• 한국진공학회지
• /
• 제8권4B호
• /
• pp.565-571
• /
• 1999

In this study, high-density plasma etching characteristics of ITO(indium tin oxide) films used for transparent electrode in dispaly devices were investigated. Plasma diagnostic and surface analysis tools were used to understand etch reaction mechanism. The etch rate of ITO was increased by the increase of reactive radicals such as H and $CH_3$ with the addition of moderate amount of $CH_4$ to Ar. However, the addition of excess amount of $CH_4$ decreased possibly due to the increased polymer formation on the ITO surface being etched. The increase of source power and bias boltage increased ITO etch rates but it decreased selectivities over under-layers $(SiO_2, Si_3N_4)$. The increase of working pressure up to 20mTorr also increased ITO etch rates, however the further increased of the pressure decreased ITO etch rates. From the analysis of XPS, a peak related to the polymer of hydrocarbon was observed on the etched ITO surface especially for high $CH_4$ conditions and it appears to affect ITO etch rates.

• 한국세라믹학회지
• /
• 제40권6호
• /
• pp.519-524
• /
• 2003

Porous carbon with high surface area and pore volume was prepared by a reverse replication process and its toluene equilibrium adsorption behavior was investigated. The preparation process of the porous carbon was composed of fellowing sub-processes in series: synthesis and template preparation of silica gel, impregnation and polymerization of DVB monomer in silica template, carbonization of DVB polymer in a silica-polymer composite, and HF-assisted selective etching of silica in carbon-silica composite. The prepared porous carbon was nano porous and had ultrahigh specific surface area (2007 ㎡/g) and large pore volume (3.07 ㎤/g). The nanoporous carbon showed rapid toluene adsorption rate and good toluene adsorption capacity, compared with a commercial Y-type zeolite. In the present study, a reverse replication process to prepare nanoporous carbons will be introduced and its application potential as a gas adsorbent will be discussed.

• 한국기계가공학회지
• /
• 제12권5호
• /
• pp.16-22
• /
• 2013

A two-dimensional photonic crystal structure was investigated using a roll-to-roll nanoreplication and physical vapor deposition processes for the inexpensive enhanced fluorescence substrate which is not sensitive to the polarization directions of excitation light source. An 8 inch silicon master having nano dot array with a diameter of 200 nm, a height of 100 nm and a pitch of 400 nm was prepared by KrF laser scanning lithography and reactive ion etching processes. A flexible polymer mold was fabricated by flat type UV replication process and a deposition of 10 nm nickel layer as an anti-adhesion layer. A roll mold was prepared by warping the flexible polymer mold on an aluminum roll base and a roll-to-roll UV replication process was carried out using the roll mold. After the deposition of ~ 100 nm $TiO_2$ layer on the replicated nano dot array, a 2 dimensional photonic crystal structure was realized with a resonance wavelength of 635 nm for both p- and s-polarized light sources.

• 폴리머
• /
• 제26권2호
• /
• pp.253-259
• /
• 2002

본 연구는 내열성, 저광학손실 광도파로용 고분자재료를 합성하고 그 물성을 조사한 것이다. 열안정성을 높이고 광학손실을 줄이기 위한 pentafluorophenylmaleimide와 복굴절률을 낮추기 위한 두가지 methacrylate 유도체와 가교제 역할을 하는 glycidylmethacrylate를 삼원 공중합하여 광가교가 가능한 poly(maleimide-co-methacrylate)를 합성하였다. 합성된 고분자들은 높은 열안정성을 나타내었고, 열처리에 의해서 가교가 됨을 확인하였다. 고분자의 굴절율은 공중합 비율에 의해서 조절가능하였고, 1.45~l.49 범위의 고분자가 합성되었다. 복굴절은$6{ imes}10^{-4}$ ~ $1{ imes}10^{-4}$ 범위의 낮은 값을 나타내었다. 이 고분자와 광개시제를 사용하여 접촉 인쇄 방식에 의한 노광과 습식 현상을 통해 깨끗한 광도파로 패턴을 얻을 수 있었다.

• Carbon letters
• /
• 제3권3호
• /
• pp.127-132
• /
• 2002

Unidirectional polymer composites were prepared using high-strength carbon fibers as reinforcement and phenolic resin as matrix precursor with keeping fiber volume fraction at 30, 40, 50 and 60% respectively. These composites were carbonized at $1000^{\circ}C$ and graphitised at $2600^{\circ}C$ in the inert atmosphere. The carbonized and graphitised composites were characterized for mechanical properties as well as microstructure. Microscopic studies were carried out of the polished surface of carbonized and graphitised composites after etching by chromic acid, to understand the effect of fiber volume fraction on oxidation at fiber-matrix interface. It is found that the flexural strength in polymer composites increases with fiber volume fraction and so does for the carbonised composites. However, the trend was found to be reversed in graphitised composites. In all the carbonized composites anisotropic region has been observed at fiber-matrix interface which transforms into columnar type microstructure upon graphitisation. The extension of strong and weak columnar type microstructure is function of fiber volume fraction. SEM microscopy of the etched surface of the sample reveal that composites containing 40% fiber volume has minimum oxidation at the interface, revealing a strong interfacial bonding.

