• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.785-791
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• 2001

High dielectric (Ba, Sr) TiO$_3$ thin films were etched in an inductively coupled plasma (ICP) as a function of Cl$_2$/Ar mixing ration. Under Cl$_2$(20)/Ar(80), the maximum etch rate of the BST films was 400 $\AA$/mim and selectivities of BST to Pt and PR were obtained 0.4 and 0.2, respectively. Etching products were redeposited on the surface of BST and resulted in varying the nature of crystallinity. Therefore, we investigated the etched surface of BST by x-ray photoelectron spectroscopy (XPS) atomic force microscopy (AFM) and x-ray diffraction (XRD). From the result of XPS analysis, we found that residues of Ba-Cl and Ti-Cl bonds remained on the surface of the etched BST for high boiling point. The morphology of the etched surfact was analyzed by AFM. A smoothsurface(roughness ~2.8nm) ws observed under Cl$_2$(20)/Ar(80), rf power of 600 W, dc bias voltage of -250 V and pressure of 10 mTorr. This changed the nature of the crystallinity of BST. From the result of XRD analysis, the crystallinities of the etched BST film under Ar only and Cl$_2$(20)/Ar(80) were maintained as similar to as-deposited BST. However, intensity of BST(100) orientation under Cl$_2$ only plasma was abruptly decreased. This indicated that CI compounds were redeposited on the etched BST surface and resulted in changed of the crystallinity of BST during the etch process.

• Transactions on Electrical and Electronic Materials
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• v.8 no.3
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• pp.110-114
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• 2007

Dependence of the thermal stability of nickel silicide on the film stress of inter layer dielectric (ILD) layer has been investigated in this study and silicon nitride $(Si_3N_4)$ layer is used as an ILD layer. Nickel silicide was formed with a one-step rapid thermal process at $500^{\circ}C$ for 30 sec. $2000{\AA}$ thick $Si_3N_4$ layer was deposited using plasma enhanced chemical vapor deposition after the formation of Ni silicide and its stress was split from compressive stress to tensile stress by controlling the power of power sources. Stress level of each stress type was also split for thorough analysis. It is found that the thermal stability of nickel silicide strongly depends on the stress type as well as the stress level induced by the $Si_3N_4$ layer. In the case of high compressive stress, silicide agglomeration and its phase transformation from the low-resistivity nickel mono-silicide to the high-resistivity nickel di-silicide are retarded, and hence the thermal stability is obviously improved a lot. However, in the case of high tensile stress, the thermal stability shows the worst case among the stressed cases.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.253-258
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• 2009

Mn-substituted $BiFeO_3$(BFO) thin films were prepared by r.f. magnetron sputtering under an Ar/$O_2$ mixture of various deposition pressures at room temperature. The effects of the deposition pressure and annealing temperature on the crystallization and electrical properties of BFO films were investigated. X-ray diffraction patterns revealed that BFO films were crystallized for films annealed above $500^{\circ}C$. BFO films annealed at $550^{\circ}C$ for 5 min in $N_2$ atmosphere exhibited the crystallized perovskite phase. The (Fe+Mn)/Bi ratio decreased with an increase in the deposition pressure due to the difference of sputtering yield. The grain size and surface roughness of films increased with an increase in the deposition pressure. The dielectric constant of BFO films prepared at various conditions shows $127{\sim}187$ at 1 kHz. The leakage current density of BFO films annealed at $500^{\circ}C$ was approximately two orders of magnitude lower than that of $550^{\circ}C$. The leakage current density of the BFO films deposited at $10{\sim}30\;m$ Torr was about $5{\times}10^{-6}{\sim}3{\times}10^{-2}A/cm^2$ at 100 kV/cm. Due to the high leakage current, saturated P-E curves were not obtained in BFO films. BFO film annealed at $500^{\circ}C$ exhibited remnant polarization(2Pr) of $26.4{\mu}C/cm^2$ at 470 kV/cm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.101-106
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• 2009

