• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.247.1-247.1
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• 2014

The capacitive coupled plasma is used widely in the semiconductor industries. Especially, the uniformity of the industrial plasma is heavily related with defect ratio of devices. Therefore, the industries need the capacitive coupled plasma source which can generate the uniform plasma and control the plasma's uniformity. To achieving the uniformity of the large area plasma, we designed multi-powered electrodes. We controlled the uniformity by controlling the power of each electrode. After this work, we started to research another concept of the plasma device. We make the plasma chamber that has multi-ground electrodes imaginary (CST microwave studio) and simulate the electric field. The shape of the multi-ground electrodes is ring type, and it is same as the shape of the multi-power electrodes that we researched before. The diameter of the side electrode's edge is 300mm. We assumed that the plasma uniformity is related with the impedance of ground electrodes. Therefore we simulated the imaginary chamber in three cases. First, we connected L (inductor) and C (capacitor) at the center of multi-ground electrodes. Second, we changed electric conductivity of multi-ground electrode. Third, we changed the insulator's thickness between the center ground electrode and the side ground electrode. The driving frequency is 2, 13.56 and 100 MHz. We switched our multi-powered electrode system to multi-ground electrode system. After switching, we measured the plasma uniformity after installing a variable vacuum capacitor at the ground line. We investigate the effect of ground electrodes' impedance to plasma uniformity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.435-443
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• 2001

As power durable RF SAW filters, AL-(0∼2wt%)Cu alloy multi-layered thin electrodes were deposited on 42° LiTaO$_3$ piezoelectric substrates by magnetron sputtering process, and then ladder-type RF SAW filters, satisfying the electrical specification of CDMA transmission band, were fabricated through optimizing SAW resonator structures. The temperature of film electrodes in SAW filter was increased with RF power, and reached the maxima to cause a failure of SAW filters at the cut-off frequencies of the RF filter band. As RF power increases, the electrodes of Al-Cu alloy showed higher power durability than that of pure Al. The multi-layer laminated film of Al-1wt.% Cu/Cu/Al-1wt%Cu resulted in the best power durability up to 4W of RF power. Every film electrode, however, was destroyed within seconds whenever applying a critical RF power to SAW filters, regardless of the composition and structure of film electrodes. The breakdown of film electrodes under FR power seems to believe due to the fatigue of electrodes caused by repetitive cyclic stress of surface acoustic wave, which is amplified as RF power increases.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.319-319
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• 2013

Even though the fabrication methods of metal oxide based thin film capacitor have been well established such as RF sputtering, Sol-gel, metal organic chemical vapor deposition (MOCVD), ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD), an applicable capacitor of printed circuit board (PCB) has not realized yet by these methods. Barium Strontium Titanate (BST) and other high-k ceramic oxides are important materials used in integrated passive devices, multi-chip modules (MCM), high-density interconnect, and chip-scale packaging. Thin film multi-layer technology is strongly demanded for having high capacitance (120 nF/$mm^2$). In this study, we suggest novel multi-layer thin film capacitor design and fabrication technology utilized by plasma assisted deposition and photolithography processes. Ba0.6Sr0.4TiO3 (BST) was used for the dielectric material since it has high dielectric constant and low dielectric loss. 5-layered BST and Pt thin films with multi-layer sandwich structures were formed on Pt/Ti/$SiO_2$/Si substrate by RF-magnetron sputtering and DC-sputtering. Pt electrodes and BST layers were patterned to reveal internal electrodes by photolithography. SiO2 passivation layer was deposited by plasma-enhanced chemical vapor deposition (PE-CVD). The passivation layer plays an important role to prevent short connection between the electrodes. It was patterned to create holes for the connection between internal electrodes and external electrodes by reactive-ion etching (RIE). External contact pads were formed by Pt electrodes. The microstructure and dielectric characteristics of the capacitors were investigated by scanning electron microscopy (SEM) and impedance analyzer, respectively. In conclusion, the 0402 sized thin film multi-layer capacitors have been demonstrated, which have capacitance of 10 nF. They are expected to be used for decoupling purpose and have been fabricated with high yield.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1136-1141
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• 2004

In recent years, demands on microelectrode have been greatly enhanced because of its potential applications and mass production of microelectrodes is needed. An electrochemical fabrication is used as an method for the simple and cheap fabrication of multi microelectrodes. In this paper, one dimensional microelectrode array is used for fabricating of multi electrodes. A diffusion layer which is formed near the electrode surface has an effect on the shape error of multi microelectrodes. The optimal distance between electrodes to minimize shape errors of multi electrodes is investigated. Multi microelectrodes which has several tens of and hundreds of micrometer in diameter are fabricated at a time.

