• 한국재료학회지
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• 제21권2호
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• pp.89-94
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• 2011

In this work, fabrication and electrochemical analysis of an individual multi-walled carbon nanotube (MWNT) electrode are carried out to confirm the applicability of electrochemical sensing. The reactive ion etching (RIE) process is performed to obtain sensitive MWNT electrodes. In order to characterize the electrochemical properties, an individual MWNT is cut by RIE under oxygen atmosphere into two segments with a small gap: one segment is applied to the working electrode and the other is used as a counter electrode. Electrical contacts are provided by nanolithography to the two MWNT electrodes. Dopamine is specially selected as an analytical molecule for electrochemical detection using the MWNT electrode. Using a quasi-Ag/AgCl reference electrode, which was fabricated by us, the nanoelectrodes are subjected to cyclic voltammetry inside a $2{\mu}L$ droplet of dopamine solution. In the experiment, RIE power is found to be a more effective parameter to cut an individual MWNT and to generate "broken" open state, which shows good electrochemical performance, at the end of the MWNT segments. It is found that the pico-molar level concentration of analytical molecules can be determined by an MWNT electrode. We believe that the MWNT electrode fabricated and treated by RIE has the potential for use in high-sensitivity electrochemical measurement and that the proposed scheme can contribute to device miniaturization.

• 한국진공학회지
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• 제6권3호
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• pp.282-286
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• 1997

$Cl_2$/ CH_4/H_2$ 혼합기체를 이용한 InP소재의 반응성 이온 에칭(RIE; reactive ion etching)방법에 있어서 기체분율, RF(radio frequency) 전력 및 시료온도를 변화시키면서 에 칭속도, 측벽 수직도, 표면손상 및 오염 등을 관찰하여 적정 에칭조건을 연구하였다. $CH_4$ 유 량 0-12sccm, Cl2 기체 유량을 3-15sccm, RF 전력 100-200W, 시료온도 150-$200^{\circ}C$로 각각 변화시켜 실험한 결과 $Cl_2$ 기체유량 및 RF 전력과 시료온도가 증가함에 따라 에칭속도가 비례하여 증가하였고 RF 전력 150W, 시편온도 $180^{\circ}C$, 10Cl2/5CH4/85H2의 적정 공정조건에 서 $80^{\circ}$정도의 측벽수직도를 갖는 메사와 미려한 에칭표면이 얻어졌으며 평균 에칭속도는 0.9$\pm$0.1$\mu\textrm{m}$/min정도였다. 전자현미경 분석 결과 $CH_4/H_2$혼합기체에 $Cl_2$를 첨가함에 따라 표 면미려도 및 메사측벽 수직도는 다소간 감소하였으나 에칭공정 중 고분자 물질의 생성이 억 제되었다.

• 한국진공학회지
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• 제19권4호
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• pp.300-306
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• 2010

소수성 고분자를 사용하여 제작한 마이크로구조에 금 나노입자를 마스크로 이용하는 반응성이온식각(RIE: Reactive Ion Etching)을 적용하여 초소수성을 갖는 마이크로-나노 혼성구조를 제작하였다. 소수성 고분자로는 PFPE (perfluoropolyether bisurethane methacrylate)를 사용하였으며 마이크로 단일구조는 PDMS (polydimethylsiloxane) 몰드를 사용하는 스탬핑 방식으로 제작하였다. 다양한 형태로 제작한 PFPE 마이크로 단일구조와 마이크로-나노 혼성구조의 표면 접촉각을 측정하여 표면 미세구조에 따른 소수성의 변화를 관찰하였다. 마이크로 단일구조의 경우 접촉각은 안정적인 값을 보이지 못하였으나 단일 구조에 나노입자를 사용한 식각을 적용해 나노구조가 형성됨에 따라 $150^{\circ}$ 이상의 접촉각을 갖는 초소수성 표면이 매우 높은 재현성으로 용이하게 형성되었다.

• Transactions on Electrical and Electronic Materials
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• 제14권1호
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• pp.32-35
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• 2013

In this paper, a manufacturing process was developed for fabricating high-quality AlGaN/GaN high electron mobility transistors (HEMTs) on silicon carbide (SiC) substrates. Various conditions and processing methods regarding the ohmic contact and pre-metal-deposition $BCl_3$ etching processes were evaluated in terms of the device performance. In order to obtain a good ohmic contact performance, we tested a Ti/Al/Ta/Au ohmic contact metallization scheme under different rapid thermal annealing (RTA) temperature and time. A $BCl_3$-based reactive-ion etching (RIE) method was performed before the ohmic metallization, since this approach was shown to produce a better ohmic contact compared to the as-fabricated HEMTs. A HEMT with a 0.5 ${\mu}m$ gate length was fabricated using this novel manufacturing process, which exhibits a maximum drain current density of 720 mA/mm and a peak transconductance of 235 mS/mm. The X-band output power density was 6.4 W/mm with a 53% power added efficiency (PAE).

