• Mass Spectrometry Letters
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• 제12권2호
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• pp.47-52
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• 2021

Evaluating the impurity concentrations in semiconductor thin films using time of flight secondary ion mass spectrometry (ToF-SIMS) is an effective technique. The mass interference between isotopes and matrix element in data interpretation makes the process complex. In this study, we have investigated the doping concentration of phosphorus in, phosphorus doped silicon thin film on glass using ToF-SIMS in the dynamic mode of operation. To overcome the mass interference between phosphorus and silicon isotopes, the quantitative analysis of counts to concentration conversion was done following two routes, standard relative sensitivity factor (RSF) and SIMetric software estimation. Phosphorus doped silicon thin film of 180 nm was grown on glass substrate using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using ToF-SIMS, the phosphorus-31 isotopes were detected in the range of 10¹~10⁴ counts. The silicon isotopes matrix element was measured from p-type silicon wafer from a separate measurement to avoid mass interference. For the both procedures, the phosphorus concentration versus depth profiles were plotted which agree with a percent difference of about 3% at 100 nm depth. The concentration of phosphorus in silicon was determined in the range of 10¹⁹~10²¹ atoms/cm³. The technique will be useful for estimating distributions of various dopants in the silicon thin film grown on glass using ToF-SIMS overcoming the mass interference between isotopes.

• 한국진공학회지
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• 제1권1호
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• pp.121-125
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• 1992

Secondary Ion Mass Spectrometry (SIMS) is widely known as highly sensitive a surface analysis technique. Efforts for quantification have been hindered, however, by the presence of matrix effects. Here we describe a new technique for the quantitative analysis of AlxGa1-xAs. Instead of Al+, Ga+, As+ ions, CsX+ ions (X=Al, Ga, As) have been detected. Intensity of these molecular ions appears to be much less affected by matrix effects. We have successfully accomplished the compositional analysis with standard deviation better than 2 percent.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.51.2-51.2
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• 2015

Understanding interfacial phenomena has been one of the main research issues not only in semiconductors but only in life sciences. I have been trying to meet the atomic scale surface and interface analysis challenges from semiconductor industries and furthermore to extend the application scope to biomedical areas. Optical imaing has been most widely and successfully used for biomedical imaging but complementary ion beam imaging techniques based on mass spectrometry and ion scattering can provide more detailed molecular specific and nanoscale information In this presentation, I will review the 27 years history of medium energy ion scattering (MEIS) development at KRISS and DGIST for nanoanalysis. A electrostatic MEIS system constructed at KRISS after the FOM, Netherland design had been successfully applied for the gate oxide analysis and quantitative surface analysis. Recenlty, we developed time-of-flight (TOF) MEIS system, for the first time in the world. With TOF-MEIS, we reported quantitative compositional profiling with single atomic layer resolution for 0.5~3 nm CdSe/ZnS conjugated QDs and ultra shallow junctions and FINFET's of As implanted Si. With this new TOF-MEIS nano analysis technique, details of nano-structured materials could be measured quantitatively. Progresses in TOF-MEIS analysis in various nano & bio technology will be discussed. For last 10 years, I have been trying to develop multimodal nanobio imaging techniques for cardiovascular and brain tissues. Firstly, in atherosclerotic plaque imaging, using, coherent anti-stokes raman scattering (CARS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) multimodal analysis showed that increased cholesterol palmitate may contribute to the formation of a necrotic core by increasing cell death. Secondly, surface plasmon resonance imaging ellipsometry (SPRIE) was developed for cell biointerface imaging of cell adhesion, migration, and infiltration dynamics for HUVEC, CASMC, and T cells. Thirdly, we developed an ambient mass spectrometric imaging system for live cells and tissues. Preliminary results on mouse brain hippocampus and hypotahlamus will be presented. In conclusions, multimodal optical and mass spectrometric imaging privides overall structural and morphological information with complementary molecular specific information, which can be a useful methodology for biomedical studies. Future challenges in optical and mass spectrometric imaging for new biomedical applications will be discussed.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권1호
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• pp.67-74
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• 2009