• Journal of information and communication convergence engineering
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• v.1 no.4
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• pp.199-204
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• 2003

In this paper, we present the thermal annealing effects of the W/$SiO_2$ multi-layer reflectors in ZnO-based FBAR devices with cobalt (Co) electrodes in comparison with those with aluminum (Al) electrodes. Various thermal annealing conditions have been implemented on the W/$SiO_2$ multi-layer reflectors formed on p-type (100) silicon substrates. The resonance characteristics could be significantly improved due to the thermal annealing and were observed to depend strongly on the annealing conditions applied to the reflectors. Particularly, the FBAR devices with the W/$SiO_2$ multi- layer reflectors annealed at $400^{\circ}C$/30min have shown superior resonance characteristics in terms of return loss and quality-factor (Q-factor). In addition, the use of Co electrodes has resulted in further improvement of the resonance characteristics as compared with the Al electrodes. As a result, the combined use of both the thermal annealing and Co electrodes seems very useful to more effectively improve the resonance characteristics of the FBAR devices with the W/$SiO_2$ multi-layer reflectors.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.88-93
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• 2012

This paper describes the machinability of the sintered carbide and tool-die steel(STD-11) by electric discharge drilling with various tubular electrodes which have multi-holes. Various types of electrode which have different diameters and materials are used with the application of continuous direct current and axial electrode feed. Inner part of electrodes are inserted with smaller tubes or Y-channel or bar. In ED-Drilling, the dielectric flushed down the interior of the rotating tube electrode, in order to remove machining debris from the hole. As result of experiments, the bigger the diameter of the electrode is, the lower the material removal rate is. Machinability of copper electrode is higher than that of brass. In machining of sintered carbide, to use oil is better than distilled water as dielectric.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.496-501
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• 2009

In micro electrochemical machining(micro-ECM), it is important to measure and control the potential of a tool electrode and a workpiece electrode because electrochemical reaction rate depends on the potential of the electrodes. When the electrode potential was measured against a reference electrode, the error of measured electrode potential could be minimized by proper tool electrode design. In this paper, multi-function electrodes consisting of a tool electrode and a reference electrode was fabricated by micro fabrication techniques. The machining conditions in micro-ECM using multi-function electrodes, such as pulse voltage parameters and electrode potential, were investigated.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.257-259
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• 2002

In investigating the characteristics of a neural network, the use of planar microelectrode array shows several advantages over normal intracellular recording[1]. A transparent indium tin oxide(ITO) multi-electrode array(MEA) was fabricated and its top surface was insulated with photodefinable polyimide(HD-8001) except the exposed area for interfacing between the ITO electrodes and the neuronal cells. The exposed ITO electrodes were platinized in order to reduce the impedance between the electrodes and electrolyte. The one-minute platinization with $0.99nA/{\mu}m^2$ current density reduced the average impedance of the electrodes from $2.5M\Omega\;to\;90k\Omega$ at 1kHz in normal ringer solution. Cardiac cells were cultured on this MEA as a pilot study before neuron culture. The signals detected by the platinized electrodes had larger amplitudes and improved signal to noise ratio(SNR) compared to non-platinized electrodes. It is clear that microelectrodes need to have lower impedance to make reliable extracellular recordings, and thus platinization is essential part of MEA fabrication. Burst spike of cultured olfactory bulb was also detected with the MEA having platinized electrodes.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.134-139
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• 2007

We report the suspension of individual multi-walled carbon nanotubes (MWNTs) from the bottom substrate using deep trench electrodes that were fabricated using optical lithography. During drying of the solution in dielectrophoretic assembly, the capillary force pulls the MWNT toward the bottom substrate, and it then remains as a deformed structure adhering to the bottom substrate after the solution has dried out. Small-diameter MWNTs cannot be suspended using thin electrodes with large gaps, but large-diameter MWNTs can be suspended using thicker electrodes. We present the statistical experimental results for successful suspension, as well as the feasible conditions for a MWNT suspension based on a theoretical approach.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1228-1232
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• 2010

The nanocomposites of polypyrrole (PPy) and multi-walled carbon nanotube (MWCNT) with different composition are synthesized by the chemical oxidative polymerization method. In these composites, the MWCNTs are uniformly coated by PPy with different thickness. The electrochemical properties of the composite electrodes are investigated by cyclic voltammetry, galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy. The full cells assembled with the PPy/MWCNT composite electrodes deliver initial specific capacitances ranging from 146.3 to 167.2 F/g at 0.5 mA/$cm^2$ and exhibit stable cycling characteristics. The effect of content of MWCNT in the composite on cycling performance of the cells is also investigated.