• JSTS:Journal of Semiconductor Technology and Science
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• 제13권4호
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• pp.395-401
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• 2013

In-situ optical emission spectroscopy (OES) is employed for leak detection in plasma etching system. A misprocessing is reported for significantly reduced silicon etch rate with chlorine gas, and OES is used as a supplementary sensor to analyze the gas phase species that reside in the process chamber. Potential cause of misprocessing reaches to chamber O-ring wear out, MFC leaks, and/or leak at gas delivery line, and experiments are performed to funnel down the potential of the cause. While monitoring the plasma chemistry of the process chamber using OES, the emission trace for nitrogen species is observed at the chlorine gas supply. No trace of nitrogen species is found in other than chlorine gas supply, and we found that the amount of chlorine gas is slightly fluctuating. We successfully found the root cause of the reported misprocessing which may jeopardize the quality of thin film processing. Based on a quantitative analysis of the amount of nitrogen observed in the chamber, we conclude that the source of the leak is the fitting of the chlorine mass flow controller with the amount of around 2-5 sccm.

• 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.

• 전자공학회논문지A
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• 제32A권7호
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• pp.85-93
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• 1995

In this study, phthalocyanine thin films were prepared by vacuum sublimation method and investigated sensing characteristics of the films. The phthalocyannies used for the prepaation of the NO$_{x}$ sensors were metal-free Pc(H$_{2}$Pc) and metal Pc(CuPc, CoPc, PbPc). And the substrate temperatures maintained during the fomation of Pc films were varied between R.T. and 200$^{\circ]C$, and the base pressure was 5${\times}10^{6}$ torr. The relationships between NO$_{2}$ sensing properties and SEM analyses as a function of substrate temperatures during the formation of the films were investigated. Among the Pc films, PbPc film showed the best sensing characteristics. Particularlly, the PbPc films prepared at 70$^{\circ]C$ of the substrage temperature showen good sensitivity of 85% to 1ppm NO$_{2}$ gas at operating temperature 190$^{\circ]C$ and response time was about 24 seconds.

• 한국전기전자재료학회논문지
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• 제18권1호
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• pp.12-16
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• 2005

Chemical mechanical polishing (CMP) process is one of the most useful methods for improving the surface roughness of films. The effects of CMP on the surface morphology of WO$_3$ films prepared by RF sputtering system were investigated in this paper. A removal rate of films increased, and the uniformity performance of surface decreased with the addition of an oxidizer to the tungsten slurry. Non-uniformity performance of surface was superior as its value was below 5 % when oxidizers of 5.0 vol% and 2.5 vol%, respectively, were added to the tungsten slurry. The optimized oxidizer concentration, reflected both the improved roughness values and hillock-free surface with the good uniformity performance, was 5.0 vol% as an atomic force microscopy(AFM) analysis of thin film topographies. Our CMP results will be a useful reference for advanced technology of thin films for gas sensor applications in the near future.

• 센서학회지
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• 제8권2호
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• pp.115-123
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• 1999

PSG(800nm)/$Si_3N_4$ (150nm)로 구성된 유전체 membrane 윗면에 heater와 감지전극을 등일면상에 동시에 형성하였다. 제작된 소자의 전체 면적은 $3.78{\times}3.78mm^2$이고, diaphragm의 면적은 $1.5{\times}1.5mm^2$이며, 감지막치 면적은 $0.24{\times}0.24mm^2$였다. 그리고 diaphragm내의 열분포 분석을 유한요소법을 이용하여 수행하였으며, 실제로 제작된 소자의 열분포와 비교하였다. 소비전력은 동작온도 $350^{\circ}C$에서 약 85mW였다. Sn 금속막을 상온과 $232^{\circ}C$의 두 가지 기판온도에서 열증착하였고, 이를 $650^{\circ}C$의 산소분위기에서 3시간 열산화함으로써 $SnO_2$ 감지막을 형성하였다. 그리고 이를 SEM과 XRD로 특성을 분석하였다. 제작된 소자에 대해서 온도 및 습도에 대한 감지막의 영향 및 부탄가스에 대한 반응특성도 조사하였다.

• 대한금속재료학회지
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• 제47권6호
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• pp.372-377
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• 2009

We report on hysteresis behavior in the electrical resistance-hydrogen concentration of Pd thin films. The variation of the electrical resistance has been investigated during the process of absorption and desorption of hydrogen gas ($H_{2}$) as a function of thickness of Pd thin films. The hysteresis behavior in the electrical resistance with $H_{2}$ concentration was found for Pd thin films and consists of $\alpha$ phase, ${\alpha}+{\beta}$ phase, and $\beta$ phase regions. The sensitivity of Pd thin films with $H_{2}$ concentration was found to follow Sieverts' law in the $\alpha$ phase region. However, the sensitivity was observed to increase abruptly with $H_{2}$ concentration in the ${\alpha}+{\beta}$ phase co-exist region. This is because Pd-H interaction is stronger in the $\beta$ phase than in the $\alpha$ phase and needs a higher concentration gradient as a driving force to desorb. The formation of the $\beta$ phase also was observed to cause the structural change because of the lattice expansion during absorption. The hysteresis height and the trace of structural change were affected by the thickness of the Pd film. As the film becomes thinner, the hysteresis height becomes lower and the amount of delamination on the surface becomes smaller. For films thinner than 20 nm in thickness, the delamination was not found but electrical resistance hysteresis was still observed.

