• 한국정밀공학회지
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• 제28권1호
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• pp.19-23
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• 2011

Recently, focused ion beam (FIB) applications have been investigated for the modification of VLSI circuit, the MEMS processing, and the localized ion doping, A multi aperture FIB system has been introduced as the demands of FIB applications for high speed and large area processing increase. A liquid metal ion source has problems, a large angular divergence and a metal contamination into a substrate. In this study, a gas ion source was introduced to replace a liquid metal ion source. The gas ion source generated inductively coupled plasma (ICP) in a quartz tube (diameter: 45 mm). Ar gas fed into the quartz was ionized by a 2 turned radio frequency antenna. The Ar ions were extracted by 2 extraction grids. The maximum extraction voltage was 10 kV. A numerical simulation was used to optimize the design of extraction grids and to predict an ion trajectory. As a result, the maximum ion current density was 38 $mA/cm^2$ and the spread of ion energy was 1.6 % for the extraction voltage.

• 전자공학회논문지 IE
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• 제44권2호
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• pp.26-31
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• 2007

카본나노튜브 전계 방출 어레이(carbon nanotube field emission array, CNT FEA)를 유리기판 상에 형성시키기 위하여 CNT 페이스트를 스크린 프린팅 후 표면처리를 수행하였다. 본 실험에서는 효과적인 표면처리 방법으로서 이온 빔을 조사(expose)시키는 방법을 연구하였다. 먼저, 유리 기판상에 감광성 CNT 페이스트를 스크린 프린팅하고 UV 후면노광 및 현상공정에 의해 선택적으로 CNT 페이스트를 남겼다. 다시 고온에서 소성후 CNT들은 바인더 성분들에 의해 문히게 된다. 본 실험에서는 소성된 CNT 페이스트의 표면상에 Ar 이온빔을 가속시켜 페이스트의 바인더(binder)를 선택적으로 제거함으로써 전계방출 특성을 향상시킬 수 있었다. 표면처리를 위한 이온 빔 가속시 이온빔의 가속에너지에 따라 특성이 크게 변화되었는데, 본 연구에서는 100 V의 낮은 가속 전압에서 가장 높은 전계방출 특성을 나타내었으며 가속 전압이 너무 높으면 바인더 성분 외에도 CNT 자체가 제거됨으로써 오히려 특정이 저하됨을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.41-43
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• 1999

Among the feffoelectric thin films that have been widely investigated for ferroelectric random access memory (FRAM) applications, SrBi$_2$Ta$_2$$O_{9}$ thin film is appropriate to memory capacitor materials for its excellent fatigue endurance. However, very few studies on etch properties of SBT thin film have been reported although dry etching is an area that demands a great deal of attention in the very large scale integrations. In this study, the a SrBi$_2$Ta$_2$$O_{9}$ thin films were etched by using magnetically enhanced inductively coupled Ar/CHF$_3$ plasma. Etch properties, such as etch rate, selectivity, and etched profile, were measured according to gas mixing ratio of CHF$_3$(Ar$_{7}$+CHF$_3$) and the other process conditions were fixed at RF power of 600 W, dc bias voltage of 150 V, chamber pressure of 10 mTorr. Maximum etch rate of SBT thin films was 1750 A77in, under CHF$_3$(Ar+CHF$_3$) of 0.1. The selectivities of SBT to Pt and PR were 1.35 and 0.94 respectively. The chemical reaction of etched surface were investigated by X-ray photoelectron spectroscopy (XPS) analysis. The Sr and Ta atoms of SBT film react with fluorine and then Sr-F and Ta-F were removed by the physical sputtering of Ar ion. The surface of etched SBT film with CHF$_3$(Ar+CHF$_3$) of 0.1 was analyzed by secondary ion mass spectrometer (SIMS). Scanning electron microscopy (SEM) was used for examination of etched profile of SBT film under CHF$_3$(Ar+CHF$_3$) of 0.1 was about 85˚.85˚.˚.

