• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.597-601
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• 2013

본 연구는 액적기반 미세유체 장치를 이용하여 단분산성 마이크로캡슐의 간단한 제조방법에 관한 것이다. 본 연구에서 제시한 제조 방법은 이중액적을 생성시키기 위해 기존의 복잡한 표면처리가 필요한 이중 유화과정을 대신하여 하나의 교차점을 가진 단일공정을 사용하고자 한다. 먼저, 분산상은 광중합이 가능한 ethoxylated trimethylolpropane triacrylate (ETPTA) 단량체와 fluorocarbon (FC-77) 오일을 사용하고 연속상은 poly(vinyl alcohol) (PVA) 수용액을 사용하였으며, 미세유체 채널 내부로 흘려 주면 하나의 교차점에 흐름이 집중되어 균일한 이중액적을 생성한다. 생성된 이중액적은 광중합을 통해 마이크로캡슐을 제조한다. 상기 방법은 ETPTA 유체의 부피유속을 조절하여 이중액적의 껍질두께 제어가 가능하고 연속상인 물의 부피유속을 조절하여 전체 직경을 제어할 수 있다. 더 나아가, 본 시스템을 사용하여 다양한 물질들을 함입한 마이크로캡슐을 제작할 수 있으며, 약물전달시스템의 응용 기술에 활용될 것으로 예측된다.

• ETRI Journal
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• 제16권1호
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• pp.45-57
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• 1994

The effects of reactive ion etching (RIE) of $SiO_2$ layer in $CHF_3/C_2F_6$ on the underlying Si surface have been studied by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometer, Rutherford backscattering spectroscopy, and high resolution transmission electron microscopy. We found that two distinguishable modified layers are formed by RIE : (i) a uniform residue surface layer of 4 nm thickness composed entirely of carbon, fluorine, oxygen, and hydrogen with 9 different kinds of chemical bonds and (ii) a contaminated silicon layer of about 50 nm thickness with carbon and fluorine atoms without any observable crystalline defects. To search the removal condition of the silicon surface residue, we monitored the changes of surface compositions for the etched silicon after various post treatments as rapid thermal anneal, $O_2$, $NF_3$, $SF_6$, and $Cl_2$ plasma treatments. XPS analysis revealed that $NF_3$ treatment is most effective. With 10 seconds exposure to $NF_3$ plasma, the fluorocarbon residue film decomposes. The remained fluorine completely disappears after the following wet cleaning.

• 한국진공학회지
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• 제7권4호
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• pp.374-380
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• 1998

글로벌 모델을 사용하여 $CF_4$ 플라즈마 내부에서의 각 중성 및 이온 라디칼 밀도를 계산하였다. 중성 입자로서는 플루오린 원자가 가장 많고, 높은 입력 전력 조건의 경우 CF 나 $CF^+$와 같은 저 분자 해리종이 주종을 이룬다. 압력이 증가 할수록 하전 입자의 밀도는 증가하나 전자 온도의 감소로 이온화율은 감소한다. 공급 가스인 $CF_4$의 해리율은 압력에 따 라 증가한후 다시 감소하는 양상을 보인다. 전자 온도 및 밀도는 입력유량에 대해서 거의 변화가 없다. $CF_4$의 해리율은 유량 증가에 따라 선형적으로 감소하며 이는 $CF_3$의 증가와 CF의 감소로 이어진다. 식각 실험 결과와의 비교를 통해 플루오로 카본 이온종 및 높은 C/F비를 갖는 중성 라디칼의 상대적 밀도 증가가 $SiO_2$/Si식각 선택도 향상에 주요함을 알 수 있다.

