• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.33.2-33.2
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• 2011

CMP (Chemical-Mechanical Planarization) 공정이란 화학적 반응과 기계적 힘을 동시에 이용하여 표면을 평탄화하는 공정으로, 반도체 산업에서 회로의 고집적화와 다층구조를 형성하기 위해 CMP 공정이 도입되었으며 반도체 패턴의 미세화와 다층화에 따라 CMP 공정의 중요성은 더욱 강조되고 있다. CMP 공정은 압력, 속도 등의 공정조건과, 화학적 반응을 유도하는 슬러리, 기계적 힘을 위한 패드 등에 의해 복합적으로 영향을 받는다. CMP 공정에서, 폴리우레탄 패드는 많은 기공들을 포함한 그루브(groove)를 형성하고 있어 웨이퍼와 직접적으로 접촉을 하며 공정 중 유입된 슬러리가 효과적으로 연마를 할 수 있도록 도와주는 역할을 한다. 하지만, 공정이 진행 될수록 그루브는 손상이 되어 제 역할을 하지 못하게 된다. 패드 컨디셔닝이란 컨디셔너가 CMP 공정 중에 지속적으로 패드 표면을 연마하여 패드의 손상된 부분을 제거하고 새로운 표면을 노출시켜 패드의 상태를 일정하게 유지시키는 것을 말한다. 한편, 금속박막의 CMP 공정에 사용되는 슬러리는 금속박막과 산화반응을 하기 위하여 산화제를 포함하는데, 산화제는 금속 컨디셔너 표면을 산화시켜 부식을 야기한다. 컨디셔너의 표면부식은 반도체 수율에 직접적인 영향을 줄 수 있는 scratch 등을 발생시킬 뿐만 아니라, 컨디셔너의 수명도 저하시키게 되므로 이를 방지하기 위한 노력이 매우 중요하다. 본 연구에서는 컨디셔너 표면에 연마 잔여물 흡착을 억제하고, 슬러리와 컨디셔너 표면 간에 일어나는 표면부식을 방지하기 위하여 소수성 자기조립 단분자막(SAM: Self-assembled monolayer)을 증착하여 특성을 평가하였다. SAM은 2가지 전구체(FOTS, Dodecanethiol를 사용하여 Vapor SAM 방법으로 증착하였고, 접촉각 측정을 통하여 단분자막의 증착 여부를 평가하였다. 또한 표면부식 특성은 Potentiodynamic polarization와 Electrochemical Impedance Spectroscopy (EIS) 등의 전기화학 분석법을 사용하여 평가되었다. SAM 표면은 정접촉각 측정기(Phoenix 300, SEO)를 사용하여 $90^{\circ}$ 이상의 소수성 접촉각으로써 증착여부를 확인하였다. 또한, 표면에너지 감소로 인하여 슬러리 내의 연마입자 및 연마잔여물 흡착이 감소하는 것을 확인 하였다. Potentiodynamic polarization과 EIS의 결과 분석으로부터 SAM이 증착된 표면의 부식전위와 부식전류밀도가 감소하며, 임피던스 값이 증가하는 것을 확인하였다. 본 연구에서는 컨디셔너 표면에 SAM을 증착 하였고, CMP 공정 중 발생하는 오염물의 흡착을 감소시킴으로써 CMP 연마 효율을 증가하는 동시에 컨디셔너 금속표면의 부식을 방지함으로써 내구성이 증가될 수 있음을 확인 하였다.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.89-99
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• 2004

At the interface of two materials with frequency-dependent material-parameters of permittivity and permeability, there may exist two kinds of surface polaritons: surface electric-polaritons(SEPs) and surface magnetic-polaritons(SMPs). Possible combinations of the material-parameters to support propagation of the two surface polaritons are suggested at the interface between metals and metamaterials such as a left-handed material. Dispersion relations are also derived in order to characterize frequency dependence of propagation of the SEP and SMP. It is found that only one propagation mode of SEP or SMP is allowed at a given set of four material parameters, and that counter-propagation of the phase and group velocities of the propagation mode can be observed even in the case when there are no double negative(or, negative-index) materials. Physical origin of the counter-propagation of the group velocity is proposed by evaluating the ratio of two electromagnetic-energy densities of a surface polariton propagating along within the two interface media, and it is confirmed by the dispersion relations.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1358-1366
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• 1988

