• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.59-61
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• 2002

In this study we attempted to diagnose the distribution of nitrogen plasma density generated using PECVD(plasma enhanced chemical vapor deposition). The distribution of plasma density formed in a PECVD chamber were measured by DLP2000. The experiment results showed that the plasma density is related to RF power and gas flow rate. As RF power gets higher, the plasma density linearly increased. And the experimental results revealed that a pressure in chamber affects plasma density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.356-357
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• 2008

The effects of $O_2$ plasma ashing process for surface treatment of nano-wire Bio-FET were investigated. In order to evaluate the plasma damage introduced by $O_2$ plasma ashing, a back-gate biasing method was developed and the electrical characteristics as a function of $O_2$ plasma power were measured. Serious degradations of electrical characteristics of nano-wire Bio-FET were observed when the plasma power is higher than 50 W. For curing the plasma damages, a forming gas anneal (2 %, $H_2/N_2$) was carried out at $400^{\circ}C$. As a result, the electrical characteristics of nano-wire Bio-FET were considerably recovered.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.1
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• pp.10-13
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• 2010

The plasma processing technologies of thin film deposition and surface treatment technique have been applied to many industrial fields. This study is purposed Large-area uniformity and surface treatment on the stainless substrate. We treat surface of stainless by $CF_4$ plasma. $CF_4$ plasma is generated by using SPM(Scanning plasma method)which is kind a of CVD. Generally, SPM has been used for uniform surface treatment using a crossed electromagnetic field. The optimum discharge condition has been studied for the gas pressure, the magnetic flux density and the distance between substrate and electrodes. In result, contact angle is increased by surface treatment using $CF_4$ Plasma. Therefore we expect that SPM to control contact angle is applied to many industries.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.8
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• pp.438-444
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• 2000

We report the effects of etch process parameters on the ohmic contact formation in the plasma etching of GaN. Planar inductively coupled plasma system with $CH_4/H_2/Ar$gas chemistry has been used as etch reactor. The contact resistance and the specific contact resistance have been investigated using transfer length method as a function of RF bias power and %Ar gas concentration in total flow rate. AES(Auger electron spectroscopy) analysis revealed that the etched GaN has nonstoichiometric Ga rich surface and was contaminated by carbon and oxygen. Especially large amount of carbon was detected at the sample etched for high bias power (or voltage) condition, where severe degradation of contact resistance was occurred. We achieved the low ohmic contact of $2.4{\times}10^{-3} {\Omega}cm^2$ specific contact resistance at the input power 400 W, RF bias power 150 W, and working pressure 10mTorr with 10 sccm $CH_4$, 15 sccm H2, 5 sccm Ar gas composition.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.4
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• pp.215-223
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• 1992

This study has been performed to investigate into some effects of temperature, gas mixing ratio and time on the optical microstructure, hardness and wear characteristics of medium carbon alloy steel treated by plasma nitriding. The results obtained from the experiment are summarized as follows: (1) Optical micrographs of AISI 4140 steel plasma-nitrided by the double stage technique have revealed that the nitrided layer is composed of the compound layer and the diffusion layer. The variation in temperature at the first stage gives effects, on the formation of compound layer and the growth rate is shown to be relatively fast at $460^{\circ}C$. (2) The thickness of compound layer has been found to increase with increasing nitrogen percentage in the gas mixture and the holding time. It is therefore recommended that a shorter holding time and a lower nitrogen percentage are more effective to produce a tougher compound layer and a diffusion layer only. (3) X-ray diffraction analysis for AISI 4140 steel has shown that the compound layer consist of ${\gamma}^{\prime}-Fe_4N$ and ${\alpha}-Fe$ and that tough compound layer diffustion layer only can be obtained by the double stage plasmanitriding process. (4) There is also a tendency that the total hardened layer depth increases with increasing temperature, time and nitrogen percentage in the first stage during the double stage plasma nitriding. (5) The wear resistance of plasma nitrided specimens has been found thobe considerably increased compared to the untreated specimens and the amount of increment has appeared to increase further with increasing nitriding temperature, holding time and notrogen percentage of gas mixture in the first stage treatment.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.71-71
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• 1999

