• Journal of Mechanical Science and Technology
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• v.15 no.9
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• pp.1268-1273
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• 2001

To successfully establish the ELID-grinding, it is important to properly select the electrolytic condition according to grinding conditions. Currently, the selection of electrolytic condition is mainly dependent on the operators experience, which is one of difficulties preventing the successful application of ELID technique. In this study, an in-process measurement system of the insulating layer using two gap sensors-a capacitance type and an eddy current type-are developed and the change of the thickness of insulating layer during ELID grinding is detected. Evaluation experiments show the possibility to control the electrolytic condition through the in-process measurement of the layer status.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.145-151
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• 1994

The multi-dielectric layer SiOz/Si3N4/SiO2(ONO) is used to scale down the memory device. In this paper, the change of composition in ONO layer due to the process condition and the conduction mechanism are observed. The composition of the oxide film grown through the oxidation of nitride film is analyzed using auger electron spectroscopy(AES). AES results show that oxygen concentration increases at the interface between oxide and nitride layers as the thickness -of the top oxide layer increases. Results of I-V measurement show that the insulating properties improve as the thickness of the top oxide layer increases. But when the thickness of the nitride layer decreases below 63.angs, insulating peoperties of film 28.angs. of top oxide and film 35.angs. turn over showing that insulating property of film 28.angs. of top oxide is better than that of film 35.angs. of top oxide. This phenomenon of turn over is thought as the result of generation of surface state due to oxygen flow into nitride during oxidation process. As the thickness of the top oxide and nitride increases, the electrical breakdown field increases, but when the thickness of top oxide reaches 35.angs, the same phenomenon of turn over occurs. Optimum film thickness for scaled multi-layer dielectric of memory device SONOS is estimated to be 63.angs. of nitride layer and 28.angs. of top oxide layer. In this case, maximum electrical breakdown field and leakage current are 18.5[MV/cm] and $8{\times}{10^-12}$[A], respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.520-524
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• 1999

Light-emitting diode(LEDs), diode arrays, and phosphor display panels are finding increased use in a variety of commercial applications. Present and anticipated application of these devices include solid state indicator and display systems. In this work, Phosphor based on ZnS:Cu are used. Relation by luminance with the thickness of insulating layer and phosphor layer are discussed. Increased thickness of insulating layer are stable on voltage to 300V. By considering thickness and voltage, optimal structure and thickness are investigated. In order to maximize even surface emission, various sieving processes are introduced. 150cd/m$^2$ luminance by various wave intensity are investigated in stable voltage and frequency.

• The Journal of Engineering Research
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• v.6 no.2
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• pp.33-38
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• 2004

To investigate the reliability of the MTJs on the roughness of insulating tunnel barrier, we prepared two MTJs with the different uniformity of barrier thickness. Namely, the one has uniform insulating barrier thickness; the other has non-uniform insulating barrier thickness as compared to different thing. As to depositing amorphous layer CoZrNb under the pinning layer IrMn, we achieved MTJ with uniform barrier thickness. Toinvestigate the reliability of the MTJs dependent on the bottom electrode, time-dependent dielectric breakdown (TDDB) measurements were carried out under constant voltage stress. The Weibull fit of out data shows clearly that $t_{BD}$ scales with the thickness uniformity of MTJs tunnel barrier. Assuming a linear dependence of log($t_{BD}$) on stress voltages, we obtained the lifetime of $10^4$years at a operating voltage of 0.4 V at MTJs comprising CoNbZr layers. This study shows that the reliabilityof new MTJs structure was improved due to the ultra smooth barrier, because the surface roughness of the bottom electrode influenced the uniformity of tunnel barrier.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.97-103
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• 2012

This study investigates thermal insulation properties of multi layer materials depending on thickness of air layers. Numerical analysis on the heat flow of different insulating materials was conducted to identify whether their temperature distributions demonstrate the reduced rate of heat transfer conclusively or not. Analytical model is divided into two categories. One is to distinguish temperature distribution of the air-layer materials from the non-air layer ones. The other is to compare the efficacy between eight-layered insulating materials with no air-layer contained and three-layered insulating materials which include an air-layer definitely. In the latter case, the identical thickness is assigned to each material. The effect of thermal insulation by including an air-layer is verified in the first analytical model. The result of the second model shows that the insulation of the eight-layered materials is coterminous at the three-layered ones with an air-layer and the thermal insulation of the two materials is imperceptible. The benefits of cost and energy saving are anticipated if air-layers are efficiently incorporated in multi layer insulating materials in a greenhouse.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.999-1002
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• 1997