The dual dielectric films have been grown on single-crystalline silicon substrates with the thickness ranging from 125A to 180A at various gas and temperature conditions by using rapid thermal process that included independent nitridation step. The film characteristics and their dependence on the contents of the hydrochloric gas and the processing time have been studied. By the addition of the hydrochloric gas, the initial oxide thickness was significantly changed, but after sequential nitridation processes the thickness of the films was nevertheless a little bit varied within 10A. All the samples of the dual dielectric films show the increased breakdown voltages in proportion to the additive contents of the hydrochloric gas and also show the higher breakdown strengths than the thermal oxide and nitrided oxide films grown by the conventional furnance process or the rapid thermal nitridation process that was composed of the dependent nitridation cycles.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.4
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• pp.59-65
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• 2001

Epoxy/$BaTiO_3$composite capacitor films with excellent stability at room temperature, uniform thickness, and electrical properties over a large area ware successfully fabricated. The composite capacitor films with good film formation capability and easy process ability were made from epoxy resin developed for ACF as a matrix and two kinds of $BaTiO_3$powders as fillers to increase the dielectric constant of the composite film. The crystal structure of the powders and its effects on dielectric constant of the films were investigated by X-ray diffraction (XRD). And the optimum amount of dispersant, phosphate ester, was determined by viscosity measurement of suspension. DSC and dielectric property tests were conducted to decide the right curing temperature and the optimum amount of the curing agent. As a result, the capacitors of 7 $\mu \textrm{m}$ thick film with 10 nF/$\textrm{cm}^2$ and low leakage current were successfully demonstrated.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.67-73
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• 2012

After flash memory card(FMC) was manufactured by $B^2it$ process, interfacial reaction of silver bump with thermal stress was studied. To investigate bonding reliability of Ag bump, thermal shock and thermal stress tests were conducted and then examined on the crack between Cu land and Ag bump interface. Diffusion reaction of Ag bump/Cu land interface was analyzed using SEM, EDS and FIB. The Ag-Cu alloy layer due to the interfacial reaction was formed at the Ag/Cu interface. As the diffusivity of Ag ${\rightarrow}$ Cu is faster than Cu ${\rightarrow}$ Ag, a lot of (Cu, Ag) alloy layers were observed at the Cu layer than Ag. These alloy layers contributed to increase the Cu-Ag bonding strength and its reliability.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.67-72
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• 1989

Room Temperature Plasma Nitridation of silicon was investigated as a new LOCOS (local oxidation of silicon) process in order to reduce the bird's beak length. In $N_2$ plasma formed by 100kHz, 400W AC power, a thin silicon nitride film (<100${\AA}$) was uniformly grown on a silicon substrate. SEM studies showed that the nitride layer formed by this method can effectively protect the silicon from oxidation and reduce the bird's beak length to $0.2{mu}m$ when 4000${\AA}$ field oxide is grown. This is a considerable improvement comparing with 0.7${mu}m,$ the bird's beak, for the conventional LOCOS process using a thick LPCVD nitride. No appreciable crystalline defect could be found around the bird's beak with SEM cross-section afrer Secco etch. Leakage current tests were carried out on the $N^+/P^-$ well and $P^+/N^-$ well diodes formed by this new LOCOS process. The electrical tests indicate that this new process has electrical properties similar or superior to those of the conventional LOCOS process.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.53-59
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• 1988

Recently, the formation of the complexes between macrocyclic polyethers and alkali metal salts have been determined by several methods. It has been suggested that the specificity of the complexation be due to the nature of the surrounding solvent molecules. The formation constant values ($K_f$) of $K^+$ are shown to be the largest among the other alkali metal cations because the ionic diameter of $K^+$ is approximately the same with the hole size of 18-crown-6. In this study the formation constants of the 1 : 1 complexes of 18-crown-6 with potassium p-substituted phenoxide are calculated by the conductance measurement in organic solvents. As a result, the $K_f$ value series among organic solvents are given in the order of $CH_3$OH > DMF > DMSO. It seems that the donor number of the solvent is a main factor in the formation of the complex between $K^+$ metal ion and 18-crown-6 molecules. At the same time, the formation constants increase with increasing the electron-withdrawing power of substituents because the phenoxide ion is stabilized by the charge dispersion.