• Tribology and Lubricants
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• 제21권3호
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• pp.107-113
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• 2005

Micro/nano adhesion and friction properties of self-assembled monolayers (SAMs) with different head- and end-group were experimentally studied according to the coating methods. Various kinds of SAM having different spacer chains (C10 and C18), head-group and end-group were deposited onto Si-wafer by dipping and chemical vapour deposition (CVD) methods under atmospheric pressure, where the deposited SAM resulted in the hydrophobic nature. The adhesion and friction properties between tip and SAM surfaces under nano scale applied load were measured using an atomic force microscope (AFM) and also those under micro scale applied load were measured using a ball-on-flat type micro-tribotester. Surface roughness and water contact angles were measured with SPM (scanning probe microscope) and contact anglemeter respectively. Results showed that water contact angles of SAMs with the end-group of fluorine show higher relatively than those of hydrogen. SAMs with the end-group of fluorine show lower nano-adhesion but higher micro/nanofriction than those with hydrogen. Water contact angles of SAMs coated by CVD method show high values compared to those by dipping method. SAMs coated by CVD method show the increase of nano-adhesion but the decrease of nano-friction. Nano-adhesion and friction mechanism of SAMs with different end-group was proposed in a view of size of fluorocarbon molecule.

• Tribology and Lubricants
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• 제35권4호
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• pp.222-228
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• 2019

As rubber products such as O-rings, which are also known as packings or toric joints, come in regular, long term contact with liquid fuel, they can eventually swell, become mechanically weakened, and occasionally crack; this diminishes both their usefulness and intrinsic lifetime and could cause leaks during the steady-state flow condition of the fuel. In this study, we evaluate the lifetime of such products through compression set tests of FKM, a family of fluorocarbon elastomer materials defined by the ASTM international standard D141; these materials have great compression, sunlight, and ozone resistance as well as a low gas absorption rate. In this process, O-rings are immersed in the liquid fuel of airtight containers that can be expressed as a compression set, and the liquid fuel leakage in a flow rig tester at variable temperatures over 12 months is investigated. Using the Power Law model, our study determined a theoretical O-ring lifetime of 2,647 years, i.e. a semi-permanent lifespan, by confirming the absence of liquid fuel leakage around the O-ring assembled fittings. These results indicate that the FKM O-rings are significantly compatible for fuel tests to evaluate long-term sealing conditions.

• Korean Chemical Engineering Research
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• 제59권4호
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• pp.632-638
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• 2021

반도체 공정에서 구리 배선 공정의 도입에 따라 플라즈마 식각에 의해 배선의 형성과정에서 구리 산화물, 불화물 및 불화탄소 등을 포함한 복합 잔류물을 형성하게 된다. 본 연구에서는 아민기(-NH₂)와 카르복실기(-COOH)를 갖는 성분으로 세정액을 제조하여 구리 배선 공정에서의 식각 잔류물 제거 특성을 분석하였다. 아민기를 포함한 세정액은 질소에 치환된 성분 및 탄소결합의 길이에 따라 세정효과에 차이를 보이며, 세정액의 pH가 증가함에 따라 구리 산화물의 식각 속도가 증가하는 경향성을 보였다. 아민기의 활성은 염기성 영역에서, 카르복실기의 활성은 산성 영역에서 이루어지며, 각각의 영역에서 구리 또는 구리 산화물과의 complex 형성을 통하여 세정공정이 진행되었다.

• 한국세라믹학회지
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• 제52권6호
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• pp.410-416
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• 2015

Recently, a new $Y_2O_3$ coating deposited using the EB-PVD method has been developed for erosion resistant applications in fluorocarbon plasma environments. In this study, surface crack formation in the $Y_2O_3$ coating has been analyzed in terms of residual stress and elastic modulus. The coating, deposited on silicon substrate at temperatures higher than $600^{\circ}C$, showed itself to be sound, without surface cracks. When the residual stress of the coating was measured using the Stoney formula, it was found to be considerably lower than the value calculated using the elastic modulus and thermal expansion coefficient of bulk $Y_2O_3$. In addition, amorphous $SiO_2$ and crystalline $Al_2O_3$ coatings were similarly prepared and their residual stresses were compared to the calculated values. From nano-indentation measurement, the elastic modulus of the $Y_2O_3$ coating in the direction parallel to the coating surface was found to be lower than that in the normal direction. The lower modulus in the parallel direction was confirmed independently using the load-deflection curves of a micro-cantilever made of $Y_2O_3$ coating and from the average residual stress-temperature curve of the coated sample. The elastic modulus in these experiments was around 33 ~ 35 GPa, which is much lower than that of a sintered bulk sample. Thus, this low elastic modulus, which may come from the columnar feather-like structure of the coating, contributed to decreasing the average residual tensile stress. Finally, in terms of toughness and thermal cycling stability, the implications of the lowered elastic modulus are discussed.

