• The Korean Journal of Ceramics
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• v.7 no.1
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• pp.26-29
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• 2001

Indium tin oxide (ITO) films were deposited on glass substrates at $300^{\circ}C$ in oxygen/argon mixtures by RF-enhanced DC-magnetron sputtering and were compared to those by conventional DC magnetron sputtering. The RF enhancement was performed using a coil above an ITO target. X-ray diffraction measurements revealed that RF-enhanced plasma affected the preferred orientation and the crystallinity of the films. The resistivity of the films prepared by RF-enhanced DC-magnetron sputtering was almost constant at oxygen content lower than 0.3% and then increased sharply with increasing oxygen content. However the resistivity of the films by conventional sputtering has little dependence on the oxygen content. Those results can be explained on the basis of the incorporation of oxygen into the ITO films due to the RF enhancement.

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.165-172
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• 1999

An enhancement technique for phase dependent image contrast in MRI(Manetic Resonance Imaging) is proposed. Because the method can enhance inherent phase contrast it is suited for susceptibility imaging and flow imaging where intravoxel phase is a source of image contrast. In this paper, applying external phase in the voxel enhances phase contrast. The external phase is generated by a tailored RF pulse so that one can control the phase contrast and even produces phase only contrast. Signal intensity due to both inherent phase and external phase is analyzed and the proposed technique is applied to a susceptibility effect only imaging and a flow effect only imaging. To verify the proposed technique, computer simulations are performed and their results are given.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.171-177
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• 2001

The adhesion enhancement from inserting a RF bias-sputtered Cr layer between Cu and polyimide (PI) has been studied. The RF bias power applied in this study was ranged from 0 to 400 W. Without the RF bias, the peel strength, which measures the adhesion strength, was nearly o g/mm. As the RF power was increased, the peel strength rose up to ~130 g/mm at 200 W, which remained constant with further increase of the RF bias power. Cross-sectional transmission electron microscopy(TEM) was used to investigate the interfacial reaction between the Cr film and PI substrate during the bias sputtering. The Cr/PI interface without the application of RF dais showed a clean, sharp interface while the RF raised Cr/PI interface had about 10~30 nm thick atomistically mixed interlayer between the metal film and PI substrate. This interlayer appeared to have resulted from the implantation of high energy adatoms during the RF bias sputtering of Cr film. This mixed layer serves as an interlocking layer, which enhances adhesion between the metal and PI layers.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.207-212
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• 2005

Al, Ti, Ta, and Cr thin films were deposited on a polyimide substrate using DC magnetron sputter to study the adhesion characteristics of metal films on polyimide substrates, while RF bias of 0 - 400 W was applied to the substrate during DC sputtering. The adhesion strength was evaluated using a 90-degree peel test. The peel tests showed that the adhesion strength was enhanced by applying the RF bias to the substrate in all specimens. Scanning electron microscopy and Auger depth profile of the fractured surfaces indicate that the polyimide underwent cohesive failure during peeling and heavy deformation was also observed in the metal films peeled from the polyimide substrate when the RF bias applied during the deposition. Cross-sectional transmission electron microscopy revealed that the metal/polyimide interface was not clear and complicated. This complicated interface, likely formed due to the RF bias applied to the substrate, was attributed to the adhesion enhancement observed during the bias sputtering.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.1
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• pp.70-83
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• 2001

In this paper, the recent progress of RF MEMS research for wireless/mobile communications is reviewed. The RF MEMS components reviewed in this paper include RF MEMS switches, tunable capacitors, high Q inductors, and thin film bulk acoustic resonators (TFBARs) to become core components for constructing miniaturized on chip RF transceiver with multi-band and multi-mode operation. Specific applications are also discussed for each of these components with emphasis on for miniaturization, integration, and performance enhancement of existing and future wireless transceiver developments.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.145-145
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• 2011

Recently, multi-hole electrode RF capacitively coupled plasma discharge is being used in the deposition of microcrystalline silicon for thin film solar cell to increase the speed of deposition. To make efficient multi-hole electrode RF capacitively coupled plasma discharge, the hole diameter is to be designed concerning the plasma parameters. In past studies, the relationship between plasma parameters such as pressures and gas species, and hole diameter for efficient plasma density enhancement is experimentally shown. In the presentation, the relationship between plasma deriving frequency and hole diameter for efficient multi-hole electrode RF capacitively coupled plasma discharge is shown. In usual capacitively coupled plasma discharge, plasma parameter, such as plasma density, plasma impedence and plasma temperature, change as frequency increases. Because of the change, the optimum hole diameter of the multi-hole electrode RF capacitively coupled plasma for high density plasma is thought to be modified when the plasma deriving frequency changes. To see the frequency effect on the multi-hole RF capacitively coupled plasma is discharged and one of its electrode is changed from a plane electrode to a variety of multi-hole electrodes with different hole diameters. The discharge is derived by RF power source with various frequency and the plasma parameter is measured with RF compensated single Langmuir probe. The shrinkage of the hole diameter for efficient discharge is observed as the plasma deriving frequency increases.

• Journal of Environmental Health Sciences
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• v.32 no.4 s.91
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• pp.268-274
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• 2006

In this study in order to evaluate the growth of RF propagation exposure rate generated according to the enhancement of its use, it is proposed for the ground to be able to examine and to contemplate the correlation between the human health and RF propagation exposure rate by measuring and analyzing the RF exposure source and exposure rate in an indoor environment. As a result of research, it is analyzed that the main exposure source of critically making effect in indoor environment is the frequency hand if radio broadcasting, mobile communication, wireless LAN, digital broadcasting, home appliance, etc., including the TV broadcasting. Among these, it is shown that the TV broadcasting and mobile communication band are the highest. And it is the concluded that RF exposure rate of the environmental sensitive equipment, like an institution for the aged, has lower possibility to exceed the human RF protection criteria by this evaluation.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.501-502
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• 2006

In this paper low power high gain amplifier is suitable for application in low power systems was designed and fabricated. The amplifier used both subthreshold bias for low power and positive feedback Q-enhancement technique for high gain. The amplifier used TSCM $0.18{\mu}m$ RF CMOS technology measures a power gain of 32.3dB, a quality factor of 366 and a power consumption of 3mW in a supply voltage of 1.8V.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.3
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• pp.15-20
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• 2007

Low temperature processed ZnO-TFTs on glass below $270^{\circ}C$ for plastic substrate applications were fabricated and their electrical properties were investigated. Films in ZnO-TFTs with bottom gate configuration were made by RF magnetron sputtering system except for $SiO_2$ gate oxide deposited by ICP-CVD. ZnO channel films were grown on glass with various Ar and $O_2$ flow ratios. All of the fabricated ZnO-TFTs showed perfectly the enhancement mode operation, a high optical transmittance of above 80% in visible ranges of the spectrum. In the ZnO-TFTs with pure Ar process, the field effect mobility, threshold voltage, and on/off ratio were measured to be $1.2\;cm^2/Vs$, 8.5 V, and $5{\times}10^5$, respectively. These characteristic values are much higher than those of the ZnO-TFTs of which ZnO channel layers were processed with additional $O_2$ gas. In addition, ZnO-TFT with pure Af process showed smaller swing voltage of 1.86v/decade compared to those with $Ar+O_2$ process.

• Proceedings of the Korean Magnestics Society Conference
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• 2015.05a
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• pp.92-94
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• 2015