• 한국전기전자재료학회논문지
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• 제18권12호
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• pp.1069-1074
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• 2005

In this work, nano-needle structures ate formed to solve problem, related to low density of quantum dots for nano floating gate memory. Such structures ate fabricated and electrical properties' of MIS devices fabricated on the nano-structures are studied. Nano floating gate memory based on quantum dot technologies Is a promising candidate for future non-volatile memory devices. Nano-structure is fabricated by reactive ion etching using $SF_6$ and $O_2$ gases in parallel RF plasma reactor. Surface morphology was investigated after etching using scanning electron microscopy Uniform and packed deep nano-needle structure is established under optimized condition. Photoluminescence and capacitance-voltage characteristics were measured in $Al/SiO_2/Si$ with nano-needle structure of silicon. we have demonstrated that the nano-needle structure can be applicable to non-volatile memory device with increased charge storage capacity over planar structures.

• 한국전기전자재료학회논문지
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• 제26권2호
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• pp.140-143
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• 2013

Lowering surface reflectance of silicon wafer by texturization is one of the most important processes to improve the efficiency of silicon solar cells. Generally, the texturing of crystalline silicon was carried out using alkaline solution. The average reflectance of this method was 11% at the wavelength between 400 and 1,000 nm. In this study, the wafers were first texturing by NaOH solution at $80^{\circ}C$ for 35 min. Then the wafers were texturing by $SF_6$ and $O_2$ plasma in RIE (Reactive Ion Etching). The average reflectance of two step texturing was reduced to below 5% at the wavelength between 400 and 1,000 nm.

• 센서학회지
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• 제6권6호
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• pp.430-436
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• 1997

SDB웨이퍼를 사용한 압저항 형태의 50 G용 가속도 센서를 실리콘 마이크로머시닝을 사용하여 제조하였다. 이 형태의 가속도 센서는 진동하는 사각형의 매스와 4개의 빔으로 구성되어 있다. 이 구조는 RIE를 이용한 건식식각과 KOH 용액을 이용한 습식식각을 이용하여 제조되었다. 정사각형의 보상구조가 매스 가장자리의 언더에칭에 기인하는 변형을 보상하기 위해 사용되었다. 제조된 센서는 인가된 가속도에 대하여 선형적인 출력전압특성을 보여주고 감도는 0에서 10 G까지 약 $88{\mu}V/V{\cdot}g$이었다.

• 대한금속재료학회지
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• 제48권11호
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• pp.1028-1034
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• 2010

In the development of 3D package, through silicon via (TSV) formation technology by using deep reactive ion etching (DRIE) is one of the key processes. We performed the Bosch process, which consists of sequentially alternating the etch and passivation steps using $SF_6$ with $O_2$ and $C_4F_8$ plasma, respectively. We investigated the effect of changing variables on vias: the gas flow time, the ratio of $O_2$ gas, source and bias power, and process time. Each parameter plays a critical role in obtaining a specified via profile. Analysis of via profiles shows that the gas flow time is the most critical process parameter. A high source power accelerated more etchant species fluorine ions toward the silicon wafer and improved their directionality. With $O_2$ gas addition, there is an optimized condition to form the desired vertical interconnection. Overall, the etching rate decreased when the process time was longer.

• 한국결정성장학회지
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• 제9권1호
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• pp.60-63
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• 1999

Ta-Al 합금 박막의 건식식각에 대하여 조사하였다. $CF_{4}$ 기체를 이용한 반응성 이온 식각(Reactive Ion Etching, RIE)이 1:1 조성의 Ta-Al 합금 박막의 식각에 적용될 수 있음을 확인하였으며, 식각속도는 $67{\AA}/min$으로 측정되었다. 그리고 $CF_{4}$ 기체는 Ta-Al 합금 박막과 $SiO_{2}$ 층간에 선택성이 없다는 것이 확인되었으며, $SiO_{2}$ 층의 식각속도는 Ta-Al 박막의 경우보다 약 12배 빠른 $800{\AA}/min$으로 측정되었다. 그 외에 $CF_{4}$ 기체를 이용한 반응성 이온 식각에서는 Shiepley 1400-27 Photo Resist 보다 AZ 5214 Photo Resist가 더 안정적이라는 것이 조사되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.387-387
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• 2013

Currently, the flash memory and the dynamic random access memory (DRAM) have been used in a variety of applications. However, the downsizing of devices and the increasing density of recording medias are now in progress. So there are many demands for development of new semiconductor memory for next generation. Magnetic random access memory (MRAM) is one of the prospective semiconductor memories with excellent features including non-volatility, fast access time, unlimited read/write endurance, low operating voltage, and high storage density. MRAM is composed of magnetic tunnel junction (MTJ) stack and complementary metal-oxide semiconductor (CMOS). The MTJ stack consists of various magnetic materials, metals, and a tunneling barrier layer. Recently, MgO thin films have attracted a great attention as the prominent candidates for a tunneling barrier layer in the MTJ stack instead of the conventional Al2O3 films, because it has low Gibbs energy, low dielectric constant and high tunneling magnetoresistance value. For the successful etching of high density MRAM, the etching characteristics of MgO thin films as a tunneling barrier layer should be developed. In this study, the etch characteristics of MgO thin films have been investigated in various gas mixes using an inductively coupled plasma reactive ion etching (ICPRIE). The Cl2/Ar, CH3OH/Ar, and CH4/Ar gas mix were employed to find an optimized etching gas for MgO thin film etching. TiN thin films were employed as a hard mask to increase the etch selectivity. The etch rates were obtained using surface profilometer and etch profiles were observed by using the field emission scanning electron microscopy (FESEM).