• Proceedings of the KWS Conference
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• 2010.05a
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• pp.32-38
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• 2010

Hybrid material(ceramic+metal) processes were developed for micro filter using ceramics coating at metal filter surface by thermal spray method, micro hole drilling at ceramic coated filter surface by femtosecond laser, and fiber laser direct welding of ceramic and metal (SUS304, SM45C) by capillary effect. Thermal spray process was used for ceramic powders and metal filters. The used ceramic powders were $Al_2O_3+40TiO_2$(Metco 131VF) powder of maximum particle size $5{\mu}m$ and ${Al_2O_3}99+$(Metco 54NS) power of maximum particle size 45m. Ceramic coated filters using thermal spray method had a great influence on powder material, particle size and coating thickness but had a fine performance as a micro filter. CW fiber laser was used to drill the top ceramic layer and melt the bottom metal layer for joining applications.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.128-133
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• 2007

In this study, we observed the shapes of CNTs formed with the thinckness of catalyst. Catalyst layer was grown by magnetron sputtering method and the thickness of Ni catalyst is the range from 20 to 80 nm. Also, the synthesis of CNT with Ni catalyst thickness was grown by hot-filament PECVD method. And, we investigated the composition of CNTs by using EDS measurement, also observed the shapes of CNTs by using HRTEM and FESEM measurements. In the result, through the TEM analysis, we observed the empty inside of CNTs and the multiwall CNTs, also confirmed the tip of CNT containing Ni. The composition of CNTs are consisted of an element of C, Ti, and Ni. As you shown the growth shapes of CNTs, the pretreatment of the catalyst before te growth of CNTs changed the particle size of the catalysts and grown the CNTs of the different shapes. Consequently, the best vertically alined and well-arranged CNTs exhibited from the substrate deposited at the catalyst thickness of 40 nm.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.91-97
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• 2004

PBT thin films were formed by rf-magnetron sputtering on $Pt/Ti/SiO_2/Si$ substrate. Bulk-PZT target containing $5\%$-excess PbO was used. After PZT thin films had been deposited at room temperature, remaining portion of the thin film was formed by in-situ process. The ferroelectric perovskite phase was formed at $650^{\circ}C$. The leakage current property was improved dramatically by 2-step sputtering, and in the sample containing optimum thickness of room temp.-layer very low leakage current of $2{\times}10^{-7}A/cm^2$ was shown. As a result of the investigation on the leakage current mechanism, the electrical conduction mechanism in all PZT thin films formed by several conditions was confirmed as bulk-limited mechanism.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.405-406
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• 2013

