• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.224-227
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• 1995

The micro-patterning by a Bow energy FIB whish has been conventionally utilized far mask-repairing was investigated. Amorphous Se$\_$75/Gee$\_$25/ resist irradiated by 9[keV]-defocused Ga$\^$+/ ion beam(∼10$\^$15/[ions/$\textrm{cm}^2$]) resulted in increasing the optical absorption, which was also observed also in the film exposed by an optical dose of 4.5${\times}$10$\^$20/[photons/$\textrm{cm}^2$]. The ∼0.3[eV] edge shift for ion-irradiated film was about twice to that obtained for photo-exposed. These large shift could be estimated as due to an increase in disorder from the decrease in the sloop of the Urbach tail. For Ga$\^$+/ FIB irradiation with a relatively low energy, 30[keV] and above the amount of dose of 1.4${\times}$10$\^$16/[ions/$\textrm{cm}^2$], the irradiated region in a-Se$\_$75/Ge$\_$25/ resist was perfectly etched in acid solution for 10[sec], which is relatively a short development time. A contrast was about 2.5. In spite of the relatively low incident energy,∼0.225[$\mu\textrm{m}$] pattern was clearly obtained by the irradiation of a dose 6.5${\times}$10$\^$16/[ions/$\textrm{cm}^2$] and a scan diameter 0.2[$\mu\textrm{m}$], from which excellent results were expected fur incident energies above 50[keV] which was conventionally used in FIBL.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.421-421
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• 2008

Generally, the polymer thick-film resistors for embedded organic or hybrid substrate are patterned by screen printing so that the accuracy of resistor pattern is not good and the tolerance of resistance is too high(${\pm}$20~30%). To reform these demerits, a method using Fodel$^{(R)}$ technology, which is the patterning method using a photosensitive resin to be developable by aqueous alkali-solution as a base polymer for thick-film pastes, was recently incorporated for the patterning of thermosetting thick-film resistor paste. Alkali-solution developable photosensitive resin system has a merit that the precise patterns can be obtained by UV exposure and aqueous development, so the essential point is to get the composition similar to PSR(photo solder resist) used for PCB process. In present research, we made the photopatternable resistor pastes using 8 kinds of epoxy acrylates and a conductive carbonblack (CDX-7055 Ultra), evaluated their developing performance, and then measured the resistance after final curing. To become developable by alkali-solution, epoxy acrylate oligomers with carboxyl group were prepared. Test coupons were fabricated by patterning copper foil on FR-4 CCL board, plating Ni/Au on the patterned copper electrode, applying the resistor paste on the board, exposing the applied paste to UV through Cr mask with resistor patterns, developing the exposed paste with aqueous alkali-solution (1wt% $Na_2CO_3$), drying the patterned paste at $80^{\circ}C$ oven, and then curing it at $200^{\circ}C$ during 1 hour. As a result, some test compositions couldn't be developed according to the kind of oligomer and, in the developed compositions, the measured resistance showed different results depending on the paste compositions though they had the same amount of carbonblack.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.101-109
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• 2004

This paper presents a novel z-axis accelerometer with perfectly aligned vertical combs fabricated using the extended sacrificial bulk micromachining (extended SBM) process. The z-axis accelerometer is fabricated using only one (111) SOI wafer and two photo masks without wafer bonding or CMP processes as used by other research efforts that involve vertical combs. In our process, there is no misalignment in lateral gap between the upper and lower comb electrodes, because all critical dimensions including lateral gaps are defined using only one mask. The fabricated accelerometer has the structure thickness of $30{\mu}m$, the vertical offset of $12{\mu}m$, and lateral gap between electrodes of $4{\mu}m$. Torsional springs and asymmetric proof mass produce a vertical displacement when an external z-axis acceleration is applied, and capacitance change due to the vertical displacement of the comb is detected by charge-to-voltage converter. The signal-to-noise ratio of the modulated and demodulated output signal is 80 dB and 76.5 dB, respectively. The noise equivalent input acceleration resolution of the modulated and demodulated output signal is calculated to be $500{\mu}g$ and $748{\mu}g$. The scale factor and linearity of the accelerometer are measured to be 1.1 mV/g and 1.18% FSO, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.387-387
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• 2012

