• Korea-Australia Rheology Journal
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• v.14 no.2
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• pp.71-76
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• 2002

Metal thin films, which are indispensable constituents of ULSI (Ultra Large Scale Integration) circuits, have been fabricated by physical or chemical methods. However, these methods have a drawback of using expensive high vacuum instruments. In this work, the fabrication of tungsten metal film by spin coating was investigated. First of all, inorganic peroxopolytungstic acid (W-IPA) powder, which is soluble in water, was prepared by dissolving metal tungsten in hydrogen peroxide and by evaporating residual solvent. Then, the solution of W-IPA was mixed with organic solvent, which was spin-coated on wafers. And then, tungsten metal films, were obtained after reduction procedure. By selecting an appropriate organic solvent and irradiating UV, the sheet resistance of the tungsten metal film could be remarkably reduced.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.264-269
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• 2000

TiO$_2$thin films were prepared on the glass by a conventional spin coating method with $TiO_2$ sol(30wt%, anatase). The thickness of the thin films were controlled by the number of coating cycles: one cycle is composed of spin coating, drying, and heating process. The reaction rate of the film was obtained by the photodecomposition of gaseous benzene under 0.44 and 2.0mW/$\textrm{cm}^2$ UV light on the film surface. For an incident UV light intensity of 0.44mW/$\textrm{cm}^2$, the reaction rate was increased with the thickness of the film, caused by extent of surface area, but there was no change over the thickness of about 4$\mu\textrm{m}$. The porous $TiO_2$ thin film has comparatively vast effective surface area, which under relatively high-intensity UV illumination causes the reaction rate to be controlled by the film thickness.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.20-26
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• 2002

The fluid flow, mass transfer, heat transfer and film thickness variation during the spin coating process are numerically studied. The model is said to be 1-dimensional because radial variations in film thickness, concentration and temperature are ignored. The finite difference method is employed to solve the equations that are simplified using the similarity transformation. In early time film thinning is due to the radial convective outflow. However that slows during the first seconds of spinning so the film thinning due to evaporation of solvent becomes sole. The time various film thickness is analyzed according to the var ious solvent fraction in the coating liquid and in the bulk of the overlying gas and the temperature variation in the liquid film during the spin coating is estimated.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.88.2-88.2
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• 2005

• Bulletin of the Korean Chemical Society
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• v.27 no.8
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• pp.1119-1120
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• 2006

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.467-471
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• 2005

In this paper, experimental methods about the flow behavior of thin polymer film by various edge patterns in the spin coating process for stable cover layer coating of a blu-ray disc is described. The blu-ray disc, a next-generation optical disc format over 25GB, consists of a 1.1m thick substrate and a 0.1mm tick cover layer. Generally, cover layer on the blu-ray disc is made by the polymer spin coating process. However, it is hard to secure sufficient coating uniformity around the rim on the cover layer. In order to get the uniform thickness deviation and to minimize the bead around the rim, the edge of the disc substrate can be modified into various patterns, such as normal plain, trench, step and chamfer pattern, etc, around the rim on the disc and experimented with various parameters, such as surface tension, viscosity, coating time, temperature and rotation speed, etc. And the optimal shape of the rim was tried to get by 3 dimensional computer simulation of the polymer expulsion process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.457-460
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• 2006

Y doped zinc oxide (YZO) thin films were deposited on F doped $SnO_2$ (FTO) glass substrate by sol-gel method using the spin-coating system. A homogeneous and stable solution was prepared by dissolving acetate in the solution added diethanolamine as sol-gel stabilizer. YZO films were obtained after preheated on the hot-plate for 5minute before each coating; the number of coating was 3 times. After the coating of last step, annealing of YZO films performed at $450^{\circ}C$ for 30 minute. In order to confirming of a ultraviolet ray interruption and down-conversion effects, optical properties of YZO films, transmission spectrum and fluorescent spectrum were used. Also, for understanding the obtained results by experiment, the elestronic state of YZO was calculated using the density functional theory The results obtained by experiment were compared with calculated structure. The detail of electronic structure was obtained by the discrete variational Xa (DV-Xa) method, which is a sort of molecular orbital full potential method. The density of state and energy levels of dopant element were shown and discussed in association with optical properties.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.113-116
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• 2005

In this paper, a computational and experimental analysis about the flow behavior of thin polymer film in the spin coating process for stable cover layer coating of a blu-ray disc is described. The blu-ray disc, a next-generation optical disc format over 25GB, consists of a 1.1mm thick substrate and a 0.1mm tick cover layer. Generally, cover layer on the blu-ray disc is made by the polymer spin coating process. However, it is hard to secure sufficient coating uniformity around the rim on the cover layer. In order to get the uniform thickness deviation and to minimize the bead around the rim, the edge of the disc substrate can be modified into various shapes around the rim on the disc and analyzed with various parameters, such as surface tension, viscosity, and rotation speed, etc. The optimal shape of the rim was tried to get by 3 dimensional computer simulation of the polymer expulsion process.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.962-964
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• 1999

We studied emitting properties of devices fabricated using the spin-coating and Langmuir-Blodgett[LB] technique. The LB technique has the advantage of precise control of the thickness better than spin-coating method. Poly(3-hexylthiophene)[P3HT] LB films used as the emitting layer in light-emitting devices. LB monolayers were deposited 27 layers onto the indium-tin-oxide[ITO] as Y-type films by the vertical dipping method. The thickness is about 80nm. Absorption spectrum of LB films presented that P3HT is regiorandom conformation. Also, current-voltage-luminance characteristics and electroluminescence spectra of light-emitting devices fabricated by LB method is studied. In current-voltage-luminescence characteristics, turn-on voltage of P3HT LB film LEDs is higher than that of spin-coating LEDs. But electroluminescence spectrum is similar to the spin-coating LEDs. The orange-red light was clearly visible in a darkened room.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.219-226
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• 2000

Amorphous Ge20As20Se60 chalcogenide thin films were prepared by spin coating technique from mixed solutions of As40Se60 and Ge40Se60 dissolved in ethylenediamine. Films were prepared at a roating speed of 3500 rpm and spinning time was 10 second and heat-treateed at 27$0^{\circ}C$ for 1 hour. The resulting film thickness and RMS roughness were approximately 340 nm and 15$\AA$. Photostructure changes were investigated with 514.5nm Ar+ laser irradiation and heat-treatment. After Ar+ laser irradiation, transmittance and transmission efficiency decreased respectively up to 24.9% at 2.43 eV and 67.5% at 3.27 eV, and absorption edge shifted toward long wavelength. Optical bandgap changed from 2.03 to 1.83 eV, and absoprtion coefficient and absorption efficiency increased up to 0.33$\times$105cm-1 at 3.37eV and 88.3% at 1.31 eV, respectively. These photodarkening state were recovered reversibly by heat-treatment at 27$0^{\circ}C$ for 1 hour. Photodarkening and thermal bleaching effects by laser irradiation and heat-treatment revealed reversible amorphous-to-amorphous transition varying only coordination number.