• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 추계학술대회 발표 논문집
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• pp.166-169
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• 2006

A promising capacitor, which has conformable step coverage and good uniformity of thickness and composition, is needed to manufacture high-density non-volatile FeRAM capacitors with a stacked cell structure. In this study, ferroelectric $Bi_{3.61}Nd_{0.39}Ti_3O_{12}$ (BNT) thin films were prepared on $Pt(111)/Ti/SiO_2/Si$ substrates by the liquid delivery system MOCVD method. In these experiments, $Bi(ph)_3$, $Nd(TMHD)_3$ and $Ti(O^iPr)_2(TMHD)_2$ were used as the precursors and were dissolved in n-butyl acetate. The BNT thin films were deposited at a substrate temperature and reactor pressure of approximately $600^{\circ}C$ and 4.8 Torr, respectively. The microstructure of the layered perovskite phase was observed by XRD and SEM. The remanent polarization value (2Pr) of the BNT thin film was $31.67\;{\mu}C/cm^2$ at an applied voltage of 5 V.

• 전자공학회논문지A
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• 제32A권12호
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• pp.101-107
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• 1995

To improve the leakage current, we developed two step sputtering method where PZT thin film in first deposited at room temperature followed by 600.deg. C deposition. The method used an amorphous PZT layer deposited at room temperature to keep a stable interface during sputtering at high temperature. PZT thin films were deposited on Pt/Ti/SiO$_{2}$/Si substrate at room temperature and 600.deg. C sequentially. The effect of the layer deposited at room temperature was investigated with regard to I-V characteristics and P-E hysteresis loop. In the case of the sample with the layer deposited at room temperature, both leakage current and dielectric constant were decreased. The thicker the layer deposited at room temperature was, the lower dielectric constant was. However, leakage current was indepenent of the variation of the thickness ratio. The sample with 200$\AA$ of the layer deposited at room temperature showed the most promising results in both dielectric constant and leakage current.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.341-344
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• 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.913-919
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• 2000

We give pressure stimulation into long chain fatty acid of LB thin films then manufacture a device under the accumulation condition that the state surface pressure is 20[mN/m]. In processing of a device manufacture, we can see the process is good from the change of a surface pressure for organic thin films and transfer ratio of area per molecule. The structure of manufactured device is Au/Arachidic acid/Al, the number of accumulated layers are 13, 17 and 19. The I-V characteristic of the device is measured from 0[V] to +1.5[V]. We have investigated the capacitance because this fatty acid system have a accumulated layers. The maximum value of measured current is increased as the number of accumulated layers are decreased. The capacitor properties of a thin film is better as the distance between electrodes is smaller. The results have shown the insulating materials and could control the conductivity by accumulated layers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.42-42
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• 2007

In the future, electronic components will be integrated on flexible polymer substrates and then miniaturized by thin films using suitable thin film technologies. In this article, the concept of a room temperature CVD is demonstrated using $Bi_3NbO_7$ (BNO) films with a cubic fluorite structure and their structural and electrical properties were investigated in films deposited without substrate heating. Effects of substrate temperature on electrical properties of BNO films were also studied. Films deposited without substrate heating (real temperature of $50^{\circ}C$) show partially crystallized BNO single phases with grain size of approximately 6.5 nm. Their dielectric and leakage properties are comparable to those of films deposited by pulsed laser deposition at room temperature. The concept of room temperature CVD will become a new paradigm in the deposition of dielectric thin films for flexible electron device applications.

• 전자공학회논문지D
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• 제35D권10호
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• pp.83-90
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• 1998

MOS 캐패시터의 게이트 전극을 비정질 상태의 실리콘으로 형성하여 GOI(Gate Oxide Integrity)특성에 미치는 불순물 활성화 열처리의 효과를 조사하였다. LPCVD(Low Pressure Chemical Vapor Deposition) 방법으로 증착한 비정질 실리콘 게이트 전극은 활성화 열처리에 의하여 다결정 실리콘 상태로 구조가 변화하며, 불순물 원자의 활성화가 충분히 이루어졌다. 또한, 비정질 상태의 게이트 전극은 커다란 압축 응력(compressive stress)을 가지지만, 활성화 열처리 온도가 700℃에서 900℃로 증가함에 따라서 응력이 완화되었고 게이트 전극의 저항도 감소하는 특성을 보였다. 또한 얇은 게이트 산화막의 신뢰성 및 산화막의 계면특성은 활성화 열처리 온도에 크게 의존하고 있었다. 900℃에서 활성화 열처리를 한 경우가 700℃에서 열처리한 경우보다 산화막내에서의 전하 포획 특성이 개선되었으며, 산화막의 신뢰성이 향상되었다. 특히, TDDB 방법으로 예측한 게이트 산화막의 수명은 700℃의 열처리에서는 3×10/sup 10/초였지만, 900℃에서의 열처리에서는 2×10/sup 12/초로 현저하게 개선되었다. 그리고, 산화막 계면에서의 계면 전하 밀도는 게이트의 응력 완화에 따라서 개선되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.271-274
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• 2003