• 한국진공학회지
• /
• 제18권2호
• /
• pp.85-91
• /
• 2009

현재 플렉시블 폴리머를 이용한 MEMS (Microelectromechanical Systems) 기술이 빠르게 발전하고 있다. 그 중에서 Polycarbonate (PC), Poly Methyl Methacrylate (PMMA)와 같은 플렉시블 폴리머 재료는 광학적 특성이 우수하고 인체 친화적이며 미세 패턴 제조 공정이 용이하다는 등의 많은 장점을 가지고 있다. 본 연구는 반응성 이온 식각 기술을 이용하여 $O_2$, $SF_6$ 그리고 $CH_4$의 삼성분계 가스의 혼합 비율에 따른 PC와 PMMA의 건식 식각 결과 및 특성 평가에 관한 것이다. 준비한 각각의 기판에 포토리소그래피 방법으로 마스크를 형성하여 샘플을 만들었다. RF 척 파워를 100 W, 총 가스 유량을 10 sccm으로 고정시켜 플라즈마 식각 실험을 실시하였다. 그 결과에 의하면 전체적으로 PMMA의 식각율이 PC보다는 약 2배 정도 높았다. 그 결과는 PC는 PMMA 보다 상대적으로 높은 녹는점을 가지고 있다는 사실과 관계가 있다고 생각한다. 또한 $O_2/SF_6/CH_4$의 삼성분계 가스와 $SF_6/CH_4$, $O_2/SF_6$, $O_3/CH_4$로 나누었을 때 $O_2/SF_6$의 혼합 가스에서 PMMA와 PC의 식각 속도가 가장 높았다 (PC: 5 sccm $O_2$/5 sccm $SF_6$에서 약 350 nm/min, PMMA: 2.5 sccm $O_2$/7.5 sccm $SF_6$에서 약 570 nm/min). SEM을 활용하여 식각된 표면을 분석한 결과 PC는 PMMA보다 상대적으로 식각 표면이 더 매끈하였다. 또한 표면 거칠기 분석결과 PC의 표면 거칠기는 1.9$\sim$3.88 nm이었지만 PMMA의 표면 거칠기는 17.3$\sim$26.1 nm로 현저하게 높았음을 확인할 수 있었다.

• 한국전기전자재료학회논문지
• /
• 제26권9호
• /
• pp.669-676
• /
• 2013

In this study, we introduce a polymer(polyimide) based pressure sensor to measure real-time heart beat and blood pressure. The sensor have been designed with consideration of skin compatibility of material, cost effectiveness, manufacturability and wireless detection. The designed sensor was composed of inductor coils and an air-gap capacitor which generate self-resonant frequency when electrical source is applied on the system. The sensor was obtained with metalization, etching, photolithography, polymer adhesive bonding and laser cutting. The fabricated sensor was shaped in circular type with 10mm diameter and 0.45 mm thickness to fit radial artery. Resonant frequencies of the fabricated sensors were in the range of 91~96 MHz on 760 mmHg pressurized environment. Also the sensor has good linearity without any pressure-frequency hysteresis. Sensitivity of the sensor was 145.5 kHz/mmHg and accuracy was less than 2 mmHg. Real-time heart beat measurement was executed with a developed hand-held measurement system. Possibility of real-time blood pressure measurement was showed with simulated artery system. After installation of the sensor on skin above radial artery, simple real blood pressure measurement was performed with 64 mmHg blood pressure variation.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 추계학술대회 논문집
• /
• pp.200-203
• /
• 2001

Micromolding methods such as micro-injection molding and micro-compression molding are most suitable for mass production of plastic micro-optics with low cost. In this study, plastic micro-optical components, such as refractive microlenses and diffractive optical elements(DOEs) with various grating patterns, were fabricated using micro-compression molding process. The mold inserts were made by ultrapricision mechanical machining and silicon etching. A micro compression molding system was designed and developed. Polymer powders were used as molded materials. Various defects found during molding were analyzed and the process was optimized experimentally by controlling the governing process parameters such as histories of mold temperature and compression pressure. Mim lenses of hemispherical shape with $250{\mu}m$ diameter were fabricated. The blazed and 4 stepped DOEs with $24{\mu}m$ pitch and $5{\mu}m$ depth were also fabricated. Optical and geometrical properties of plastic molded parts were tested by interferometric technique.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.1078-1082
• /
• 2003

A feasibility study for the fabrication of master replication with nanostructures by Nanoimprint Lithography (NIL) was investigated for application of polymer Photonic Bandgap (PBG) devices used in photonic IC. Large area gratings of $9{\times}15(mm^2)$ with p = 400 nm was successfully embossed on PMMA on silicon wafer and the embossing parameters (temperature, pressure, time) were established. A precise control of $O_2$ plasma Reactive Ion Etching (RIE) process time allowed window opening over the whole area despite the presence of wafer bending. Master replication with aspect ratio 1 was successfully fabricated, but master replication with aspect ratio 3 needs to optimize parameters. All replications were done in a NIL process.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.366-370
• /
• 1997

This paper descibes a micro groove machining process on the polyurethane biopolymer by KrF excimer laser. To investigate the etch charcteristics of polyurethane biopolymer quantitatively,laser system for ablation was installed with high precison moter and then polymer ablation experiment, in which paramteters were fluence,pulse repetition rate,numbers of pulses and assist gas, was carred out. In this experiment, we found out that the value of critical energy density for ablation is 30mJ/cmsup2/ and the etching rate is more dependent on the pulse number and fluence than any other pamameter. Finally, we machined micro grooves for fiexibility as width 300.mu.m depth 100.mu.m and port for micro-devices mounting as length 100.mu.m width 300.mu.m depth .mu.m on the outer wallof polyurethane biopolymer tube which is used as medical device.