In this paper, Thin films of $HfO_2$/Hf were deposited on p-type wafer by Atomic Layer Deposition (ALD). We studied the electrical and material characteristics of $HfO_2$/Hf/Si MOS capacitor depending on thickness of Hf metal layer. $HfO_2$ films were deposited using TEMAH and $O_3$ at $350^{\circ}C$. Samples were then annealed using furnace heating to $500^{\circ}C$. Round-type MOS capacitors have been fabricated on Si substrates with $2000\;{\AA}$-thick Pt top electrodes. The composition rate of the dielectric material was analyzed using TEM (Transmission Electron Microscopy), XRD (X-ray Diffraction) and XPS (X-ray Photoelectron Spectroscopy). Also the capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) characteristics were measured. We calculated the density of oxide trap charges and interface trap charges in our MOS device. At the interface between $HfO_2$ and Si, both Hf-Si and Hf-Si-O bonds were observed, instead of Si-O bond. The sandwiched Hf metal layer suppressed the growing of $SiO_x$ layer so that $HfSi_xO_y$ layer was achieved. And finally, the generation of both oxide trap charge and interface trap charge in $HfO_2$ film was reduced effectively by using Hf metal layer.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.202-208
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• 1997

Bi-layered SrBi2Ta2O9(SBT) films were deposited on Pt/Ti/SiO2/Si sibstrates by rf magnetron sputt-ering at room temperature and then were annealed at 75$0^{\circ}C$, 80$0^{\circ}C$ and 85$0^{\circ}C$ for 1 hour in oxygen at-mosphere. The film composition of SrBi2Ta2O9 was obtained after depositing at room temperature and annealing at 80$0^{\circ}C$. Excess 20mole% Bi2O3 and 30 mole% SrCO3 were added to the target to compensate for the lack of Bi and Sr in SBT film. 200 nm thick SBT film exhibited and dense microstructure, adielectric constant of 210, and a dissipation factor of 0.05 at 1 MHz frequency. The films exhibited Curie temperature of 32$0^{\circ}C$ and a dielectric constant of 314 at that temperature under 100 kHz frequency. The remanent polarization(2Pr) and the coercive field(2Ec) of the SBT films were 9.1 $\mu$C/$\textrm{cm}^2$ and 85 kV/cm at an applied voltage of 3V, resspectively and the SBT film showed a fatigue-free characteristics up to 1010 cy-cles under 5V bipolar pulse. The leakage current density of the SBT film was about 7$\times$10-7A/$\textrm{cm}^2$ at 150 kV/cm. Fatigue-free SBT films prepared by rf magnetron sputtering can be suitable for application to non-volatile memory device.

• Progress in Superconductivity
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• v.14 no.1
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• pp.45-51
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• 2012

Microwave metrology for the thickness of metallic or superconductive films provides a new way to measure the film thickness in a non-invasive way by using microwave resonators, with the measurement accuracy affected by standard uncertainties in the resonator quality factor, temperature-dependent resonant frequency and the dimensions of the resonators. Here we study effects of the standard uncertainty in the thickness, $t_{cal}$, of a calibration $YBa_2Cu_3O_{7-{\delta}}$ (YBCO) film on the measured thicknesses, $t_{RF}$, by using a ~ 40 GHz microwave resonator. For the study, we used five YBCO films having the thicknesses of 70 - 360 nm, for which relative standard uncertainties in $t_{RF}$ due to that in $t_{cal}$ are obtained. The standard uncertainty in $t_{cal}$ was determined with the surface roughness of the film taken into account. It appeared that relative standard uncertainty in $t_{cal}$ significantly affects the $t_{RF}$ values, with the values of 1% (5%) in the former resulting in those of 1-2% (5-9%) for the latter at 10 K. Our results show that, for realizing relative standard uncertainties less than 5% in $t_{RF}$ for all the YBCO films, the surface roughness of the calibration films should be small enough to realize a relative standard uncertainty of less than 2.7% in $t_{cal}$.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.60-65
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• 2009