결정 Si 및 비정질 Si 태양전지는 환경친화적이며 안정적인 물질로 전력변환 및 에너지 저장 장치에 중요하기 때문에 연구가 활발하게 진행되고 있다. 고효율 Si 태양전지를 제작하여 상용화하기에는 여러 가지 문제점이 있다. 공기와 비교하여 높은 굴절률을 갖고 있기 때문에 발생하는 반사를 줄이기 위해서 필요한 무반사 코팅층(Anti-reflective coating; ARC)은 주로 SiO2 와 SiNx 와 같은 유전체를 이용하여 사용하지만 이들 ARC 증착은 PECVD와 같은 진공장비를 사용하므로 제작 비용이 높아지는 단점이 있다. 나노선 또는 나노 팁과 같은 sub-wavelength 구조를 표면에 만들어 반사율을 줄이는 작업을 통해 ARC 공정비용을 감소하고 효율을 증진하는 연구가 활발히 진행되고 있다. CdS 양자점을 태양전지 표면에 형성함으로 ARC로 해결할 수 없는 단파장영역에 해당하는 부분을 줄이는 연구가 진행되었으며, 비정질의 경우 원기둥 형태의 태양전지 형태와 더불어 지름 방향으로의 PN 접합 나노로드 배열을 만들어 흡수면을 증가하여 효율을 증가한 연구도 진행되었다. 태양전지 표면의 형태를 V-groove 형태로 형성하여 입사하는 태양전지의 광밀도를 증가하는 이론적 결과도 발표되었다. 본 연구에서는 Si 태양전지의 표면변형에 따른 태양전지의 전력변환효율의 변화를 관찰하기 위하여 태양전지 표면의 texture 지름을 $3{\sim}15{\mu}m$, 간격을 $5{\sim}20{\mu}m$로 변화하고, 태양전지 표면의 나노 패턴을 2~10 nm 로 변화하여 반사율과 전력변환효율을 비교하였다. 나노와 마이크로 패턴은 각각 polystyrene nanosphere 와 photo mask를 이용하여 제작하였으며 PN junction Si 태양전지는 spin on dopant 방식으로 제작하여 성능을 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.460-460
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• 2012

반도체 Device가 Shrink 함에 따라 Pattern Size가 작아지게 되고, 이로 인해 Photo Resist 물질 자체만으로는 원하는 Patterning 물질들을 Plasma Etching 하기가 어려워지고 있다. 이로 인해 Photoresist를 대체할 Hard Mask 개념이 도입되었으며, 이 Hardmask Layer 중 Amorphous Carbon Layer 가 가장 널리 사용되고 지고 있다. 이 Amorphous Carbon 계열의 Hardmask를 Etching 하기 위해서 기본적으로 O2 Plasma가 사용되는데, 이 O2 Plasma 내의 Oxygen Species들이 가지는 등 방성 Diffusion 특성으로 인해, 원하고자 하는 미세 Pattern의 Vertical Profile을 얻는데 많은 어려움이 있어왔다. 이를 Control 하기 인해 O2 Plasma Parameter들의 변화 및 Source/Bias Power 등의 변수가 연구되어 왔으며, 이와 다른 접근으로, N2 및 CO, CO2, SO2 등의 여러 Additive Gas 들의 첨가를 통해 미세 Pattern의 Profile을 개선하고, Plasma Etching 특성을 개선하는 연구가 같이 진행되어져 왔다. 본 논문에서 VLSI Device의 Masking Layer로 사용되는, Carbon 계 유기 층의 Plasma 식각 특성에 대한 연구를 진행하였다. Plasma Etchant로 사용되는 O2 Plasma에 새로운 첨가제 가스인 카르보닐 황화물 (COS) Gas를 추가하였을 시 나타나는 Plasma 내의 변화를 Plasma Parameter 및 IR 및 XPS, OES 분석을 통하여 규명하고, 이로 인한 Etch Rate 및 Plasma Potential에 대해 비교 분석하였다. COS Gas를 정량적으로 추가할 시, Plasma의 변화 및 이로 인해 얻어지는 Pattern에서의 Etchant Species들의 변화를 통해 Profile의 변화를 Mechanism 적으로 규명할 수 있었으며, 이로 인해 기존의 O2 Plasma를 통해 얻어진 Vertical Profile 대비, COS Additive Gas를 추가하였을 경우, Pattern Profile 변화가 개선됨을 최종적으로 확인 할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.658-658
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• 2013

