• 센서학회지
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• 제9권2호
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• pp.90-95
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• 2000

$Si_3N_4/SiO_2/Si_3N_4$/Si 판위에 MgO 박막을 성장하여 MgO 단결정과 결정배향성이 유사한 초전형 적외선 센서용 기판을 제작하였다. RF 마그네트론 스퍼터링법으로 MgO 박막을 성장하였고, 그 위에 Pt 하부전극과 PLT 박막을 성장시킨 후 c축 배향성을 조사하였다. $500^{\circ}C$의 기판온도와 30 mTorr의 분위기 압력 및 160 W의 RF power에서 성장된 MgO 박막이 단결정 MgO가 가지는 배향성 정도의 우수한 a축 배향성을 보였고, 그 위에 성장된 PLT 박막은 MgO 단결정 기판위에 성장된 것과 거의 회절강도 변화가 유사한 c축 배향성을 보였다.

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.309-316
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• 2014

A large particle accelerator requires an ultrahigh vacuum (UHV) system of average pressure under $1{\times}10^{-7}$ Pa for mitigating the impact of beam scattering from the residual gas molecules. The surface inside the beam ducts should be controlled with an extremely low thermal outgassing rate under $1{\times}10^{-9}Pa{\cdot}m^3/(s{\cdot}m^2)$ for the sake of the insufficient pumping speed. To fulfil the requirements, the aluminum alloys were adopted as the materials of the beam ducts for large accelerator that thanks to the good features of higher thermal conductivity, non-radioactivity, non-magnetism, precise machining capability, et al. To put the aluminum into the large accelerator vacuum systems, several key technologies have been developed will be introduced. The concepts contain the precise computer numerical control (CNC) machining process for the large aluminum ducts and parts in pure alcohol and in an oil-free environment, surface cleaning with ozonized water, stringent welding process control manually or automatically to form a large sector of aluminum ducts, ex-situ baking process to reach UHV and sealed for transportation and installation, UHV pumping with the sputtering ion pumps and the non-evaporable getters (NEG), et al. The developed UHV technologies have been applied to the 3 GeV Taiwan Photon Source (TPS) and revealed good results as the expectation. The problems of leakage encountered during the assembling were most associated with the vacuum baking which result in the consequent trouble shootings and more times of baking. Then the installation of the well-sealed UHV systems is recommended.

• 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˚.˚.

• 센서학회지
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• 제5권3호
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• pp.87-92
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• 1996

Pb과잉인 PLT 타겟을 이용하여 MgO(100) 단결정 기판위에 고주파 마그네트론 스펏터링법으로 PLT박막을 제조하였으며, c-축 배향에 따른 물리적 및 전기적 특성을 조사하였다. PLT박막의 c-축 배향성은 제조조건에 따라 변화하며, 본 연구에서의 제조조건은 기판온도가 $640^{\circ}C$, 분위기압이 10 mTorr, $Ar/O_{2}$비가 10 및 고주파 전력밀도가 $1.7 W/cm^{2}$이었다. 이러한 조건에서 제조된 PLT 박막은 표면에서의 Pb/Ti 비가 1/2, 저항률이 $8{\times}10^{11}{\Omega}{\cdot}cm$ 및 비유전률이 110 이었다. PLT박막을 이용하여 초전형 적외선 센서를 제조하였으며, 제조된 적외선 센서의 피크 대 피크 전압은 450 mV, 신호대 잡음비는 7.2 였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.441-443
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• 2005

According as CCFL(Cold Cathode Fluorescent lamp) of light source in Backlight unit for Note PC (Personal computer) is presently needed to low power consumption and long life time, the development focus of CCFL is going on the discharge gas, phosphor and electrode material. First of all, discharge voltage characteristic of CCFL is closely connected with electrode material For low discharge voltage, the characteristic of electrode material is needed to low work function, low sputtering ratio and superior manufacturing property. We developed new CCFL with Nb/Ni Clad electrode superior to conventional CCFL. Because Nb/Ni Clad electrode with Ni material and Nb material, the electrical characteristic is superior to other electrode materials. The electrode of Nb/Ni Clad is composed that Ni of outside material has superior manufacturing property and Nb of inside material has low work function. Nb/Ni Clad of new electrode material is made by process of Rolling mill at high pressure and heat treatment. We compared electrical characteristic of Nb/Ni clad electrode with conventional Mo electrode by measurement. Mo electrode and Nb/Ni Clad electrode of cup type with diameter 1.1 mm and length 3.0mm are used to this experiment. Material content of Mo electrode is Mo 100%. But, Nb/Ni Clad electrode is composed by content of Nb 40% and Ni 60%. The result of comparison measurement between new CCFL with Nb/Ni Clad electrode and conventional CCFL was appeared that CCFL with Nb/Ni Clad electrode had superior characteristic than conventional CCFL. As a result of experiment, we completed Note PC with low power consumption and long life time by application of new CCFL with Nb/Ni Clad electrode.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.448-448
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• 2010

