• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.427-428
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• 2008

• Journal of Radiation Industry
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• v.4 no.4
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• pp.335-339
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• 2010

In this study, the surface of polyimide (PI) films was modified using ion implantation to enhance its adhesion to a deposited copper (Cu) layer. The surfaces of the PI films were implanted with 150 keV $Xe^+$ ions at fluences varying from $1{\times}10^{14}$ to $1{\time}10^{16}ions\;cm^{-2}$. The Cu layers were then deposited on the implanted PI. The surface properties of the implanted PI film were investigated based on the contact angle measurements, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Furthermore, the adhesive strength between the deposited Cu layer and PI film was estimated through a scratch test using a nanoindenter. As a result, the surface environment of the PI film was changed by the ion implantation, which could have a significant effect on the adhesion between the deposited Cu layer and the PI.

• Bulletin of the Korean Chemical Society
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• v.11 no.4
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• pp.290-296
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• 1990

Ion-surface collision studies at low kinetic energies (1-100 eV) provide a unique opportunity for investigating reactions and collision dynamics at surfaces. A special ion optics system for generating an energy- and mass-selected ion beam of this energy is designed and constructed. An ultrahigh vacuum (UHV) reaction chamber, in which the ions generated from the beamline collide with a solid surface, is equipped with Auger electron spectroscopy (AES) and thermal desorption spectrometry (TDS) as in-situ surface analytical tools. The resulting beam from the system has the following characteristics : ion current of 5-50 nA, energy spread < 2eV, current stability within ${\pm}5%,$ and unit mass resolution below 20 amu. The performance of the instrument is illustrated with data representing the implantation behavior of $Ar^+$ into a graphite (0001) surface.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.59-59
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• 1999

DLC(diamond-like carbon)필름은 다이아몬드와 유사한 강도, 낮은 마차계수, 높은 Optical band gap, NEA(negative electron affinity)등의 우수한 특성을 가지고 있어, 내마모 코팅이나 정보저장 매체의 윤활 코팅, FED(field emission display)의 전계방출소자등 다양한 분야에의 응용이 연구되고 있다. DLC 필름은 PECVD(plasma enhanced chemical vapor deposition), IBAD(ion beam assisted deposition), Laser ablation, Cathodic vacuum arc등의 process를 이용하여 증착되고 있다. 특히 이러한 필름의 물성은 입사되는 이온의 에너지에 의해 좌우되는데, Lifshitz 등의 연구에 의하여 hyperthermal species를 이용한 DLC 필름의 성장은 초기에 subsurface로의 shallow implantation이 일어난 후 높은 sp3 fraction을 갖는 필름이 연속적으로 성장한다는 subplantation model이 제시 되었다. 본 연구에서는 기판과 subplantation 영역이 이후 계속하여 증착되는 순수 DLC 필름의 특성 변호에 미치는 영향에 대하여 관심을 가지고 실험을 행하였다. 본 실험에서는 상기 제시되어 있는 방법보다도 더욱 정확하고도 독립적으로 탄소 음이온의 에너지와 flux를 조절할 수 있는 Cs+ ion beam sputtering system을 이용하여 탄소 음이온의 에너지를 40eV에서 200eV까지 변화시키며 필름을 증착하였다. Si(100) 웨이퍼를 기판으로 사용하였고 증착 압력은 5$\times$10-7torr 였으며 인위적인 기판의 가열은 하지 않았다. 또한 Ion beam deposited DLC film의 growth process를 연구하기 위하여 200eV의 탄소 음이온을 시간(증착두께)을 변수로 하여 증착하였고, 이 때에는 Kaufman type의 gas ion beam을 이용하여 500eV의 Ar+ ion으로 pre-sputering을 행하였다. 탄소 음이온의 에너지와 증착두께에 따라 증착된 film 내의 sp3/sp2 ratio 의 변화를 XPS plasmon loss 와 Raman spectra를 이용하여 분석하였다. 또한 증착두께에 따른 interlayer의 결합상태를 관찰하기 위하여 AES와 XPS 분석을 보조로 행하였다.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.459-463
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• 2000

Direct use of negative ions for modification of materials has opened new research such as charging-free ion implantation and new materials syntheses by pure kinetic bonding reactions. For these purposes, a new solid-state ce-sium ion source has been developed in the laboratory scale. In this paper, diamond like carbon(DLC) films were prepared on silicon wafer by a negative cesium ion gun. This system does not need any gas in the chamber; deposition occurs under high vacuum. The ion source has good control of the C- beam energy(from 80 to 150eV). The result of Raman spectrophotometer shows that the degree of diamond-like character in the films, $sp^3$ fraction, increased as ion beam energy increases. The nanoindentation hardness of the films also increases from 7 to 14 GPa as a function of beam energy. DLC films showed ultra-smooth surface(Ra~1$\AA$)and an impurity-free quality.

• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.236-243
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• 2009

Proton Engineering Frontier Project (PEFP) has supplied the metal ions to users by using an installed metal ion implanter of 120 keV. At present a feasibility study is being performed for a cobalt ion implantation. For a cobalt ion extraction we studied to sustain the high temperature($648^{\circ}C$) for metal ions vaporization from a cobalt chloride powder by using an alumina crucible in the ion source. The temperature condition of the crucible was satisfied with the plasma generation at the arc current of 120V and EHC power of 250W. The extracted beam current of $Co^+$ ions was dependent on the arc current in the plasma. The maximum beam current was $100{\mu}A$ at 0.18A of the arc current. The 3 peak currents of the extracted ions such as $Co^+$, $CoCl^+$ and $Cl^+$ were obtained by adjusting a mass analyzing magnet and the $Co^+$ ion beam peak current fraction as around 70% in the sum of the peak currents. The fluence of the implanted cobalt ions at the $10{\mu}A$ of the beam current and 90 minutes of the implantation time into an aluminum sample as measured around $1.74{\times}10^{17}#/cm^2$ by a quantitative analysis method of RBS (Rutherford Backscattering Spectrometry).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.90-90
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• 2010

We investigated the modification of optical response properties of titanium dioxide (TiO2) coatings on the ceramic water-purification filters by using ultraviolet-visible absorption spectroscopy and X-ray diffraction. The TiO2 coatings were prepared on ceramic substrate by e-beam evaporation method. These amorphous TiO2 were turned into anatase phase by heat treatment at $700^{\circ}C$ for 2 hours. The doping of N atoms into the TiO2 coatings was done by using 70KeV of N＋ ion implantation with the dose of $1.0{\times}1017$ ions/cm2, followed by post-irradiation heat treatment at $550^{\circ}C$ for 2 hours. Methylene blue test of TiO2 coatings to solar irradiation showed that the post-evaporation heated TiO2 was photocatalytic and N-doped TiO2 reacted to the visible part of solar irradiation.

• Journal of Radiation Industry
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• v.6 no.4
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• pp.317-322
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• 2012

In this study, the preparation of a temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted surface was performed using an eco-friendly and biocompatible ion beam-induced surface graft polymerization. The surface of a perfluoroalkoxy (PFA) film was activated by ion implantation and N-isopropylacrylamide (NIPAAm) was then graft polymerized selectively onto the activated regions of the PFA surfaces. Based on the results of the peroxide concentration and grafting degree measurements, the amount of the peroxide groups formed on the implanted surface was dependant on the fluence, which affected the grafting degree. The results of the FT-IR-ATR, XPS, and SEM confirmed that the NIPAAm was successfully grafted onto the implanted PFA. Moreover, the contact angle measurement at different temperatures revealed that the surface of the PNIPAAm-grafted PFA film was temperature-responsive.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.30-33
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• 1992

This thesis was investigated on ion-induced characteristics in a-$Se_{75}Ge_{25}$ positive and negative resists for focused-ion-beam microlithogaphy. The exposed a-$Se_{75}Ge_{25}$ inorganic thin film shows an increase in optical absorption after exposure to~$10_{16}$ dose of Ga+. The observed shift in the absorption edge toward longer wavelengths is consistent with that in films exposed to band-gap photons(~$10^{21}$photons/cm2). This result may be related with microstructural rearrangements with in the short range of SeGe network. Due to changes in the short range order, the chemical bonding may be affected, which results in increased chemical dissolution in ion-induced film. Also, this resist exhibits good thermal stability because of its high Tg(~$220^{\circ}C$). When focused ion beams are used for direct exposure of resist over a substrate, unwanted implantation of the substrate may be an issue. A possible way to avoid this is to match the thickness of the resist to the range of ions in the resist. Thin aspect is currently under investigation.

• Journal of the Korean Vacuum Society
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• v.14 no.2
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• pp.91-96
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• 2005

The silicon-on-insulator (SOI) wafer fabrication technique has been developed by using ion-cut process, based on proton implantation and wafer bonding techniques. It has been shown by SRIM simulation that 65keV proton implantation is required for a SOI wafer (200nm SOI, 400nm BOX) fabrication. In order to investigate the optimum proton dose and primary annealing condition for wafer splitting, the surface morphologic change has been observed such as blistering and flaking. As a result, effective dose is found to be in the $6\~9\times10^{16}\;H^+/cm^2$ range, and the annealing at $550^{\circ}C$ for 30 minutes is expected to be optimum for wafer splitting. Direct wafer bonding is performed by joining two wafers together after creating hydrophilic surfaces by a modified RCA cleaning, and IR inspection is followed to ensure a void free bonding. The wafer splitting was accomplished by annealing at the predetermined optimum condition, and high temperature annealing was then performed at $1,100^{\circ}C$ for 60 minutes to stabilize the bonding interface. TEM observation revealed no detectable defect at the SOI structure, and the interface trap charge density at the upper interface of the BOX was measured to be low enough to keep 'thermal' quality.