• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 Proceedings of The 6th korea-china joint workshop on nuclear waste management
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• pp.300-315
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• 2005

Recently plasma surface-cleaning or surface-etching techniques have been focused in the respect of decontamination of spent or used nuclear parts and equipment. In this study decontamination rate of metallic cobalt surface was experimentally investigated via its surface etching rate with a $CF_4-O_2$ mixed gas plasma and metallic surface wastes of cobalt oxides were simulated and decontaminated with $NF_3$ - Ar mixed gas plasma. Experimental results revealed that a mixed etchant gas with about $80{\%}\;CF_4-20{\%}\;O_2$ gives the highest reaction rate of cobalt disk and the rate reaches with a negative 300 DC bias voltage up to $0.43\;{\mu}m$/min at $380^{\circ}C$ and $20{\%}\;NF_3-80\%$ Ar mixed gas gives $0.2\;{\mu}m$/min of reaction rate of cobalt oxide film.

• 한국결정성장학회지
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• 제24권5호
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• pp.196-201
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• 2014

화학적 습식 에칭을 통해 AlN와 GaN의 결함 및 표면 특성을 분석했다. 화학적 습식 에칭은 단결정의 결함을 선택적으로 에칭하기 때문에 결정의 품질을 평가하는 좋은 방법으로 주목 받고 있다. AlN와 GaN의 단결정은 NaOH/KOH 용융액을 이용하여 에칭을 했으며, 에칭 후 표면 특성을 알아보기 위해 주사전자현미경(SEM)과 원자힘 현미경(AFM)을 촬영했다. 에치 핏의 깊이를 측정하여 표면에 따른 에칭 속도를 계산했다. 그 결과 AlN와 GaN 표면에는 두 개의 다른 형태에 에치 핏이 형성 되었다. (0001)면의 metal-face(Al, Ga)는 육각 추를 뒤집어 놓은 형태를 갖는 반면 N-face는 육각형 형태의 소구 모양(hillock structure)을 하고 있었다. 에칭 속도는 N-face가 metal-face(Al, Ga)보다 각 각 약 109배(AlN)와 5배 정도 빨랐다. 에칭이 진행되는 동안 에치 핏은 일정한 크기로 증가하다 서로 이웃한 에치 핏들과 합쳐지는 것으로 보여졌다. 또한 AlN와 GaN의 에칭 공정을 화학적 메커니즘을 통해 알아 보았는데, 수산화 이온($OH^-$)과 질소의 dangling bond에 영향을 받아 metal-face(Al, Ga)와 N-face가 선택적으로 에칭되는 것으로 추론되었다.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.846-851
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• 2007

In this work, the etching characteristics of $Ge_2Sb_2Te_5(GST)$ thin films were investigated using an inductively coupled plasma (ICP) of $Cl_2/Ar$ gas mixture. To analyze the etching mechanism, an optical emission spectroscopy (OES) and surface analysis using X-ray photoelectron spectroscopy (XPS) were carried out. The etch rate of the GST films decreased with decreasing Ar fraction. At the same time, high selective etch rate over $SiO_2$ films was obtained and the selectivity over photoresist films decreased with increasing the he fraction. From XPS results, we found that Te halides were formed at the etching surface and Te halides limited the etch rate of the GST films.

• 한국진공학회지
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• 제1권1호
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• pp.37-42
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• 1992

16M/64M DRAM 제조공정에 적용할 수 있는 ECR 방식의 플라즈마 etcher를 개발 하여 Poly-Si 식각공정에 적용하였다. 공정압력, 사용가스 및 초고주파 전력의 공정변수 변 화에 따른 Poly-Si의 식각율 및 선택비 변화를 조사하였다. 초고주파의 전력이 증가할수록 식각율과 Oxide에 대한 선택비가 증가하는 경향을 보였으며 6mT의 공정압력에서 최적치를 보였다. 공정가스 SF6/SF6 + Cl2의 값이 증가할수록 식각율 및 선택비의 감소가 있었으며 이는 최적 공정변수를 찾지 못하였기 때문으로 분석된다.

