• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.87-90
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• 2002

In recent year, BLT($Bi_{3.25}La_{0.75}Ti_{3}O_{12}$) has been one of promising substitute materials at the ferroelectric random access memory applications. We manufactured $Bi_{3.25}La_{0.75}Ti_3O_{12}$ Target with a ceramic process. The BLT target was sintered at ${1100^{\circ}C}$ for 4 hours. Using RF magnetron sputtering, a deposited BLT thin films were estimated about ferroelectric properly as a functions of post annealing temperatures. The BLT thin films showed a promoted ferroelectric characteristics at the post annealied sample of ${700^{\circ}C}$. This sample exhibited the (117) preferred crystal orientation, current density of $3{\times}10^{-8}A/cm^2$, a remanent polarization of $8{\mu}C/cm^2$ and a coercive field of 42.1 KV/cm respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.574-577
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• 2002

In recent year, BLT$(Bi_{3.25}La_{0.75}Ti_3O_{12})$ has been one of promising substitute materials at the ferroelectric random access memory applications. We manufactured $(Bi_{3.25}La_{0.75}Ti_3O_{12})$ Target with a ceramic process. The BLT target was sintered at $1100^{\circ}C$ for 4 hours. Using RF magnetron sputtering, a deposited BLT thin films were estimated about ferroelectric property as a functions of post annealing time. The BLT thin films showed a promoted ferroelectric characteristics at the post annealied sample for 30 minutes. This sample exhibited the (117) preferred crystal orientation, current density of $2{\times}10^{-8}A/cm^2$, a remanent polarization of $10{\mu}C/cm^2$ and a coercive field of 62.1 KV/cm respectively.

• Journal of the Korean Ceramic Society
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• v.40 no.12
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• pp.1189-1196
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• 2003

Ferroelectric B $i_{3.25}$L $a_{0.75}$ $Ti_3$ $O_{12}$ (BLT) solution was synthesized by sol-gel process. BLT thin films were deposited on Pt/Ti $O_2$/ $SiO_2$/Si substrates by spin-coating. In this experiments, Bi(TMHD)$_3$, La(III)2-Methoxyethoxide, and Ti(IV) i-propoxide were used as starting materials, which were dissolved in 2-Methoxyethanol. Rapid Thermal Annealing (RTA) was used to promote crystallization of BLT thin films. The thin films with RTA process were compared with those with non-RTA process on electrical properties. After RTA process, the remanent polarization value (2Pr) of BLT thin films annealed at 72$0^{\circ}C$ was 20.46 $\mu$C/$\textrm{cm}^2$ which was approximately 27% higher than that of non-RTA process at 5 V.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1450-1451
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• 2006

In this paper, we first applied the chemical mechanical polishing (CMP) process to the planarization of ferroelectric film in order to obtain a good planarity of electrode/ferroelectric film interface. $Bi_{3.25}La_{0.75}Ti_{3}O_{12}$ (BLT) ferroelectric fan was fabricated by the sol-gel method. Removal rate and non-uniformity (WIWNU%) were examined by change of silica slurries pH(10.3, 11.3, 12.3). Surface roughness of BLT thin films before and after CMP process was inquired into by atomic force microscopy (AFM). Effects of silica slurries pH(10.3, 11.3, 12.3) were investigated on the CMP performance of BLT film by the surface analysis of X-ray photoelectron spectroscopy(XPS).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.486-491
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• 2002

We have fabricated $Bi_{3.25}La_{0.75}Ti_3O_12$ (BLT) thin films on the Pt/Ti/$SiO_2$/Si substrates using a metalorganic decomposition (MOD) method with annealing temperature from $550^{\circ}C$ to $750^{\circ}C$. The structural properties of BLT films examined by x-ray diffraction (XRD). From XRD analysis. BLT thin films show polycrystalline structure. The layered-perovskite phase was obtained by spin-on films at above $600^{\circ}C$ for 1h. Scanning electron microscopy (SEM) showed uniform surface composed of rodlike grains. The grain size of BLT films increased with increasing annealing temperature. The BLT film annealed at $650^{\circ}C$ was measured to have a dielectric constant of 279, dielectric loss of 1.85(%), remanent polarization of $25.66\mu C/\textrm{cm}^2$, and coercive field of 84.75 kV/cm. The BLT thin films showed little polarization fatigue test up to $3.5{\times}10^9$ bipolar cycling at 5 V and 100 kHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.463-466
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• 2001

