Anisotropic etching of polysilicon in a Cl₂/ CH₃Br / O₂ Plasma

Whi Kun Yi 한국진공학회(ASCT) 1999 Journal of Korean Vacuum Science & Technology Vol.3 No.1

The characteristic behaviors of CH₃Br were examined first for the dry etching of polysilicon in a Cl₂/CH₃Br/O₂ plasma. CH₃Br is revealed one of the excellent additive gases to control anisotropy of etching profile and to give no undercutting for various types of polysilicons. CH₃Br acts as a passivation precursor on the side wall in etch cavity by forming polymer-like films such as CH_xBr_y(x+y=1, 2). The decrease of etch selectivity due to the reaction of the C-containing species from CH₃Br with the surface O atoms of SiO₂ was overcome by the addition of O₂ into plasma, resulting that the selectivity increased by 2~3 times. According to the results of optical emission signals, CH₃Br should be dissociated into several fragments to give more hydrogen atoms than bromine atoms in our helical resonator system.

Vibrational Spectroscopic Study of Benzenethiol on Silver Surface

Yi, Whi-Kun,Park, Cheol-Woo,Kim, Myung-Soo,Kim, Kwan Korean Chemical Society 1987 Bulletin of the Korean Chemical Society Vol.8 No.4

Vibrational spectroscopy has been applied to the benzenethiol molecule adsorbed on the silver surface. The results of infrared and Raman spectral studies have led to the conclusion that benzenethiol is chemisorbed dissociatively on the silver surface by rupture of S-H bond and the benzenethiolate formed upon adsorption is bound to silver via its sulfur atom. It seemed more likely that benzenethiol is adsorbed as being inclined to the silver surface. On contact with oxygen, the geometry of the adsorbed species appeared to bear a resemblance to that of silver benzenethiolate salt. The infrared bands of adsorbed species remained with little decrease of intensity even after the prolonged evacuation at 673 K, indicating that benzenethiol is very strongly chemisorbred to the silver surface.

Vibrational Spectroscopic Study of Benzenethiol Adsorbed on $\gamma-Al_2O_3$

Yi, Whi-Kun,Park, Cheol-Woo,Kim, Myung-Soo,Kwan, Kim Korean Chemical Society 1987 Bulletin of the Korean Chemical Society Vol.8 No.4

Adsorption of Benzenethiol on $\gamma-Al_2O_3$ supported Ni and Mo ; Infrared Spectroscopic Study

Yi, Whi-Kun,Kim, Kwan Korean Chemical Society 1988 Bulletin of the Korean Chemical Society Vol.9 No.4

Anisotropic etching of polysilicon in a $Cl_2/CH_3Br/O_2$ Plasma

Yi, Whi-Kun The Korean Vacuum Society 1999 Journal of Korean Vacuum Science & Technology Vol.3 No.1

The characteristic behaviors of CH3Br were examined first for the dry etching of polysilicon in a Cl2/CH3Br/O2 plasma. CH3Br is revealed one of the excellent additive gases to control anisotropy of etching profile and to give no undercutting for various typed of polysilicons. CH3Br acts as a passivation precursor on the side wall in etch cavity by forming polymer-like films such as CHxBry(x+y=1,2). The decrease of etch selectivity due to the reaction if the C-containing species from CH3Br with the surface O atoms of SiO2 was overcome by the addition of O2 into plasma, resulting that the selectivity increased by 2~3 times. According to the results of optical emission signals, CH3Br should be dissociated into several fragments to give more hydrogen atoms than bromine atoms in our helical resonator system.

고밀도 플라즈마를 사용한 Cl₂ / Poly - Si 건식 식각

이휘건(Whi Kun YI) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.1

고밀도 플라즈마 source인 helical resonator의 특성을 알기 위해 Langmuir probe를 사용하여 특성 변수들-플라즈마 밀도, 전자 온도, 이온 전류 밀도-의 값을 측정하였다. 또한 Cl₂/poly-Si 시스템에서의 식각반응 메카니즘을 규명하기 위해 Si와 SiCl의 에미션 시그날을 분석하였다. Cl₂/poly-Si 식각 시스템계에서는 화학 식각에 의한 반응이 물리식각에 의한 반응보다 주됨을 알 수 있다. 또한 폴리 실리콘 내의 불순물 P농도가 증가함에 따라 식각의 화학반응 산출물인 SiCl의 양이 물리식각 산출물인 Si의 양보다 급격히 증가하는 양상을 보였다. 이는 표면 반응중 형성된 Si-Cl 결합을 통해 실리콘 내부의 전자들이 Cl 쪽으후 이동함으로써 Si-Cl은 더욱 유동적이며 이온화된 특성을 갖게 되고, 따라서 Cl₂^+와 같은 에천트들이 표면에 흡착될 확률이 커져 SiCl_x의 형성을 용이하게 하기 때문으로 생각된다. 즉 불순물 P 농도가 증가함에 따라 표면의 Si를 제거하는데는 물리식각보다 화학식각이 더욱 큰 역할을 하는 것으로 밝혀졌다. The characteristic parameters of high density plasma source (Helical Resonator) have been measured with Langmuir probe to get the plasma density, electron temperature, ion current density, etc. Optical emission spectra of Si and SiCl have been analyzed in Cl₂/poly-Si system to elucidate etching mechanism. In this system, the main reaction to remove silicon atoms on the surface is proceeding mostly through chemical reaction, not pure physical reaction. The emission intensity of SiCI (chemical etching product) increases much faster than Si (pure physical etching product) with increasing the concentration of impurities (P). This is due to the electron transfer from substrate to the surface via Si-Cl bond. As a result, Si-Cl bond becomes more ionic and mobile, therefore the Cl-containing etchant forms SiCl_x with surface more easily. Consequently, for the removal of Si atom from poly silicon surface, the chemical etching is more favorable than physical etching with increasing P concentrations.

