• 한국광학회지
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• 제20권2호
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• pp.118-122
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• 2009

PET 필름 위에 LCD 백라이트의 프리즘 집광시트의 역할을 대체 할 수 있는 microlens array(MLA) 시트를 설계하고 제작하였다. Photoresist thermal reflow 공정으로 두께 $100{\mu}m$ PET 필름 위에 MLA를 제작하였고, 노광 시간과 reflow의 온도, 시간 등의 변수에 따른 MLA의 형상 변화를 측정하였다.

• 마이크로전자및패키징학회지
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• 제20권2호
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• pp.23-28
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• 2013

마이크로렌즈 어레이는 광학 시스템의 기본 부품으로, 사용 목적에 따라 초점거리가 다르게 제작되며, 대체로 긴 초점거리의 렌즈들이 많이 제작되고 있다. 본 논문에서는 졸겔(sol-gel) 내부에 들어있는 형광으로 염색된 물질을 관찰하기 위하여 마이크로렌즈 어레이를 제작하였다. 일반적으로 형광 현미경에서 관찰되는 형광 빛은 그 강도가 약하지만 마이크로렌즈를 이용할 경우 빛을 집중시켜 선명한 관찰이 가능하게 한다. 이를 실현시키기 위해 photoresist thermal reflow법을 사용하여 초점 거리가 짧은 마이크로렌즈를 제작하였으며, 렌즈의 형상 관련 오차를 측정하였다. 측정 오차에 기반을 둔 포토마스크 보정 및 스핀 코팅 조건을 조정하여 적합한 마이크로렌즈의 직경과 형상을 구현하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.179-182
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• 2011

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.323-324
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• 2012

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.274.2-274.2
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• 2013

We described a simple and efficient fabrication method for generating microfluidic channels with a circular-cross sectional geometry by exploiting the reflow phenomenon of a thick positive photoresist. Initial rectangular shaped positive photoresist micropatterns on a silicon wafer, which were fabricated by a conventional photolithography process, were converted into a half-circular shape by tuning the temperature to around $105^{\circ}C$. Through optimization of the reflow conditions, we could obtain a perfect circular micropattern of the positive photoresist, and control the diameter in a range from 100 to 400 ${\mu}m$. The resultant convex half-circular photoresist was used as a template for fabricating a concave polydimethylsiloxane (PDMS) through a replica molding process, and a circular PDMS microchannel was produced by bonding two half-circular PDMS layers. A variety of channel dimensions and patterns can be easily prepared, including straight, S-curve, X-, Y-, and T-shapes to mimic an in vivo vascular network. To inform an endothelial cell layer, we cultured primary human umbilical vein endothelial cells (HUVECs) inside circular PDMS microchannels, and demonstrated successful cell adhesion, proliferation, and alignment along the channel.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1582-1584
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• 1996

The polycrystalline silicon thin film transistors (poly-Si TFT) are the most promising candidate for active matrix liquid crystal displays (AMLCD) for their high mobilities and current driving capabilities. The leakage current of the poly-Si TFT is much higher than that of the amorphous-Si TFT, thus larger storage capacitance is required which reduces the aperture ratio fur the pixel. The offset gated poly-Si TFTs have been widely investigated in order to reduce the leakage current. The conventional method for fabricating an offset device may require additional mask and photolithography process step, which is inapplicable for self-aligned source/drain ion implantation and rather cost inefficient. Due to mis-alignment, offset devices show asymmetric transfer characteristics as the source and drain are switched. We have proposed and fabricated a new offset poly-Si TFT by applying photoresist reflow process. The new method does not require an additional mask step and self-aligned ion implantation is applied, thus precise offset length can be defined and source/drain symmetric transfer characteristics are achieved.

• 전자공학회논문지A
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• 제33A권7호
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• pp.127-133
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• 1996

In this paper, we propose a new fabrication method for poly-Si TFTs with a self-aligned offset gated structure by employing a photoresist reflow process. Compared with the conventional poly-Si TFTs, the device is consist of two gate electrodes, of which one is the entitled main gate where the gate bias is employed and the other is the entitled subgate which is separate form both sides of the main gate. The poly-Si channel layer below the offset oxide is protected form the injected ion impurities for the source/drain implantation and acts as an offset region of the proposed device. The key feature of oru new device is the offset region due to the offset oxide. our experimental reuslts show that the offset region, due to the photoresist reflow process, has been sucessfully obtained in order to fabricate the offset gated poly-Si TFTs. The maximum ON/OFF ratio occurs at the L$_{off}$ of 1.1${\mu}$m and exceeds 1X10$^{6}$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.644-647
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• 2003

Resulting from reproducibility and possibility of mass production. many researches to fabricate micro lens array using lithography have been developed. However, it still remains the level of fabricating compensation lens. Therefore, to realize the fabrication of lens having high numerical aperture can be the key technology of ultra slim optical system. Reflow phenomenon have been researched to make lens having high refractive power. And through those researches, the possibility to fabrication of high refractive power lens has been investigated. In this paper, we analyze the effect of many parameters in reflow process to get an aspheric shape with high repeatability. And we make possible to estimate shape error, through we give direct information about decrease in volume of photoresist.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 동계학술발표회 논문집
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• pp.543-544
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• 2009

• Journal of the Optical Society of Korea
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• 제18권1호
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• pp.71-77
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• 2014

We present design and fabrication of a multi-focusing microlens array (MLA) using a thermal reflow method. To obtain multi-focusing properties with different numerical apertures at the elemental lens of the MLA, double-cylinder photoresist (PR) structures with different diameters were made within the guiding pattern with both photolithographic and partial developing processes. Due to the base PR layer supporting the thermal reflow process and the guiding structure, the thermally reflowed PR structure had different radii of curvatures with lens shapes that could be precisely modeled by the initial volume of the double-cylinder PR structures. Using the PR template, the hexagonally packed multi-focusing MLA was made via the replica molding method, which showed four different focal lengths of 0.9 mm, 1.1 mm, 1.6 mm, and 2.5 mm, and four different numerical apertures of 0.1799, 0.2783, 0.3973, and 0.4775.