• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.757-763
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• 2017

본 연구에서는 50 mN급 마이크로 추력기를 활용하여, ADN 기반 추진제인 LMP-103S의 연소 실험을 수행하였다. 마이크로 추력기는 MEMS 공정 과정을 거쳐 감광유리로 제작하였다. LMP-103S 분해용 촉매로 $Pt/{\gamma}-Al_2O_3$를 사용하였다. 연소 실험 초기에 촉매 예열을 위해 90 wt.% 과산화수소를 주입하였으며, 이후 LMP-103S를 주입하여 연소 실험을 수행하였다. 실험 결과 백금 촉매 환경에서 LMP-103S의 점화가 이루어짐을 확인하였으며, 연소실 온도는 $650^{\circ}C$로 형성되었다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.103-104
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• 2002

The influence of the slip flow on the MEMS/MST based gas-lubricated proceeding bearing is investigated. Based on the modified Reynolds equation, the numerical analysis of the finite difference method was developed by applying the first order slip flow approximation. The numerical prediction of bearing performance provides the significant results concerning the slip flow effect in micro scale gas-lubricated proceeding bearing. The result indicates that the load-carrying capacity as well as the rotordynamic coefficients were significantly reduced due to the slip flow. Through this work, it is concluded that the slip flow effect could not be ignored in the micro gas-lubricated proceeding bearing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.68-68
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• 2009

최근 디스플레이 산업의 발달로 LCD 판넬의 수요가 급증함에 따라 검사장치 분야도 동반 성장하고 있다. LCD 검사를 위한 probe unit은 미세전기기계시스템 (MEMS) 공정을 이용하여 제작된다. 본 연구에서는 probe card의 미세 슬릿을 제작하기 위한 Si 깊은 식각 공정을 수행하였다. 공정에 사용된 장비는 STS 사의 D-RIE 시스템으로 식각가스로 $SF_6$, passivation용으로 $C_4F_8$ 가스를 각각 사용하였다. 식각용 마스크는 $30{\sim}50{\mu}m$의 선폭을 probe card의 패턴에 따라 제작되었으며, 분석은 SEM 측정을 이용하였다. 식각 공정 중 발생하는 scallop은 시료를 oxidation 시켜 $SiO_2$ 층을 형성한 후에 식각용액에 에칭하여 제거하였다. 제거전 scallop의 크기는 약 120 nm에서 제거후 약 $50{\mu}m$로 크게 개선됨을 SEM 사진으로 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.125-128
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• 2004

In this paper, a novel processing technique for fabrication of high-temperature MEMS based on polymer-derived SiCN microstructures is described. PDMS molds are fabricated on SU-8 photoresist using standard UV-photolithographic processes. Liquid precursors are injected into the PDMS mold. And then, the resulting solid polymer structures are crosslinked under isostatic pressure, and pyrolyzed to form a ceramic capable of withstanding over $1500^{\circ}C$. These fabricated SiCN structures would be applied for high-temperature applications, such as heat exchanger and combustion chamber.

• 한국재료학회지
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• 제24권10호
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• pp.532-537
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• 2014

In this study, highly sensitive hydrogen micro gas sensors of the multi-layer and micro-heater type were designed and fabricated using the micro electro mechanical system (MEMS) process and palladium catalytic metal. The dimensions of the fabricated hydrogen gas sensor were about $5mm{\times}4mm$ and the sensing layer of palladium metal was deposited in the middle of the device. The sensing palladium films were modified to be nano-honeycomb and nano-hemisphere structures using an anodic aluminum oxide (AAO) template and nano-sized polystyrene beads, respectively. The sensitivities (Rs), which are the ratio of the relative resistance were significantly improved and reached levels of 0.783% and 1.045 % with 2,000 ppm H2 at $70^{\circ}C$ for nano-honeycomb and nano-hemisphere structured Pd films, respectively, on the other hand, the sensitivity was 0.638% for the plain Pd thin film. The improvement of sensitivities for the nano-honeycomb and nano-hemisphere structured Pd films with respect to the plain Pd-thin film was thought to be due to the nanoporous surface topographies of AAO and nano-sized polystyrene beads.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.27.2-27.2
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• 2010

In recent years, there is a strong requirement of low cost, stable microelectro mechanical systems (MEMS) for resonators, microswitches and sensors. Most of these devices consist of freely suspended microcantilevers, which are usually made by the etching of some sacrificial materials. Herein, we have attempted to use Si nanowires, inherited from the parent Si wafer, as a sacrificial material due to its porosity, low cost and ease of fabrication. Prior to the fabrication of the Si nanowires silver nanoparticles were continuously formed on the surface of Si wafer. Vertically aligned Si nanowires were fabricated from the parent Si wafers by aqueous chemical route at $50^{\circ}C$. Afterwards, the morphological and structural characteristics of the Si nanowires were investigated. The morphology of nanowires was strongly modulated by the resistivity of the parent wafer. The 3-step etching of nanowires in diluted KOH solution was carried out at room temperature in order to control the fast etching. A layer of $Si_3N_4$ (300 nm) was used for the selective fabrication of nanowires. Finally, a freely suspended bridge of zinc oxide (ZnO) was fabricated after the removal of nanowires from the parent wafer. At present, we believe that this technique may provide a platform for the inexpensive fabrication of futuristic MEMS.

