• Journal of the Microelectronics and Packaging Society
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• v.26 no.1
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• pp.35-39
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• 2019

To date, porous alumina structures have been implemented by electrochemical anodization technique. The anodizing methods can easy to make a porous aluminum oxide film with a regular arrangement, but oxide film with complex structure type such as pillar-on-pore is relatively difficult to implement. Therefore, this study aims to observe the change of anodized oxide pore size, thickness, and structure in a phosphoric acid solution according to applied anodization voltage conditions. For the implementation of hybrid composite oxide structures, it is possible to create by modulating anodization voltage. The experimental conditions were performed at the applied anodization voltage of 100 V and 120 V in 10% phosphoric acid solution, respectively. The experimental results were able to observe the structure of oxides in the form of porous and composite structures (pillar-on-pore), depending on each condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.64-69
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• 2011

Super-hydrophobic properties have been achieved on the rf-sputtered polytetrafluoroethylene(PTFE) films deposited on etched aluminum surfaces. The microstructural evolution created after etching has been investigated by FESEM. The water contact angle over $160^{\circ}$ can be achieved on the rf-sputtered ultra-tihn PTFE film less than 10 nm coated on aluminum surface etched with 7 wt.%, 12.5 wt.%, and 15 wt.% HCl concentration for 12 min. XPS analysis have revealed the presence of a large quantity of $-CF_3$ and $-CF_2$ groups in the rf-sputtered PTFE films that effectively can reduce the surface energy of etched aluminum. The presence of patterned morphology along with the low surface energy at the rf-sputtered PTFE coating makes the aluminum surface with high super-hydrophobic property.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.802-806
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• 1998

polyimide를 입힌 SiO2 wafer상에 증착된 알루미늄 박막의 두께 및 소둔 여부에 따른 hillock의 거동을 atomic force microscopy (AFM)을 이용하여 분석하였다. 증착된 상태의 박막에서 성장 hillock이 관찰되었으며 박막 두께가 증가할수록 hillock의 크기는 증가한 반면 밀도는 감소하였다. 소둔 후 hillock의 평균 크기는 증가하였으나 밀도는 감소하였다. 이러한 hillock 밀도의 감소는 견고한 wafer상에 직접 증착된 알루미늄 박막에서와 다르다. 이는 유연한 polymide 박막에 의한 응력 완화로 응력유기 입계확산이 이루어지지 않아 hillock 이 추가로 형성되지 않은 상태에서 큰 hillock이 성장하면서 작은 hillock을 흡수하기 때문으로 판단된다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.113-113
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• 2011

알루미늄 박막 커패시터 제작을 위해 선택적인 알루미늄 etching과 anodizing을 이용한 유전체($Al_2O_3$) 형성, 전극층 형성을 위한 무전해 Ni-P 도금을 진행하였다. $5{\mu}m$ patterns/$10{\mu}m$ space를 가지는 dot patterns을 알루미늄 기판에 patterning하고, 이를 각각의 전류밀도 조건에서 etching한 후, barrier type anodizing을 진행하였다. 유전체에 전극층은 무전해 Ni-P 도금을 통해 형성하였으며, 이렇게 제작된 알루미늄 박막 커패시터 특성을 평가하였다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.3
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• pp.155-165
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• 2024

A hybrid thin film was prepared by doping reduced graphene oxide (rGO) into a sol-gel solution mixed with aluminum, titanium, and strontium using a brush coating method. The annealing temperature was carried out at 160, 260, and 360℃, and the difference in oxidation reaction was observed. The sol-gel solution created during the membrane manufacturing process generates a contractile force due to the shear stress of the brush bristles, forming a microgroove structure. This structure was confirmed through scanning electron microscopy analysis, and the presence of rGO was clearly revealed. As the annealing temperature increases, the oxidation and reduction reactions on the thin film surface become more active, so the intensity of the surface mixture increases. Moreover, the electro-optical properties were stabilized and improved by increasing the intensity of the mixtures. Likewise, the voltage-capacitance values are also significantly improved. Lastly, the transmittance measurement showed that it was suitable for liquid crystal display application.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.287-291
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• 2005

We have investigated and tried to improve the characteristics of the thin $HfO_2$ layer deposited by ALD for fabricating a MOSFET device where the $HfO_2$ film worked as the gate dielectric. The substrate of MOSFET device is p-type (100) silicon wafer over which the $HfO_2$ dielectric layer with thickness of $5\~6\;nm$ has been deposited. Then the $HfO_2$ film was annealed with $1\~20\;atm\;H_2$ gas and subsequently aluminum electrodes was made so that the active area was $5{\times}10^{-5}\;cm^2$. We have found out that the drain current and transconductance increased by $5\~10\%$ when the $H_2$ gas pressure was 20 atm, which significantly contributed to the reliable operation of the high-density MOSFET devices.