Ga-doped ZnO (GZO)는 $300^{\circ}C$ 이상의 온도에서는 전기적으로 불안정하기 때문에 CIGS, CdTe, DSC와 같은 태양전지의 높은 공정온도 때문에 사용이 제한적이다. ZTO thin film은 Al2O3, SiO2, TiO2, ZnO tihin film과 비교하여 산소 및 수분에 대하여 투과성이 상대적으로 낮은 것으로 알려져 있다. 따라서 GZO single layer에 비하여 ZTO-GZO multi-layer를 구성하여 TCO를 제작하면, 높은 공정온도에서도 사용 가능하다. 실제 제작된 GZO single layer (300 nm)에서 비저항이 $7.69{\times}10^{-4}{\Omega}{\cdot}cm$에서 $500^{\circ}C$에서 열처리 후 $7.76{\times}10^{-2}{\Omega}{\cdot}cm$으로 급격하게 상승한다. ZTO single layer (420 nm)는 as-grown에서는 측정 불가했지만, $400^{\circ}C$에서 열처리 후 $3.52{\times}10^{-1}{\Omega}{\cdot}cm$ $500^{\circ}C$에서 열처리 후 $4.10{\times}10^{-1}{\Omega}{\cdot}cm$으로 열처리에 따른 큰 변화가 없다. 또한 ZTO-GZO multi-layer (720 nm)의 경우 비저항이 $2.11{\times}10^{-3}{\Omega}{\cdot}cm$에서 $500^{\circ}C$에서 열처리 후 $3.67{\times}10^{-3}{\Omega}{\cdot}cm$으로 GZO에 비하여 상대적으로 변화폭이 작다. 또한 ZTO의 두께에 따른 영향을 확인하기 위하여 ZTO를 2 scan, 4 scan, 6 scan 공정 진행 및 $500^{\circ}C$에서 열처리 후 ZTO, ZTO-GZO thin film의 비저항을 측정하였다. ZTO의 경우 $3.34{\times}10^{-1}{\Omega}{\cdot}cm$ (2 scan), $3.62{\times}10^{-1}{\Omega}{\cdot}cm$ (4 scan), $4.1{\times}10^{-1}{\Omega}{\cdot}cm$ (6 scan)으로 큰 차이가 없으며, ZTO-GZO에서도 $3.73{\times}10^{-3}{\Omega}{\cdot}cm$ (2 scan), $3.42{\times}10^{-3}{\Omega}{\cdot}cm$ (4 scan), $3.67{\times}10^{-3}{\Omega}{\cdot}cm$ (6 scan)으로 큰 차이가 없음을 확인하였다. 염료감응 태양전지에 적용하여 기존에 사용되는 FTO대신에 ZTO-GZO를 사용하며, 가격적 측면, 성능적 측면에서 개선 가능할 것으로 생각된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.2
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• pp.70-74
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• 2009

Effect of the processing variables on the formation of $Pb(Sc_{1/2}Nb_{1/2})O_3$(hereafter PSN) thin layers prepared on Pt(111)/Ti/$SiO_2$/Si substrates using the sol-gel and the spin coating method has been studied. After each deposition, the coated films were heated at $370^{\circ}C$ for 5 min. Then they were finally sintered at temperature range of $600{\sim}700^{\circ}C$ by RTA(rapid thermal annealing). The final multilayered films showed a (111) preferred orientation. On a while, the layer-by-layer crystallization of multilayered amorphous thin films without the intermediate heating exhibited a (100) preferred orientation. In case of heat treatment in the tube furnace with the heating rate of $4^{\circ}C/min$, (100) and (111) oriented thin layers were formed simultaneously. The microstructure of the deposited films were dense and crack-free with thickness of 300nm, irrespective of the processing variables.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.137-137
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• 2009

Thin-film transistors (TFTs) that can be prepared at low temperatures have attracted much attention due to the great potential for flexible electronics. One of the mainstreams in this field is the use of organic semiconductors such as pentacene. But device performance of the organic TFTs is still limited by low field effect mobility or rapidly degraded after exposing to air in many cases. Another approach is amorphous oxide semiconductors. Amorphous oxide semiconductors (AOSs) have exactly attracted considerable attention because AOSs were fabricated at room temperature and used lots of application such as flexible display, electronic paper, large solar cells. Among the various AOSs, a-IGZO was considerable material because it has high mobility and uniform surface and good transparent. The high mobility is attributed to the result of the overlap of spherical s-orbital of the heavy pest-transition metal cations. This study is demonstrated the effect of thickness channel layer from 30nm to 200nm. when the thickness was increased, turn on voltage and subthreshold swing were decreased. a-IGZO TFTs have used a shadow mask to deposit channel and source/drain(S/D). a-IGZO were deposited on SiO2 wafer by rf magnetron sputtering. using power is 150W, working pressure is 3m Torr, and an O2/Ar(2/28 SCCM) atmosphere at room temperature. The electrodes were formed with Electron-beam evaporated Ti(30nm) and Au(70nm) structure. Finally, Al(150nm) as a gate metal was evaporated. TFT devices were heat treated in a furnace at $250^{\circ}C$ in nitrogen atmosphere for an hour. The electrical properties of the TFTs were measured using a probe-station to measure I-V characteristic. TFT whose thickness was 150nm exhibits a good subthreshold swing(S) of 0.72 V/decade and high on-off ratio of 1E+08. Field effect mobility, saturation effect mobility, and threshold voltage were evaluated 7.2, 5.8, 8V respectively.

