• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.41-41
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• 1998

Rare earth metal films have been used as a buffer layer for growing ferroelectric t thin film or a seed layer for magnetic multilayer. But when it was deposited on s semiconductor substrates for the application of magneto-optic (MO) storage media, it i is difficult to exactly measure magnetic cons떠nts due to shunting current, and so it n needs to grow metal films on insulator substrate to reduce such effect. Recently, it w was reported that ultra-thin Pt layer were epitaxially grown on A12O:J by ion beam s sputtering in 비떠 high vacuum and it can be used as a seed layer for the growth of C Co-contained magnetic multilayer. In this stu$\phi$, Pt thin film were epi떠xially grown on AI2D3 ($\alpha$)OJ) by RF magnetron s sputtering. The crystalline structure was analyzed by transmission electron microscope ( (TEM) and Rutherford Back Scattering (RBS)/Ion Channeling. In TEM study, Pt was b believed to be twinned on AI잉3($\alpha$)01) su$\pi$ace about Pt(ll1) plane.Moreover, RBS c channeling spectra showed that minimum scattering yield of Pt(111)/AI2O:J(1$\alpha$)OJ) was 4 4% and Pt(11J)/AI2D3($\alpha$)OJ) had 3-fold symmetry.

• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1544-1553
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• 2005

In this article, a micro cantilever array actuated by PZT films is designed and fabricated for micro fluidic systems. The design features for maximizing tip deflections and minimizing fluid leakage are described. The governing equation of the composite PZT cantilever is derived and the actuating behavior predicted. The calculated value of the tip deflection was 15 ${\mu}m$ at 5 V. The fabrication process from SIMOX (Separation by oxygen ion implantation) wafer is presented in detail with the PZT film deposition process. The PZT films are characterized by investigating the ferroelectric properties, dielectric constant, and dielectric loss. Tip deflections of 12 ${\mu}m$ at 5 V are measured, which agreed well with the predicted value. The 18 ${\mu}l/s$ leakage rate of air was observed at a pressure difference of 1000 Pa. Micro cooler is introduced, and its possible application to micro compressor is discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04b
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• pp.3-5
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• 2008

The $SrBi_2Ta_2O_9$ thin films are deposited on Pt-coated electrode(Pt/$TiO_2/SiO_2$/Si) using RF magnetron sputtering method. The ferroelectric properties of SBT capacitors with annealing temperatures were studied. Through the x-ray diffraction analysis and the scanning electron microscopy (SEM), it could be observed that crystallization of the SBT thin film started around $650^{\circ}C$ and complete crystallization was accomplished around $750^{\circ}C$ and grains grew from a small spheric form to rod-like. For the leakage current density of the SBT capacitor depending upon various annealing atmospheres, capacitor annealed in the oxygen atmosphere showed the most excellent characteristic, and they were respectively about $2.13\times10^{-9}[A/cm^2]$ at 5V and 340.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.186-189
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• 2003

The MFIS capacitors were fabricated using a metalorganic decomposition method. Thin layers of $ZrO_2$ and $CeO_2$ were deposited as a buffer layer on Si substrate and BLT thin films were used as a ferroelectric layer. The electrical and structural properties of the MFIS structure were investigated. X -ray diffraction was used to determine the phase of the BLT thin films and the quality of the $ZrO_2$ and $CeO_2$ layer. AES show no interdiffusion and the formation of amorphous $SiO_2$ layer is suppressed by using the $ZrO_2$ and $CeO_2$ film as buffer layer between the BLT film and Si substrate. The width of the memory window in the C-V curves for the $BLT/ZrO_2/Si$ and $BLT/CeO_2/Si$ structure is 2.94 V and 1.3V, respectively. The experimental results show that the BLT-based MFIS structure is suitable for non-volatile memory FETs with large memory window.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.56-61
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• 1999

Highly conductive oxide films of BaRuO$_3$ have been grown heteroepitaxially on (100) LaAlO$_3$ single crystalline substrates by using pulsed laser deposition. The films are c-axis oriented with an in-plane epitaxial relationship of <010><100>BaRuO$_3$ // <110>LaAlO$_3$. Atomic force microscopy (AFM) observation shows that they consist of a fine-arranged network of grains and have a mosaic microstructure. Generally temperature-dependent resistivity shows the transition from metallic curve to semiconductor-metallic twofold curve by the deposition conditions for Ru oxide based materials like SrRuO$_3$, CaRuO$_3$, BaRuO$_3$, etc.. This twofold curve comes from the structural similarity of Ru oxide based materials including BaRuO$_3$. We find that the distance of Ru-Ru bonding in the unit cell of BaRuO$_3$ as well as the grain boundary scattering could be the two important causes of these interesting conductive properties.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.2
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• pp.49-54
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• 2003