• Transactions on Electrical and Electronic Materials
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• 제18권2호
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• pp.74-77
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• 2017

In this work, we investigated the etching characteristics of TaNO thin films and the selectivity of TaNO to $SiO_2$ in an $O_2$/CF4/Ar inductively coupled plasma (ICP) system. The maximum etch rate of TaNO thin film was 297.1 nm/min at a gas mixing ratio of O2/CF4/Ar (6:16:4 sccm). At the same time, the etch rate was measured as a function of the etching parameters, such as the RF power, DC-bias voltage, and process pressure. X-ray photoelectron spectroscopy analysis showed the efficient destruction of the oxide bonds by the ion bombardment, as well as the accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the $CF_4$-containing plasmas.

• 동굴
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• 제82호
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• pp.1-4
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• 2007

In this paper, the etching of Au films using photoresist masks on Si substrates was investigated using a capacitively coupled plasma etch reactor. The advantages of plasma etch techniques over current methods for Au metalization include the ability to simplify the metalization process flow with respect to resist lift-off schemes, and the ability to cleanly remove etched material without sidewall redeposition, as is seen in ion milling. The etch properties were measured for different gas mixing ratios of CF4/Ar, and chamber pressures while the other conditions were fixed. According to statistical design of experiment (DOE), etching process of Au films was characterized and also 20 samples were fabricated followed by measuring etch rate, selectivity and etch profile. There is a chemical reaction between CF4 and Au. Au- F is hard to remove from the surface because of its high melting point. The etching products can be sputtered by Ar ion bombardment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.20-20
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• 1998

I Ion beam technology has recently attracted much interest because it has exciting t technological p아:ential for surface analysis, ion beam mixing, surface cleaning and etching i in thin film growth and semiconductor fabrication processes, etc. Es야~cially, ion beam s sputtering has been widely used for sputter depth profiling with x-photoelectron S spectroscopy (XPS) , Auger electron s$\pi$~troscopy(AES), and secondary-ion mass S야i따oscopy(SIMS). However, The problem of surface compositional ch없1ge due to ion b bombardment remains to be understo여 없ld solved. So far sputtering processes have been s studied by s따face an외ysis tools such as XPS, AES, and SIMS which use the sputtering p process again. It would be improbable to measure the modified surface composition profiles a accurately due to ion beam bombardment with surface analysis techniques based on sputter d depth profiling. However, recently Medium energy ion scattering spectroscopy(MEIS) has b been applied to study the sputtering of solid surface at ion bombardment and has been p proved that it has been extremely valuable in probing the surface composition 뻐d s structure nondestructively and quantita디vely with less than 1.0 nm depth resolution. To u understand the sputtering processes of solid surface at ion bombardment, The Molecular D Dynamics(MD) and Monte Carlo(MC) simulation has been used and give an intimate i insight into the sputtering processes of solid surfaces. In this presentation, the sputtering processes of alloys and compound samples at ion b bombardment will be reviewed and the MEIS results for the Ar+ sputter induced altered l layer of the TazOs thin film 뻐dd없nage profiling of Ar+ ion sputt얹"ed Si(100) surface will b be discussed with the results of MD and MC simulation.tion.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.60-60
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• 2000

