• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.186.1-189
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• 2001

Ferroelectric $Bi_{4-x}$La$_{x}$Ti$_3$O$_{12}$ (BLT)thin films with various compositions(x=0.65, 0.70, 0.75) were prepared on Pt//Ti/SiO$_2$/Si(100) substrate by metal-organic deposition. The electrical and structural characteristics of BLT thin films were investigated to develop ferroelectric thin films for capacitor layers of FRAM. After spin coating, thin films were annealed at $650^{\circ}C$ for 1hour in oxygen atomosphere. Scanning electron micrographs showed uniform surfaces composed of rod-like grains. The $Bi_{4-x}$La$_{x}$Ti$_3$O$_{12}$ (x=0.70) thin film capacitors with a Pt top electrode showed better ferroelectric properties than other films. At the applied voltage of 5V, the dielectric constant($\varepsilon$$_{r}$), dissipation factor(tan$\delta$),remanent polarization(2Pr), and coercive field(2Ec) of the $Bi_{4-x}$La$_{x}$Ti$_3$O$_{12}$ (x=0.70)thin films were about 272.54, 0.059, 32.4 $\mu$C/cm$^2$, 2Ec=119.9kV/cm. Also the capacitor did not show any significant fatigue up to 4.8$\times$10$^{10}$ read/write switching cycles.hing cycles.s.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1321-1322
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• 2007

$Ar/Cl_2$, $Ar/CH_4$ 및 $Ar/Cl_{2}/CH_{4}$ 유도결합 플라즈마의 가스 혼합비에 따른 BLT 박막의 식각 메커니즘과 선택비, 식각 후 박막 표면의 조성변화를 조사하였다. BLT 박막의 최대식각률은 $Ar/Cl_2$ 플라즈마에서의 Ar 가스 혼합비가 80%일 때 50.8 nm의 값을 보였다. 이 때, 1sccm의 $CH_4$ 첨가를 통하여 선택비와 식각률을 개선할 수 있었다. 박막 표면의 xPS 분석을 통해 BLT 박막 표면의 조성변화는 Cl 원자와의 반응에 의한 화학적 식각 손상이 H 원자와의 반응에 의한 그것보다 크다는 것을 알 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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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 $550^{\circ}C$ to $750^{\circ}C$. 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 $3.5{\times}10^{9}$ bipolar cycling at a 5V and 100kHz.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.49-52
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• 2003

The role of gas ratio with the crystallization behavior and electrical properties in $Bi_{3.25}La_{0.75}Ti_3O_{12}$(BLT) thin films by rf magnetron sputtering method has not been precisely defined. In this work, the ferroelectric properties of these films with gas variation was investigated. BLT thin films were deposited on the Pt/Ti bottom electrode by rf magnetron sputtering method and then they were crystallized by rapid thermal annealing (RTA). The experiment showed that all BLT films indicated perovskite polycrystalline structure with preferred orientation (020) and (0012). And no pyrochlore phase was observed. The fabricated film annealed with $O_2$ of 15 sccm showed that value of leakage current was $9.67{\times}10^{-7}A/cm^2$ at 50kV /em, and the value of remanent polarization (2Pr=Pr+-Pr-) was $11.8{\mu}C/cm^2$. Therefore we induce access to memory device application by rf-magnetron sputtering method in this report.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.851-856
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• 2003

We have investigated the material and electrical properties of $Bi_{4-x}La_xTi_3O_{12}$ (BLT) ferroelectric thin film for ferroelectric nonvolatile memory applications of capacitor type and single transistor type. The 120nm thick BLT films were deposited on $Pt/Ti/SiO_2/Si$ and $SiO_2/Nitride/SiO_2$ (ONO) substrates by the sol-gel spin coating method and were annealed at $700^{\circ}C$. It was observed that the crystallographic orientation of BLT thin films were strongly affected by the excess Bi content and the intermediate rapid thermal annealing (RTA) treatment conditions regardeless of two type substrates. However, the surface microstructure and roughness of BLT films showed dependence of two different type substrates with orientation of (111) plane and amorphous phase. As increase excess Bi content, the crystallographic orientation of the BLT films varied drastically in BLT films and exhibited well-crystallized phase. Also, the conversion of crystallographic orientation at intermediate RTA temperature of above $450^{\circ}C$ started to be observed in BLT thin films with above excess 6.5% Bi content and the rms roughness of films is decreased. We found that the electrical properties of BLT films such as the P-V hysteresis loop and leakage current were effectively modulated by the crystallographic orientations change of thin films.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.07a
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• pp.114-118
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• 2001