• 한국통신학회논문지
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• 제35권11A호
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• pp.1091-1096
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• 2010

Stiction in microelectromechanical systems (MEMS) has been a major failure mechanism. Especially, in RF MEMS switches, moving parts often suffered in-use and release related stiction problems. Some materials and methods have been used to prevent this problem. Diamond-like carbon (DLC) has not only been used as a protective material owing to its good mechanical properties but also has been used as a hydrophobic material. Its properties could be controlled by post annealing treatment in various conditions. We synthesized DLC films using a radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method on silicon substrates using methane ($CH_4$) and hydrogen ($H_2$) gas. Then, the change of the hydrophobic property of the films was investigated undervarious annealing temperatures in nitrogen and in oxygen ambient. The films, that were annealed above $700^{\circ}C$ in nitrogen ambient, showed a high contact angle of water (> $90^{\circ}$) even though their mechanical property was sacrificed to some degree. The structural variation and the changes of the hydrophobic and mechanical properties of the DLC films were analyzed by Raman spectrum, contact angle measurement, surface profiler, and a nanoindentation test.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.187-188
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• 2005

In this paper, big free standing metal structures for electrostatic MEMS switches are easily fabricated using photoresist sacrificial layer. The entire process sequence, through the removal of the sacrificial layer, is kept below 150 $^{\circ}C$ to avoid curing problem of photoresist sacrificial layer. Metal structure is fabricated by thermal evaporator and a self test electrode is fabricated underlying metal suspended structure for testing by electrostatic force. The new wet release process is considered using methanol rinse, general wet release process cause stiction problem by capillary force during drying, and the yield is dramatically improved than previous wet release process using DI water rinse. The fabrication becomes much simpler and cheaper with use of a photoresist sacrificial layer.

• 반도체디스플레이기술학회지
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• 제5권2호
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• pp.33-36
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• 2006

Many issues arose to use the Pb-free solder as adhesive materials in MEMS ICs and packaging. Then this study for easy and simple sealing method using adhesive materials was carried out to maintain hermetic characteristic in MEMS Package. In this study, Hermetic characteristic using negative PR (XP SU-8 3050 NO-2) as adhesive at the interface of Si test coupon/glass substrate and Si test coupon/LTCC substrate was examined. For experiment, the dispenser pressure was 4 MPa and the $200\;{\mu}m{\Phi}$ syringe nozzle was used. 3.0 mm/sec as speed of dispensing and 0.13 mm as the gap between Si test coupon and nozzle was selected to machine condition. 1 min at $65^{\circ}C$ and 15 min at $95^{\circ}C$ as Soft bake, $200\;mj/cm^2$ expose in 365 nm wavelength as UV expose, 1 min at $65^{\circ}C$ and 6 min at $95^{\circ}C$ as Post expose bake, 60 min at $150^{\circ}C$ as hard bake were selected to activation condition of negative PR. Hermetic sealing was achieved at the Si test coupon/ glass substrate and Si test coupon/LTCC substrate. The leak rate of Si test coupon/glass substrate was $5.9{\times}10^{-8}mbar-l/sec$, and there was no effect by adhesive method. The leak rate of Si test coupon/LTCC substrate was $4.9{\times}10^{-8}mbar-l/sec$, and there was no effect by dispensing cycle. Better leak rate value could be achieved to use modified substrate which prevent PR flow, to increase UV expose energy and to use system that controls gap automatically with vision.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.5288-5293
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• 2014

본 논문은 차세대 ROADM을 구성하는 핵심기술인 파장선택스위치에서 기존에 사용되는 MEMS소자 기술대신에 LCOS 디스플레이 기술을 적용한 파장선택스위치의 특성을 고찰한 논문이다. LCOS소자를 이용한 5개의 포트를 갖는 파장선택 스위치 시스템을 구성하고 응답특성과 빔제어 특성, insertion loss와 channel isolation등 파장선택 스위치로서의 기본적인 특성들을 검토하였다. 본 파장선택스위치의 응답특성은 11.6 mS 로 양호하며 LCOS상에서의 grating 이미지 패턴에 따른 입사빔의 편향특성이 잘 구현되었다. C밴드내의 40개 채널에 대한 Insertion loss 측정에서 채널에 따라 5.5~12.7 dB 사이의 값이 측정되었으며 인접채널간의 channel isolation 측정은 16~18 dB 값이 측정되었다. 기존의 MEMS소자를 이용한 파장선택스위치 상용화된 제품에 비해 특성은 아직 다소 부족하지만 향후 보완연구에 의해 LCOS소자를 이용한 파장선택스위치 시스템의 기술경쟁력이 충분히 확보될 것으로 기대한다.