• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.116-119
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• 2003

Self-patterning of thin films using photosensitive sol solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. In this study, ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) and $La_{0.5}Sr_{0.5}CoO_3$(LSCO)thin films have been prepared by spin coating method using photosensitive sol solution. $Sr(OC_2H5)_2$, $Bi(TMHD)_3$ and $Ta(OC_2H)_5)_5$ were used as starting materials for SBT solution and $La(OCH_2CH_2OCH_3)_3$, $Sr(OC_2H_5)_2$, $CO(OCH_2CH_2OCH_3)_2$ were used for LSCO solution. Solubility difference by UV irradiation on LSCO thin film allows to obtain a fine patterning due to M-O-M bond formation. The lowest resistivity($4{\times}10^{-3}{\Omega}cm$) of LSCO thin films was obtained by annealing at $740^{\circ}C$.

• Journal of the Korean Society of Clothing and Textiles
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• v.36 no.10
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• pp.1117-1124
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• 2012

This study was a preliminary study to investigate the influence of surface morphology and characteristics on the self-cleaning of substrates. PI film was treated by $O_2$ plasma to modify the surface; in addition, AFM and Fe-SEM were employed to examine the morphological changes induced on a PI film treated by $O_2$ plasma and surface energies calculated from measured contact angles between several solutions and PI film based on the geometric mean and a Lewis acid base method. The surface roughness of PI film treated by $O_2$ plasma increased with the duration of the $O_2$ plasma on PI film due to the increased surface etching. The contact angle of film treated by $O_2$ plasma decreased with the increased treatment time in water and surfactant solution; in addition, the surface energy increased with the increased treatment times largely attributed to the increased portion on the polar surface energy of PI film. The coefficient of the correlation between surface roughness and surface polarity such as contact angle and surface energy was below 0.35; however, it was over 0.99 for the contact angle and surface energy.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.2
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• pp.101-105
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• 2006

Nanoscale floating-gate characteristic of colloidal Au nanoparticles electrostatically assembled on the oxidized surface of Si nanowires have been investigated. The Si nanowire split-gate transistor structure was fabricated by electron beam lithography and subsequent reactive ion etching. Colloidal Au nanoparticles with ${\sim}5$ nm diameters were selectively deposited onto the Si nanowire surface by 2 min electrophoresis. It was found that electric fields applied to the self-aligned split side gates allowed charge to be transferred on the Au nanoparticles. It was observed that the depletion mode cutoff voltage, induced by the self-aligned side gates, was shifted by more than 1 V after Au nanoparticle electrophoresis. This may be due to the semi-one dimensional nature of the narrow Si nanowire transport channel, having much enhanced sensitivity to charges on the surface.

• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.203-210
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• 2011

Objectives: The purpose of this study was to evaluate the effect of various application methods of one-step self-etch adhesives to microtensile resin-dentin bond strength. Materials and Methods: Thirty-six extracted human molars were used. The teeth were assigned randomly to twelve groups (n = 15), according to the three different adhesive systems (Clearfil Tri-S Bond, Adper Prompt L-Pop, G-Bond) and application methods. The adhesive systems were applied on the dentin as follows: 1) The single coating, 2) The double coating, 3) Manual agitation, 4) Ultrasonic agitation. Following the adhesive application, light-cure composite resin was constructed. The restored teeth were stored in distilled water at room temperature for 24 hours, and prepared 15 specimens per groups. Then microtensile bond strength was measured and the failure mode was examined. Results: Manual agitation and ultrasonic agitation of adhesive significantly increased the microtensile bond strength than single coating and double coating did. Double coating of adhesive significantly increased the microtensile bond strength than single coating did and there was no significant difference between the manual agitation and ultrasonic agitation group. There was significant difference in microtensile bonding strength among all adhesives and Clearfil Tri-S Bond showed the highest bond strength. Conclusions: In one-step self-etching adhesives, there was significant difference according to application methods and type of adhesives. No matter of the material, the manual or ultrasonic agitation of the adhesive showed significantly higher microtensile bond strength.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.80-81
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• 2012