졸-겔법으로 Pt/Ti/$SiO_2$/Si 기판위에 $Bi_{3.7}$/$La_{0.75}$$Ti_3O_{12}$(BLT) 강유전체 박막을 형성하였다. As-coated BLT 박막은 $600^{\circ}C$의 후속 열처리온도에서 결정화 되었으며 전형적인 Bi 층상 페롭스카이트 결정구조를 나타내었다. 또한 후속 열처리온도를 증가함에 따라 결정성이 향상되었다. $700^{\circ}C$의 온도에서 후속 열처리된 BLT 박막의 비 유전상수($\varepsilon_{r}$)와 유전손실($\textrm{tan}\delta$)은 5KHz 주파수에서 약 402와 0.04를 각각 나타내었다 $800^{\circ}C$에서 후속 열처리된 BLT박막의 경우 5V의 인가 전압에서 잔류분극 2Pr($Pr^{+}$-$Pr^{-}$)값은 약 32.5$\mu$C/$Cm^2$을 나타내었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.73-74
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• 2006

Ferroelectric thin films have been widely investigated for future nonvolatile memory application. We fabricated the BLT ($(Bi,La)_4Ti_3O_{12}$) films on Si using a STA ($SrTa_2O_6$) buffer layer BLT and STA film were prepared by sol-gel method. Measurement data by XRD and AFM, showed that BLT film and STA films were well crystallized and a good surface morphology. From C-V measurement reward that the Au/BLT/STA/Si structure showed a clockwise hysteresis loop with a memory window of 1.5 V for the bias voltage sweep of ${\pm}5$ V. From results, the Au/BLT/STA/Si structure is useful for FeFETs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.23-26
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• 2003

The BLT thin film and MgO buffer layer were fabricated using a metalorganic decomposition method and the DC sputtering technique. The MgO thin film was deposited as a buffer layer on $SiO_2/Si$ and BLT thin films were used as a ferroelectric layer. The electrical of the MFIS structure were investigated by varying the MgO layer thickness. TEM showsno interdiffusion and reaction that suppressed by using the MgO film as abuffer layer. The width of the memory window in the C-Y curves for the MFIS structure decreased with increasing thickness of the MgO layer Leakage current density decreased by about three orders of magnitude after using MgO buffer layer. The results show that the BLT and MgO-based MFIS structure is suitable for non-volatile memory FETs with large memory window.

• Molecules and Cells
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• v.38 no.9
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• pp.821-828
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• 2015

Monocytes are the major inflammatory cells that infiltrate most solid tumors in humans. The interaction of tumor cells with infiltrating monocytes and their adhesion to these monocytes play a significant role in altering the tumor to become more aggressive. Recently, exposure to lipopolysaccharide (LPS) was suggested to promote cancer cell adhesion to monocytes; however, little is known about the details of the signaling mechanism involved in this process. In this study, we found that LPS up-regulates ICAM-1 expression in MDA-MB-231 breast cancer cells, which facilitates their adhesion to THP-1 monocytes. In addition, we analyzed the signaling mechanism underlying the up-regulation of ICAM-1 and found that the siRNA-mediated depletion of BLT2 markedly suppressed the LPS-induced expression of ICAM-1 in MDA-MB-231 cells and the subsequent adhesion of these cells to THP-1 monocytes. Moreover, we demonstrated that myeloid differentiation primary response gene 88 (MyD88) lies downstream of LPS/TLR4 and upstream of BLT2 and that this 'MyD88-BLT2' cascade mediates ERK activation and subsequent ICAM-1 expression, which is critical for the adhesion of MDA-MB-231 cells to THP-1 monocytes. Taken together, our results demonstrate for the first time that LPS up-regulates ICAM-1 expression in breast cancer cells via a MyD88-BLT2-ERK-linked signaling cascade, leading to the increased adhesion of breast cancer cells to monocytes.