• Korean Journal of Materials Research
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• v.21 no.6
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• pp.309-313
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• 2011

The power capacitors used as vehicle inverters must have a small size, high capacitance, high voltage, fast response and wide operating temperature. Our thin film capacitor was fabricated by alumina layers as a dielectric material and a metal electrode instead of a liquid electrolyte in an aluminum electrolytic capacitor. We analyzed the micro structures and the electrical properties of the thin film capacitors fabricated by nano-channel alumina and metal electrodes. The metal electrode was filled into the alumina nano-channel by electroless nickel plating with polyethylene glycol and a palladium catalyst. The spherical metals were formed inside the alumina nano pores. The breakdown voltage and leakage current increased by the chemical reaction of the alumina layer and $PdCl_2$ solution. The thickness of the electroless plated nickel layer was 300 nm. We observed the nano pores in the interface between the alumina layer and the metal electrode. The alumina capacitors with nickel electrodes had a capacitance density of 100 $nF/cm^2$, dielectric loss of 0.01, breakdown voltage of 0.7MV/cm and leakage current of $10^4{\mu}A$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.815-819
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• 2014

Aluminum nitride (AlN) thin film and TiN film as a buffer layer were deposited on INCONEL 600 substrate by reactive RF magnetron sputtering at room temperature(R.T.) under 25~75% $N_2/Ar$ atmosphere. The as-deposited AlN films at 25~50% $N_2/Ar$ showed a polycrystalline phase of hexagonal AlN, and an amorphous phase. The peak of AlN (002) plane, which was determinant on a performance of piezoelectric transducer, became strong with increasing the $N_2/Ar$ ratio. Any change in the preferential orientation of the as-deposited AlN films was not observed within our $N_2$ concentration range. The piezoelectric sensing properties of AlN module were performed using pressure-voltage measurement system. The output signal voltage of AlN module showed a linear behavior between 20~80 mV in 1~10 MPa range, and the pressure-sensing sensitivity was calculated as 3.6 mV/MPa.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.117-123
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• 2018

Recently, aqueous method has attracted lots of attention because it enables the solution-processed metal oxide thin film with high electrical properties in low temperature fabrication condition to various flexible devices. Focusing the development of aqueous route, many researchers are only focused on metal oxide materials. However, for expansive application of the aqueous-based metal oxide films, the systematic study of performance change with process variables for the development of aqueous-based metal oxide insulator film is urgently required. Here, we propose importance of process variables to achieve high electrical-performance metal oxide insulator based on the aqueous method. We found that the significant process variables including precursor solution temperature and humidity during the spincoating process strongly affect chemical, physical, and electrical properties of $AlO_x$ insulators. Through the optimization of significant variables in process, an $AlO_x$ insulator with a leakage current value approximately $10^5$ times smaller and a breakdown voltage value approximately 2-3 times greater than un-optimized $AlO_x$ was realized. Finally, by introducing the optimized $AlO_x$ insulators to solutionprocessed $InO_x$ TFTs, we successfully achieved $InO_x/AlO_x$ TFTs with remarkably high average field-effect mobility of ${\sim}52cm^2V^{-1}\;s^{-1}$ and on/off current ratio of 106 at fabrication temperature of $250^{\circ}C$.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.759-766
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• 1994

Our investigation aimed to reduce the leakage current of $Ta_2O_5$ thin film capacitor by layering SnOz thin film layer under Ta thin film, thereby supplying extra oxygen ions from the $SnO_{2}$ underlayer to enhance the stoichiometry of $Ta_2O_5$ during the oxidation of Ta thin film. Tantalum was evaporated by e-beam or sputtered on p-Si wafers with various deposition temperatures and was oxidized by dry--oxygen at the temperatures between $500^{\circ}C$ and $900^{\circ}C$. Aluminum top and bottom electrodes were formed to make Al/$Ta_2O_5$/p-Si/Al or $Al/Ta_2O_5/SnO_2$p-Si/AI MIS type capacitors. LCR meter and pico-ammeter were used to measure the dielectric constants and leakage currents of the prepared thm film capacitors. XRD, AES and ESCA were employed to confirm the crystallization of the thin f~lm and the compositions of the films. Dielectric constant of $Ta_2O_5$ thin film capacitor with $SnO_{2}$ underlayer was found to be about 200, which is about 10 times higher than that of $Ta_2O_5$ thin film capacitor without $SnO_{2}$ underlayer. In addition, higher oxidation temperatures increased the dielectric constants and reduced the leakage current. Higher deposition temperature generally gave lower leakage current. $Ta_2O_5/SnO_2$ capacitor deposited at $200^{\circ}C$ and oxidized at $800^{\circ}C$ showed significantly lower leakage current, $10^{-7}A/\textrm{cm}^2$ at $4 \times 10^{5}$V/cm, compared to the one without $SnO_{2}$ underlayer. XRD showed that $Ta_2O_5$ thin film was crystallized above $700^{\circ}C$. AES and ESCA showed that initially the $SnO_{2}$, underlayer supplied oxygen ions to oxidize the Ta layer, however, Sn also diffused into the Ta thin film layer to form a new $Ta_xSn_YO_Z$ , ternary oxide layer after all.