• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.135-137
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• 2006

To improve device yield and throughput, faults in plasma processing equipment should be quickly and accurately diagnosed. Despite many useful information of ex-situ sensor measurements, their applications to recognize plasma faultshave not been investigated. In this study, a new technique to identify fault causes by recognizing X-ray photoelectron spectroscopy (XPS) using neural network and continuous wavelet transformation (CWT). The presented technique was evaluated with the plasma etch data. A totalof 17 experiments were conducted for model construction. Model performance was investigated from the perspectives of training error, testing error, and recognition accuracy with respect to various thresholds. CWT-based BPNN models demonstrated a higher prediction accuracy of about 26%. Their advantages over pure XPS-based models were conspicuous in all three measures at small networks.

• Vacuum Magazine
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• v.3 no.4
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• pp.8-13
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• 2016

The need of space-resolved x-ray photoelectron spectroscopy (XPS) has developed scanning photoelectron microscopy (SPEM). SPEM provides space-resolved XPS data from a spot of a sample as well as images of specific element, chemical state, valency distribution on the surface of a sample. Based on technical advancement of tight x-ray focusing, sample positioning accuracy, and electron analyzer efficiency, SPEM is now capable of providing ~100 nm space resolution for typical XPS functionality, and SPEM has become actively applied for the investigation of chemical state, valency, and electronic structure on the surface of newly discovered materials, such as graphene layers, dichalcogenide 2D-materials, and heterogenous new functional materials.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.117-117
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• 2015

Availability of X-ray photoelectron spectroscopy (XPS) for the identification of ionic liquids (ILs) was tested. Commercially available ionic liquids (1-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM] $BF_4$), (1-butyl-3-methyl imidazolium trifluoromethanesulfonate ([BMIM] OTf), (1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM] $PF_6$), 1-hexyl-3-imidazolium hexafluorophosphate ([HMIM] $PF_6$), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] $Tf_2N$) were qualitatively and semi-quantitatively analyzed with XPS. In order to confirm whether the results of XPS were correct, conventional method such as a nuclear magnetic resonance (NMR) was performed. After the XPS results were convinced by NMR, we synthesized ILs (1-(4-sulfonic acid) butyl-3-butylimidazolium trifluoromethanesulfonate ([SBBIM] OTf), 1-(4-sulfonic acid) propyl-3-methylimidazolium trifluoromethanesulfonate ([SPMIM] OTf), and 1-(4-sulfonic acid) propyl-3-butylimidazolium trifluoromethanesulfonate ([SPBIM] OTf) and analyzed it with XPS and NMR as well. It was successful the usage of XPS to analyze ILs without any purification processes.

• Analytical Science and Technology
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• v.7 no.1
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• pp.115-124
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• 1994

The corroded surface of cold rolled steel sheet in the process of rinsing after alkali-cleaning was examined by means of X-ray Photoelectron Spectroscopy(XPS). In addition, the surface-treated cold rolled steel with 0.05wt% $Na_5P_3O_{10}$ solution for the purpose of preventing the corrosion was examined by means of XPS and the results were compared with those for the non-treated cold rolled steel. It was found that the corroded surface consists of $Fe_2O_3$, FeO and $Fe(OH)_3$ and the thickness of the oxide layer is about $1500{\AA}$. On the other hand, in the case of surface-treated cold rolled steel, the phosphate layer of $60{\AA}$ thickness was found to act as a protective film over the relatively thin Fe oxide layer.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.168-171
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• 2017

In this study, we observed degradation mechanism of FKM O-ring by X-ray photoelectron spectroscopy(XPS) at atmosphere condition. FKM O-ring had 3.53mm of cross-sectional diameter and 91.67mm of inner diameter. After thermal degradation, oxygen atom concentration of FKM O-ring was increased to 20.39%, and fluorine atom concentration was decreased to 8.29%. We observed that degradation reaction occurred by oxidation reaction. By C1s and F1s peak analysis, we confirmed that oxidation reaction usually occurred at C-F bonding of FKM main chain. Also, carboxyl group(C-OH, C=O, O=C-O) produced by oxidation reaction from O1s peak analysis.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.51-56
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• 1996