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1170-1175
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• 1998

PZT films without lower electrode were deposited on the highly doped Si(100) substrate with MgO buffer layer (Mgo/si) by RF magnetron sputtering method followed by the rapid thermal annealing at $650^{\circ}C$ . We investigated the dependences of the crystalline and electrical properties on the MgO thickness and the RTA post annealing. The PZT films on bare Si (without MgO) showed pyrochlore crystal structure while those on MgO(50 )/Si substrates showed the typical perovskite crystal structures. From SEM and AES analysis, the thickness of PZT films was about 7000 showing relatively smooth interface. The depth profiles indicated that atomic species were distributed homogeneously in the PZT/MgO/Si substrate. The dielectric constant($\varepsilon_{r}$ ) and remanent polarization(2Pr) were about 300 and $14\mu$C/$\textrm{cm}^2$;, respectively. The leakage current was about $3.2\mu$/A$\textrm{cm}^2$.

• Transactions of the Korean hydrogen and new energy society
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• v.2 no.1
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• pp.47-56
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• 1990

Pure titanium rods were oxidized by anodic oxidation, furnace oxidation and flame oxidation and used as a electrode in the photodecomposition of water. The maximum photoelectrochemical conversion efficiency(${\eta}$) was found for flame oxidized electrode ($1200^{\circ}C$ for 2 min in air), 0.8 %. Anodically oxidized electrodes have minimum photoelectrochemical conversion efficiencies, 0.3 %. Furnace oxidized electrode ($800^{\circ}C$ for 10min in air) has 0.5% phtoelectrochemical efficiency and shows a band-gap energy of about 2.9eV. The efficiency shows a parallelism with the presence of the metallic interstitial compound $TiO_{O+X}$(X < 0.33) at the metal-semiconductor interface, the thickness of the sub oxide layer and that of the external rutile scale.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.437-438
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• 2007

In this paper a embedded decoupling capacitor design with gap structure will be discussed. A novel structure is modeling and analization by High Frequency Structure Simulator (HFSS). Proposed capacitor have $2m{\times}2m$ in rectangular shape. The film thickness of copper/dielectric film/substrate is respectively 35um/20um/35um. A dielectric layer of BaTiO3/epoxy has the relative permittivity of 25. Compare of the planar decoupling capacitor, capacitance densities of this structure in the range of $55{\mu}F$/mm2 have been obtained with 50um gap while capacitance densities of planar structure $55{\mu}F$/mm2 in the same size. The frequency dependent behavior of capacitors is numerically extracted over a wide frequency bandwidth 500MHz-7GHz. The decoupling capacitor can work at high frequency band increasing the gap size.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.942-947
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• 2001

Thickness dependence of orientation on piezoelectric and electrical properties was investigated by PZT (52/48) films by diol based sol-gel method. The thickness of each layer by spinning at one time was $0.2{\mu}m$ and crack-free films could be successfully deposited on 4 inches Pt/Ti/$SiO_2$/Si substrates by 0.5 mol solutions in the range from $0.2{\mu}m$ to $3.8{\mu}m$. Excellent P-E hysteresis curves were achieved, which were attributed to the well-densified PZT films and columnar grain without pores or any defects between interlayers. The (111) preferred orientation of films were shown in the range of thickness below $1{\mu}m$. As the thickness increased, the (111) preferred orientation disappeared from $1{\mu}m$ to $3{\mu}m$ region, and the orientation of films became random above $3{\mu}m$. Dielectric constants and longitudinal piezoelectric coefficient, $d_{33}$, measured by pneumatic method were saturated around the value of about 1400 and 300 pC/N respectively above the thickness of $1{\mu}m$.