• 한국기계가공학회지
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• 제19권2호
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• pp.38-46
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• 2020

The purpose is to evaluate the structural characteristics of 750 mm diameter injection spiral blades under various operating conditions. A fiber-glass reinforced polypropylene material was employed to the injection blades, and mechanical tests on two kinds of glass-reinforced polypropylene were performed to evaluate the mechanical properties and to select a suitable candidate material. Also, three kinds of spiral blade geometries were studied to observe the influence of fixing rods between blades. For this, structural analyses were conducted to understand the role of fixing rods under a range of rotating speed. In addition, modal analysis was performed to confirm the resonance in the operating speed range. One-way fluid-structure interaction (FSI) analysis was carried out to know its mechanical integrity under dangerous wind speed conditions. Through this work, the structural characteristics of the proposed spiral blade geometries were studied under various operating conditions, and the requirements of mechanical properties of blades were determined.

• 센서학회지
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• 제11권1호
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• pp.54-59
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• 2002

본 논문은 Si기판 직접접합기술과 전기화학적 식각정지를 이용하여 마이크로 시스템용 매몰 공동을 갖는 SOI 구조물의 일괄제조에 대한 새로운 공정기술에 관한 것이다. 저비용의 전기화학적 식각정지법으로 SOI의 정확한 두께를 제어하였다. 핸들링 기판 위에서 Si 이방성 습식식각으로 공동을 제조하였다. 산화막을 갖는 두 장의 Si기판을 직접접합한 후, 고온 열처리($1000^{\circ}C$, 60분)를 시행하고 전기화학적 식각정지로 매몰 공동을 갖는 SDB SOI 구조를 박막화하였다. 제조된 SDB SOI 구조물 표면의 거칠기는 래핑과 폴리싱에 의한 기계적인 방법보다도 우수했다. 매몰 공동을 갖는 SDB SOI 구조는 새로운 마이크로 센서와 마이크로 엑츄에이터에 대단히 효과적이며 다양한 응용이 가능한 기판으로 사용될 것이다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권4호
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• pp.175-183
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• 2002

In this paper, the surface modification effect of self-assembled monolayer(SAM) of 1-dodecanethiol [$CH_3$($CH_2$)$_{11}$SH] used as an anti-adhesive film in micromolding process was studied. Monolayers of 1-dodecanethiol[$CH_3$(CH$_2$)$_{11}$SH] were obtained by immersing a metal place in pure 1-dodecanethiol. SAM film on the nickel plate has been examined by using X-ray photoelectron spectroscopy(XPS). The focus has been placed on S-Ni bonding. From the XPS analysis, sulfur atoms were detected from the SAM film as a chemical composition of S-Ni. In order to measure an adhesion force of the SAM-coated nickel surface, atomic force microscopy(AFM) was used in force-distance mode, which whows the micro-adhesive force on solid surface. It was shown that adhesion forces measured from the SAM-coated nickel surface and the Ni surface without SAM coating were 3.52nN and 5.32nN, respectively. In order to investigate the effect of SAM coating on the surface foughness the replica in demolding process, hot embossing experiments were performed using a SAM-coated nickel master and a nickel master without SAM coating. Surface roughness of replica from the SAM-coated master showed 25nm and that of replica from master without SAM coating was 35nm. The smoother surface roughness of the replica from the SAM-coated, master is believed to result from reduction in the adhesion forces.ces.

• 대한기계학회논문집A
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• 제35권9호
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• pp.1015-1020
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• 2011

최근, MEMS/NEMS 기술을 이용하여 기능성 나노 구조물을 제작하기 위한 공정기술 중에, 마스터 스템프에 형성된 나노패턴을 웨이퍼 등에 복제할 수 있는 나노임프린트 리소그래피 기술이 활발히 연구되고 있다. 본 연구에서는 기존 멀티헤드방식 나노임프린팅 장비에서 사용되던 전동모터를 대신하여 플렉셔 메커니즘과 결합된 나노스템프를 구동하기 위한 사각 형상의 중공형 압전액추에이터를 설계, 제작하였으며, 제조공정이 다른 각각의 시제품의 변위, 발생력 및 응답특성에 관한 검토를 수행한다. 또한, 압전 액추에이터의 변위제어에 대한 제어수법을 간단히 소개하였으며, 제작한 프로토타입의 PI제어기에 의한 변위 제어결과를 소개한다.

