• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.261-263
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• 1993

The effects of the magnetic field and gas pressure on the etching characteristics were investigated in the axial magnetic field enhanced RIE system. This system has many advantages compared with the conventional RIE system ; the capability of operating at low pressure, low self-bias voltage, high electron density and high etch rate in the low pressure, but also has disadvantages such as the nonconformity of plasma density which intensifies as the magnitude of magnetic field increases. To overcome this problem we made some grooved anode and tried to find the optimal pressure and B-field strength.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1582-1584
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• 2008

This paper reports a simple fabrication method for creating the superhydrophobic polymer surface using a plasma etching. Generally, it is necessary for the superhydrophobic surfaces to have a rough structure on surface with the composition of the low surface energy. In this study, Poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), acrylonitrile butadiene styrene (ABS) with superhydrophobic surface were fabricated using $O_2$ plasma etching and vapor deposition with the fluoroalkylsilane self-assembled monolayers. The plasma treated polymer surfaces are covered with the nano-pillar shaped structures after treatment for $1{\sim}2min$. And these samples with FOTS SAMs coating are showed the superhydrophobicity having the water contact angle of around $150^{\circ}$ and sometimes around $180^{\circ}$ depending on the treatment time. Furthermore the nanostructured polymer is transparent for the visible light.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.261-266
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• 1998

In developing the high density memory device, the etching of fine pattern is becoming increasingly important. Therefore, definition of ultra fine line and space pattern and minimization of damage and contamination are essential process. Also, the high density plasma in low operating pressure is necessary. The candidates of high density plasma sources are electron cyclotron resonance plasma, helicon wave plasma, helical resonator, and inductively coupled plasma. In this study, planar type magnetized inductively coupled plasma etcher has been built. The density and temperature of Ar plasma are measured as a function of rf power, flow rate, external magnetic field, and pressure. The oxide etch rate and selectivity to polysilicon are measured as the above mentioned conditions and self-bias voltage.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.265.1-265.1
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• 2013

Nanoporous anodic aluminum oxide (AAO), a self-ordered hexagonal array has various applications for nanofabrication such as nanotemplate, and nanostructure. In order to obtain highly-ordered porous alumina membranes, Masuda et al. proposed a two-step anodization process however this process is confined to small domain size and long hours. Recently, alternative methods overcoming limitations of two-step process were used to make prepatterned Al surface. In this work, we confirmed that there is a specific tendency used a PDMS stamp to obtain a pre-patterned Al surface. Using the nanoindentaions of a PDMS stamp as chemical carrier for wet etching, we can easily get ordered nanoporous template without two-step process. This chemical etching method using a PDMS stamp is very simple, fast and inexpensive. We use two types of PDMS stamps that have different intervals (800nm, 1200nm) and change some parameters have influenced the patterning of being anodized, applied voltage, soaking and stamping time. Through these factors, we demonstrated the patterning effect of large scale PDMS stamp.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.41-46
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• 2003

In order to evaluate the sufficient etching time for successful bonding and also minimizing unnecessary mineral loss, the enamel surface roughness analysis was performed using confocal laser scanning microscopy. Sixty extracted sound human molar teeth were imbedded in the center of acrylic cylinder using self-curing clear resin exposing buccal surface, and then polished with series of SiC paper(220, 500, 800, 1000, 2000, 4000 grit). Each specimen was randomly assigned to six groups(N=10). 37% phosphoric acid was applied to the polished tooth surface for 10, 20, 30, 40, 50, 60 seconds respectively and washed with copious water. After the surface roughness analysis, five roughness parameters(Sa, Sq, Sz, Sdr, Ra) were statistically analysed by ANOVA and Duncan post hoc test. We found that the all five parameters had higher roughness value in 30 seconds etching time, especially parameter Sz showed the lowest value in 10 seconds etching time and the highest value in 30 seconds etching time compared with the other etching times(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.165-172
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• 2019

The purpose of this study was to evaluate the effect of application time and phosphoric acid etching of 8th generation adhesives containing functional monomer on adhesive performance in primary teeth. 80 extracted non-carious human primary teeth were selected and divided into 8 groups based on 3 factors: (1) adhesive: G-Premio bond and Single bond universal; (2) application time: shortened time and manufacture's instruction; (3) acid etching mode: self-etching and total-etching. Shear bond strength was measured using a universal testing machine, and fractured surface were observed under scanning electron microscope. Microleakage was evaluated by dye penetration depth. G-Premio bond were not significant different in shear bond strength and microleakage depending on application time of adhesive and acid etching mode. In Single bond universal, shear bond strength of short application time was significantly lower than that of long adhesive application time (p = 0.014). Clinically applicable shear bond strength values (> 17 MPa) were identified in all groups. These results suggested that G-Premio bond be used clinically for a short application time without phosphoric acid etching.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.24.1-24.1
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• 2010

