's power law [2-4]. Good surface roughness was also obtained for the densification of multilevel memory structure by CMP process [3]. The well prepared BLT capacitors fabricated by CMP process should have the sufficient ferroelectric properties for FRAM; therefore, in this study the electrical properties of the BLT capacitor fabricated by CMP process were analyzed with the process parameters. Especially, the effects of CMP pressure, which had mainly affected the removal rate of BLT thin films [2], on the electrical properties were investigated. In order to check the influences of the pressure in eMP process on the ferroelectric properties of BLT thin films, the electrical test of the BLT capacitors was performed. The polarization-voltage (P-V) characteristics show a decreased the remanent polarization (Pr) value when CMP process was performed with the high pressure. The shape of the hysteresis loop is close to typical loop of BLT thin films in case of the specimen after CMP process with the pressures of 4.9 kPa; however, the shape of the hysteresis loop is not saturated due to high leakage current caused by structural and/or chemical damages in case of the specimen after CMP process with the pressures of 29.4 kPa. The leakage current density obtained with positive bias is one order lower than that with negative bias in case of 29.4 kPa, which was one or two order higher than in case of 4.9 kPa. The high pressure condition was not suitable for the damascene process of BLT thin films due to the defects in electrical properties although the better efficiency of process. by higher removal rate of BLT thin films was obtained with the high pressure of 29.4 kPa in the previous study [2].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1993.05a
• /
• pp.100-103
• /
• 1993

Ferroelectric lean-titanate thin films were fabricated by sol-gel processing. Sol-gel derived $PbTiO_3$ thin films crystallized into the expected tetragonal perovskite structure when heated to $600^{\circ}C$ and above. The effects of annealing temperature on grain size made with SEM observation are reported. The films heated at $650^{\circ}C$ for 30min showed a square-type hysteresis loop with $P_r$ and $E_c$ of $11.5{\mu}C/cm^2$, 115kV/cm, respectively.

• Journal of the Korean Vacuum Society
• /
• v.5 no.1
• /
• pp.62-66
• /
• 1996

$(Ba_{1-x}Sr_xTiO_3$ (BST) thin films have been grown on Pt-coated MgO by metal -organic chemical vapor deposition. X-ray diffraction results showed that BST films were grown on a Pt/MgO substrate with (100) preferred orientation perpendicular to the surface. The lineawr relationship of P-E curve obtained form hysteresis loop measurement indicated that the BST films had a Curie transitions below room temperature . Films deposited at $900^{\circ}C$ exhibited a smooth and dense microstructure, a dielectric constant of 202, and a dissipation facotr of 0.02 at 100kHz. The leakage current density of the BST films is about $2\times10^{-10} \;A/\textrm{cm}^2$$ at an applied electric field of 0.2 MV/cm. The electrical behavior on the current-voltage characteristics is well explained by the bulk-limited Pool-Frenkel emission.