• 열처리공학회지
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• 제24권1호
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• pp.31-36
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• 2011

$TiO_2$ films were deposited on a glass substrate with RF magnetron sputtering and then surface of $TiO_2$ films were electron beam irradiated in a vacuum condition to investigate the effect of electron bombardment on the thin film crystallization, surface roughness and gas sensitivity for hydrogen. $TiO_2$ films that electron beam irradiated at 450eV were amorphous phase, while the films irradiated at 900 eV show the anatase (101) diffraction peak in XRD pattern. AFM measurements show that the roughness is depend on the electron irradiation energy. As increase the hydrogen gas concentration and operation temperature, the gas sensitivity of $TiO_2$ and $TiO_2$/ZnO films is increased proportionally and $TiO_2$ films that electron beam irradiated at 900 eV show the higher sensitivity than the films were irradiated at 450eV. From the XRD pattern and AFM observation, it is supposed that the crystallization and rough surface promote the hydrogen gas sensitivity of $TiO_2$ films.

• 전기화학회지
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• 제8권1호
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• pp.32-36
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• 2005

본 연구는 $WO_3$ 박막과 $NiO-WO_3$ 박막을 고진공 저항가열식 thermal evaporation 법으로 (100) n형의 실리콘 단결정 기판 위에 증착시켰고, 막의 결정성 증진을 위하여 공기 중 $500^{\circ}C$에서 30분 동안 열처리하였다. 박막의 결정성 및 결정구조를 분석하기 위해서 X선 회절분석기를 사용하였고, 표면 및 단면 관찰을 위해서는 주사전자현미경을 이용하였다. 그리고 화학 조성 결합에너지는 XPS를 이용하였다. 순수 $WO_3$ 박막의 결정 크기는 $500^{\circ}C$에서 30분 동안 공기중 열처리에 의해서 $0.6{\mu}m$로 성장하였고 $WO_3$ 박막의 두께가 증가할수록 거의 변화 없이 일정하였다. 반면, NiO가 첨가된 $WO_3$ 박막 두께별 결정크기는 각각 $0.12{\mu}m,\;0.28{\mu}m,\;0.32{\mu}m$및 $0.43{\mu}m$로 순수 $WO_3$ 박막에 비해 치밀한 표면을 형성하였고, 최대 5배정도 성장이 억제되었다. 가스감도 측정은 대기 중에서의 센서 저항 값을 기준으로 측정가스 저항 값의 비율 $(R_{NOx}/R_{air})$로 가스감도를 나타내었다. 전기적 성질은 MFC로 NOx가스 5ppm을 일정히 유지시켰고, Multimeter로 계측하여 컴퓨터에 자동 계측되는 시스템을 사용하였다. 순수 $WO_3$박막보다는 $NiO-WO_3$ 박막이 우수한 NOx 감도특성을 보였고 센서의 작동온도는 $250^{\circ}C$에서 우수한 감도를 나타내었다.

• 센서학회지
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• 제18권5호
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• pp.349-352
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• 2009

This paper describes the fabrication and characteristics of micro heaters built on AlN($0.1{\mu}m$)/3C-SiC($1{\mu}m$) suspended membranes by surface micromachining technology. In this work, 3C-SiC and AlN films are used for high temperature environments. Pt thin film was used as micro heaters and temperature sensor materials. The resistance of temperature sensor and the power consumption of micro heaters were measured and calculated. The heater is designed for operating temperature up to about $800^{\circ}C$ and can be operated at about $500^{\circ}C$ with a power of 312 mW. The thermal coefficient of the resistance(TCR) of fabricated Pt resistance of temperature detector(RTD)'s is 3174.64 ppm/$^{\circ}C$. A thermal distribution measured by IR thermovision is uniform on the membrane surface.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.245-248
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• 2012

본 논문에서는 실리콘 기반의 기술과 차별화하여 저온동시소성세라믹 (LTCC) 기판을 이용하여 대표적 압전물질인 PZT 박막의 최적의 증착조건을 연구하였다. LTCC 기술은 실리콘 기반의 기술에 비하여 낮은 생산 단가, 높은 수율, 3차원 구조물의 용이한 제작성 등으로 인하여 센서 및 액추에이터와 같은 10 um ~ 수백 um 정도의 중규모 디바이스를 제작하는데 있어서 중요한 역할을 담당하고 있다. LTCC 기판은 NEG사의 MLS 22C 상용 파우더를 이용하여 100 um 두께의 그린쉬트를 적층하고 동시소결하여 400 um 두께로 제작하였다. 제작한 기판위에 Pt/Ti 하부전극을 증착하고 RF 마그네트론 스퍼터링 방법을 이용하여 PZT 박막의 증착조건을 연구하였다. 증착조건으로는 RF 전력과 아르곤과 산소 가스비를 가변하여 실시하였으며, XRD와 EDS를 사용하여 박막의 결정성 및 성분을 분석하였다. 실험을 통하여 얻어진 최적의 증착조건은 RF 전력 125W, 아르곤과 산소비 15:5에서 가장 우수한 특성을 나타내는 것을 확인하였다.