• 한국진공학회지
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• 제12권S1호
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• pp.63-66
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• 2003

It is experimentally shown that a $TiO_2$ film on Si(111) substrate was prepared by using the technique of D.C. reaction sputter deposition with $Ar^{+}$ ion beam bombardment, and a layer-like structure was observed from the depth profile of the interface between $TiO_2$ film and Si substrate with Scanning Electron Microscopy and Electron Probe. It was also surprisingly discovered that Ti atoms could be detected at about 9 $\mu$m depth. The $TiO_2$-Si interface bombarded by $Ar^{+}$ ion beams revealed multi-layer structures, a mechanism might be caused by defect diffusion, impurity and matrix relocation. Multi-relocations of impurity and matrix atoms were as a result of profile broadening of the $TiO_2$-Si interface, and the spread due to matrix relocation in this system is shown to exceed much more the spread due to impurity relocation.

• Nuclear Engineering and Technology
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• 제35권3호
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• pp.226-233
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• 2003

The discharge characteristics of a prototype ion source was investigated, which was developed and upgraded for the NBI (Neutral Beam Injection) heating system of KSTAR (Korea Superconducting Tokamak Advanced Research). The ion source was designed for the arc discharge of magnetic bucket chamber with multi-pole cusp fields. The ion source was discharged by the emission-limited mode with the control of filament heating voltage. The maximum ion density was 4 times larger than the previous discharge controlled by a space-charge-limited mode with fully heated filament. The plasma (ion) density and arc current were proportional to the filament voltage, but the discharge efficiency was inversely proportional to the operating pressure of hydrogen gas. The maximum ion density and arc current were obtained with constant arc voltage ($80{\sim}100V$), as $8{\times}10^{11}cm^{-3}$ and 1200 A, respectively. The estimated maximum beam current was about 35 A, extracted by the accelerating voltage of 80kV.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.322-325
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• 2005

The shrinking critical dimensions of modern technology place a heavy requirement on optimizing feature shapes at the micro- and nano scale. In addition, the use of ion beams in the nano-scale world is greatly increased by technology development. Especially, Focused ion Beam (FIB) has a great potential to fabricate the device in nano-scale. Nevertheless, FIB has several limitations, surface swelling in low ion dose regime, precipitation of incident ions, and the re-deposition effect due to the sputtered atoms. In recent years, many approaches and research results show that the re-deposition effect is the most outstanding effect to overcome or reduce in fabrication of micro and nano devices. A 2D string based simulation software AMADEUS-2D $(\underline{A}dvanced\;\underline{M}odeling\;and\;\underline{D}esign\;\underline{E}nvironment\;for\;\underline{S}putter\;Processes)$ for ion milling and FIB direct fabrication has been developed. It is capable of simulating ion beam sputtering and re-deposition. In this paper, the 2D FIB simulation is demonstrated and the characteristics of ion beam induced direct fabrication is analyzed according to various parameters. Several examples, single pixel, multi scan box region, and re-deposited sidewall formation, are given.

• Nuclear Engineering and Technology
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• 제36권4호
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• pp.357-363
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• 2004

A prototype long pulse ion source was developed, and the beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) of the Korea Superconducting Tokamak Advanced Research (KSTAR). The ion source consists of a magnetic bucket plasma generator, with multi-pole cusp fields, and a set of tetrode accelerators with circular apertures. Design requirements for the ion source were a 120kV/65A deuterium beam and a 300 s pulse length. Arc discharges of the plasma generator were controlled by using the emission-limited mode, in turn controlled by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas with a maximum arc power of 100 kW were produced using the constant power mode operation of an arc power supply. A maximum ion density of $8.3{\times}10^{11}\;cm^{-3}$ was obtained by using electrostatic probes, and an optimum arc efficiency of 0.46 A/kW was estimated. The accelerating and decelerating voltages were applied repeatedly, using the re-triggering mode operation of the high voltage switches during a beam pulse, when beam disruptions occurred. The decelerating voltage was always applied prior to the accelerating voltage, to suppress effectively the back-streaming electrons produced at the time of an initial beam formation, by the pre-programmed fast-switch control system. A maximum beam power of 0.9 MW (i.e. $70\;kV{\times}12.5\;A$) with hydrogen was measured for a pulse duration of 0.8 s. Optimum beam perveance, deduced from the ratio of the gradient grid current to the total beam current, was $0.7\;{\mu}perv$. Stable beams for a long pulse duration of $5{\sim}10\;s$ were tested at low accelerating voltages.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.543-546
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• 2005

We have investigated the alignment ability of multi-domains by using ion beam irradiation on diamond-like carbon (DLC) thin film layers. The DLC thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) system and the low energy ion beam is irradiated from Kaufman type ion gun. The direction of liquid crystal alignment is varied by the direction of Ar ion beam irradiation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.368-368
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• 2008