The adhesion interface formation between copper and poly(ethylene terephthalate)(PET), poly(methyl methacrylate)(PMMA) and Polyimide films was treated using Ion assisted reaction system to sequential sputter deposition by High-Frequency ion source. The ion beam modification system used a new type of low power HF ion thruster for space application as new low thruster electric propulsion system. Low power HF ion thruster with diameter 100mm gives the opportunity to obtain beams of Ar+ with currents 20~150 mA (current density 0.5~3.5 mA/cm2) and energy 200~2500eV at HF power level 10~150 W. Using Ar as a working gas it is possible to obtain thrust within 3~8 mN. Contact angles for untreated films were over 95$^{\circ}$ and 80 for Pet, 10o for PMMA and 12o for PI samples as a condition of ion assisted reaction at the ion dose of 10$\times$1016 ions/cm2, the ion beam potential of 1.2 keV and 4 ml/min for environmental gas flow rate. 900o peel tests yielded values of 15 to 35 for PET, 18 to 40 and 12 to 36 g/min. respectively. High resolution X-ray photoelectron spectrocopy is the Cls region for Cu metal on these polymer substrates showed increases in C=O-O groups for polymide, whereas PET and PMMA treated samples showed only C=O groups with increase the ion dose. Finally, unstable polymer surface can be changed from hydrophobic to hydrophilic formation such as C-O and C=O that were confirmed by the XPS analysis, conclusionally, the ion assisted reaction is very effective tools to attach reactive ion species to form functional groups on C-C bond chains of PET, PMMA and PI.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.147-151
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• 1999

YBCO step-edge Josephson junction were fabricated on sapphire substrates. The steps were formed on R-plane sapphire substrates by using Ar ion milling with PR masks. The step angle was controlled in the wide range from 25$^{\circ}$ to 50$^{\circ}$ by adjusting both the Ar ion incident angle and the photoresist mask rotation angle relative to the incident Ar ion beam. CeO$_2$ buffer layer and in-situ YBa$_2Cu_3O_{7-{\delta}}$ (YBCO) thin films was deposited on the stepped R-plane sapphire substrates by pulsed laser deposition method. The YBCO film thickness was varied to obtain the ratio of film thickness to step height in the range from 0.5 to 1. The step edge junction exhibited RSJ-like behaviors with I$_cR_n$ product of 100 ${\sim}$ 300 ${\mu}$V, critical current density of 10$^3$ ${\sim}$ 10$^5$ A/ cm$^2$ at 77 K.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.62-65
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• 2001

$SrBi_2Ta_2O_{9}$ thin films were etched in inductively coupled $Cl_{2}$/$CF_{4}$/Ar plasma. The maximum etch rate was 1060 $\AA\textrm{m}$/min in $Cl_{2}$/$CF_{4}$/Ar (80). The chemical reactions on the etched surface were studied with x-ray photoelectron spectroscopy. The etching of SBT thin films in $Cl_{2}$/$CF_{4}$/Ar were etched by chemically assisted reactive ion etching. The small addition of $Cl_2$ into $CF_4$(20)/Ar(80) plasma will decrease the fluorine radicals and the increase Cl radical.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.408-408
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• 2012

It is well known that magnetic random access memory (MRAM) is nonvolatile memory devices using ferromagnetic materials. MRAM has the merits such as fast access time, unlimited read/write endurance and nonvolatility. Although DRAM has many advantages containing high storage density, fast access time and low power consumption, it becomes volatile when the power is turned off. Owing to the attractive advantages of MRAM, MRAM is being spotlighted as an alternative device in the future. MRAM consists of magnetic tunnel junction (MTJ) stack and complementary metal- oxide semiconductor (CMOS). MTJ stacks are composed of various magnetic materials. FePt thin films are used as a pinned layer of MTJ stack. Up to date, an inductively coupled plasma reactive ion etching (ICPRIE) method of MTJ stacks showed better results in terms of etch rate and etch profile than any other methods such as ion milling, chemical assisted ion etching (CAIE), reactive ion etching (RIE). In order to improve etch profiles without redepositon, a better etching process of MTJ stack needs to be developed by using different etch gases and etch parameters. In this research, influences of $O_2$ gas on the etching characteristics of FePt thin films were investigated. FePt thin films were etched using ICPRIE in $CH_4/O_2/Ar$ gas mix. The etch rate and the etch selectivity were investigated in various $O_2$ concentrations. The etch profiles were studied in varying etch parameters such as coil rf power, dc-bias voltage, and gas pressure. TiN was employed as a hard mask. For observation etch profiles, field emission scanning electron microscopy (FESEM) was used.