Magnetic random access memory (MRAM) has made a prominent progress in memory performance and has brought a bright prospect for the next generation nonvolatile memory technologies due to its excellent advantages. Dry etching process of magnetic thin films is one of the important issues for the magnetic devices such as magnetic tunneling junctions (MTJs) based MRAM. CoFeB is a well-known soft ferromagnetic material, of particular interest for magnetic tunnel junctions (MTJs) and other devices based on tunneling magneto-resistance (TMR), such as spin-transfer-torque MRAM. One particular example is the CoFeB - MgO - CoFeB system, which has already been integrated in MRAM. In all of these applications, knowledge of control over the etching properties of CoFeB is crucial. Recently, transferring the pattern by using milling is a commonly used, although the redeposition of back-sputtered etch products on the sidewalls and the low etch rate of this method are main disadvantages. So the other method which has reported about much higher etch rates of >$50{\AA}/s$ for magnetic multi-layer structures using $Cl_2$/Ar plasmas is proposed. However, the chlorinated etch residues on the sidewalls of the etched features tend to severely corrode the magnetic material. Besides avoiding corrosion, during etching facets format the sidewalls of the mask due to physical sputtering of the mask material. Therefore, in this work, magnetic material such as CoFeB was etched in an ICP etching system using the gases which can be expected to form volatile metallo-organic compounds. As the gases, carbon monoxide (CO) and ammonia ($NH_3$) were used as etching gases to form carbonyl volatiles, and the etched features of CoFeB thin films under by Ta masking material were observed with electron microscopy to confirm etched resolution. And the etch conditions such as bias power, gas combination flow, process pressure, and source power were varied to find out and control the properties of magnetic layer during the process.

• 한국결정성장학회지
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• 제8권4호
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• pp.599-604
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• 1998

본 논문은 PZT 박막의 기억소자 응용을 위한 Pt 그리고 RuO2 박막을 조사하였다. 초고주파 마그네트론 스퍼터링 방법을 이용하여 하부전극을 성장하였으며, 조사된 실험변수는 기판온도, 가스 부분압, RF 전력 그리고 후열처리 등이다. 기판온도는 Pt, $RuO_2$박막의 결정구조 뿐만 아니라 표면구조 및 비저항 성분에 크게 영향을 주었다. Pt 박막의 XRD 분석으로 기판온도가 상온에서 $200^{\circ}C$까지는 (111) 그리고 (200) 면이 혼재하는 결과를 보였으나 $300^{\circ}C$에서는 (111) 면으로 우선 방위 성장 특성을 보였다. XRD와 AFM 해석으로부터 Pt 박막 성장시 기판온도 $300^{\circ}C$, RF 전력 80W가 추천된다. 산소 분압비를 0~50%까지 가변하여 조사한 결과 산소가 5% 미만으로 공급되면 Ru 금속이 성장되고, 산소 분압비가 10 ~40%까지는 Ru와 $RuO_2$ 상이 공존하였으며 산소 분압비가 50%에서는 순수한 $RuO_2$상만이 검축되었다. 이 결과로부터 RuO2/Ru 이층 구조의 하부전극 형성이 산소 가스 부분압을 조절하여 한번의 공정으로 성장 가능하며, 이런 구조를 이용하면 금속의 낮은 비저항을 유지하면서도 PZT 박막의 산소 결핍에 의한 기억소자의 피로도 문제를 완화할 것으로 사료된다. 후 열처리 온도를 상온에서부터 $700^{\circ}C$까지 증가할 때 Pt와 $RuO_2$의 비저항 성분은 선형적 감소 추세를 보였다. 본 논문은 강유전체 기억소자 응용을 위한 최적화된 하부전극 제적조건을 제시한다.

