• Journal of the Korean Physical Society
• /
• 제73권9호
• /
• pp.1346-1350
• /
• 2018

An electrode-evaporation technology on both the top and bottom sides of the bare vertical-type single chip separated from the traditional substrate by cooling, was developed for III-nitride vertical-type single chip LEDs with thick GaN epilayer. The post-process of the cooling step was followed by sorting the bare vertical-type single chip LEDs into the holes in a pocket-type shadow mask for deposition of the electrodes at the top and bottom sides of bare vertical-type single chip LEDs without the traditional substrate for electrode evaporation technology for vertical-type single chip LEDs. The variation in size of the hole between the designed shadow mask and the deposited electrodes owing to the use of the designed pocket-type shadow mask is investigated. Furthermore, the electrical and the optical properties of bare vertical-type single chip LEDs deposited with two different shapes of n-type electrodes using the pocket-type shadow mask are investigated to explore the possibility of the e-beam evaporation method.

• 한국산학기술학회논문지
• /
• 제12권4호
• /
• pp.1993-1998
• /
• 2011

반도체 산업은 지속적으로 비약적인 발전을 이루어내면서 점점 고집적회로를 제작하기 위하여 패턴의 미세화가 이루어지게 되었다. 현재 미세 나노패턴의 형성을 위하여 여러층의 하드마스크가 사용되고 있으며, 화학증기증착(CVD)공정을 이용하여 형성한다. 이에 본 연구에서는 스핀공정(spin-on process)이 가능한 유-무기 하이브리드 중합체를 이용한 단일층의 하드마스크를 제작하였는데, 하드마스크 내의 무기계 성분이 감광층 보다 쉽게 식각되는 반면에 하드마스크의 유기계 성분으로 인해 substrate층 보다 덜 식각되었다. 유-무기 하이브리드 중합체를 이용한 하드마스크막의 광학 및 표면 특성을 조사하였고, 감광층과 하드마스크막의 식각비를 비교하여 유-무기소재의 하이브리드중합체에 대한 미세패턴을 형성시킬 수 있는 하드마스크막으로써의 유용성을 확인하였다.

• 전자공학회논문지A
• /
• 제32A권8호
• /
• pp.94-106
• /
• 1995

A three-dimensional(3D) Monte Carlo simulator for boron ion implantation into <100>single-crystal silicon considering the mask structure has been developed to predict the mask-dependent impurity doping profiles of the implanted boron at low energies into the reduced area according to the trend of a reduction in the size of semiconductor devices. All relevant important parameters during ion implantation have been taken into account in this simulator. These are incident energy, tilt and rotation of wafer, orientation of silicon wafer, presence of native silicon dioxide layer, dose, wafer temperature, ion beam divergence, masking thickness, and size and structure of open window in the mask. The one-dimensional(1D) results obtained by using the 3D simulator have been compared with the SIMS experiments to demonstrate its capabilities and confirem its reliability, and we obtained relatively accurate 1D doping profiles. Through these 3D simulations considering the hole structure and its size, we found the mask effects during boron ion implantation process.

• 한국생산제조학회지
• /
• 제19권6호
• /
• pp.834-840
• /
• 2010

Photo lithography process is very important technology to fabricate highly integrated micro patterns with high precision for semiconductor and display industries. Up to now, mask type lithography process has been generally used for this purpose; however, it is not efficient for small quantity and/or frequently changing products. Therefore, in order to obtain higher productivity and lower manufacturing cost, the mask type lithography process should be replaced. In this study, a maskless lithography system using the DMD(Digital Micromirror Device) is developed, and the exposure condition and optical properties are analyzed and simulated for a single beam case. From the proposed experimental conditions, required exposure experiments were preformed, and the results were investigated. As a results, 10${\mu}m$ spots can be generated at optimal focal length.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1175-1178
• /
• 2005

Brittle materials, especially single-crystal silicon wafer, are widely used for sensors, IC industry, and MEMS applications. e general machining process of crack easy materials is by chemical agents, but it is hazardous and time consuming. Also, it is difficult to get high aspect ratio micro structure. As an alternative tool, an AJM(Abrasive jet machining) is promising method in terms of high aspect ratio and production cost. In this study, to get more precise detail compared to general AJM, photo polymer mask, SU-8, used in photolithography was applied in AJM. Process parameters such as abrasive diameter, air pressure, nozzle diameter, flow rate of abrasive in AJM and a variety of conditions in spin coating were decided. Finally, micro channel and mixer was fabricated to see the efficiency of the AJM with photo polymer mask.

