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Seoul, South Korea

Kim Y.,Microsystem Packaging Center | Kim S.E.,Seoul National University of Science and Technology
Journal of the Korean Ceramic Society | Year: 2012

Nitrogen-incorporated SnO2 thin films were deposited by rf magnetron sputtering. Comparative structural, electrical and optical studies of thin films deposited by sputtering of the Sn metallic target and sputtering of the SnO2 ceramic target were conducted. The SnO2 thin films deposited by sputtering of the Sn metallic target had a higher electrical conductivity due to a higher carrier concentration than those by sputtering of the SnO2 ceramic target. Structurally the SnO2 thin films deposited by sputtering of the SnO2 ceramic target had a better crystallinity and a larger grain size. This study confirmed that there were distinct and clear differences in electrical, structural, and optical characteristics between SnO2 thin films deposited by reactive sputtering of the Sn metallic target and by direct sputtering of the SnO 2 ceramic target. Source


Kim S.-P.,Seoul National University of Science and Technology | Kim Y.,Microsystem Packaging Center | Kim S.-D.,Seoul National University of Science and Technology | Kim S.E.,Seoul National University of Science and Technology
Journal of the Korean Ceramic Society | Year: 2011

Tin oxide thin films were deposited by rf reactive sputtering and annealed at 400°C for 1 h in vacuum. To minimize the influence such as reduction, oxidation, and doping on tin oxide thin films during annealing, a vacuum ambient annealing was adopted. The structural, optical, and electrical properties of tin oxide thin films were characterized by X-ray diffraction, atomic force microscope, UV-Vis spectrometer, and Hall effect measurements. After vacuum annealing, the grain size of all thin films was slightly increased and the roughness (Ra) was improved, however irregular and coalesced shapes were observed from the most of the films. These irregular and coalesced crystal shapes and the possible elimination of intrinsic defects might have caused a decrease in both carrier concentration and mobility, which degrades electrical conductivity. Source


Kim Y.,Microsystem Packaging Center | Kim S.-P.,Seoul National University of Science and Technology | Kim S.-D.,Seoul National University of Science and Technology | Kim S.E.,Seoul National University of Science and Technology
Korean Journal of Materials Research | Year: 2010

Tin oxide thin films were prepared on borosilicate glass by rf reactive sputtering at different deposition powers, process pressures and substrate temperatures. The ratio of oxygen/argon gas flow was fixed as 10 sccm/60 sccm in this study. The structural, electrical and optical properties were examined by the design of experiment to evaluate the optimized processing conditions. The Taguchi method was used in this study. The films were characterized by X-ray diffraction, UV-Vis spectrometer, Hall effect measurements and atomic force microscope. Tin oxide thin films exhibited three types of crystal structures, namely, amorphous, SnO and SnO2. In the case of amorphous thin films the optical band gap was widely spread from 2.30 to 3.36 eV and showed n-type conductivity. While the SnO thin films had an optical band gap of 2.24-2.49 eV and revealed p-type conductivity, the SnO2 thin films showed an optical band gap of 3.33-3.63 eV and n-type conductivity. Among the three process parameters, the plasma power had the most impact on changing the structural, electrical and optical properties of the tin oxide thin films. It was also found that the grain size of the tin oxide thin films was dependent on the substrate temperature. However, the substrate temperature has very little effect on electrical and optical properties. Source


Kang S.-G.,Microsystem Packaging Center | Kim Y.,Microsystem Packaging Center | Kim S.E.,Seoul National University of Science and Technology | Kim S.,Seoul National University of Science and Technology
Electronic Materials Letters | Year: 2013

The effects of heat treatment on room temperature ferromagnetism of Co-doped ZnO were investigated with a (ZnO 20Å/Co x Å)20 multilayer structure where x = 1. 5, 3, 4. 3, 6 and 9 Å. As the thickness of the Co sub-layer increased, the ZnO/Co multilayer changed its magnetic state from diamagnetism at Co 1. 5 Å and 3 Å to weak ferromagnetism at Co 4. 3 Å and strong ferromagnetism at Co 6 Å and 9 Å. The heat treatment, in a vacuum at 400°C, changed the diamagnetic property into a ferromagnetic one, resulting in room temperature ferromagnetism for all Co sub-layer thicknesses. The improvement in ferromagnetism could be ascribed to the exchange coupling between dispersed Co atoms through XRD, optical transmittance and TEM analysis. © 2013 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht. Source


Kang S.-G.,Microsystem Packaging Center | Kim Y.,Microsystem Packaging Center | Kim E.-S.,Seoul National University of Science and Technology | Lim N.,Seoul National University of Science and Technology | And 4 more authors.
2011 IEEE International 3D Systems Integration Conference, 3DIC 2011 | Year: 2011

3D wafer stacking [1-3] offers numerous opportunities such as memory stacking, logic stacking, heterogeneous device stacking, optical and RF interconnection, and system-on-chip. 3D integration can provide high performance, reduced cost, reduced size, and effective integration of divergent process flows. Wafer stacking is favored for a high volume manufacturing compared to chip to chip and chip to wafer processes. However, there are still many fabrication processes to be developed and reliability issues to be considered in order to implement wafer-to-wafer (W2W) stacking process. © 2011 IEEE. Source

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