In this study, in order to set ELID conditions in the internal grinding wheel, the characteristics with the variations of grit size, output voltage and peak current were examined by using conventional machining center(M/C) equipped with electrolytic in-process dressing(EL1D). The initial working voltage was lowered and the working current was high with increasing grit size. The insulating layer thickness increased, as the final voltage increased with the output voltage and peak current. The initial wear rate of the wheel machined with ELID were measured indirectly by using surface roughness tracer. The initial wear rate of the wheel with ELID increased along with high grit size. In case that the grit size with ELID was low, the output voltage and peak current had to be increased to increase the insulating layer thickness. In case of the high grit size, the output voltage and the peak current were established low, which made the insulating layer thickness decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.85-88
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• 1998

Light-emitting diode(LEDs), diode arrays, and phosphor display panels are finding increased use in a variety of commercial applications. Present and anticipated application of these devices include solid state indicator(e.g., digital clocks, meter readout) and display systems(e.g., instrument panels, TV display), the application being determined by the light -output capability and size availability(cost) of the particular device. In this work, Phosphor based on ZnS:Cu are used. Relation by luminance with the thickness of insulating layer and phosphor layer are discussed. Increased thickness of insulating layer are stable on voltage to 300V. By considering thickness and voltage, optimal structure and thickness are investigated. Also in order to maximize even surface emission, various sieving process are introduced. Very similar phosphor particle size is selected. Luminance by various wave intensity is also investigated. 150cd/m$^2$ luminance are investigated in stable voltage and frequency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.903-906
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• 2011

The electroplating and electro-less plating methods have been applied for the high density chip interconnect of the Copper Pillar Tin Bump (CPTB) preparation. The CPTB was prepared, which had been electroplated about $100{\mu}m$ pitch of copper layer firstly, and then the Tin layer was deposited on the copper pillar surface to protect the oxidation of it. It was also very important to get uniform thickness of electroplated copper layer, though it was difficult and sensitive. In order to control the thickness distribution, it was examined that the current separating disk of Insulating Gate with a hole in the center was installed between electrodes. The current flows through the center hole of the Insulating Gate in the cylindrical electroplating bath and the other parts were blocked to protect current flowing. The main current flowed through the center hole of the Insulating Gate directly to the opposite electrode of wafer disk. As the results, it was verified that the copper layer was thick in the center part of wafer disk with distribution of thinner to the outer part toward edge.

• Transactions on Electrical and Electronic Materials
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• v.4 no.4
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• pp.13-17
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• 2003

This paper deals with the edge effect in thin insulating films, focusing on their dependence on film thickness. The finding is that the electric field is lowered at the edge as the film thickness is reduced, which, in turn, is closely related to dielectric breakdown voltage. In order to analyze this phenomenon, a simple capacitor model is introduced with which dependence of dielectric breakdown voltage around the electrode edge on the film thickness is explained. Due to analytical difficulty to get the expression of electrical field strength at the edge, an equivalent circuit approach is used to find the voltage expression first and then the electric field expression using it. The relation gets to an agreement with the experimental findings shown in the paper. This outcome may be extended to solve similar problems in multi-layer insulating films.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.132-132
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• 2011

The sheet resistance (Rs) of undoped GaN films on AlN/c-plane sapphire substrate was investigated in which the AlN films were grown by R. F. magetron sputtering method. The Rs was strongly dependent on the AlN layer thickness and semi-insulating behavior was observed. To clarify the effect of crystalline property on Rs, the crystal structure of the GaN films has been studied using x-ray scattering and transmission electron microscopy. A compressive strain was introduced by the presence of AlN nucleation layer (NL) and was gradually relaxed as increasing AlN NL thickness. This relaxation produced more threading dislocations (TD) of edge-type. Moreover, the surface morphology of the GaN film was changed at thicker AlN layer condition, which was originated by the crossover from planar to island grains of AlN. Thus, rough surface might produce more dislocations. The edge and mixed dislocations propagating from the interface between the GaN film and the AlN buffer layer affected the electric resistance of GaN film.