Monte Carlo simulation is widely used for predicting ion implantation profiles in amorphous targets. Here, we compared Monte Carlo simulation results with a vast database of ion implantation secondary ion mass spectrometry (SIMS), and showed that the Monte Carlo data sometimes deviated from the experimental data. We modified the electron stopping power model, calibrated its parameters, and reproduced most of the database. We also demonstrated that Monte Carlo simulation can accurately predict profiles in a low energy range of around 1keV once it is calibrated in the higher energy region.

• Mass Spectrometry Letters
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• 제2권4호
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• pp.80-83
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• 2011

Isotope ratio analysis of nuclear materials in individual particles is of great importance for nuclear safeguards. Although secondary ion mass spectrometry (SIMS) and thermal ionization mass spectrometry (TIMS) are utilized for the analysis of individual uranium particles, few studies were conducted for the analysis of individual uranium-plutonium mixed oxide particles. In this study, we applied SIMS and inductively coupled plasma mass spectrometry (ICP-MS) to the isotope ratio analysis of individual U-Pu mixed oxide particles. In the analysis of individual U-Pu particles prepared from mixed solution of uranium and plutonium standard reference materials, accurate $^{235}U/^{238}U$, $^{240}Pu/^{239}Pu$ and $^{242}Pu/^{239}Pu$ isotope ratios were obtained with both methods. However, accurate analysis of $^{241}Pu/^{239}Pu$ isotope ratio was impossible, due to the interference of the $^{241}Am$ peak to the $^{241}Pu$ peak. In addition, it was indicated that the interference of the $^{238}UH$ peak to the $^{239}Pu$ peak has a possibility to prevent accurate analysis of plutonium isotope ratios. These problems would be avoided by a combination of ICP-MS and chemical separation of uranium, plutonium and americium in individual U-Pu particles.

• 한국전기전자재료학회논문지
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• 제14권12호
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• pp.959-964
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• 2001

We investigated the etching characteristics of YMnO$_3$ thin films in high-density plasma etching system. In this study, YMnO$_3$ thin films were etched with CF$_4$/Ar gas chemistries in inductively coupled plasma(ICP). Etch rates of YMnO$_3$ increased up to 20% CF$_4$ in CF$_4$/(CF$_4$+Ar), but decreased with furthermore increasing CF$_4$ in CF$_4$/(CF$_4$+Ar). In optical emission spectroscopy (OES) analysis, F radical and Ar* ions in plasma at various gas chemistries decreased with increasing CF$_4$ content. Chemical states of YMnO$_3$ films exposed in plasma were investigated with x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). There is a chemical reaction between metal (Y, Mn) and F and metal-fluorides were removed effectively by Ar ion sputtering. YF$_{x}$, MnF$_{x}$ such as YF, YF$_2$, YF$_3$ and MnF$_3$ were detected using SIMS analysis. The etch slope is about 65$^{\circ}$ and cleasn surface. surface of the etched YMnO$_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The etch profile was also investigated by scanning electron microscopy (SEM).EM).

• 한국재료학회지
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• 제23권1호
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• pp.7-12
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• 2013

The $Cu_2ZnSnS_4$ (CZTS) thin film solar cell is a candidate next generation thin film solar cell. For the application of an absorption layer in solar cells, CZTS thin films were deposited by pulsed laser deposition (PLD) at substrate temperature of $300^{\circ}C$ without post annealing process. Deposition time was carefully adjusted as the main experimental variable. Regardless of deposition time, single phase CZTS thin films are obtained with no existence of secondary phases. Irregularly-shaped grains are densely formed on the surface of CZTS thin films. With increasing deposition time, the grain size increases and the thickness of the CZTS thin films increases from 0.16 to $1{\mu}m$. The variation of the surface morphology and thickness of the CZTS thin films depends on the deposition time. The stoichiometry of all CZTS thin films shows a Cu-rich and S-poor state. Sn content gradually increases as deposition time increases. Secondary ion mass spectrometry was carried out to evaluate the elemental depth distribution in CZTS thin films. The optimal deposition time to grow CZTS thin films is 150 min. In this study, we show the effect of deposition time on the structural properties of CZTS thin film deposited on soda lime glass (SLG) substrate using PLD. We present a comprehensive evaluation of CZTS thin films.

