• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.573-574
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• 2008

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.65-66
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• 2009

This paper describes a procedure developed to fabricate negative photo resist SUMS to a semi-insulating (SI)-GaAs-based substrate. SU-8 is attractive for micromachine multi-layer circuit fabrication, because it is photo-polymerizable resin, leading to safe, and economical processing. This work demonstrates SUMS photo resist can be used for RFIC/MMIC application.

• Journal of information and communication convergence engineering
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• v.13 no.1
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• pp.56-61
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• 2015

The demand for high-aspect-ratio structures has been increasing in the field of semiconductors and other applications. Here, we present the commercially available negative-tone SU-8 as a potential resist that can be used for direct patterning of high-aspect-ratio structures at the submicron scale and the nanoscale. Such resist patterns can be used as polymeric molds to create high-aspect-ratio metallic submicron and nanoscale structures by using electroplating. Compared with poly (methyl methacrylate) (PMMA), we found that the negative tone resist required an exposure dose that was less than that of PMMA of equal thickness by a factor of 100-150. Patterning of up to 4:1 aspect ratio SU-8 structures with a minimum feature size of 500 nm was demonstrated. In addition, nanoimprint lithography was studied to further extend the aspect ratio to realize a minimum feature size of less than 10 nm with an extremely high aspect ratio in the negative resist.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.310-316
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• 2009

Micro lens array(MLA) is widely used in information technology(IT) industry fields for various applications such as a projection display, an optical power regulator, a micro mass spectrometer and for medical appliances. Recently, MLA have been fabricated and developed by using a reflow method having the processes of micro etching, electroplating, micro machining and laser local heating. Laser thermal relaxation method is introduced in marking of microdots on the surface of densified glass. In this paper, we have proposed a new direct fabrication process using UV laser local thermal-expansion(UV-LLTE) and investigated the optimal processing conditions of MLA on the surface of negative photo-resist material. We have also studied the 3D shape of the micro lens obtained by UV laser irradiation and the optimal process conditions. And then, we made chrome mold by electroplating. After that, we made MLA using chrome mold by hot embossing processing. Finally, we have measured the opto-physical properties of micro lens and then have also tested the possibility of MLA applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.113-115
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• 1994

We considered the ion and photo-induced properties as a function of wavelength by exposing the light over the band gap of a-Ag/a-$Se_{75}$$Ge_{25}$ and the low-energy defocused $Ga^{+}$ ion beam on Ag/a-$Se_{75}$$Ge_{25}$ thin film. This film acts as a negative resist for photo or ion beam lithography. We observed that the absorbance coefficient decreased with increasing the photo-exposing time and exposing the ion beam. The bandgap shifts toward longer wavelength called a "darkening effect" are observed in the films exposed to both photons and ions. We suggest that a primary step in the Ag layer and a secondary step is in a-$Se_{75}$$Ge_{25}$ film layer.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.10
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• pp.23-30
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• 1999

We experimented on the sub 50nm patterning using E-beam lithography system. SAL601 negative E-beam resist was used for this experiment. In order to utilize the maximum ability of E-beam system, firstly, we reduced the PR thickness to 100nm, and the field size to 200 ${um}m$. Then PEB (Post Expose Bake) time/temperature, which is one of the very important factors when SAL601 is used, were reduced for minimum line width. In addition, digitizing is optimized for better results. Quantum wire and quantum dot which can be used for nanoscale memory device, such as single electron memory device, are fabricated using these developed lithography techniques.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.241-244
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• 2004

Microlens patterned micro-mold fabrication method for Light Guiding Plate(LGP), kernel part of LCD-BLU(Back Light Unit), was presented. Instead of erosion dot pattern for LCP optical design, microlens pattern, fabricated by LIGA-reflow process, was applied. Optical pattern design method was also developed not only for negative pattern LGP, but also positive pattern LGP. In order to achieve flow balance during the micro-injection molding process and dimensional accuracy, two LGP pattern was made in one micro-mold.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.280-283
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• 2004

Micro-lens patterned micro-mold fabrication method for Light Guiding Plate(LGP), kernel part of LCD-BLU(Back Light Unit), was presented. Instead of erosion dot pattern for LGP optical design, micro-lens pattern, fabricated by LIGA-reflow process, was applied. Optical pattern design method was also developed not only for negative pattern LGP, but also positive pattern LGP. During injection molding process, experimental study was conducted to improve replication quality and brightness of ${\sim}50um$ micro-lens pattern mold. The effect of mold temperature for the replication quality of micro-lens array was studied.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1914-1917
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• 2001

3D Feed Horn Shape MEMS Antenna Array는 적외선 이미지 소자 또는 Tera hertz band 등에서 많은 응용을 할 수 있는 장점을 가진 MEMS 구조체 이다. 하지만 일반적인 MEMS 공정을 이용해서 3D Feed Horn Shape MEMS antenna array를 구현하기는 적합하지 않았다. 본 논문에서는 마스크와 웨이퍼가 일체 된 형태의 경사된 척이 초 저속으로 회전하면서 노광을 할 수 있는 새로운 방식과 미러 반사구조를 이용해서 평행광을 얻을수 있는 노광장치 (MRPBI : Mirror Reflected Parallel Beam Illuminator) System제작방법을 제안하였다. 3D Feed Horn Shape MEMS Antenna의 구조적인 high apect ratio의 특성에 의해서 SU-8과 PMER Negative Photo resist를 이용한 기본적인 실험을 통해 3D 구조체의 구현 가능성을 증명하였다. 또한 Microbolometer의 성능향상을 위한 이론적인 3D MEMS Antenna Model들을 HFSS(High Frequency Structure Simulator)을 이용해서 그 최적구조를 제안하고 3D MEMS Antenna Gain 값을 비교 분석하였다.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.275-280
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• 2005

We propose a new approach to greatly simplify the fabrication of conventional nanoimprint lithography (NIL) by combined nanoimprint and photolithography (CNP). We introduce a hybrid mask mold (HMM) made from UV transparent material with a UV-blocking Cr metal layer placed on top of the mold protrusions. We used a negative tone photo resist (PR) with higher selectivity to substrate the CNP process instead of the UV curable monomer and thermal plastic polymer that has been commonly used in NIL. Self-assembled monolayer (SAM) on HMM plays a reliable role for pattern transfer when the HMM is separated from the transfer layer. Hydrophilic $SiO_2$ thin film was deposited on all parts of the HMM, which improved the formation of SAM. This $SiO_2$ film made a sub-10nm formation without any pattern damage. In the CNP technique with HMM, the 'residual layer' of the PR was chemically removed by the conventional developing process. Thus, it was possible to simplify the process by eliminating the dry etching process, which was essential in the conventional NIL method.