• 센서학회지
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• 제24권6호
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• pp.379-384
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• 2015

An infrared image sensor is a core device in a thermal imaging system. The fabrication method of a focal plane array (FPA) is a key technology for a high resolution infrared image sensor. Each pixels in the FPA have $Si_3N_4/SiO_2$ membranes including legs to deposit bolometric materials and electrodes on Si readout circuits (ROIC). Instead of polyimide used to form a sacrificial layer, the feasibility of an amorphous silicon (${\alpha}-Si$) was verified experimentally in a $8{\times}8$ micro-bolometer array with a $50{\mu}m$ pitch. The elimination of the polyimide sacrificial layer hardened by a following plasma assisted deposition process is sometimes far from perfect, and thus requires longer plasma ashing times leading to the deformation of the membrane and leg. Since the amorphous Si could be removed in $XeF_2$ gas at room temperature, however, the fabricated micro-bolomertic structure was not damaged seriously. A radio frequency (RF) sputtered nickel oxide film was grown on a $Si_3N_4/SiO_2$ membrane fabricated using a low stress silicon nitride (LSSiN) technology with a LPCVD system. The deformation of the membrane was effectively reduced by a combining the ${\alpha}-Si$ and LSSiN process for a nickel oxide micro-bolometer.

• 센서학회지
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• 제30권6호
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• pp.388-394
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• 2021

The conventional microelectromechanical system (MEMS) process has been used to fabricate sensors with high costs and high-volume productions. Emerging 3D printing can utilize various materials and quickly fabricate a product using low-cost equipment rather than traditional manufacturing processes. 3D printing also can produce the sensor using various materials and design its sensing structure with freely optimized shapes. Hence, 3D printing is expected to be a new technology that can produce sensors on-site and respond to on-demand demand by combining it with open platform technology. Therefore, this paper reviews three standard 3D printing technologies, such as Fused Deposition Modeling (FDM), Direct Ink Writing (DIW), and Digital Light Processing (DLP), which can apply to the sensor fabrication process. The review focuses on strain/load sensors having both sensing material features and structural features as well. NCPC (Nano Carbon Piezoresistive Composite) is also introduced as a promising 3D material due to its favorable sensing characteristics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.96-97
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• 2012

In nitride and oxide film deposition, sputtered metals react with nitrogen or oxygen gas in a vacuum chamber to form metal nitride or oxide films on a substrate. The physical properties of sputtered films (metals, oxides, and nitrides) are strongly influenced by magnetron plasma density during the deposition process. Typical target power densities on the magnetron during the deposition process are ~ (5-30) W/cm2, which gives a relatively low plasma density. The main challenge in reactive sputtering is the ability to generate a stable, arc free discharge at high plasma densities. Arcs occur due to formation of an insulating layer on the target surface caused by the re-deposition effect. One current method of generating an arc free discharge is to use the commercially available Pinnacle Plus+ Pulsed DC plasma generator manufactured by Advanced Energy Inc. This plasma generator uses a positive voltage pulse between negative pulses to attract electrons and discharge the target surface, thus preventing arc formation. However, this method can only generate low density plasma and therefore cannot allow full control of film properties. Also, after long runs ~ (1-3) hours, depends on duty cycle the stability of the reactive process is reduced due to increased probability of arc formation. Between 1995 and 1999, a new way of magnetron sputtering called HIPIMS (highly ionized pulse impulse magnetron sputtering) was developed. The main idea of this approach is to apply short ${\sim}(50-100){\mu}s$ high power pulses with a target power densities during the pulse between ~ (1-3) kW/cm2. These high power pulses generate high-density magnetron plasma that can significantly improve and control film properties. From the beginning, HIPIMS method has been applied to reactive sputtering processes for deposition of conductive and nonconductive films. However, commercially available HIPIMS plasma generators have not been able to create a stable, arc-free discharge in most reactive magnetron sputtering processes. HIPIMS plasma generators have been successfully used in reactive sputtering of nitrides for hard coating applications and for Al2O3 films. But until now there has been no HIPIMS data presented on reactive sputtering in cluster tools for semiconductors and MEMs applications. In this presentation, a new method of generating an arc free discharge for reactive HIPIMS using the new Cyprium plasma generator from Zpulser LLC will be introduced. Data (or evidence) will be presented showing that arc formation in reactive HIPIMS can be controlled without applying a positive voltage pulse between high power pulses. Arc-free reactive HIPIMS processes for sputtering AlN, TiO2, TiN and Si3N4 on the Applied Materials ENDURA 200 mm cluster tool will be presented. A direct comparison of the properties of films sputtered with the Advanced Energy Pinnacle Plus + plasma generator and the Zpulser Cyprium plasma generator will be presented.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1706-1710
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• 2004