현재 소자 제작에 응용되는 수소화된 비정질 실리콘은 PECVD 방법으로 제작하는 것이 보편적인 방법이다. 그러나 비정질 실리콘 박막 트랜지스터는 band gap edge 근처에서 국재준위가 많아 mobility가 작으며 상온에서 조차 불안정하여 신뢰성이 높지 않고, 도핑된 비정질 실리콘의 높은 비저항 등의 단점으로 인하여 고속 회로에 응용이 불가능하다. 반면 다결정질 실리콘 박막 트랜지스터는 a-Si:H TFT 에 비해 재현성이 우수하고 high resolution, high resolution, high contrast LCD에 응용할 수 있다. 하지만, 다결정 실리콘의 grain boundary로 인해 단결정에 비해 많은 defect 들이 존재하여 전도성을 감소시킨다. 따라서 Mobility를 증가시키기 위해서 grain size를 증가시키고 grain boundary 내에 존재하는 trap center를 감소시켜야 한다. 따라서 본 실험에서는 PECVD 장비로 초기 기판을 plasma 처리하여 다결정 실리콘 박막을 제작하여, 기판 처리에 대한 다결정 실리콘 박막의 성장의 특성을 조사하였다. 실험 방법으로는 PECVD 시스템을 이용하여 SiH4 gas와 H2 gas를 선택적으로 증착시키는 LBL 방법을 사용하여 $\mu$c-Si:H 박막을 제작하였다. 비정질 층을 gas plasma treatment 하여 다결정질 실리콘의 증착 initial stage 관찰을 주목적으로 관찰하였다. 다결정 실리콘 박막의 구조적 성질을 조사하기 위하여 Raman, AFM, SEM, XRD를 이용하여 grain 크기와 결정화도에 대해 측정하여 결정성장 mechanism을 관측하였다. LBL 방법으로 증착시킨 박막의 Raman 분석을 통해서 박막 증착 초기에 비정질이 증착된 후에 결정질로 상태가 변화됨을 관측할 수 있었고, SEM image를 통해서 증착 회수를 증가시키면서 grain size가 작아졌다 다시 커지는 현상을 볼 수 있었다. 이 비정질 층의 transition layer를 gas plasma 처리를 통해서 다결정 핵 형성에 영향을 관측하여 적정한 gas plasma를 통해서 다결정질 실리콘 박막 증착 공정을 단축시킬 수 있는 가능성을 짐작할 수 있었고, 또한 표면의 roughnes와 morphology를 AFM을 통하여 관측함으로써 다결정 박막의 핵 형성에 알맞은 증착 표면 특성을 분석 할 수 있었다.

• Journal of the Korean institute of surface engineering
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• v.34 no.1
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• pp.10-16
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• 2001

Recently plasma etching research has been focused on the metal surfaces in the nuclear industry. In this study, surface etching reaction of metallic Co and Mo, principal contaminants in the spent nuclear components, in CF$_4$/O$_2$, gas plasma has been experimentally investigated to look into the applicability and the effectiveness of the technique for the surface decontamination. Experimental variables are $CF_4$/$O_2$ ratio and substrate temperature between 29$0^{\circ}C$ and 38$0^{\circ}C$. Experimental results Show that the optimum gas composition is 80%CF$_4$-20%$O_2$ and the metallic Co and Mo are etched out well enough in the temperatures range. Cobalt starts to be etched above $350^{\circ}C$ and the etching rate increases with increasing substrate temperature. Maximum rate achieved at 38$0^{\circ}C$ under 220 W r.f. plasma power is 0.06 $\mu\textrm{m}$/min. On the other hand, the metallic Mo is etched easily even at low temperature and the reaction rate drastically increases as the substrate temperature goes up. Highest rate obtained under the same conditions is $1.9\mu\textrm{m}$/min. OES (Optical Emission Spectroscopy) analysis reveals that the intensities of F atom and CO molecule reach maximum at the optimum gas composition, which demonstrates that the principal reaction mechanism is fluorination and/or carbonyl reaction. It is confirmed, therefore, that dry processing technique using reactive plasma is quite feasible and applicable for the decontamination of surface-contaminated parts or equipments.

• 한국가스학회:학술대회논문집
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• 1998.09a
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• pp.277-280
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• 1998

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.253.1-253.1
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• 2014

Plasma technology has been widely used for decontamination, differentiation, and disease treatment. Recently, studies show that plasma has effects on increasing seed germination and plant growth. In spite of increasing number of studies about plasma effects, the interaction between plasma and plants has been rarely informed. In this study, we have analyzed the effects of nonthermal atmospheric pressure plasma on seed germination and growth of coriander (Coriandum sativum), a medicinal plant. We used to Ar, air, and N2 plasma on seed as feeding gases. Plasma was discharged at 0.62 kV, 200 mA, 9.2 W. Seed germination was increased over time when treated with N2 based DBD plasma for exposure times of 30 seconds and 1 minute, everyday. After 7 days, about 80~100% of seeds were germinated in the treatment with N2 based DBD plasma, compared to control (about 40%, only gas treated seeds). In order to elucidate the mechanism of increased germination, we have analyzed characteristics of changes in plant hormones and seed surface structure by SEM.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.5
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• pp.265-269
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• 2000

$(Ba, Sr)TiO_3$thin films were etched with a magnetically enhanced inductively coupled plasma (MEICP) at different CF4/Ar gas mixing ratios. Experimental was done by varying the etching parameters such as rf power, dc bias and chamber pressure. The maximum etch rate of the BST films was $1800{AA}/min$ under $CF_4/(CF_4+Ar)$ of 0.1, 600 W/350 V and 5 mTorr. The selectivity of BST to Pt and PR was 0.6, 0.7, respectively. X-ray photoelectron spectroscopy (XPS) results show that surface reaction between Ba, Sr, Ti and C, F radicals occurs during the (Ba, Sr)TiO3 etching. To analyze the composition of surface residue after the etching, films etched with different CF_4/Ar$ gas mixing ratio were investigated using XPS and secondary ion mass spectroscopy (SIMS).