• 한국진공학회지
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• 제1권1호
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• pp.115-120
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• 1992

SIMS는 뛰어난 원소검출감도와 깊이 분해능을 가지고 있어서 깊이에 따른 미량불 순물 분석에 필수적인 장비이지만, 시료와 불순물의 변화에 따라 이온화율과 깍이는 속도가 달라서 일어나는 matrix effect 때문에 표준 시료없이 정량분석을 할 수 없는 문제점이 있 다. 이런 SIMS의 단점을 보완하기 위한 방법으로 개발된 여러 가지 SNMS 기술 중 SIMS에 아무런 기계장치를 덧붙이지 않고도 정량화 개선효과를 가져오는 CsX+ SNMS에 대한 연구 를 진행하여, 지금까지 밝혀진 실리콘 산화막 등에서의 주성분원소 조성비분석을 통해 SNMS 기능을 확인하고 SIMS의 주 분석대상인 분순물 농도분석에의 적용가능성을 실험해 보았다. 이를 위해 실리콘에 BF2 이온 주입 후 붕소분포 분석시 강한 matrix effect를 나타 내는 불소의 효과를 SNMS와 SIMS로 비교하였으며, 검출한계와 dynamic range도 조사하였 다. 실험결과 CsX+ SNMS 기술은 matrix effect 때문에 실제분포와 다른 값으로 검출되는 불순물 시료분석에 적용할 수 있음을 알았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.286-289
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• 1991

We simulated ion implantation and annealing condition of 1 ${\mu}m$ CMOS device using process simulator, SUPREM-II. In this simulation, optimal condition of ion implantation for symmetric threshold voltage determination of PMOS and NMOS region, junction depth and sheet resistance of source/drain region, impurity profile of each region are investigated. Ion implantation dose for 3 ${\mu}m$ N-well junction depth and symmetric threshold voltage of $|0.6|{\pm}0.1$ V were $1.9E12Cm^{-2}$(for phosphorus), $1.7E122Cm^{-2}$(for boron) respectively. Also annealing condition for dopant activation are examined about $900^{\circ}C$, 30 minutes. After final process step, N-well junction, P+ S/D junction and N+ S/D junction depth are calculated 3.16 ${\mu}m$, 0.45 ${\mu}m$ and 0.25 ${\mu}m$ respectively.

• 한국결정성장학회지
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• 제6권1호
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• pp.19-31
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• 1996

갈륨 비소 반도체 결정을 성장시키는 데 많이 사용되는 수평브렷지만법에 의하여 성장된 갈륨비소 단결정 내에셔 불순물 분포를 알아보기 위하여 액상에서 열전달, 물질전달, 유 체흐름과 고상에서 열전달을 묘사하는 과도기 모탤을 수립하였고 유한요소법과 음함수 척분법 에 의하여 수치모사를 행하였다. 그 결과 Gr이 작은 경우에는 확산조절성장의 특성을 보였으며 G Gr이 1,700 정도만 되어도 농도의 최소값이 계면 근처로 이동하였다. 응고가 진행됨에 따라 계 면의 곡률이 증가하였고, 흐름에 의한 혼합이 안정될 때까지 수직편석이 증가하였다. 수펑편석 은 응고가 진행됨에 따라 증가하였지만 흐름의 강도가 강한 경우에는 곧 일정하게 유지되였다. G Gr이 아주 작거나 큰 경우에는 Smith식과 Scheil식의 경우와 잘 일치하였다.

• 분석과학
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• 제13권4호
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• pp.504-510
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• 2000

Glycyrrhizin은 감초(Glycyrrhizae Radix)의 주성분으로써 항궤양, 항염증, 항알러지, 진해작용을 하는 것으로 알려져 있으며 glycyrrhetinic acid에 2당류가 연결된 매우 hydrophilic하고 분자량이 큰(mw=822.92) 물질이다. 본 연구에서는 on-line high performance liquid chromatography (HPLC)/electrospray ionization (ESI)- mass spectrometery (MS)를 이용하여 각종 glycyrrhizin 표준품들의 불순물들에 대한 구조 규명을 하였다. 사용한 HPLC column은 $C_{18}$($3.9{\times}300mm$, $10{\mu}m$)이었으며 이동상은 acetic acid/$H_2O$(1:15):acetonitrile=3:2를 0.8ml/min으로 흘려주었고 용출물을 post-column splitter를 사용하여 50:1로 split시켜서 ESI-MS에 주입하였다. ESI-MS는 negative mode이었으며 CapEx voltage는 100 V에서 각 불순물들의 분자량이 측정되었고 구조규명을 위하여 CapEx voltage를 80-300 V까지 변화시켜주는 CID (collision induced dissoclation) 기법을 사용함으로써 fragment를 얻을 수 있었고 이를 바탕으로 구조규명을 하였다. 주요 불순물의 구조는 glycyrrhetic acid moiety에 수산화기(-OH)가 붙은 형태와 glycyrrhetic acid moiety의 12번 위치에서 환원이 일어난 형태 이었다. 표준품의 순도는 약 90% 정도이었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.358-358
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• 2012

