• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.607-610
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• 2004

The Pb $(Zr_{0.52}Ti_{0.48})O_3/(Ba_{0.6}Sr_{0.4}TiO_3$ [PZT(52/48)/BST(60/40)] heterolayered thin films were fabricated on the Pt/Ti/$SiO_2$/Si by RF sputtering method. The structural properties of the PZT(52/48)/BST(60/40) heterolayered thin films were investigated with Ar/$O_2$ ratio condition. All the PZT(52/48)/BST(60/40) heterolayered thin films had shown the PZT(111), (200) and BST(200) Peaks of the tetragonal structure. Increasing the Ar/$O_2$ ratio, the average roughness was increased. The thickness ratio of the to the PZT and BST thin film was 1:2. In the case of the PZT(52/48)/BST(60/40) heterolayered thin films with Ar/$O_2$ ratio of 80/20, the average roughness was 3.4 [nm].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.157-160
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• 2004

Ferroelectric $(Ba_xSr_{1-x})TiO_3$ (BST) thin films have been deposited on (001) MgO single crystals by a pulsed laser deposition (PLD) method. The structure of deposited BST thin films were investigated by an x-ray diffractometer. Calculated c-axis lattice parameters of the BST films exhibit a strong lattice distortion, which was not observed in ceramic BST at room temperature. This lattice distortion of BST has been attributed to strains caused by lattice constant difference between film and substrate, oxygen vacancies in BST film, and thermal expansion difference between film and substrate. Ferroelectric properties at 10 GHz have been measured using a HP 8510C vector network analyzer. Dielectric properties, capacitance tunability and quality factor, of the interdigitaed capacitors fabricated on BST films were calculated from the measured s-parameters. Two distinct behaviors in structural, opitical, and microwave properties of BST films were observed; below and above 200 mTorr of oxygen pressure in the deposition chmber.

• 한국전기전자재료학회논문지
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• 제13권1호
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• pp.28-32
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• 2000

Structural and electrical properties of (Ba, Sr)TiO\ulcorner (BST) thin films prepared by pulsed laser depositon were investigated to verify the influences of post-annealing in oxygen ambient. Increase of post-anneal-ing time in oxygen ambient resulted in not only grain growth but also improvement of crystallinity of BST films. Although the post-annealing in oxygen ambient resulted in the increase of surface roughness, it assisted the dielectric constant increase by eliminating oxygen vacancies. The electrical property enhancement including high dielectric constant and low leakage current density was associated with introducing high pressure of oxygen during the post-annealing.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.740-742
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• 1998

In this paper, we described the effect of rapid thermal annealing on the electrical properties of interfacial layer between various top electrodes and $(Ba_{0.5}Sr_{0.5})TiO_3$ thin films. BST thin films were fabricated on Pt/TiN/$SiO_2$/Si substrate by RF magnetron sputtering technique. AI, Ag, and Cu films for the formation of top electrode were deposited on BST thin films by thermal evaporator. Top electrodes/BST/Pt capacitor annealed with rapid thermal annealing at various temperature. In $(Ba_{0.5}Sr_{0.5})TiO_3$ thin films with Cu top electrode annealed at $500^{\circ}C$, the dielectric constant was measured to the value of 366 at 1.2 [kHz] and the leakage current was obtained to the value of $5.85{\times}10^{-7}\;[A/cm^2}$ at the forward bias of 2 [V].

• 한국세라믹학회지
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• 제37권11호
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• pp.1126-1129
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• 2000

The crystallographic orientations of $Ba_{0.6}$S $r_{0.4}$Ti $O_3$(BST) thin film deposited by a metal-organic chemical vapor deposition on (111) textured Pt electrode were studied with a transmission electron microscopy. The fully crystallized BST thin film (50nm) has (100) and (110) preferred orientations. A high resolution transmission electron microscopy study has revealed the crystallographic orientation relationships between BST thin film and Pt electrode. These relationships explained the preferred orientation of BST film on (111) textured Pt electrode. With these results, we could represent the atomic arrangement at the BST/Pt interface.e.e.

