• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.149-149
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• 2006

• Proceedings of the Korea Association of Crystal Growth Conference
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• 2000.06a
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• pp.87-125
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• 2000

A new paradigm of crystal growth was suggested in a charged cluster model, where charged clusters of nanometer size are suspended in the gas phase in most thin film processes and are a major flux for thin film growth. The existence of these hypothetical clusters was experimentally confirmed in the diamond and silicon CVD processes as well as in gold and tungsten evaporation. These results imply new insights as to the low pressure diamond synthesis without hydrogen, epitaxial growth, selective deposition and fabrication of quantum dots, nanometer-sized powders and nanowires or nanotubes. Based on this concept, we produced such quantum dot structures of carbon, silicon, gold and tungsten. Charged clusters land preferably on conducting substrates over on insulating substrates, resulting in selective deposition. if the behavior of selective deposition is properly controlled, charged clusters can make highly anisotropic growth, leading to nanowires or nanotubes.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.126-134
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• 1996

Tungsten silicide films were deposited on the phosphorus-doped poly-Si/SiO$_{2}$/Si-substrates by LPCVD (low pressue chemical vapor deposition). The formation and various properties of tungsten silicide processed by furnace annealing in N$_{2}$ ambient were evaluated by using XRD. AFM, 4-point probe and SEM. And the redistribution of phosphorus atoms has been observed by SIMS. The crystal structure of the as-deposited tungsten silicide films were transformed from the hexagonal to the tetragonal structure upon annealing at 550.deg. C. The surface roughness of tungsten polycide films were found to very smoothly upon annelaing at 850.deg. C and low phosphorus concentration in polysilicon layer. The sheet resistance of tungsten polycide low phosphorus concentration in polysilicon layer. The sheet resistance of tungsten polycide films are measured to be 2.4 .ohm./ㅁafter furnace annealing at 1100.deg. C, 30min. It was found that the sheet resistance of tungsten polycide films upon annealing above 1050.deg. C were independant on the phosphorus concentration of polysilicon layer and furnace annealing times. An out-diffusion of phosphorus impurity through tungsten silicide film after annealing in $O_{2}$ ambient revealed a remarkably low content of dopant by oxide capping.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.719-726
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• 2021

Through the process of chemical vapor deposition, Tungsten Hexafluoride (WF₆) is widely used by the semiconductor industry to form tungsten films. Tungsten Hexafluoride (WF₆) is produced through manufacturing processes such as pulverization, wet smelting, calcination and reduction of tungsten ores. The manufacturing process of Tungsten Hexafluoride (WF₆) is required thorough quality control to improve productivity. In this paper, a real-time detection system for oxidation defects that occur in the manufacturing process of Tungsten Hexafluoride (WF₆) is proposed. The proposed system is implemented by applying YOLOv5 based on Convolutional Neural Network (CNN); it is expected to enable more stable management than existing management, which relies on skilled workers. The implementation method of the proposed system and the results of performance comparison are presented to prove the feasibility of the method for improving the efficiency of the WF₆ manufacturing process in this paper. The proposed system applying YOLOv5s, which is the most suitable material in the actual production environment, demonstrates high accuracy (mAP@0.5 99.4 %) and real-time detection speed (FPS 46).

• Journal of the Korean Chemical Society
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• v.38 no.7
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• pp.473-479
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• 1994

Tungsten thin film was deposited on p-(100) silicon substrate by using the LPCVD(low pressure chemical vapor deposition) technique. $WF_6$ was used as a source gas for tungsten and $SiH_4$ was used as a reducing gas for $WF_6$. Tungsten thin film was deposited by either SiH4 or Si substrate reduction of $WF_6$ under cold-wall condition and it was deposited by $SiH_4$ reduction of $WF_6$ under hot-wall condition. The crystal structure of deposited thin film under both conditions were identified to be bcc (body centered cubic). The physical and electrical properties of deposited thin films were investigated. The deposited film under hot-wall condition changed to $WSi_2$ film by the annealing under $800^{\circ}C.$ From the experimental results and theoretical considerations, the change of the crystal structure of the thin film by annealing was discussed. $WSi_2$ thin film, which was known to have good compatibility with Si substrate, could be produced under hot-wall condition although the film properties were superior under cold-wall condition.