In practical operation, the exposed surfaces may get dirty thus degrade the performance of devices. So the combination of self cleaning and antireflection is very desirable for use in outdoor photovoltaic and displaying devices, self cleaning windows and car windshields. For the purpose of self cleaning, the surface needs to be either superhydrophobic or superhydrophilic. However, in practice AR in the visible region and self cleaning are a pair of competitive properties. To satisfy the requirements for superhydrophobic or superhydrophilic surfaces, high surface roughness is required. But it usually cause severely light scattering. Photo-responsive coatings (TiO2, ZnO etc.) can lead to superhydrophilic. However, the refractive indices are high. Thus for porous structure, controlling pore size in the underwavelength scale to reduce the light scattering is very crucial for highly transparent and self cleaning antireflection coating. Herein, we demonstrate a simple method to make high performance broadband antireflection layer on the glass surface, by "carving" the surface by hot alkali solution. Etched glass has superhydrophilic surface. By chemical modification, it turns to superhydrophobic. Enhanced transparency (up to 97%) in a broad wavelength range was obtained by short time etching. Also antifogging effect has been demonstrated, which may offer advantage for devices working at high humidity environment or underwater. Compositional dependence of the properties was observed by comparing three different commercially available glasses.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.294-294
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• 2013

소수성을 띄는 표면은 자연으로부터 시작된 연구이다. 연잎, 소금쟁이 다리, 매미 날개 등 많은 자연의 표면은 150o보다 높은 접촉각을 지니기 때문에 물에 대한 반발이 심해져 약간의 기울임에도 쉽게 물방울이 굴러 떨어지고 이때 먼지를 제거할 수 있다. 자연현상을 이용해 물질 표면의 소수성 제어에 대한 다양한 연구가 진행 중이다. 친수성과 소수성은 일반적으로 표면에서 물방울의 contact angle 측정으로 확인 할 수 있다. Contact angle이 $90^{\circ}$ 작을 경우 친수성, $90^{\circ}$보다 클 경우 소수성이라고 한다. 이러한 기술을 이용해서 solar cell, 자동차 유리, 건물외벽, 등 다양한 분야에서 사용하고 있으며, 소수성 구조를 만드는 방법으로는 laser ablation, wet etching, 리소그라피 공정이 있는데, laser ablation의 경우 가격이 비싸다는 단점을 가지고 있으며, 반면 가격이 저렴한 wet etching의 경우 제어가 힘들다는 단점을 지니고 있다. 리소그라피 공정은 비싼 비용과 시간을 소비해야 하는 단점을 지니고 있다. 본 연구에서는 이러한 단점들을 개선하기 위해 공정 시간의 감소와, 저 비용으로 제작이 가능한 RIE (Recative Ion Etching)로 피라미드 구조를 만들었다. 형성된 구조물에 투명하고 균일하며, 낮은 계면에너지를 갖고 있는 PDMS (polydimethelsiloxine)로 mold을 수행하였다. RIE를 이용한 표면 구조는 Gas, Flow rate, Pressure, Power, Time 등을 조절하여 단결정 실리콘 기판 위에 피라미드의 크기를 조절하였다. 피라미드의 크기가 커짐에 따라 물과 PDMS가 닿는 면적이 줄어들면서 높은 소수성을 가지게 되는데, 높은 소수성 구조를 가지는 피라미드 형상을 찾기 위한 실험을 진행하였다. RIE 조건은 Flow rate: 30 sccm, Temperature: $10^{\circ}C$ Pressure: 100 mTorr, Power: 200 W, Process Time: 5~50 min으로 조절하며 공정을 수행하였고 RIE공정 후 SAMs (Self-Assembly Monolayers)을 진행하였으며, 마지막으로 PDMS를 이용하여 mold공정을 진행하였다. 그리고 SEM (Scanning Electron Microscope)장비를 이용하여 Etching된 단면을 관찰하였으며, 접촉각을 측정하였다. Process Time을 50 min로 공정하였을 때, 측정된 접촉각은 $134^{\circ}$였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.40-44
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• 2002

The motivation of this work is to use SAM(Self-Assembled Monolayer) for developing a rapid and flexible non-photolithographic nano-structure fabrication technique which can be utilized in micro-machining of metals as well as silicon-based materials. The fabrication technique implemented in this work consists of a two-step process, namely, mechanical scribing followed by chemical etching. From the experimental results, it was found that thiol on copper surface could be removed even under a few nN normal load. The nano-tribological characteristics of thiol-SAM on various metals were largely dependent on the native oxide layer of metals. Based on these findings, nano-patterns with sub-micrometer width and depth on metal surfaces such as Cu, Au and Ag could be obtained using a diamond-coated tip.

• Journal of Magnetics
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• v.13 no.2
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• pp.53-56
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• 2008

This study proposes a simple nano-patterning process for the fabrication of magnetic nanodot arrays on a large area substrate. Ni nanodots were fabricated on a large area (4 inches in diameter) Si substrate using the soft lithographic technique using self-assembled surface micelles of Polystyrene-block-Poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer formed at the air/water interface as a mask. The hexagonal array of micelles was successfully transferred to a Ni thin film on a Si substrate using the Langmuir-Blodgett technique. After ion-mill dry etching, a magnetic Ni nanodot array with a regular hexagon array structure was obtained. The Ni nanodot array showed in-plane easy axis magnetization and typical soft magnetic properties.