Structural properties of rf sputtered boron nitride films were studied as a function of deposition parameters such as nitrogen pressure, substrate temperature and substrate bias using X-ray photoelectron spectroscopy and Auger electron spectroscopy. Composition and information on chemical bonding of resultant films was determined by XPS. XPS core level spectra showed that ratio of boron to nitrogen varied from 3.11 to 1.45 with respect to partial nitrogen pressure. Curve fitting of XPS spectra revealed three kinds of bonding mechanism of boron in the films. XPS peak positions of both B 1s and N 1s shifted to higher energy with higher nitrogen pressure as well as increase in substrate bias voltage. AES was used to see possible contamination of films by carbon or oxygen as well.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1341-1345
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• 2007

The surface chemistry of D2O dosed Zircaloy-4 (Zry-4) surface followed by Ar-ion bombardment and annealing was studied by means of X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS). In the XPS study, Ar-ion bombardment caused decrease of the oxygen on the surface region of Zry-4 and therefore led to change the oxidation states of the zirconium from oxide to metallic form. In addition, oxidation states of zirconium were changed to lower oxidation states of zirconium due to depopulation of oxygen on the surface region by annealing. Up to about 787 K, the bulk oxygen diffused out to the subsurface region and after this temperature, the oxygen on the surface of Zry-4 was depopulated. UPS study showed that the valence band spectrum of the D2O exposed Zry-4 exhibited a dominant peak at around 13 eV and no clear Fermi edge was detected. After stepwise Ar+ sputtering processes, the decrease of the oxygen on the surface of Zry-4 led to suppress the dominant peak around 13 eV, the peak around 9 eV and develop a new peak of the metallic Zr 4d state (20.5-21.0 eV) at the Fermi level.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.505-510
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• 2012

Cobalt oxide nanostructure materials have been prepared by adding several concentrations of spectator Ni ions in solution, and analyzed by electron microscopy, X-day diffraction, calorimetry/thermogravimetric analysis, UV-vis absorption, Raman, and X-ray photoelectron spectroscopy. The electron microscopy results show that the morphology of the nanostructures is dramatically altered by changing the concentration of spectator ions. The bulk XRD patterns of $350^{\circ}C$-annealed samples indicate that the structure of the cobalt oxide is all of cubic Fd-3m $Co_3O_4$, and show that the major XRD peaks shift slightly with the concentration of Ni ions. In Raman spectroscopy, we can confirm the XRD data through a more obvious change in peak position, broadness, and intensity. For the un-sputtered samples in the XPS measurement process, the XPS peaks of Co 2p and O 1s for the samples prepared without Ni ions exhibit higher binding energies than those for the sample prepared with Ni ions. Upon $Ar^+$ ion sputtering, we found $Co_3O_4$ reduces to CoO, on the basis of XPS data. Our study could be further applied to controlling morphology and surface oxidation state.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.281-283
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• 2005

Processing Plasmas are very sensitive to a variation in process parameters, To maintain process quality and device field, plasma malfunction should be tightly monitored with high sensitivity. A new monitoring method is presented and this was accomplished by applying discrete wavelet transformation to X-ray photoelectron spectroscopy. XPS data were collected during a plasma etching of silicon carbide. Various effects of DWT factor on fault sensitivity were optimized experimentally. Compared to raw data, total percent sensitivity for DWT data demonstrated a significantly improved sensitivity to plasma faults induced by bias power.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.100-105
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• 1992

Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) analyses have been performed on double-structured Au/V and Au/Ti thin films after heat treatment at 500$^{\circ}$C in air. V- and Tiunderlays sandwiched between gold thin films and SiOz substrates form oxides on the free surface of gold films during the heat treatment. The chemical compositions of the oxides were identified as V205 and TiOz in Au/V and Au/Ti thin films, respectively.