• 한국정밀공학회지
• /
• 제23권8호
• /
• pp.39-46
• /
• 2006

Nano-scale fabrication of silicon substrate based on the use of atomic force microscopy (AFM) was demonstrated. A specially designed cantilever with diamond tip, allowing the formation of damaged layer on silicon substrate by a simple scratching process, has been applied instead of conventional silicon cantilever for scanning. A thin mask layer forms in the substrate at the diamond tip-sample junction along scanning path of the tip. The mask layer withstands against wet chemical etching in aqueous KOH solution. Diamond tip acts as a patterning tool like mask film for lithography process. Hence these sequential processes, called tribo-nanolithography, TNL, can fabricate 2D or 3D micro structures in nanometer range. This study demonstrates the novel fabrication processes of the micro cantilever and diamond tip as a tool for TNL using micro-patterning, wet chemical etching and CVD. The developed TNL tools show outstanding machinability against single crystal silicon wafer. Hence, they are expected to have a possibility for industrial applications as a micro-to-nano machining tool.

• 센서학회지
• /
• 제24권3호
• /
• pp.155-158
• /
• 2015

In this paper, in-situ heat cooling with temperature monitoring is reported to solve thermal issues in electric vehicle (EV) batteries. The device consists of a thick graphene cooler on top of the substrate and a platinum-based resistive temperature sensor with an embedded heater above the graphene. The graphene layer is synthesized by using chemical vapor deposition directly on the Ni layer above the Si substrate. The proposed thick graphene heat cooler does not use transfer technology, which involves many process steps and does not provide a high yield. This method also reduces the mechanical damage of the graphene and uses only one photomask. Using this structure, temperature detection and cooling are conducted simultaneously using one device. The temperature coefficient of resistance (TCR) of a $1{\times}1mm^2$ temperature sensor on 1-$\grave{i}m$-thick graphene is $1.573{\times}10^3ppm/^{\circ}C$. The heat source cools down $7.3^{\circ}C$ from $54.4^{\circ}C$ to $47.1^{\circ}C$.

• Transactions on Electrical and Electronic Materials
• /
• 제16권4호
• /
• pp.169-172
• /
• 2015

Although, there are several research studies on the engineering of the graphene layers using different etching techniques, there is not any comprehensive study on the effects of using different etching masks in the reactive ion etching (RIE) method on the quality and uniformity of the etched graphene films. This study investigated the effects of using polystyrene and conventional photolithography resist as a etching mask on the engineering of the number of graphene layers, using RIE. The effects were studied using Raman spectroscopy. This analysis indicated that the photo-resist mask is better than the polystyrene mask because of its lower post processing effects on the graphene surface during the RIE process. A single layer graphene was achieved from a bi-layer graphene after 3 s of the RIE process using oxygen plasma, and the bi-layer graphene was successfully etched after 6 s of the RIE process. The bilayer etching time was significantly smaller than reported values for graphene flakes in previous research.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제13권3호
• /
• pp.1434-1449
• /
• 2019

Video object segmentation is a significant task in computer vision, but its performance is not very satisfactory. A method of video object segmentation using weakly temporal information is presented in this paper. Motivated by the phenomenon in reality that the motion of the object is a continuous and smooth process and the appearance of the object does not change much between adjacent frames in the video sequences, we use a feed-forward architecture with motion estimation to predict the mask of the current frame. We extend an additional mask channel for the previous frame segmentation result. The mask of the previous frame is treated as the input of the expanded channel after processing, and then we extract the temporal feature of the object and fuse it with other feature maps to generate the final mask. In addition, we introduce multi-mask guidance to improve the stability of the model. Moreover, we enhance segmentation performance by further training with the masks already obtained. Experiments show that our method achieves competitive results on DAVIS-2016 on single object segmentation compared to some state-of-the-art algorithms.

• Journal of the Optical Society of Korea
• /
• 제11권1호
• /
• pp.40-43
• /
• 2007

We propose a taper-underlaid spot-size converter (TU-SSC) with an offset which consists of two vertically stacked taper layers. The designed TU-SSC reduces coupling loss of a high index-contrast waveguide with $1.5%{\Delta}$ to a single mode fiber from 1.5 dB to 0.27 dB. We also considered the effects of mask misalignment in the fabrication process of TU-SSC, and optimized the design of TU-SSC so that the additional loss of TU-SSC for the mask misalignment of $3{\mu}m$ in the photo-lithography process was as low as 0.13 dB.