• 조명전기설비학회논문지
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• 제20권7호
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• pp.6-13
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• 2006

각 종 전자 디바이스의 투명전도막으로 많이 사용되는 ITO 및 ZnO:Al 박막을 스퍼터링법에 의해 제작하였다. 가스압력 및 기판온도 등의 최적조건하에서 제작된 ITO 및 ZnO:Al 박막은 각각 $1.67{\times}10^{-3}[{\Omega}-cm]$ 및 $2.2{\times}10^{-3}[{\Omega}-cm]$의 비저항율과 89.61[%] 및 90.88[%]의 가시광 영역에서의 광투과율을 나타내었다. ZnO:Al과 ITO 투명전극을 이용하여 5인치의 PDP 셀을 동일한 제조조건하에서 제작하였다. ZnO:Al의 경우 Ne(base)-Xe(8%)의 가스 혼합비, 그리고 400[Torr]의 압력조건에서 가장 잘 동작되었으며, $200{\sim}300$[V]의 인가전압 범위에서 $836[cd/m^2]$의 평균휘도를 나타내었다. 고휘도 및 저 소비전력특성을 위한 중요한 파라메타인 광효율은 전원 주파수가 $10{\sim}50[Khz]$의 범위에서 $1.2{\sim}1.6[lm/W]$정도를 나타내었으며, ITO의 경우 휘도 및 광 발생 효율은 약 10[%]정도 상승하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.97-97
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• 2013

Recently, Cu2ZnSn(S,Se)4 (CZTSS), which is one of the In- and Ga- free absorber materials, has been attracted considerable attention as a new candidate for use as an absorber material in thin film solar cells. The CZTSS-based absorber material has outstanding characteristics such as band gap energy of 1.0 eV to 1.5 eV, high absorption coefficient on the order of 104 cm-1, and high theoretical conversion efficiency of 32.2% in thin film solar cells. Despite these promising characteristics, research into CZTSS based thin film solar cells is still incomprehensive and related reports are quite few compared to those for CIGS thin film solar cells, which show high efficiency of over 20%. I will briefly overview the recent technological development of CZTSS thin film solar cells and then introduce our research results mainly related to sputter based process. CZTSS thin film solar cells are prepared by sulfurization of stacked both metallic and sulfide precursors. Sulfurization process was performed in both furnace annealing system and rapid thermal processing system using S powder as well as 5% diluted H2S gas source at various annealing temperatures ranging from $520^{\circ}C$ to $580^{\circ}C$. Structural, optical, microstructural, and electrical properties of absorber layers were characterized using XRD, SEM, TEM, UV-Vis spectroscopy, Hall-measurement, TRPL, etc. The effects of processing parameters, such as composition ratio, sulfurization pressure, and sulfurization temperature on the properties of CZTSS absorber layers will be discussed in detail. CZTSS thin film solar cell fabricated using metallic precursors shows maximum cell efficiency of 6.9% with Jsc of 25.2 mA/cm2, Voc of 469 mV, and fill factor of 59.1% and CZTS thin film solar cell using sulfide precursors shows that of 4.5% with Jsc of 19.8 mA/cm2, Voc of 492 mV, and fill factor of 46.2%. In addition, other research activities in our lab related to the formation of CZTS absorber layers using solution based processes such as electro-deposition, chemical solution deposition, nano-particle formation will be introduced briefly.

• 한국진공학회지
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• 제21권6호
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• pp.333-341
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• 2012

본 연구는 RF 마그네트론 스퍼터링법을 이용하여 산소유량 변화에 따라 증착된 ITO 박막 구조적, 전기적, 광학적 특성을 분석하였다. ITO (Indium Tin Oxide) 박막은 $1.0{\times}10^{-3}$ Torr의 공정 압력과 2 kW 및 13.56 MHz의 RF 전력, 1,000 sccm의 Ar 가스 조건하에 0~12 sccm의 $O_2$ 가스 유량을 변경하면서 증착하였다. 광투과율 측정은 적분구를 이용하였으며, 측정 파장 범위는 300~1,100 nm이다. 4-point probe를 이용하여 면저항을 측정하였으며, Hall Measurement System을 이용하여 비저항, 캐리어 농도 및 전자이동도를 측정하였다. Scanning electron microscope 장비를 이용하여 ITO 박막 표면을 분석하였고, 박막의 거칠기는 Atomic force microscope을 이용하여 측정하였다. ${\gamma}$-Focused ion beam system을 이용하여 ITO 박막의 이차전자방출계수를 측정하였으며, 이차전자방출계수 값으로 Auger neutralization mechanism 분석법을 이용해 ITO 박막의 일함수를 결정하였다. 3 sccm의 산소 유량에서 증착된 ITO 박막의 비저항은 약 $2.4{\times}10^{-4}{\Omega}{\cdot}cm$로 가장 좋았으며, 광학적 특성 또한 84.93% (Weighted average)로 가장 좋은 것을 확인할 수 있었다. 이 조건에서 이차전자방출 계수가 가장 높았고 일함수는 가장 낮은 경향의 일치함을 확인하였다.