[ $Sr_xBa_{1-x}Nb_2O_6$ ] (SBN, $0.25{\leq}x{\leq}0.75$) ceramic is a ferroelectric material with tetragonal tungsten bronze (TTB) type structure, which has a high pyroelectric coefficient and a nonlinear electro-optic coefficient value. In spite of its advantages, SBN has not been investigated well compared to other ferroelectric materials with perovskite structure. In this study, SBN thin film was manufactured by ion beam sputtering technique using the prepared SBN target in $Ar/O_2$ atmosphere. SBN30 thin films of different thickness were pre-deposited as a seed layer on $Pt(100)/TiO_2/SiO_2/Si$ substrate followed by SBN60 deposition up to $4500\;{\AA}$ in thickness. As-deposited SBN60/SBN30 layer was heat-treated at different temperatures of 650, 700, 750, and $800\;^{\circ}C$ in air, respectively, The crystallinity and orientation behavior as well as electric properties of SBN60/SBN30 multi-layer were examined. The deposited layer was uniform and the orientation was shown primarily along (001) plane from XRD pattern. There was difference in the crystal structure with heat-treatment temperature, and the electric properties depended on the heating temperature and the seed-layer thickness. In electric properties of Pt/SBN60/SBN30/Pt thin film capacitor prepared, the remnant polarization (2Pr) value was $15\;{\mu}C/cm^2$, the coercive field (Ec) 65 kV/cm, and the dielectric constant 1492, respectively.

• 한국세라믹학회지
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• 제43권11호
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• pp.688-692
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• 2006

Ferroelectric lanthanides-substituted $Bi_4Ti_3O_{12}$ $(Bi_{4-x}Ln_xTi_3O_{12}, BLnT)$ thin films approximately 200 nm in thickness were deposited by metal organic chemical vapor deposition onto Pt(111)/Ti/SiO$_2$/Si(100) substrates. Many researchers reported that the lanthanides substitution for Bi in the pseudo-perovskite layer caused the distortion of TiO$_6$ octahedron in the a-b plane accompanied with a shift of the octahedron along the a-axis. In this study, the effect of lanthanides (Ln=Pr, Eu, Gd, Dy)-substitution and crystallization temperature on their ferroelectric properties of bismuth titanate $(Bi_4Ti_3O_{12}, BIT)$ thin films were investigated. As BLnT thin films were substituted to lanthanide elements (Pr, Eu, Gd, Dy) with a smaller ionic radius, the remnant polarization (2P$_r$) values had a tendency to increase and made an exception of the Eu-substituted case because $Bi_{4-x}Eu_xTi_3O_{12}$ (BET) thin films had the smaller grain sizes than the others. In this study, we confirmed that better ferroelectric properties can be expected for films composed of larger grains in bismuth layered peroskite materials. The crystallinity of the thin films was improved and the average grain size increased as the crystallization temperature,increased from 600 to 720$^{\circ}C$. Moreover, the BLnT thin film capacitor is characterized by well-saturated polarization-electric field (P-E) curves with an increase in annealing temperature. The BLnT thin films exhibited no significant degradation of switching charge for at least up to $1.0\times10^{11}$ switching cycles at a frequency of 1 MHz. From these results, we can suggest that the BLnT thin films are the suitable dielectric materials for ferroelectric random access memory applications.

• 대한전자공학회논문지SD
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• 제37권4호
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• pp.15-24
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• 2000

고유전 커패시터의 유전완화 특성은 시간영역에서 나타나는 커패시터의 동적특성으로 이해될 수 있으며 이것은 DRAM의 재충전 시간동안 충전된 전하를 잃어버리는 가장 주된 요인으로 인식된다. 그러므로 DRAM 동작에 미치는 영향을 고려하기 위하여 고유전 커패시터의 유전완화에 대한 등가회로를 만드는 것이 필수적이다. 그러나 아직까지 등가회로를 만들 수 있는 일반적이고 이론적인 방법이 제시되지 않고 있다. 근 본 연구에서는 고유전 커패시터의 등가회로를 주파수 영역에서 모델링하는 새로운 방법을 개발하였다. 이 방법은 이론적인 체계를 갖춘 일반적인 방법이다. 또한, 본 연구에서는 실험과정을 통해서 이 방법의 타당성으로 확인하였고, 궁극적으로 새로운 방법으로 얻어진 등가회로를 활용하여 유전완화가 DRAM 동작에 미치는 영향을 고찰하였다.

• 한국세라믹학회지
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• 제44권8호
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• pp.403-406
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• 2007

Ferroelectric Ce-doped $Bi_4Ti_3O_{12}$ (BCT) thin films were deposited by liquid delivery metal organic chemical vapor deposition (MOCVD) onto a $Pt(111)/Ti/SiO_2/Si(100)$ substrate. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure, the surface, and the cross-section morphology of the deposited ferroelectric flims. After annealing above $640^{\circ}C$, the BCT films exhibited a polycrystalline structure with preferred (001) and (117) orientations. The BCT lam capacitor with a top Pt electrode showed a large remnant polarization ($2P_r$) of $44.56{\mu}C/cm^2$ at an applied voltage of 5 V and exhibited fatigue-free behavior up to $1.0{\times}10^{11}$ switching cycles at a frequency of 1 MHz. This study clearly reveals that BCT thin film has potential for application in non-volatile ferroelectric random access memories and dynamic random access memories.