• The korean journal of orthodontics
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• v.36 no.6
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• pp.451-464
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• 2006

The purpose of this study was to search for an appropriate method of coating $TiO_2$ on orthodontic appliances. $TiO_2$ thin films were deposited on orthodontic wires and brackets using sol-gel, CVD (Chemical Vapor Deposition) and PE-CVD (Plasma Enhanced-CVD) methods. The roughness of $TiO_2$-coated surfaces was investigated via scanning electron microscope (SEM) and adhesive strength of $TiO_2$ thin films was measured by adhesive tape pull test. Methylene blue degradation test was carried out to evaluate the photocatalytic activity of $TiO_2$ and the corrosion resistance of $TiO_2$ thin films against fluoride solution was also analyzed by observing the surfaces of $TiO_2$-coated wires and brackets via SEM after immersion in sodium fluoride solution. Through the comparison of properties and photocatalytic activity of $TiO_2$ thin films according to the coating methods, the following results were obtained. Smoother surfaces of $TiO_2$ thin films were generated by CVD or PE-CVD methods than through the sol-gel method or the control. Adhesive strength of the $TiO_2$ thin films was highest in PE-CVD and gradually became lower in the order of CVD, then the sol-gel method. Photocatalytic activity of $TiO_2$ thin films on methylene blue was the highest in PE-CVD and gradually became lower in the order of CVD, then the sol-gel method. Corrosion resistance of $TiO_2$ thin films against fluoride solution was stronger in CVD and PE-CVD methods than in the sol-gel method. The results of this study suggest that the CVD or PE-CVD methods is more appropriate than the sol-gel method for $TiO_2$ coating on orthodontic wires and brackets.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.166-174
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• 1993

Abstract The crack resistance of PSG(Phosphosilicate Glass) and PE-SiN(Plasma Enhanced CVD S${i_2}{N_4}$)films deposited on aluminium thin films on Si substrate was analyzed in this study. PSG was deposited by AP-CVD and PE- SiN by PE-CVD. All the films underwent repeated heat cycles at 45$0^{\circ}C$for 30 min. Crack formation and development were examined between each heat cycle. The crack behavior was found to be closely related to the stresses in the films. The stress induced by the difference in thermal expansion behavior between the passivation layers and underlying aluminum film may cause the crack. Crack resistance decreases as the thickness of PSG films increases due to the high tensile stress of the films. Phosphorus in the PSG films releases tensile stress and consequently the stress of the films tends to show compressive stress. As a result, crack resistance increased as the concentratin of P in the PSG films increased. Crack resistance in the PE-SiN films also increased with compressive stress. An experimental model to predict crack generation in the PSG and PE-SiN films during heat cycle was suggested.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.399-400
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• 2009

• Journal of the Semiconductor & Display Technology
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• v.19 no.2
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• pp.16-21
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• 2020

How accurately reproducible energy is delivered to the wafer in the process of making thin films using PE-CVD (Plasma enhanced chemical vapor deposition) during the semiconductor process. This is the most important technique, and most of the reaction on the wafer surface is made by thermal energy. In this study, we studied the method of monitoring the change of thermal energy transferred to the wafer surface by monitoring the temperature change according to the change of the thin film formed on the showerhead facing the wafer. Through this research, we could confirm the monitoring of wafer thin-film which is changed due to abnormal operation and accumulation of equipment, and we can expect improvement of semiconductor quality and yield through process reproducibility and equipment status by real-time monitoring of problem of deposition process equipment performance.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.67-72
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• 2020

This study analyzes the method of adhesion and improvement between heat.er and RF filter in PE-CVD equipment through TRIZ method and proposes a solution. TRIZ Solution such as function analysis, 9-window matrix, ASIT, and Root cause analysis were used. The contact temperature between the heater and the RF filter was 20% and the surface temperature was lowered to 5.7℃, suggesting an improvement method for the thermal expansion of the PE-CVD equipment hot zone.