The application of BZO (Boron-doped Zinc Oxide) films use as the TCO(Transparent Conductive Oxide) material for display and solar cell industries, where the conductivity of the BZO films plays a critical role for improvement of cell performance. Thin BZO films are deposited on glass substrates by using RF sputter system. Then charging flow rates of O2 gas from zero to 10 sccm, thereby controlling the impurity concentration of BZO. BZO deposited on soda lime glass and RF power was 300 W, frequency was 13.56 MHz, and working pressure was $5.0{\times}10-6$ Torr. The Substrate and glass between distance 200 mm. We measured resistivity, conductivity, mobility by hall measurement system. Optical properties measured by photo voltaic device analysis system. We measured surface build according to oxygen flow rate from XPS (X-ray Photoelectron Spectroscopy) system. The profile of the energy distribution of the electrons emitted from BZO films by the Auger neutralization is measured and rescaled so that Auger self-convolution arises, revealing the detail structure of the valence band. It may be observed coefficient ${\gamma}$ of the secondary electron emission from BZO by using ${\gamma}$-FIB (Gamma-Focused Ion Beam) system. We observed the change in electrical conductivity by correlation of the valence band structure. Therefore one of the key issues in BZO films may be the valence band that detail structure dominates performance of solar cell devices. Demonstrating the secondary electron emission by the Auger neutralization of ions is useful for the determination of the characteristics of BZO films for solar cell and display developments.

• 한국결정성장학회지
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• 제18권5호
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• pp.195-199
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• 2008

반도체용 규소 원료는 11 N급의 고순도이나 가격이 고가이고 또한 생산이 제한되어서 폭발적인 태양전지의 수요를 따르지 못하고 있어 저급(5$\sim$6 N)의 UMG(Upgraded Metallurgical Grade)를 사용하자 하는 노력이 진행 중이다. 이 5$\sim$6 N급에서는 dopant 원소인 붕소(B)외 인(P)의 농도가 1 ppm 이상 존재한다. 이들 원료를 사용하여서 결정 성장을 하였을 경우에 존재하는 여러 불순물들의 편석계수(segregation coefficient)를 활용하여 화학적, 전기적 성질을 예상 하여본 결과 결정성장 초기에는 붕소(B)의 농도가 인(P) 보다 높아 p영역이 발생하고 후반부에는 인의 농도가 붕소 보다 높아 n 형 기판이 생성됨을 보았다. 또한 응고속도를 조절하여 여러 불순물을 제거하고자 히는 노력은 편식계수가 적은 금속 일소들의 제거에는 효과적이나 편석계수가 큰 붕소와 인의 제거에는 효과가 크지 않음을 예상 할 수 있다.

• 공업화학
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• 제10권1호
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• pp.160-165
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• 1999

Gel 표준 물질의 핵자기 공명적 완화 성질들이 다공성 매체내 유체의 핵자기 공명적 완화 성질들과 잘 부합될 수 있기 때문에, agarose gel은 다공성 매체내 유체의 성질을 측정하기 위한 표준 물질로 사용될 수 있다. 다공성 매체의 세공도(porosity)와 포화도(saturation)를 결정하기 위한 표준물질의 사용을 논의하였고, gel의 핵자기 공명적 성질에 대한 필요조건들도 제시하였다. 2.0 Tesla에서 측정된 agarose gel의 완화시간은 agarose 농도와 상자기성 불순물의 ($CuSO_4$) 농도 함수로 표시하였고, agarose gel 조성과 완화시간 사이의 실험적 결과를 나타내었다. 세공도 분포에 대한 평균값은 17.7%이고, 이 값은 중량 분석법에 의해 계산된 값과 잘 일치한다. 끝으로, agarose gel을 표준 물질로 사용한 비혼화성 2상 유체실험을 수행하였다. 포화 profile들은 균일한 다공성 매체내에서 일차원 치환실험을 했을 때 계산된 결과와 잘 일치하고 있다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권3호
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• pp.213-224
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• 2010

