• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제23권5호
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• pp.353-357
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• 2010

Recently, silicon etching have received much attention for display industry, nano imprint technology, silicon photonics, and MEMS application. After the etching process, removing of etch mask and residue of sidewall is very important. The investigation of the etched mask removing was carried out by using the ashing, HF dipping and acid cleaning process. Experiment shows that oxygen component of reactive gas and photoresist react with silicon and converting them into the mask fence. It is very difficult to remove by using ashing or acid cleaning process because mask fence consisted of Si and O compounds. However, dilute HF dipping is very effective process for SiOx layer removing. Finally, we found optimized condition for etched mask removing.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.312-316
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• 2015

Through silicon via (TSV) technology holds the promise of chip-to-chip or chip-to-package interconnections for higher performance with reduced signal delay and power consumption. It includes high aspect ratio silicon etching, insulation liner deposition, and seamless metal filling. The desired etch profile should be straightforward, but high aspect ratio silicon etching is still a challenge. In this paper, we investigate the use of etch hard mask for finer TSVs etching to have clear definition of etched via pattern. Conventionally employed photoresist methods were initially evaluated as reference processes, and oxide and metal hard mask were investigated. We admit that pure metal mask is rarely employed in industry, but the etch result of metal mask support why hard mask are more realistic for finer TSV etching than conventional photoresist and oxide mask.

• Korean Journal of Materials Research
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• 제28권4호
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• pp.208-213
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• 2018

Epitaxial ($11{\bar{2}}0$) a-plane GaN films were grown on a ($1{\bar{1}}02$) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient $H_2/NH_3$ mixture gas at $1140^{\circ}C$ after carbonization by the pyrolysis in ambient $H_2$ at $1100^{\circ}C$. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ${\omega}-2{\theta}$ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After $Ar^+$ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.

• Proceedings of the KIEE Conference
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.268-270
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• 2004

This paper reports a novel masking method with various mask materials for wet etching of glass. Various mask materials such as Cr/Au, Ti/Au, Polyimide and thick SU-8 photoresist were investigated for borosilicate glass (Borofloat33) etching in concentrated hydrofluoric acid (48% HF). Polyimide and thick SU-8 photoresist are not suitable as masking material due to its poor adhesion to glass surfaces. Titanium has good adhesion is suitable as the first layer to make multi-protective layers. The best protection was obtained with a combination of Ti/Au, polyimide and Ti/Au as masking material with etch depth of $350{\mu}m$ achieved.

• Proceedings of the KIEE Conference
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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.

• Journal of the Korean Graphic Arts Communication Society
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• 제26권1호
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• pp.73-85
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• 2008

We have manufactured a photoresist which has excellent dispersity and good applying property due to 330cps of viscosity for environment-friendly and economical maskless screen plate making. And the photoresist applied on the screen stretched was exposed without mask by beam projector with CRT light source. Then it was developed by air spray with $1.7kgf/cm^2$ of injection pressure. The pencil hardness and solvent resistance of curing photoresist film were worse than those of conventional photoresist film and the maximum resolution of line image formed by maskless screen plate making was 0.5 mm since the exposure system for maskless plate making has weak light intensity and the diffusion of light. But we could obtain maskless screen plate which has sharp edges of line image and confirm a possibility of dry development process by air spray method.

• Journal of the Semiconductor & Display Technology
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• 제16권4호
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• pp.16-19
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• 2017

For the economical and environmental-friendly fabrication of polisher, Mo mask layer were sputtered on glass substrate instead of Cr mask material. Mo mask layers were sputtered by pulsed-DC sputtering and Photoresist patterns were formed on Mo mask layer for different develop times and optimized. After Mo mask layer were patterned and exposed glass was wet etched by HF solution for different etching times, the remaining Mo mask was stripped by using Al etchant. Develop time of 30 sec and HF wet etching time of 3 min were selected as optimized process condition and applied to the fabrication of polisher.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.141-141
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• 2003

• Journal of the Semiconductor & Display Technology
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• 제18권2호
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• pp.48-52
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• 2019

Virtual metrology, which is one of APC techniques, is a method to predict characteristics of manufactured films using machine learning with saving time and resources. As the photoresist is no longer a mask material for use in high aspect ratios as the CD is reduced, hard mask is introduced to solve such problems. Among many types of hard mask materials, amorphous carbon layer(ACL) is widely investigated due to its advantages of high etch selectivity than conventional photoresist, high optical transmittance, easy deposition process, and removability by oxygen plasma. In this study, VM using different machine learning algorithms is applied to predict the thickness of ACL and trained models are evaluated which model shows best prediction performance. ACL specimens are deposited by plasma enhanced chemical vapor deposition(PECVD) with four different process parameters(Pressure, RF power, $C_3H_6$ gas flow, $N_2$ gas flow). Gradient boosting regression(GBR) algorithm, random forest regression(RFR) algorithm, and neural network(NN) are selected for modeling. The model using gradient boosting algorithm shows most proper performance with higher R-squared value. A model for predicting the thickness of the ACL film within the abovementioned conditions has been successfully constructed.

• Journal of the Korean Graphic Arts Communication Society
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• 제26권2호
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• pp.45-54
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• 2008

We have manufactured a photoresist which has excellent dispersity and good applying property due to 330 cps of viscosity for environment-friendly and economical maskless screen plate making. And the photoresist applied on the screen stretched was exposed with mask by UV-LED light source so we could manufacture the photoresist which proper for the UV light source. And it was developed by air spray with $1.7\;kgf/cm^2$ of injection pressure. Because of the excellence of power and resolution of the UV-LED light sourse, the pencil hardness and solvent resistance of curing photoresist film were excellent as those of conventional photoresist film. Moreover the $100{\mu}m$-width stripe image which has sharp edges was formed. So we confirmed a possibility of dry development process by air spray method.