• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.352-356
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• 2023

The integration of bioelectronic devices with the skin is a promising strategy for personalized healthcare monitoring and diagnostics. On-skin bioelectrodes hold great potential for the real-time tracking of physiological parameters. However, persistent challenges of stability and reliability have instigated exploration beyond conventional noble metals. This study focuses on the ionic passivation and oxidation dynamics of copper-based on-skin thin-film bioelectrodes. Through parylene chemical vapor deposition, we harness a controlled thin film of parylene insulation to counter the intrinsic susceptibility of copper to oxidation in the ionic environment. The results represent the relationship among the parylene insulation thickness, copper oxidation, and electrode impedance over temporal intervals. Comparative analyses indicate that the short-term stability of the copper electrode is comparable to that of the gold electrode. Therefore, we propose a cost-effective strategy for fabricating copper-based on-skin bioelectrodes by introducing enhanced ionic stability within a discernible operational timeframe. This study enriches our understanding of on-skin bioelectronics and affordable material choices for practical use in wearable healthcare devices.

• Journal of Sensor Science and Technology
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• v.13 no.3
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• pp.195-198
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• 2004

For a diffusion barrier against copper, tantalum nitride films have been deposited on $SiO_{2}$ by atomic layer deposition (ALD), using PEMAT(Pentakis(ethylmethylamino)tantalum) and $NH_{3}$ as precursors, Ar as purging gas. The deposition rate of TaN at substrate temperature $250^{\circ}C$ was about $0.67{\AA}$ per one cycle. The stability of TaN films as a Cu diffsion barrier was tested by thermal annealing for 30 minutes in $N_{2}$ ambient and characterized through XRD, sheet resistance, and C-V measurement(Cu($1000{\AA}$)/TaN($50{\AA}$)/$SiO_{2}$($2000{\AA}$)/Si capacitor fabricated), which prove the TaN film maintains the barrier properties Cu below $400^{\circ}C$.

• Macromolecular Research
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• v.14 no.1
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• pp.38-44
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• 2006

Vacuum deposited copper phthalocyanine (CuPc) was placed as a thin interlayer between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in a multi-layered, organic, light-emitting diode (OLEOs). The well-stacked CuPc layer increased the stability and efficiency of the devices. Thermal annealing after CuPc deposition and magnetic field treatment during CuPc deposition were performed to obtain a stacked-CuPc layer; the former increased the stacking density of the CuPc molecules and the alignment of the CuPc film. Thermal annealing at about 100$^{circ}C$ increased the current flow through the CuPc layer by over 25$\%$. Surface roughness decreased from 4.12 to 3.65 nm and spikes were lowered at the film surface as well. However, magnetic field treatment during deposition was less effective than thermal treatment. Eventually, a higher luminescence at a given voltage was obtained when a thermally-annealed CuPc layer was placed in the present, multi-layered, ITO/CuPc/NPD/Alq3/LiF/AI devices. Thermal annealing at about 100$^{circ}C$ for 3 h produced the most efficient, multi-layered EL devices in the present study.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.24-27
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• 2023

Until now, many research activities have been conducted to commercialize high-temperature superconducting (HTS) wires for electric applications. Most of all researchers have focused on enhancing the piece length, critical current density, mechanical strength, and throughput of HTS wires. Recently, HTS magnet for generating high magnetic field shows degraded performance due to the deformation of HTS wire by high electro-magnetic force. The deformation can be derived from widthwise thickness non-uniformity of HTS wire mainly caused by wet processes such as electro-polishing of metal substrate and electro-plating of copper. Gradient sputtering process is designed to improve the thickness uniformity of HTS wire along the width direction. Copper stabilizing layer is deposited on HTS wire covered with specially designed mask. In order to evaluate the thickness uniformity of HTS wire after gradient sputtering process, the thickness distribution across the width is measured by using the optical microscope. The results show that the gradient deposition process is an effective method for improving the thickness uniformity of HTS wire.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.215-215
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• 2009

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.05a
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• pp.109-109
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• 1999

• Proceedings of the Korean Vacuum Society Conference
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• 2007.08a
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• pp.71-71
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• 2007

• Journal of the Korean institute of surface engineering
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• v.25 no.4
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• pp.173-180
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• 1992

The effects of the stabilizing additives such as NaCN, 2-MBT and Thiourea on bath decom-position, plating rate and surface morphology have been studied. Bath stability was increased in the order of an additive-free bath, and NaCN-, 2-MBT-, and Thiourea-stabilized baths. The sta-bilizing effects may be attributed to the stability of Cu(II) -complexes. The plating rate is the re-verse order of the bath stability. Accelerative effect of 2-MBT in proper quantity(0.3mg/$\ell$) may be explained by visualizing it absorbed through benzene ring or sulfur atom on portions of the sub-strates. The strong bond of the complexing part of the molecule to nearby chelated copper ions would tend to accelerate plating by making it easier for the Cu2+ -ligand bond to be broken. Sur-face morphologies of copper deposits depend on the bath additives. Electroless copper deposits from the 2-MBT stabilized baths are finer than the deposits from the NaCN- and Thiourea- stabi-lized baths due to the strong adsorption on the substrates.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.663-666
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• 2000

Laser direct writing of micro-patterned copper lines has been achieved by pyrolytic decomposition of copper formate films (Cu(HCOO)$_2$$.$4H$_2$O), as a precursor, using a focused Ar$\^$+/ laser beam ($\lambda$= 514 nm) on PCB boards and glass substrates. The linewidth and thickness of the lines were investigated as a function of laser power and scan speed. The profiles of the lines were measured by scanning electron microscope (SEM), surface profiler (${\alpha}$-step) and atomic force microscopy (AFM). The electrical resistivities of the patterned lines were also investigated as a function of laser parameter using probe station and semiconductor analyzer. we compared resistivities of the patterned lines with that of the Cu bulk, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.21-24
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• 1998

The properties of ZrN layer deposited by Sputtering system have been investigated in the application of diffusion barrier layer to copper. ZrN layer exhibited a excellent barrier property up to $700^{\circ}$ and higher resistivity. If an excess $O_2$is protected during the process of ZrN deposition, ZrN layer will be possible to use a diffusion barrier layer to copper.