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.246-251
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• 2005

Plasma enhanced chemical vapor deposition(PE-CVD) method has an advantage in synthesizing carbon nanotubes(CNTs) at lower temperature compared with thermal enhanced chemical vapor deposition(TE-CVD) method. In this study, CNTs was prepared by using PE-CVD method. The growth rate of CNT was faster more than 100 times on using Invar alloy than iron as catalyst. It was found that chrome silicide was formed at the interface between chrome layer and silicon substrate which should be considered in designing process. Nanoparticles of Invar catalyst were found oxidized on their surfaces with a depth of 10 m. Microstructure was analyzed by scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray spectrometry. Based on the result of analysis, growth mechanism at an initial stage was suggested.

• Korean Journal of Materials Research
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• v.3 no.1
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• pp.12-18
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• 1993

Abstract The effect of the film stress on the thermal stability of TiSi, films under the dielectric overcoat was investigated. TiS$i_2$ films with the sheet resistance of 1.2 ohm/sq. were produced by a solid-state reaction between sputtered Ti film and single-crystalline Si in an RTA (rapid thermal anneal) machine. Dielectric overcoats such as the USG (Undoped Silicate Glass, Si$O_2$) film and the PE-SiN(S$i_3$$N_4$) film were deposited by AP-CVD and PE-CVD, respectively, on the TiS$i_2$ film. The thermal stability of the TiSi, film was evaluated by changes in the sheet resistance, film stress and microstructure after furnace anneals at 90$0^{\circ}C$. Agglomeration of the TiSi2 film high temperatures results in the increase of sheet resistance and the decrease of tensile stress of TiSi, film. The stress level of the TiSi" PE-SiN and ~SG films at 90$0^{\circ}C$C was 1.3${\times}{10^{9}}$, 1.25 ${\times}{10^{10}}$, 2.26 ${\times}{10^{10}}$ dyne/c$m^2$ in tensile, respectively. Dielectric films deposited by CVD on TiSi, was effective on preventing agglomeration of TiSi,. The PE-SiN film mproved the thermal stability of TiSi, more effectively than the AP-CVD USG film. It is considered that agglomeration of the TiS$i_2$ film under the stress of dielectric overcoat at high temperature can be caused by a diffusional flow of atom called Nabarro-Herring microcreep.reep.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.368-376
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• 2003

In this research, DLC thin films are produced as several hundred nm thickness by PE-CVD method. And then these thin films are estimated tribological characteristics to find out useful possibilities as a protecting film for high-quality function and life extension at MEMs by mechanical properties observation . These are measured thickness and residual stress of DLC coating. Compared after measuring friction coefficient, adhesion force, hardness, cohesive force of coating films. As results all test, we can decide several conclusions. First, friction coefficient decreased, as the load increased. otherwise, friction coefficient increased, as thickness of coating film increased under low load$(1\~50mN)$. Secod, adhesion force increased as thickness of coating films. Third, hardness of coating film is affected by substrate coating film when it is less than thickness of 300nm and it has general hardness of DLC coating film when it is more than thickness of 500nm. Fourth, cohesive force of coating film is complexly affected by hardness, adhesion force, residual stress, etc.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.248-248
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• 2012

Synthesis graphene on Cu substrate by plasma-enhanced chemical vapor deposition (PE-CVD) is investigated and its quality's affection factors are discussed in this work. Compared with the graphene synthesized at high temperature in chemical vapor deposition (CVD), the low-temperature graphene film by PE-CVD has relatively low quality with many defects. However, the advantage of low-temperature is also obvious that low melting point materials will be available to synthesize graphene as substrate. In this study, the temperature will be kept constant in $400^{\circ}C$ and the graphene was grown in plasma environment with changing the plasma power, the flow rate of precursors, and the distance between plasma generator coil and substrates. Then, we investigate the effect of temperature and the influence of process variables to graphene film's quality and characterize the film properties with Raman spectroscopy and sheet resistance and optical emission spectroscopy.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.55-60
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• 2020

This study designed High impedance filter to reduce RF loss to heater heating wire and increase RF current flowing to heater ground wire. Effects such as D / R improvement and process reproducibility could be seen. In addition, RF parameter distribution optimization was possible by understanding the RF path of PE-CVD equipment using Plasma and designing filter.