Graphene is an attractive material for various device applications due to great electrical properties and chemical properties. However, lack of band gap is significant hurdle of graphene for future electrical device applications. In the past few years, several methods have been attempted to open and tune a band gap of graphene. For example, researchers try to fabricate graphene nanoribbon (GNR) using various templates or unzip the carbon nanotubes itself. However, these methods generate small driving currents or transconductances because of the large amount of scattering source at edge of GNRs. At 2009, Bai et al. introduced graphene nanomesh (GNM) structures which can open the band gap of large area graphene at room temperature with high current. However, this method is complex and only small area is possible. For practical applications, it needs more simple and large scale process. Herein, we introduce a photosensitive graphene device fabrication using CdSe QD coated nano-porous graphene (NPG). In our experiment, NPG was fabricated by thin film anodic aluminum oxide (AAO) film as an etching mask. First of all, we transfer the AAO on the graphene. And then, we etch the graphene using O2 reactive ion etching (RIE). Finally, we fabricate graphene device thorough photolithography process. We can control the length of NPG neckwidth from AAO pore widening time and RIE etching time. And we can increase size of NPG as large as 2 $cm^2$. Thin CdSe QD layer was deposited by spin coatingprocess. We carried out NPG structure by using field emission scanning electron microscopy (FE-SEM). And device measurements were done by Keithley 4200 SCS with 532 nm laser beam (5 mW) irradiation.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.230-234
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• 2011

In this work, the primary material for a single layered hardmask which can afford a spin-on process was prepared by the minture of organic and inorganic sources. The preparation of hybrid polymer was attempted by esterification from silanol terminated siloxane compounds and acetonide-2,2-bis(methoxy)propionic acid. The optical, thermal and morphological properties of the test hardmask film was examined in terms of cross-linking agent and additives. In addition, the etch rate of hardmask film and photo resist layer were compared. The hybrid polymer prepared from organic and inorganic materials was found to be useful for hardmask film to form the nano-patterns.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.243-248
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• 2011

In this paper, we propose a new method to extract palm lines and read it with simple techniques from one photo. We use morphological information and 8-directional contour tracking algorithm. From the digitalized image, we transform original RGB information to YCbCr color model which is less sensitive to the brightness information. The palm region is extracted by simple threshold as Y:65~255, Cb:25~255, Cr:130~255 of skin color. Noise removal process is then followed with morphological information of the palm such that the palm area has more than quarter of the pixels and the rate of width vs height is more than 2:1 and 8-directional contour tracking algorithm. Then, the stretching algorithm and Sobel mask are applied to extract edges. Another morphological information that the meaningful edges(palm lines) have between 10 and 20 pixels is used to exclude noise edges and boundary lines of the hand from block binarized image. Main palm lines are extracted then by labeling method. This algorithm is quite effective even reading the palm from a photographed by a mobile phone, which suggests that this method could be used in various applications.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.6
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• pp.43-49
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• 2000

The TiN thin films were deposited by ALE(atomic layer epitaxy) on (100) silicon substrate. The TiN thin films were characterized by means of XRD, 4-point probe, AFM, AES and SEM. TEMAT(terakis(ethyl methy lamino)titanium) and $NH_3$ were injected into the reactor in sequence of TEMAT-$N_2-NH_3-N_2$ to ensure a saturated surface reaction. As a result, the depostion rate of the TiN film was controlled by self-limiting growth mechanism at temperature range form 150 to 220 $^{\circ}C$. Deposited TiN films, all of which show amorphous structure, had a fixed deposition rate of 4.5 ${\AA}$/cycle. The resistivity of 210 ~ 230 ${\mu}{\Omega}{\cdot}$cm and the surface r.m.s. roughness of 7.9 ~ 9.3 ${\AA}$ were measured. When TiN film of 2000 ${\AA}$ were deposited, a excellent step coverage were observed in a trench structure of 0.43${\mu}m$ contacts with 6:1 aspect ratio.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.207.1-207.1
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• 2012

One of the key aspects of the upcoming Ultra-Fast Observatory (UFFO) Pathfinder for Gamma-Ray Bursts(GRBs) identification will be the UFFO Burst Alert & Trigger Telescope(UBAT), based on a novel space telescope technique. The UBAT consists of coded mask, hopper, and detector module(DM). The UBAT DM consists of YSO crystal arrays, multi-anode photo mulipliers, and readout electronics. We will present the design and construction of the UBAT DM, and the response of the UBAT DM to X-ray sources.