• Journal of Information Display
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• 제2권4호
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• pp.1-7
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• 2001

This paper investigates the characteristics of a newly developed high density hollow cathode plasma(HCP) system and its application for the etching of silicon wafers. We used $SF_6$ and $O_2$ gases in the HCP dry etch process. This paper demonstrates very high plasma density of $2{\times}10^{12}cm^{-3}$ at a discharge current of 20 rna, Silicon etch rate of 1.3 ${\mu}m$/min was achieved with $SF_6/O_2$ plasma conditions of total gas pressure of 50 mTorr, gas flow rate of 40 seem, and RF power of200W. This paper presents surface etching characteristics on a crystalline silicon wafer and large area cast type multicrystlline silicon wafer. We obtained field emitter tips size of less than 0.1 ${\mu}m$ without any photomask step as well as with a conventional photolithography. Our experimental results can be applied to various display systems such as thin film growth and etching for TFT-LCDs, emitter tip formations for FEDs, and bright plasma discharge for PDP applications. In this research, we studied silicon etching properties by using the hollow cathode plasma system.

• 반도체디스플레이기술학회지
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• 제17권4호
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• pp.97-100
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• 2018

$NF_3$ Plasma etching of silicon was conducted by injecting only $NF_3$ gas into reactive ion etching. $NF_3$ Plasma etching was done in intermediate pressure. Silicon etching by $NF_3$ plasma in reactive ion etching was diagnosed through residual gas analyzer and optical emission spectroscopy. In plasma etching, optical emission spectroscopy is generally used to know what kinds of species in plasma. Also, residual gas analyzer is mainly to know the byproducts of etching process. Through experiments, the results of optical emission spectroscopy during silicon etching by $NF_3$ plasma was analyzed with connecting the results of etch rate of silicon and residual gas analyzer. It was confirmed that $NF_3$ plasma etching of silicon in reactive ion etching accords with the characteristic of reactive ion etching.

• 대한소아치과학회지
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• 제32권3호
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• pp.472-480
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• 2005

치면열구전색술의 우식예방효과는 전색제의 유지력과 밀접한 연관이 있으며, 이는 전 단계 과정인 산부식제의 열구 내 침투율에 따라 달라질 수 있다. 본 연구에서는 교합면 소와 및 열구에 산부식제의 효과적인 침투를 위해 여러 가지 방법을 적용하여 비교 분석하였다. 이를 위해 발거된 상악 제 1, 2 소구치 40개를 각각 10개씩 4개의 군으로 나누었다. I군은 교합면 소와 및 열구 부위에 통법에 따라 산부식제를 도포하였고 II군은 각 치아의 교합면 소와 및 열구부위에 산부식제 도포와 함께 초음파 진동을 주었다. III군은 각 치아의 교합면 소와 및 열구부위에 열구성형술(Fissurotomy)를 시행한 후 산부식제를 도포하였고, IV군은 각 치아의 교합면 소와 및 열구부위에 열구성형술후 산부식제 도포와 초음파 진동을 동시에 시행하였다. 이상의 실험 후 각 군의 산부식제 침투도를 비교 연구하여 다음과 같은 결과를 얻었다. 1. 각 군의 산부식제 침투도를 비교한 결과, 각각 III군과 IV군에서 I군에 대해 향상된 침투도를 관찰할 수 있었다(P<0.05). 2. 부위별 군에 따른 침투도를 비교한 결과, 근심 소와부위와 원심 소와부위에서는 III군과 IV군이 I군에 대해 향상된 침투도를 보였으나(P<0.05), 열구 중앙부위는 각 군 간에 차이가 없었다(P>0.05).

• 청정기술
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• 제9권3호
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• pp.101-105
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• 2003