• 한국전기전자재료학회논문지
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• 제13권7호
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• pp.592-597
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• 2000

In this study (B $a_{0.5}$/S $r_{0.5}$)Ti $O_3$[BST(50/50)] ceramic thin films were prepared by the Sol-Gel method BST(50/50) stock solution was made and spin-coated on the Indium Tin Oxide(ITO)/glass substrate at 4000 rpm for 30 seconds. The coated films were dried at 35$0^{\circ}C$ for 10 minutes and annealed at 650~75$0^{\circ}C$ for 1 hour. The microstructural properties of the BST(50/50) thin film were studied by the XRD and AFM. The ferroelectric perovskite phase was formed at the annealing condition of 75$0^{\circ}C$ for 1 hour. Dielectric constant and loss of this thin were 370, 3.7% at room temperature respectively. The polarization switching voltage showed the good value of 3V. The leakage current density of the BST(50/50) thin film was 10$^{-7A}$c $m^2$with applied voltage of 1.5V. BST(50/50) thin film capacitors having good dielectric and electrical properties are expecting for the application to the dielectric material of DRAM.RAM.M.

• 한국세라믹학회지
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• 제32권4호
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• pp.441-447
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• 1995

Ba0.65Sr0.35TiO3 (BST) thin films were deposited on Pt/SiO2/Si(100) substrate by rf magnetron sputtering. The substrate temperature changed from 35$0^{\circ}C$ to 55$0^{\circ}C$ and crystalline BST thin films were deposited above 45$0^{\circ}C$. Most of the films had (111) preferred orientation regardless of deposition temperature, but the films changed to (100) preferred orientation as gas pressure increased. The dielectric constant increased with increasing substrate temperature and film thickness, and ranged from 100 to 600 at room temperature. The leakage current increased as substrate temperature increased or as film thickness decreased.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권3호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.73-76
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• 2009

ZnBo이 첨가된 (Ba,Sr)$TiO_3$ 후막을 이용한 planner capacitor의 전기적 특성을 조사하였다. 후막은 알루미나 기판에 스크린 프린팅기법에 의해서 제작되었고 $1200^{\circ}C$의 온도에서 소결하였다. 출발 물질인 BST의 저온 소결을 위해서 ZnBO를 첨가하였다. ZnBO가 1, 3, 5 wt% 첨가된 경우 소결온도가 $1200^{\circ}C$의 낮은 온도에서 소결되는 것을 확인했으며 ZnBO의 첨가랑이 증가함에 따라서 유전율은 감소하고 유전손실는 증가 하는 현상이 나타났다. 1, 3, 5 wt%의 ZnBO가 첨가된 (Ba,Sr)$TiO_3$는 각각 756, 624, 554의 유전율를 보였다. 또한 ZnBO의 양이 증가함에 따라서 누설전류가 감소되는 것을 확인하였고, ZnBO의 첨가가 grain의 성장과 density가 증가되어 누설전류의 양이 감소하게 되는 것으로 분석되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.33-36
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• 1999

In this paper, $Ba_{0.5}$Sr$_{0.5}$TiO$_3$ thin-films were prepared on Pt/Ti/Si0$_2$/Si substrates by RF magnetron sp-uttering method. We investigated electric and dielectric properties of BST thin-films with various ann-ealing temperature using in-sute RTA. Deposition conditions of BST films were set substrate temperat-ure, 30$0^{\circ}C$ and working gas ratio, Ar:O$_2$=90:10. After BST films deposited, we fabricated a capacitor of MIM structure with Al top electrode for measurement. Post-annealing using RTA performed at 40$0^{\circ}C$, $600^{\circ}C$, 80$0^{\circ}C$ for 60 sec, respectively. Also we exacted crystallization and composition of BST thin-films by XRD analysis. In measurement result, this capacitors showed a dielectric constant of about 200 at 1MHz and leakage current density of 5$\times$10$^{-8}$ A/$\textrm{cm}^2$ at 1.5V Microstructure of BST thin-films exhibited effective quality in low-temperature annealed 71ms than high-temperature annealed 71ms.s.s.