• Journal of the Korean Chemical Society
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• v.62 no.1
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• pp.24-29
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• 2018

Despite the great potential for the versatile applications in food industry and medical area, chitosan as a biocompatible cationic polysaccharide has suffered from the limited solubility under physiological condition. Herein, we demonstrated the electrostatic formation of chitosan-based polyplex particles, counterbalanced by polyacrylate as an anionic polyelectrolyte. The resulting polyplex exhibited pH- and composition-dependent changes in their surface charges as measured by zeta potential, which can be employed to provide the interparticle repulsive forces for enhanced colloidal stability in homogeneous solution. Subsequently, amide coupling between the acrylates and glucosamine residues of chitosan inside the polyplex further generated the hydrogel particles, which showed the temperature-sensitive swelling property. This aspect can be attributed to the partial formation of acryl amide residues, which have been generally known to possess the lower critical solution temperature (LCST).

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.196.1-196.1
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• 2015

전 세계적으로 환경에 대한 인식이 증대됨에 따라 친환경적인 소재의 개발 연구가 필요한 상황이고, 대표적으로 셀룰로오스를 이용한 종이기판을 활용하는 방안이 새로운 연구화두로 떠오르고 있다. 종이를 기본으로 한 전기전자 회로구성의 가능성을 보기위해 종이 위해 전자회로 구성요소를 형성시켜야 할 필요가 있다. 이를 위해 본 연구팀은 상용 복사 용지위에 마이크로 단위의 패터닝을 구현하는 연구를 진행하였다. 마이크로 패터닝 구현 방법은 다음과 3가지로 요약할 수 있다;1. 리소그래피 공정, 2. 메탈마크스를 사용한 물질 증착, 3. 잉크젯 프린팅. 리소그래피 공정을 위해서 발수처리를 한 종이 위에 실리콘기반 공정과 마찬가지로 레지스트를 코팅하고 노광과 디벨롭, 증착과 리프트오프 과정을 거쳤다. 공정 결과 패터닝이 어느 정도 잘 되는 것을 확인할 수 있었다. 두번째로 상용 메탈마스크를 제작하여 종이 위에 그대로 증착하는 방법을 사용하였다. 이 방법은 액상공정을 요구하지 않기 때문에 발수처리가 필요하지 않고 종이의 기본성질을 그대로 유지 할 수 있다는 장점이 있다. 마지막으로 잉크젯 프린팅 공정은 복사용지를 인쇄할 때 사용하는 간단한 상용프린터를 이용하였다. 이 방법은 앞의 두 공정보다는 다소 패턴 사이즈가 크다는 단점이 있지만 원하는 모양을 자유롭게 패터닝 할 수 있고 그만큼 대량 생산에 용이하다는 장점이 있다.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.235-239
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• 2002

A novel ultra-narrow linewidth DFB laser in the extended FBG ring cavity having kHz linewidth is presented. The method of linewidth compression was realized by introducing an extended fiber ring cavity into the cavity between the external FBG and the Bragg grating inside a DFB laser diode. Optimum optical feedback control was achieved by using an optical circulator and a variable optical attenuator to prevent mode hopping induced by spatial hole burning. To prove the validity of the proposed scheme, a self-heterodyne measurement set-up with fiber delay line of 63 km was utilized for the ultra-narrow linewidth measurement. A 3 dB linewidth of less than 3 kHz was demonstrated, which is resolution limited performance. This linewidth is equivalent to 3 dB linewidth of 2$\times$10$^{-8}$ nm.