MEMS(Micro Electro Mechanical System) 기술에서 실리콘 식각기술의 중요성으로 플라즈마 식각기술의 개발이 꾸준히 진행되고 있다. 본 연구에서는 ICP(Inductive Coupled Plasma)를 이용하여 플라즈마를 발생시켜, 이온에너지를 증가시키지 않고도 이온밀도를 높이고 이온입자들에 의한 식각의 방향성을 가할 수 있는 새로운 플라즈마 기술을 이용하였다. 이같이 플라즈마를 이용하여 실리콘웨이퍼를 식각하여 제조하는 MEMS 응용분야는 다양하나, 본 연구에서는 미생물배양에 응용할 수 있는 PCR(Polymerase Chain Reaction)장치 제작을 위한 식각에 이용하였다. Platen power, Coil power 및 Process pressure에 다양한 변화를 주어 각 변수에 따른 식각속도를 관찰하였다. 각 공정별 변수를 변화시킨 결과 Platen 12W, Coil power 500W, 식각/Passivation Cycle 6/7sec 일 경우 식각속도는 $1.2{\mu}m/min$ 이었고, sidewall profile은 $90{\pm}0.7^{\circ}$로 나타나 매우 우수한 결과를 보였다. 분 연구에 SF6를 식각에 이용하였으며 공정의 최적화를 통하여 사용량을 최소화하여환경영향이 최소가 될 수 있는 가능성이 있었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.38.1-38.1
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• 2009

Plasma etching is an essential process for electronic device industries and the particulate contamination during plasma etching has been interested as a big issue for the yield of productivity. The oxynitride glasses have a merit to prevent particulate contamination due to their amorphous structure and plasma etching resistance. The YSiAlON oxynitride glasses with increasing nitrogen content were manufactured. Each oxynitride glasses were fluorine-plasma etched and their plasma etching rate and surface roughness were compared with reference materials such as sapphire, alumina and quartz. The reinforcement mechanism of plasma etching resistance of the YSiAlON glasses studied by depth profiling at plasma etched surface using electron spectroscopy for chemical analysis. The plasma etching rate decreased with nitrogen content and there was no selective etching at the plasma etched surface of the oxynitride glasses. The concentration of silicon was very low due to the generation of SiF4 very volatile byproduct and the concentration of aluminum and yttrium was relatively constant. The elimination of silicon atoms during plasma etching was reduced with increasing nitrogen content because the content of the nitrogen was constant. And besides, the concentration of oxygen was very low on the plasma etched surface. From the study, the plasma etching resistance of the glasses may be improved by the generation of nitrogen related structural groups and those are proved by chemical composition analysis at plasma etched surface of the YSiAlON oxynitride glasses.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.391-392
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• 2012

In these days, the desire for the precise and tiny displays in mobile application has been increased strongly. Currently, laser displays ranging from large-size laser TV to mobile projectors, are commercially available or due to appear on the market [1]. In order to achieve a mobile projectors, the semiconductor laser diodes should be used as a laser source due to their size and weight. In this presentation, the continuous etch characteristics of Pd and AlGaN/GaN superlattice for the fabrication of blue laser diodes were investigated by using inductively coupled $CHF_3$ and $Cl_2$ -based plasma. The GaN laser diode samples were grown on the sapphire (0001) substrate using a metal organic chemical vapor deposition system. A Si-doped GaN layer was grown on the substrate, followed by growth of LD structures, including the active layers of InGaN/GaN quantum well and barriers layer, as shown in other literature [2], and the palladium was used as a p-type ohmic contact metal. The etch rate of AlGaN/GaN superlattice (2.5/2.5 nm for 100 periods) and n-GaN by using $Cl_2$ (90%)/Ar (10%) and $Cl_2$ (50%)/$CHF_3$ (50%) plasma chemistry, respectively. While when the $Cl_2$/Ar plasma were used, the etch rate of AlGaN/GaN superlattice shows a similar etch rate as that of n-GaN, the $Cl_2/CHF_3$ plasma shows decreased etch rate, compared with that of $Cl_2$/Ar plasma, especially for AlGaN/GaN superlattice. Furthermore, it was also found that the Pd which is deposited on top of the superlattice couldn't be etched with $Cl_2$/Ar plasma. It was indicating that the etching step should be separated into 2 steps for the Pd etching and the superlattice etching, respectively. The etched surface of stacked Pd/superlattice as a result of 2-step etching process including Pd etching ($Cl_2/CHF_3$) and SLs ($Cl_2$/Ar) etching, respectively. EDX results shows that the etched surface is a GaN waveguide free from the Al, indicating the SLs were fully removed by etching. Furthermore, the optical and electrical properties will be also investigated in this presentation. In summary, Pd/AlGaN/GaN SLs were successfully etched exploiting noble 2-step etching processes.