This paper presents a feedback-controlled, MEMS-fabricated microaccelerometer (${\mu}$XL). The ${\mu}$XL has received much commercial attraction, but its performance is generally limited. To improve the open-loop performance, a feedback controller is designed and experimentally evaluated. The feedback controller is applied to the x/y-axis ${\mu}$XL fabricated by sacrificial bulk micromachining (SBM) process. Even though the resolution of the closed-loop system is slightly worse than open-loop system, the bandwidth, linearity, and bias stability are significantly improved. The noise equivalent resolution of open-loop system is 0.615 mg and that of closed-loop system is 0.864 mg. The bandwidths of open-loop and closed-loop system are over 100 Hz. The input range, non-linearity and bias stability are improved from ${\pm}$10 g to ${\pm}$18 g, from 11.1 %FSO to 0.86 %FSO, and from 0.221 mg to 0.128 mg by feedback control, respectively

• 센서학회지
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• 제13권4호
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• pp.258-263
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• 2004

In this study, we carried out a basic study for the development of optical transcutaneous $pCO_{2}$ gas sensor and analyzer using non-invasive method. The basic principle of $pCO_{2}$ measurement is adapted Beer lambert's law and embodied the system using NDIR method. This measuring system was composed of a IR lamp, a optical filter, a optical reaction chamber, pyroelectric sensor and a signal process. We measured $EtCO_{2}'s$ concentration in basis step instead of $pCO_{2}$ gas that can collect by inflicting heat in outer skin. We minimize the size of optical reaction chamber which takes up the largest volume, to make the portable sensor. We made optical reaction chamber in Si wafer using MEMS technology and the optical reaction chamber was shortened to 2 mm and we carried out an experiment. When we injected the $EtCO_{2}$ to the inside of the optical reaction chamber, we could confirm change of 4.6 mV. The system response time was within 2 second that is fairly fast.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1214-1218
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• 2005

As demands for precision parts are increased, existing methods to fabricate them such as MEMS, LIGA technology have the technical limitations like high precision, high functionality and ultra miniaturization. A micro-stereolithography technology based on $DMD^{TM}$(Digital Micromirror Device) can meet these demands. In this technology, STL file is the standard format as the same of conventional rapid prototyping system, and 3D part is fabricated by stacking layers that are sliced as 2D section from STL file. Whereas in conventional method, the resin surface is cured as scanning laser beam spot according to the section shape, but in this research, we use integral process which enables to cure the resin surface at one time. In this paper, we deal with the dynamic pattern generation and $DMD^{TM}$ operation to fabricate micro structures. Firstly, we address effective slicing method of STL file, conversion to bitmap, and dynamic pattern generation. Secondly, we suggest $DMD^{TM}$ operation and optimal support manufacturing for $DMD^{TM}$ mounting. Thirdly, we examine the problems on continuous stacking layers, and their improvements in software aspects.