• Journal of Surface Science and Engineering
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• v.41 no.5
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• pp.214-219
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• 2008

Indium tin oxide (ITO) films were deposited on PET substrate by RF superimposed DC magnetron sputtering using ITO (doped with 10 wt% $SnO_2$) target. Substrate temperature was maintained below $750^{\circ}C$ without intentionally substrate heating during the deposition. The discharge voltage of DC power supply was decreased from 280 V to 100 V when superimposed RF power was increased from 0 W to 150 W. The electrical properties of the ITO films were improved with increasing of superimposed RF power. In the result of cyclic bending test, relatively high mechanical property was obtained for the ITO film deposited with RF power of 75 W under DC current of 0.75 A which could be attributed to the decrease of internal stress caused by decrease in both deposition rate and plasma impedance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.145-148
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• 2006

Cold gas dynamic spray is a relatively new coating process by which coatings can be produced without significant heating during the process. Cold gas dynamic spray is conducted by powder sprayed by supersonic gas jet, and generally called the kinetic spray or cold-spray. Cold-spray was developed in Russia in the early 1980s to overcome the defect of thermal spray method. Its low process temperature can minimize thermal stress and also reduce the deformation of the substrate. Most researches on cold-spray have focused on micro scale coating, but our research team tried to apply this method to macro scale deposition. The macro scale deposition causes deformation of a thin substrate which is usually convex to the deposited side. In this research, the main cause of the deformation was investigated using 6061-T6 aluminum alloy and properties of deposited aluminum layer such as coefficient of thermal expansion, Elastic modulus, hardness, electric conductivity were measured. From the result of the analysis, it was concluded that compressive residual stress was the main reason of substrate deformation while CTE had little effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.506-509
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• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with in-situ photoalignment method on polyimide (PI) surfaces using thin plastic substrates. The LC aligning capabilities and pretilt angle of the thin plastic substrates by in-situ photoalignment method were better than that of the glass substrate by general photoalignment. Also, the LC pretilt angle increased with increasing heating temperature and exposure time. And EO characteristics of photoaligned TN-LCDs using in-situ photodissociation method on glass substrate and on plastic substrate are also excellent.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.373-376
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• 2009

In this paper we report upon an investigation into the effect of DC bias voltage on the electrical and optical properties of Gallium doped zinc oxide (GZO) film. GZO films were deposited on glass substrate without substrate temperature by RF magnetron sputtering from a ZnO target mixed with 5 wt% $Ga_{2}O_{3}$. we investigated sample properties of bias voltage change in 0 to -60 V. We were able to achieve as low as $5.89{\times}10^{-4}{\Omega}cm$ and transmittance over 88 %. without substrate heating.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.64-68
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• 2003

ITO_{(n)}/Si_{(p)}$ solar cell is fabricated by vaccum deposition method under the resistance heating with substrate temperature kept about 200[$^{\circ}C$] and than their properties are investigated. The maximum output of fabricated solar cell is obtained when the composition of the thin film is consisted of indium oxide 91[mole %] and tin oxide 9(mole %). The solar cell electrical charateristics can be improved by annealing but are deteriorated at temperature above 600[$^{\circ}C$] for longer than 15[min].

• Journal of the Korean Vacuum Society
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• v.5 no.2
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• pp.169-174
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• 1996

The applications of the high density plasma sources to the etching in semiconductor fabrication process are actively studied because of the more strict requirement from the dry etching process due to shrinking down of the critical dimension. But in the oxide etching with the high density plasma sources, abundant fluorine atoms released from the flurocarbon feed gas make it difficult to get the highly selective $SiO_2/Si$ etching. In this study, to improve the $SiO_2/Si$ etch selectivity through the control of the radical loss channels, we propose the wall heating , one of methods of controlling loss mechanisms. With appearance mass spectroscopy(AMS) and actinometric optical emission spectroscopy(OES), the increase of both radicals impinging on the substrate and existing in bulk plasma, and the decrease of the fluorine atom with wall temperature are observed. As a result, a 40% improvement of the selectivity was achieved for the carbon rich feed gas.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.403-404
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• 2007

We prepared the Al doped ZnO (AZO) thin film on polyethersulfon (PES) without any substrate heating by Facing Targets Sputtering (FTS) system. ZnO doped the content of Al 2 wt% was used and the sputtering conditions were gas pressure 1mTorr and input power 100W. The electrical, structural and optical properties of AZO thin films were investigated. To investigate the as-deposited thin film properties, we employed four-point probe, UV/VIS spectrometer, X-ray diffractometer (XRD), scanning electron microscopy (SEM), Hall Effect measurement system and Atomic Force Microscope (AFM).

• Progress in Superconductivity
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• v.8 no.2
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• pp.186-192
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• 2007

High $J_c\;YBa_2Cu_3O_{7-x}$ superconducting films have been fabricated $LaAlO_3(100)$ substrate by MOD method using dichloroacetic acid(DCA) as chelating solvent for preparing precursor solution. Heating rate was varied in order to optimize the calcination heat treatment condition in DCA-MOD method. Coated films were calcined at lower temperature up to $500^{\circ}C$ in flowing humid oxygen atmosphere. The heating rate was calcined from $13.3^{\circ}C/min\;to\;0.28^{\circ}C/min$. Conversion heat treatment was performed $800^{\circ}C$ for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. Surface and cross sectional SEM microstructures showed that particle sizes were increased with heating rate at a calcination step. The amount of pores was increased with heating rate in the calcined films. Dense microstructure and sharp texture were developed in an YBCO films after conversion heat treatment. A high critical current density (Jc) of $1.26MA/cm^2$ (@77 K and self-field) was obtained for the YBCO film which was prepared with a heating rate of $0.28^{\circ}C/min$.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.26-30
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• 2005

Stamper surface temperature is very critical in replicating the high density optical disc substrates using injection molding as the pit or land/groove patterns on the optical disc substrate have decreased due to the rapid increase of areal density. During the filling stage, the polymer melt in the vicinity of the stamper surfaces rapidly solidifies and the solidified layer generated during polymer filling greatly deteriorates transcribability and fluidity of polymer melt. To improve transcribability and fluidity of polymer melt, stamper surface temperature should be controlled such that the growth of the solidified layer is delayed during the filling stage. In this study, the effect of heating on replication process was simulated numerically. Then, an injection mold equipped with instant active heating system was designed and constructed to raise the stamper surface temperature over the glass transition temperature during filling stage of the injection molding. Also, the closed loop controller using the Kalman filter and the linear quadratic Gaussian regulator was designed. As a result, the stamper surface temperature was controlled according to the desired reference stamper surface temperature.

• Korean Journal of Materials Research
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• v.17 no.2
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• pp.91-95
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• 2007

Electromigration characteristics of Sn-3.5Ag flip chip solder bump were analyzed using flip chip packages which consisted of Si chip substrate and electroplated Cu under bump metallurgy. Electromigration test temperatures and current densities peformed were $140{\sim}175^{\circ}C\;and\;6{\sim}9{\times}10^4A/cm^2$ respectively. Mean time to failure of solder bump decreased as the temperature and current density increased. The activation energy and current density exponent were found to be 1.63 eV and 4.6, respectively. The activation energy and current density exponent have very high value because of high Joule heating. Evolution of Cu-Sn intermetallic compound was also investigated with respect to current density conditions.