• 공업화학
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• 제30권4호
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• pp.499-503
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• 2019

GaInP/GaAs 양자우물(quantum well)구조를 N-AlGaInP/p-GaInP 이종 접합구조 태양전지에 도입하여 그 특성을 조사하고 양자우물구조가 없는 태양전지와 비교하였다. 에피층은 (100)평면이 (111)A 방향으로 $6^{\circ}$ 기울어진 p-GaAs 기판 위에 성장하였다. 태양전지 박막구조는 두께 400 nm의 N-AlGaInP 층에 590 nm의 p-GaInP와 210 nm의 GaInP/GaAs 양자 우물 구조(10 nm GaInP/5 nm GaAs의 14겹 구조)가 도입된 양자우물 태양전지 구조와 800 nm의 p-GaInP의 단일이종접합 구조로 이루어진다. 측정결과 $1{\times}1mm^2$의 태양전지에서 단락전류밀도($J_{sc}$)는 양자우물구조가 도입된 태양전지에서는 $9.61mA/cm^2$, 양자우물 구조가 없는 태양전지에서는 $7.06mA/cm^2$가 각각 측정되었다. 이차이온질량 분석법(SIMS)과 외부양자효율(external quantum efficiency) 측정을 통하여 단락전류 증가에 의한 효율증가가 흡수 스펙트럼의 확대가 아닌 양자우물에 의한 carrier 재결합의 억제에 의한 효과임을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.17-20
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• 2001

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectric were fabricated, and nitrogen distribution and bonding species which contributing memory characteristics were analyzed. Also, memory characteristics of devices according to anneal temperatures were investigated. The devices were fabricated by 0.35$\mu\textrm{m}$ retrograde twin well CMOS processes. The processes could be simple by in-situ process of nitridation anneal and reoxidation. The nitrogen distribution and bonding state of gate dielectric were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary ton Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). Nitrogen concentrations are proportional to nitridation anneal temperatures and the more time was required to form the same reoxidized layer thickness. ToF-SIMS results show that SiON species are detected at the initial oxide interface and Si$_2$NO species near the new Si-SiO$_2$ interface that formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. These could be said that nitrogen concentration near initial interface is limited to a certain quantity, so excess nitrogen are redistributed near the Si-SiO$_2$ interface and contributed to electron trap generation.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.276-276
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• 2013

Time-Of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Atomic Force Microscopy (AFM) are the useful instruments to measure nanostructures of material surfaces. Surface pattern formation in blending homopolymer and diblock copolymer films was investigated as a function of film thickness and annealing conditions. In this study, surface structures of blending homopolymer [deuterated polystyrene (Mn 20,000), poly (methyl methacrylate) (Mn 18,000)] and diblock copolymer [Poly (deuteratedstyrene(d8)-b-methyl methacrylate) (Mn 19,500-18,100)] films were observed. The AFM result indicated that the nanostructures and film thickness depended on temperature, concentration and solvent. TOF-SIMS depth profiling was obtained for the lamellar morphology of symmetric dPS-b-PMMA which is found to orient parallel to the surface of the substrate. Elemental and molecular depth profiles measured in the negative ion mode by a Cs+ primary ion beam demonstrate variations in hydrogen, deuterium, carbon, oxygen, hydrocarbons and deuterated hydrocarbons within the diblock copolymer according to the depth.