In recent year, Ferroelectric BLT($Bi_{4-x}$La$_{x}$Ti$_3$O$_{12}$) is a promising candidate materials. This study was Practiced to make good conditions of BLT targets. In this study, calcination and sintering temperature were kept at 75$0^{\circ}C$, 110$0^{\circ}C$ for 2 hour respectively. the density obtained 7.612, 7.98, 7.877 g/㎤ as La$_2$O$_3$ contents were 0.0mol%, 0.25mo1%, 0.5mol%. Especially, the lanthanum content of 0.5 mol% measured C-axis (117) preferred orientation more than the others targets in the XRD. In $\varepsilon$$_{r}$-f relationship using by HP 4194 A impedance analyzer, the 0.5 mol% observed above 200 relative dielectric constant. but the dissipation factor was higher than others targets at 100Hz~13MHz range. SEM photograph with the content of La$_2$O$_3$ was observed like rod and plate types.types.s.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.764-769
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• 2002

The effect of excess Bi contents on the ferroelectric properties of B $i_{3.25}$ L $a_{0.75}$ $Ti_3$ $O_{12}$ (BLT) thin films has been investigated. Bismuth lanthanum titanate thin films with excess Bi contents were prepared onto Pt/Ti/ $SiO_2$/Si substrate by metalorganic decomposition (MOD) technique. The structure and morphology of the films were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. From the XRD analysis, BLT thin films show polycrystalline structure and the layered-perovskite phase was obtained over 10% excess of Bi contents. As a result of ferroelectric characteristics related to the Bi content of the BLT thin film, the remanent polarization and dielectric constant decreased with increasing over Bi content of 10% excess. The BLT film with Bi content of 10% excess was measured to have a dielectric constant of 326 and dielectric loss of 0.024. The BLT thin films showed little polarization fatigue test up to 3.5$\times$10$^{9}$ bipolar switching cycling.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.183-186
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• 2004

The metal-ferroelectric-insulator-semiconductor(MFIS) capacitors were fabricated using a metalorganic decomposition (MOD)method. The $CeO_2$ thin films were deposited as a buffer layer on Si substrate and $Bi_{3.25}La_{0.75}Ti_3O_{12}$ (BLT) thin films were used as a ferroelectric layer. The electrical and structural properties of the MFIS structure were investigated by varying the $CeO_2$ layer thickness. The width of the memory window in the capacitance-voltage (C-V)curves for the MFIS structure decreased with increasing thickness of the $CeO_2$ layer. Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) show no interdiffusion by using the $CeO_2$ film as buffer layer between the BLT film and Si substrate. The experimental results show that the BLT-based MFIS structure is suitable for non-volatile memory field-effect-transistors (FETs) with large memory window.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.352-355
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• 2003

[ $Bi_{3.25}La_{0.75}Ti_3O_{12}$ ] (BLT) thin films were prepared by using metal organic decomposition method onto the LaNiO3 (LNO) bottom electrode. Both the structure and morphology of the films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). Even at low temperatures ranging from 450 to $650^{\circ}C$, the BLT thin films were successfully deposited on LNO bottom electrode and exhibited (117) orientation. The BLT thin films annealed as low as $600^{\circ}C$ showed excellent ferroelectricity, higher remanent polarization and no significant degradation of switching charge at least up to $5{\times}10^9$ switching cycles at a frequency of 100 kHz and 5 V. For the annealing temperature of $600^{\circ}C$, the remanent polarization $P_r$ and coercive field were $23.5\;{\mu}C/cm^2$ and 120 kV/cm, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.565-568
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• 2001

We have fabricated $Bi_{3.25}$$La_{0.75}$ti$_3$O$_{12}$ (BLT) thin(200nm) films on the Pt/Ti/SiO$_2$/Si substrates using a MOD(Metalorganic decomposition) method with annealing temperature from 55$0^{\circ}C$ to 75$0^{\circ}C$. The structural properties of the films examined by x-ray diffraction. The layered-perovskite phase obtained above $600^{\circ}C$. Scanning electron micrographs showed uniform surface composed of rodlike grains. The grain size increased with increasing annealing temperature. The BLT thin films showed little polarization fatigue test up to 3.5x10$^{9}$ bipolar cycling at a 5V and 100kHz.kHz.