• Journal of the Korean institute of surface engineering
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• v.30 no.6
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• pp.374-381
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• 1997

We have studied the effect of the interface between tungsten silicide and polysilicon the silicide reaction. The results showed that the cleaning of the silicon surface prior to the deposition of tungsten silicide affected the interface properties, thereby leading to the difference in the resistivity and surface morhpology of tungsten silicide. Compared with HF cleaning, the use of SCl cleaning yielded higher resistivity of tungsten silicide at the low anneal temperature (up to $900^{\circ}C$). However, furtherature to $1000^{\circ}C$ reduced the resistivity significantly, similar to that obtained with HF cleaning. It was also observed that the annealing of WSix/HF-cleaned poly-si allowed the formation of bucking weve (partially decohesion area) on the surface. In contrast, the use of SCl celaning did not produce the buckling waves on the surface. Also the presence of 200$\AA$ -thick TiW between tungsten silicide and HF-cleaned poly-Si effectively prevented the formation of the waves. However, high-temperature annealing of WSix/200A-TiW/Poly-Si allowed the excess silicon in tungsten silicide to precipitate inside the silcide, causing the slight increase of the resistivity after annealing at $1050^{\circ}C$.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05b
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• pp.135-137
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• 1992

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.43-47
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• 2008

Cubic boron nitride(c-BN) films were deposited on tungsten carbide insert tool by microwave plasma enhanced chemical vapor deposition(MPECVD) from a gas mixture of triethyl borate$(B(C_2H_5O)_3)$, ammonia $(NH_3)$, hydrogen$(H_2)$ and argon(Ar). The qualities of deposited thin film were investigated by x-ray diffrac-tion(XRD), field emission scanning electron microscopy(FE-SEM) and micro Raman spectroscope. The surface morphologies of the synthesised BN as well as crystallinity appear to be highly dependent on the flow rate of $B(C_2H_5O)_3$ and $(NH_3)$ gases. The deposited film had more crystallized phases with 5 scem of $B(C_2H_5O)_3$ and $(NH_3)$ gases than with 2 sccm, and the phase was identified as c-BN by micro Raman spectroscope and XRD. The adhesion strength were also increased with increasing flow rates of $B(C_2H_5O)_3$ and $(NH_3)$ gases.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.321-327
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• 2000

Tungsten(W) thin films with good adhesion property and low resistivity (~10 $\mu$\Omega$$.cm) were deposited directly on $SiO_2$ by LPCVD. The adhesion property of W thin films on $SiO_2$ improves as the temperature and/or $SiH_4/WF_6$ gas ratio increase. Specifically tungsten thin films could be deposited on $SiO_2$ even at $350^{\circ}C$ if the gas ratio of 2 was employed. The resistivity of tungsten thin films deposited at $350^{\circ}C$ was high due to the presence of $\beta$-W. However, the resistivity can be minimized by increasing the amount of $H_2$ gas flow. Therefore, it is shown in this work that the adhesion of tungsten thin films on $SiO_2$ can be improved simply by controlling the process parameters (e.g., temperature, gas ratio and $H_2$ flow rate) without employing complex deposition methods or additional glue layers.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.25.2-25.2
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• 2011

The tungsten oxide wire-like nanostructure is fabricated by deposition and thermal oxidation of tungsten metal on porous single wall carbon nanotubes (SWNTs). The morphology and crystalline quality of materials are investigated by SEM, TEM, XRD and Raman analysis. The results prove that $WO_3$ wire-like nanostructure fabricated on SWNTs show highly porous structures. Exposure of the sensors to NH3 gas in the temperature range of 150~300$^{\circ}C$ resulted in the highest sensitivity at $250^{\circ}C$ with quite rapid response and recovery time. Response time as a function of test concentrations and NH3 gas sensing mechanism is reported and discussed.