An optically controlled silicon MESFET (OPFET) was fabricated by diffusion process to enhance the quantum efficiency, which is the most important optoelectronic device performance usually affected by ion implantation process due to large number of process induced defects. The desired impurity distribution profile and the junction depth were obtained solely with diffusion, and etching processes monitored by atomic force microscope, spreading resistance profiling and C-V measurements. With this approach fabrication induced defects are reduced, leading to significantly improved performance. The fabricated OPFET devices showed proper I-V characteristics with desired pinch-off voltage and threshold voltage for normally-on devices. The peak photoresponsivity was obtained at 620 nm wavelength and the extracted external quantum efficiency from the photoresponse plot was found to be approximately 87.9%. This result is evidence of enhancement of device quantum efficiency fabricated by the diffusion process. It also supports the fact that the diffusion process is an extremely suitable process for fabrication of high performance optoelectronic devices. The maximum gain of OPFET at optical modulated signal was obtained at the frequency of 1 MHz with rise time and fall time approximately of 480 nS. The extracted transconductance shows the possible potential of device speed performance improvements for shorter gate length. The results support the use of a diffusion process for fabrication of high performance optoelectronic devices.

• 분석과학
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• 제37권2호
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• pp.98-113
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• 2024

The current investigation entails the characterization of five degradation products (DPs) formed under different stress conditions of loteprednol using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, this study developed a stable high-performance liquid chromatography (HPLC) method for evaluating loteprednol along with impurities. The method conditions were meticulously fine-tuned which involved the exploration of the appropriate solvent, pH, flow of the mobile phase, columns, and wavelength. The method conditions were carefully chosen to successfully resolve the impurities of loteprednol and were employed in subsequent validation procedures. The stability profile of loteprednol was exposed to stress degradation experiments conducted under five conditions, and DPs were structurally characterized by employing LC-MS/MS. The chromatographic resolution of loteprednol and its impurities along with DPs was effectively achieved using a Phenomenex Luna 250 mm C18 column using 0.1 % phosphoric acid, methanol, and acetonitrile in 45:25:30 (v/v) pumped isocratically at 0.8 mL/min with 243 nm wavelength. The method produces an accurate fit calibration curve in 50-300 ㎍/mL for loteprednol and LOQ (0.05 ㎍/mL) - 0.30 ㎍/mL for its impurities with acceptable precision, accuracy, and recovery. The stress-induced degradation study revealed the degradation of loteprednol under basic, acidic, and photolytic conditions, resulting in the formation of seven distinct DPs. The efficacy of this method was validated through LC-MS/MS, which allowed for the verification of the chemical structures of the newly generated DPs of loteprednol. This method was appropriate for assessing the impurities of loteprednol and can also be appropriate for structural and quantitative assessment of its degradation products.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.363-363
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• 2008

The development of dry etching process for sapphire wafer with plasma has been key issues for the opto-electric devices. The challenges are increasing control and obtaining low plasma induced-damage because an unwanted scattering of radiation is caused by the spatial disorder of pattern and variation of surface roughness. The plasma-induced damages during plasma etching process can be classified as impurity contamination of residual etch products or bonding disruption in lattice due to charged particle bombardment. Therefor, fine pattern technology with low damaged etching process and high etch rate are urgently needed. Until now, there are a lot of reports on the etching of sapphire wafer with using $Cl_2$/Ar, $BCl_3$/Ar, HBr/Ar and so on [1]. However, the etch behavior of sapphire wafer have investigated with variation of only one parameter while other parameters are fixed. In this study, we investigated the effect of pressure and other parameters on the etch rate and the selectivity. We selected $BCl_3$ as an etch ant because $BCl_3$ plasmas are widely used in etching process of oxide materials. In plasma, the $BCl_3$ molecule can be dissociated into B radical, $B^+$ ion, Cl radical and $Cl^+$ ion. However, the $BCl_3$ molecule can be dissociated into B radical or $B^+$ ion easier than Cl radical or $Cl^+$ ion. First, we evaluated the etch behaviors of sapphire wafer in $BCl_3$/additive gases (Ar, $N_2,Cl_2$) gases. The behavior of etch rate of sapphire substrate was monitored as a function of additive gas ratio to $BCl_3$ based plasma, total flow rate, r.f. power, d.c. bias under different pressures of 5 mTorr, 10 mTorr, 20 mTorr and 30 mTorr. The etch rates of sapphire wafer, $SiO_2$ and PR were measured with using alpha step surface profiler. In order to understand the changes of radicals, volume density of Cl, B radical and BCl molecule were investigated with optical emission spectroscopy (OES). The chemical states of $Al_2O_3$ thin films were studied with energy dispersive X-ray (EDX) and depth profile anlysis of auger electron spectroscopy (AES). The enhancement of sapphire substrate can be explained by the reactive ion etching mechanism with the competition of the formation of volatile $AlCl_3$, $Al_2Cl_6$ or $BOCl_3$ and the sputter effect by energetic ions.