Recently, one of the critical issues in the etching processes of the nanoscale devices is to achieve ultra-high aspect ratio contact (UHARC) profile without anomalous behaviors such as sidewall bowing, and twisting profile. To achieve this goal, the fluorocarbon plasmas with major advantage of the sidewall passivation have been used commonly with numerous additives to obtain the ideal etch profiles. However, they still suffer from formidable challenges such as tight limits of sidewall bowing and controlling the randomly distorted features in nanoscale etching profile. Furthermore, the absence of the available plasma simulation tools has made it difficult to develop revolutionary technologies to overcome these process limitations, including novel plasma chemistries, and plasma sources. As an effort to address these issues, we performed a fluorocarbon surface kinetic modeling based on the experimental plasma diagnostic data for silicon dioxide etching process under inductively coupled C4F6/Ar/O2 plasmas. For this work, the SiO2 etch rates were investigated with bulk plasma diagnostics tools such as Langmuir probe, cutoff probe and Quadruple Mass Spectrometer (QMS). The surface chemistries of the etched samples were measured by X-ray Photoelectron Spectrometer. To measure plasma parameters, the self-cleaned RF Langmuir probe was used for polymer deposition environment on the probe tip and double-checked by the cutoff probe which was known to be a precise plasma diagnostic tool for the electron density measurement. In addition, neutral and ion fluxes from bulk plasma were monitored with appearance methods using QMS signal. Based on these experimental data, we proposed a phenomenological, and realistic two-layer surface reaction model of SiO2 etch process under the overlying polymer passivation layer, considering material balance of deposition and etching through steady-state fluorocarbon layer. The predicted surface reaction modeling results showed good agreement with the experimental data. With the above studies of plasma surface reaction, we have developed a 3D topography simulator using the multi-layer level set algorithm and new memory saving technique, which is suitable in 3D UHARC etch simulation. Ballistic transports of neutral and ion species inside feature profile was considered by deterministic and Monte Carlo methods, respectively. In case of ultra-high aspect ratio contact hole etching, it is already well-known that the huge computational burden is required for realistic consideration of these ballistic transports. To address this issue, the related computational codes were efficiently parallelized for GPU (Graphic Processing Unit) computing, so that the total computation time could be improved more than few hundred times compared to the serial version. Finally, the 3D topography simulator was integrated with ballistic transport module and etch reaction model. Realistic etch-profile simulations with consideration of the sidewall polymer passivation layer were demonstrated.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.123-126
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• 2002

Samples of Nb/Al-Al$O_{x}$/Nb tunnel junction with the size of 50$\mu$m $\times$ 50$\mu$m were fabricated by employing self-aligning and reactive ion etching technique. In the samples with high-quality, $V_{m}$ value (the product of the critical current and subgap resistance measured at 2 mV) was 34 mV at the critical current density $J_{c}$ = 500 A/$cm^{2}$ and $V_{g}$ value (the gap voltage) was 2.8 mV. In the higher $J_{c}$, voltage fluctuation in the current rising at the gap voltage was observed. The $V_{m}$ and $J_{c}$ value were 8 mV and 900 A/$cm^{2}$, respectively.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.5
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• pp.22-26
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• 2003

In this work, a new non-photolithographic micro-fabrication technique is presented. The motivation of this work is to overcome the demerits of the most commonly used photolithographic techniques. The micro-fabrication technique presented in this work is a two-step process which consists of mechanical scribing followed by chemical etching. This method has many advantages over other micro-fabrication techniques since it is simple, cost-effective, rapid, and flexible. Also, the technique can be used to obtain a metal structure which has sub-micrometer width patterns. In this paper, the concept of this method and its application to microsystem technology are described.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.228-233
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• 2002

In this work, a new non-photolithographic micro-fabrication technique is presented. The motivation of this work is to overcome the demerits of the most commonly used photolithographic techniques. The micro-fabrication technique presented in this work is a two-step process which consists of mechanical scribing followed by chemical etching. This method has many advantages over other micro-fabrication techniques since it is simple, cost-effective, rapid, and flexible. Also, the technique can be used to obtain a metal structure which has sub-micrometer width patterns. In this paper, the concept of this method and its application to microsystem technology are described.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.907-912
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• 2005

Micro-patterns of $Pb(Zr_{0.53}Ti_{0.47})O_3$, PZT, thin films with a MPB composition were deposited on $Pt/Ti/SiO_2/Si$ substrate from molecular-designed PZT precursor solution by using self-assembledmonolayer(SAM) as a template. This method includes deposition of SAM followed by the optical etching by exposing the SAM to the UV-light, leading to the patterned SAM as a selective deposition template. The pattern of SAM was formed by irradiating UV-light to the SAM on a substrate and/or patterned PZT thin film through a metal mask for the selective deposition of patterned PZT or lanthanum nickel oxide (LNO) precursor films from alkoxide-based precursor solutions. As a result, patterned ferroelectric PZT and PZT/LNO thin film capacitors with good electrical properties in micrometer size could be successfully deposited.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.129-137
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• 1995

AlGaAs/GaAs HBTs have been fabricated using SABM (Self-Aligned Base Metal) process technique. The mesa type HBTs were fabricated through following steps: isolation implant, wet etching, metal lift-off, and airbridge interconnection process. The fabricated HBTs with 2umx10um size emitter showed a common emitter current gain of 10 at a collector current density of Jk=100kA/cm$^{2}$, a breakdown volgate BVCEO of 8V, and the ideality factors of base and collector junctions of 1.6 and 1.1, respectively. On-wafer S-Parameter measurement at 0.5~18GHz has been made for the characterization of the common emitter HBTx with a 2umx10um size emitter. The extrapolated current gain cut-off frequency of ft=30GHz and maximum oscillation frequency of fmax=23 GHz were obtained at a collector current density of Jc=70kA/cm$^{2}$. Small signal HBT equivalent circuit was extracted from the S-Parameter data.