We performed a study on optical properties of $BaSm_2Ti_4O_{12}$ thin films by vacuum ultra violet spectroscopic ellipsometry in the $0.92{\sim}8.6\;eV$ energy range. For the analysis of the measured ellipsometric spectra, a 5-layer model was applied where optical property of the $BaSm_2Ti_4O_{12}$ layer was well represented by a Tauc-Lorentz dispersion function. Our analysis clearly showed new structure in high energy region at about 7.5 eV Consistent changes of refractive index & extinction coefficient of the $BaSm_2Ti_4O_{12}$ thin film by the growth and annealing temperatures were also confirmed.

• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.363-369
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• 2002

We have designed conductive transparent filters using a low-emissivity coating such as [dielectric|Ag|dielectric] for display applications. The design is the repetition of [$TiO_{2}$|Ti|Ag |$TiO_{2}$] to increase the transmittance in the visible and decrease the transmittance in the near IR. The conductive transparent filters are deposited by a radio frequency(RF) magnetron sputtering system. The optical, structural and electrical properties of the filters were investigated and the optical spectra are compared with simulated spectra. The thickness of the deposited Ag films is above 13 ㎚ to increase the conductivity and that of $TiO_{2}$ films is 24 ㎚ to increase the transmittance in the visible range. Ti blockers are employed to prevent the Ag films from being oxidized by an oxygen gas during the reactive sputtering process. Also, it is shown that the thicker Ti film is necessary as the period increases. Finally, a filter with repetition of the basic structure three times shows the better cut-off near infrared(NIR) and the sheet resistance as low as 2Ω/□ which is enough to shield an unnecessary electromagnetic waves for a display panel.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.173-181
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• 1992

Tantalum pentoxide($Ta_{2}O_{5}$) thin films on p-type (100) silicon wafer were fabricated by RF reactive sputtering. Physical properties and structure of the specimens were examined by XRD and AES. From the C-V analysis, the dielectric constant of $Ta_{2}O_{5}$ films was in the range of 10-12 in the reactive gas atmosphere in which 10% of oxygen gas is mixed. The ratio of Ta : 0 was 1 : 2 and 1 : 2.49 by AES and RBS examination, respectively. The heat-treatment at $700^{\circ}C$ in $O_{2}$ ambient led to induce crystallization. When the heat-treatment temperature was $1000^{\circ}C$, the dielectric constant was 20.5 in $O_{2}$ ambient and 23 in $N_{2}$ ambient, respectively. The crystal structure of $Ta_{2}O_{5}$ film was pseudo hexagonal of ${\delta}-Ta_{2}O_{5}$. The flat band voltage shift(${\Delta}V_{FB}$) of the specimens and the leakage current density were decreased for higher oxygen mixing ratio. The maximum breakdown field was 2.4MV/cm at the oxygen mixing ratio of 10%. The $Ta_{2}O_{5}$ films will be applicable to hydrogen ion sensitive film and gate oxide material for memory device.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.196-202
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• 1997

Perovskite lanthanum doped lead titanate ($(Pb,La)TiO_{3}$ or PLT) thin films were successfully fabricated on Pt/TijSiO.iSi substrates at the temperatures as low as $440~500^{\circ}C$ by eleclron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVII). Since the volatilities of the MC sources arid oxide molecules (especially Ph oxide) increased with increasing deposition temperature, the film deposition rate and the (I'b + La)/'Ti ratio decreased Stoichiometric perovskite PL'T films with good dielectric and leakeage current properties were obtained at the temperatures of $460~480^{\circ}C$. The lanthanum content of the film was nearly directly propotional to $La(DPM)_{3}$ flow rate. As the La/Ti ratio increased from 3.0 to 9.5%, the dielectric constant increased from 360 to 650 and the leakeage current density at 100kV/cm electric field decreased from $4{\times}10^{-5}$ to $4{\times}10_{-8}A/cm^2$.