• 한국의류학회지
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• 제20권2호
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• pp.350-361
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• 1996

The objectives of this study mere 1) to investigate whether the different nonwoven fabric types influenced on the objective and subjective wear performances of the experimental pesticide protective pants, 2) to detect whether the different finishes treated to the nonwoven fabrics influenced on the objective and subjective wear performances of the experimental pants, and 3) to detect the relationships between objective wear performances and subjective wear sensation. Three types of nonwoven fabrics (T (Tyvek$\textregistered$), 5 (Sontara$\textregistered$) and K (Kimlon$\textregistered$)) were used as test specimens. By pad-dry.cure method, each of the specimen was treated with fluorocarbon compound for water-oil repellent finish (Tw, Sw, Kw). And each of specimen was treated with organic silicon quarternary ammonium salts and then treated with fluorocabon compound for dual functional finish (76, 50, Kd). Using the three water-oil repellent finished fabrics and the three dual functional finished fabrics, six experimental protective pants (Cl (Tw), C2 (Sw), C3 (Kw), C4 (76), C5 (56), C6 (Kd)) were made according to the same pattern suggested by the Rual Guidance Office. The wear trials of experimental pesticide protective pants were performed in a conditioned vinyl plastic hothouse ($30\pm1^{\circ}C$, $70\pm5%$R.H., 0.25m/sec air velocity). The measurements of skin temperature, microclimate temperature and humidity on the subjects were obtained by the themohygromenter. The subjective wear sensations were measured using previously developed thermal, humidity and overall comfort scales. The results obtained from this study were as follows: 1) There were siginificant differences among nonwoven fabric types on the objective and subjective wear performances, therefore, the skin temperature, microclimate temperature and humidity of subjects who wore the experimental pants made with Sontara were siginificantly lower than those who wore the others. And, the experimental pants made with Sontara were assessed as more comfortable than the others in terms of the subjective thermal, humidity and overall wear sensations. 2) There were no significant differences between two finish types on the objective and subjective wear Performances. 3) The microclimate humidity on the thigh was highly correlated with the overall subjective comfort sensations and the next highly correlated one was the mean skin temperature. That is, the higher the microclimate humidity and the mean skin temperature, the higher the overall subjective comfort sensation ratings which mean the overall subjective sensation was very uncomfortable.

• 한국진공학회지
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• 제7권4호
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• pp.403-409
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• 1998

본 연구에서는 자장강화된 유도결합형 플라즈마를 사용하여 이 플라즈마의 특성을 조사하고 또한 산화막 식각에 미치는 영향에 대하여 조사하였다. 자장 강화를 위해 4쌍의 영구자석이 사용되었고, 산화막 식각을 위해 $C_2F_6, CHF_3, C_4F_8$ 가스 및 이들 혼합가스가 사 용되었으며 첨가가스로 $H_2$를 사용하였다. 자장강화된 유도결합형 플라즈마 특성 분석을 위 해 Langmuir probe와 optical emission spectrometer를 이용하여 산화막 식각 속도 및 photoresist에 대한 식각 선택비를 stylus profilometer를 이용하여 측정하였다. 이온 밀도에 있어서 자장 유무에 따른 큰 변화는 관찰되지 않았으나 이온전류밀도의 균일도는 자장을 가 한 경우 웨이퍼가 놓이는 기판 부분에서 상당히 증가된 것을 알 수 있었다. 또한 자장이 가 해진 경우, 자장을 가하지 않은 경우에 비해 플라즈마 전위가 감소된 반면 전자온도 및 라 디칼 밀도는 크게 증가되는 것을 알 수 있었으며 산화막 식각시에도 높은 식각 속도와 식각 균일도를 보였다. 산화막 식각을 위해 수소가스를 사용한 가스조합중에서 C4F8/H2가스조합 이 가장 우수한 식각 속도 및 photoresist에 대한 식각 선택비를 나타내었으며 공정변수를 최적화 함으로써 순수 C4F8에서 4이상의 선택비와 함께 8000$\AA$/min의 가장 높은 식각속도 를 얻을 수 있었으며, 50%C4F8/50%H2에서 4000$\AA$/min의 산화막 식각 속도와 함께 15이상 의 식각 선택비를 얻을 수 있었다.