Ion implantation has been widely developed during the past decades to become a standard industrial tool. To comply with the growing needs in ion implantation, innovative technology for the control of ion beam parameters is required. Beam current, beam profile, ion fractions are of great interest when uniformity of the implant is an issue. Especially, it is important to measure the spatial distribution of beam power and also the energy distribution of accelerated ions. This energy distribution is influenced by the proportion of mass for ion in the plasma generator(ion source) and by charge exchange and dissociation within the accelerator structure and also by possible collective effects in the neutralizer which may affect the energy and divergence of ions. Hydrogen atom has been the object of a good study to investigate the energy distribution. Hydrogen ion sources typically produce multi-momentum beams consisting of atomic ion ($H^+$) and molecular ion ($H_2^+$ and $H_3^+$). In the beam injector, the molecular ions pass through a charge-exchanges gas cell and break up into atomic with one-half (from $H_2^+$) or one-third (from $H_3^+$) according to their accelerated energy. Burrell et al. have observed the Doppler shifted lines from incident $H^+$, $H_2^+$, and $H_3^+$ using a Doppler shift spectroscopy. Several authors have measured the proportion of mass for hydrogen ion and deuterium using an ion source equipped with a magnetic dipole filter. We developed an ion implanter with 50-KeV and 20-mA ion source and 100-keV accelerator tube, aiming at commercial uses. In order to measure the proportion of mass for ions, we designed a filter system which can be used to measure the ion fraction in any type of ion source. The hydrogen and helium ion species compositions are used a filter system with the two magnets configurations.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.181-184
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• 2004

Thin films of single phase, polycrystalline silicon germanium (Si$_{1-x}$ Ge$_{x}$) were prepared by ion-beam evaporation (IBE) using Si-Ge multi-phase targets. After irradiation of the targets by a pulsed light ion beam with peak energy of 1 MV, 450 and 480 nm thick films were deposited on Si single crystal and quartz glass substrates, respectively. From XRD analysis, the thin films consisted of a single phase Si$_{1-x}$ Ge$_{x}$, whose composition is close to those of the targets.rgets.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.945-946
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• 2008

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.269-269
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• 2012

A new ion source has been designed, fabricated, and installed at the NBTS (Neutral Beam Test Stand) at the KAERI (Korea Atomic Energy Research Institute) site. The goalis to provide a 100 keV, 2MW deuterium neutral beam injection as an auxiliary heating of KSTAR (Korea Super Tokamak Advanced Research). To cope with power demand, an ion current of 50 A is required considering the beam power loss and neutralization efficiency. The new ion source consists of a magnetic cusp bucket plasma generator and a set of tetrode accelerators with circular copper apertures. The plasma generator for the new ion source has the same design concept as the modified JAEA multi-cusp plasma generator for the KSTAR prototype ion source. The dimensions of the plasma generator are a cross section of $59{\times}25cm^2$ with a 32.5 cm depth. The anode has azimuthal arrays of Nd-Fe permanent magnets (3.4 kG at surface) in the bucket and an electron dump, which makes 9 cusp lines including the electron dump. The discharge properties were investigated preliminarily to enhance the efficiency of the beam extraction. The discharge of the new ion source was mainly controlled by a constant power mode of operation. The discharge of the plasma generator was initiated by the support of primary electrons emitted from the cathode, consisting of 12 tungsten filaments with a hair-pin type (diameter = 2.0 mm). The arc discharge of the new ion source was achieved easily up to an arc power of 80 kW (80 V/1000 A) with hydrogen gas. The 80 kW capacity seems sufficient for the arc power supply to attain the goal of arc efficiency (beam extracted current/discharge input power = 0.8 A/kW). The accelerator of the new ion source consists of four grids: plasma grid (G1), gradient grid (G2), suppressor grid (G3), and ground grid (G4). Each grid has 280 EA circular apertures. The performance tests of the new ion source accelerator were also finished including accelerator conditioning. A hydrogen ion beam was successfully extracted up to 100 keV /60 A. The optimum perveance is defined where the beam divergence is at a minimum was also investigated experimentally. The optimum hydrogen beam perveance is over $2.3{\mu}P$ at 60 keV, and the beam divergence angle is below $1.0^{\circ}$. Thus, the new ion source is expected to be capable of extracting more than a 5 MW deuterium ion beam power at 100 keV. This ion source can deliver ~2 MW of neutral beam power to KSTAR tokamak plasma for the 2012 campaign.

• Applied Science and Convergence Technology
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• 제25권5호
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• pp.92-97
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• 2016

Surface erosion using focused ion beam irradiation is the most promising technology for the realization of micro/nanofabrication. However, accurate fabrication of predefined structures is still challenging. This article introduces a single step surface driving method to fabricated predefined curved structures. The previously reported multi step surface driving method (MSDM) has been modified so that a single ion dose profile can be used instead of multiple ion dose profiles. Experimental realization of the method is presented with the fabrication of predefined curved surfaces as well as reference to surface propagation theory. For the purpose of verification, simulations are performed on the basis of a sound mathematical model.