We have investigated the effects of hydrogen annealing on the physical and electrical properties of $SrBi_{2}Ta_{2}O_9(SBT)$ thin films in the Pt/SBT/Si (MFS) structure and Pt/SBT/Pt (MFM) one, respectively. The microstructure and electrical characteristics of the SBT films were deteriorated after hydrogen annealing due to the damage of the SBT films during the annealing process. To investigate the reason of the degradation of the SBT films in this work, in particular, the effect of the Pt top electrodes, SBT thin films deposited on Si, Pt, respectively, were annealed with the same process conditions. From the XRD, XPS, P-V, and C-V data, it was seen that the SBT itself was degraded after $H_2$ annealing even without the Pt top electrodes. In addition, the degradation of the SBT films after $H_2$ annealing was accelerated by the catalytic reaction of the Pt top electrodes which is so-called hydrogen degradation. To prevent this phenomenon, we proposed the alternative top electrode material, i.e. Ir, and the electrical properties of the SBT thin films were examined in the $Ir/IrO_2/SBT/IrO_2$ structures before and after the H$_2$ annealing and recovery heat-treatment processes. From the results of the P-V measurement, it could be concluded that Ir is one of the promising candidate as the electrode material for degradation resistance in the MFM structure using SBT thin films.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.367-371
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• 2001

In this paper, theS $r_2$(T $a_{1-x}$ , N $b_{x}$)$_2$ $O_{7}$(STNO) films among ferroelectric materials having a low dielectric constant for metal-ferroelectric-semiconductor field effect transistor(MFS-FET) were discussed. The STNO thin films were deposited on p-type Si(100) at room temperature by co-sputtering with S $r_2$N $b_2$ $O_{7(SNO)}$ ceramic target and T $a_2$ $O_{5}$ ceramic target. The composition of STNO thin films was varied by adjusting the power ratios of SNO target and T $a_2$ $O_{5}$ target. The STNO films were annealed at 8$50^{\circ}C$, 90$0^{\circ}C$ and 9$50^{\circ}C$ temperature in oxygen ambient for 1 hour. The value of x has significantly influenced the structure and electrical properties of the STNO films. In the case of x= 0.4, the crystallinity of the STNO films annealed at 9$50^{\circ}C$ was observed well and the memory windows of the Pt/STNO/Si structure were 0.5-8.3 V at applied voltage of 3-9 V and leakage current density was 7.9$\times$10$_{08}$A/$\textrm{cm}^2$ at applied voltage of -5V.of -5V.V.V.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.115-118
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• 2000

Uncooled pyroelectric infrared detectors based on BST(B $a_{-x}$S $r_{x}$Ti $O_3$) thin films have been fabricated by RF magnetron sputtering and surface Micromachining technology. The detectors form BST thin film ferroelectric capacitors grown by RF magnetron sputtering on N/O/N(S $i_3$ $N_4$/ $SiO_2$/S $i_3$ $N_4$) membrane. The sputtered BST thin film exhibits highly c-axis oriented crystal structure that no poling treatment for sensing applications is required. This is an essential factor to increase the yield for realization of an infrared image sensor. surface-Micromachining technology is used to lower the thermal mass of the detector by giving maximum sensor efficiency Gold-black is evaporated on top of the sensing elements used the thermal evaporator. fabricated uncooled pyroelectric infrared detectors is highly output voltage at the low temperature(1$^{\circ}C$).).).

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.141-153
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• 1997

The paraelectric cubic-to-ferroelectric tetragonal phase transition of the thin Pb(Zr, Ti)$O_3$ (PZT) films grown on MgO(001) substrate was investigated in a series of synchrotron x-ray scattering experiments. As the thickness of the film decreases the transition temperature and the amount of the tetragonal distortion were decreased continuously Different from only the c-domains were existent in the thinnest 25nm thick film. Based on this we propose a model for the domain structure of the tetragonal PZT/MgO(100) film that is very different from the ones suggested in literature. We attribute the suppression of the transition to the substrate field that prefers the c-type domains near the interface and suppresses the tetragonal distortion to minimize the film-substrate lattice mismatch.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.133-133
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• 2003

최근에 강유전체 매체와 원자력 현미경 (Atomic Force Microscopy, AFM)을 이용한 초고밀도 정보 저장 장치에 대한 연구가 활발히 진행되고 있다. 이와 아울러 나도 크기의 도메인에 대하 연구에 있어서 PZT 박막의 분극 방향에 따른 SrRuO$_3$의 저항 변화를 AFM 탐침을 이용하여 감지하는 방법을 제안하였다. 본 연구에서는 Metal tip/semiconductor/barrier oxide/ferroelectric 구조에서 강유전체 분극에 의한 저항 변화의 가능성을 실험하고자, 이와 등가 구조인 Pt tip/n-Si/SiO$_2$ 구조에서 Pt 탐침과 반도체 층 사이의 I-V 특성을 측정함으로써, 게이트 전압에 따른 반도체 층의 저항변화에 대해서 분석해 보았다. 그 결과 게이트 전압에 따라서 과밀 지역 (accumulation layer)과 공핍 지역 (depletion layer)이 형성됨에 따라서 반도체 층의 정항이 변하여 I-V 특성이 변하게 됨을 관찰하였으며, 이 결과로부터 분극 방향에 따라서도 반도체 층의 저항이 변할 수 있음을 알 수 있었다.