한국의 난민 규범 제도화와 내재화의 간극: 입법과정과 규범 혁신가

홍건식 ( Kun Sik Hong ),장휘 ( Whi Chang ) 한국사회역사학회 2021 담론 201 Vol.24 No.1

본 연구는 한국의 국제 난민 규범 내재화의 한계를 난민법 관련 행위자들의 입법과정을 중심으로 살펴본다. 한국은 1992년 ‘난민의 지위에 관한 협약’과 ‘난민의 지위에 관한 의정서’를 비준했지만 2012년 난민법이 제정될 때까지 난민 문제에 소극적으로 대응해 왔다. 대규모의 난민 유입의 경험이 없었던 한국 사회에서 보수 정당의 전향적인 난민법 도입은 어떻게 이루어졌을까? 난민 인권 보호라는 국제 규범의 내재화 과정이 한국 사회에서 어떤 과정을 거치며 완성되지 못하는가? 이에 본 연구는 규범 혁신가의 입법 과정을 통해 난민 규범의 내재화와 제도화 과정을 살펴보고 현재적 차원에서 난민법의 한계에 대하여 논한다. This paper discusses the limitations in internalization of international refugee norms in the Republic of Korea (ROK), focusing on the actors in the legislative process of the Refugee Law. The ROK ratified the Convention and Protocol Relating to the Status of Refugees in 1992 but had responded passively to refugee issues until the Refugee Law was legislated. How did the conservative party initiate the legislation of the Refugee Law in Korean society that had never experienced a massive influx of refugees? What is the process of internalizing the international norms of the protection of refugee human rights in its society? This paper explores the internalization and institutionalization of refugee norms through the legislative process, highlighting the role of a norm entrepreneur and discusses the limitations of it.

Conducting Properties of Polypyrrole Coated Imogolite

Lee, Yun-Ha,Kim, Bum-Joong,Yi, Whi-kun,Takahara, Atsushi,Sohn, Dae-Won Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.11

Imogolite which has chemical composition, $(HO)_3Al_2O_3SiOH$, was synthesized with orthosilicate acid and aluminium chloride at low pH solution. It has extremely large aspect ratio with an external diameter of 2nm and the length of a few micrometers. The high aspect ratio of the imogolite could make the material as the filler for the high strength fiber and as the wire for the electronic applications. Here, Imogolite that derives considerable microporosity from a nanometer-sized tubular structure has been modified with a conducting polymer, polypyrrole. Its bonding and wiring structure were confirmed by IR and TEM. The measured conductivity after modification with polypyrrole increased with polypyrrole thickness at various voltage conditions.

Improved Field Emission Currents of Carbon Nanotubes after Laser Irradiation

Lee, Jung-Woo,Park, Jae-Hong,Yi, Whi-Kun Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.10

Field emission (FE) currents were measured for silver-pasted and glass-pasted single-walled carbon nanotubes (SWNTs) after illuminating the tubes with a pulsed 532 nm laser. A very low turn-on field of approximately 0.4 V/m m and a high current density ~1700 $\mu A/cm^2$ at 3.5 V/m m was obtained for the silver-pasted SWNTs after laser irradiation but on the whole, no improvements were found for the glass-pasted SWNTs. Two roles of laser irradiation for the silver-pasted SWNTs were proposed. First, the embedded SWNTs and SWNT bundles inside the silver paste were immerged on the outer surface due to an instantaneous melting or annealing of the silver metals by the laser resulting in an increase of the field emission sites. Second, the laser irradiation was thought to improve the electrical contact between SWNTs and the silver metal by reducing the contact resistance via laser-induced thermal annealing, which was responsible for increasing the FE currents.

Carbon-Nanotube Based Field-Emission Displays for Large Area and Color Applications

Choi, Won-Bong,Lee, Nae-Sung,Yi, Whi-Kun,Jin, Yong-Wan,Choi, Yong-Soo,Han, In-Taek,Jang, Hyeong-Yong,Kim, Hoonn-Young,Kang, Jung-Ho,Yun, Min-Jae,Park, Sang-Hyeun,Yu, Se-Gi,Jang, Jae-Eun,You, Jang-Hun The Korean Infomation Display Society 2000 Journal of information display Vol.1 No.1

The first 9-inch carbon nanotube based color field emission displays (FEDs) are integrated using a paste squeeze technique. The panel is composed of 576 x 242 lines with implementation of low voltage phosphors. The uniform and moving images are achieved only at $2V/{\mu}m$, This demonstrates a turning point of nanotube for large area and full color applications.