• Korea-Australia Rheology Journal
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• v.14 no.2
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• pp.63-70
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• 2002

Chemical mechanical planarization (CMP) is the polishing process enabled by both chemical and mechanical actions. CMP is used in the fabrication process of the integrated circuits to achieve adequate planarity necessary for stringent photolithography depth of focus requirements. And recently copper is preferred in the metallization process because of its low resistivity. We have studied the effects of chemical reaction on the polishing rate and surface planarity in copper CMP by means of numerical simulation solving Navier-Stokes equation and copper diffusion equation. We have performed pore-scale simulation and integrated the results over all the pores underneath the wafer surface to calculate the macroscopic material removal rate. The mechanical abrasion effect was not included in our study and we concentrated our focus on the transport phenomena occurring in a single pore. We have observed the effects of several parameters such as concentration of chemical additives, relative velocity of the wafer, slurry film thickness or ash)tract ratio of the pore on the copper removal rate and the surface planarity. We observed that when the chemical reaction was rate-limiting step, the results of simulation matched well with the experimental data.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.103-110
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• 1993

Abstract It has been attempted to make the copper-graphite composites by deposition of copper on the surface of graphite through the hydrogen reduction of copper chlorides. Both KISH and natural graphites of less than 325 mesh were used as substrates and the hydrogen reduction also was conducted in the range of 350-50$0^{\circ}C$. The distribution of copper on the surface of graphite was found to increase with the decrease of reduction temperature. In addition. the partial pressure of hydrogen played an important role in the overall rate of reduction which was substantially dominated by the chemical reaction on the surface of each particle. It was concluded that the reduction temperature should be maintained as low as possible to accomplish the well distribution of copper in the composites.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.37-46
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• 2015

In this paper, the heat transfer characteristics of PCB (Printed Circuit Board) with cabon CCL (Copper Claded Layer) were studied through experiments and numerical analysis to compare of PCBs with conventional the FR-4 core and heavy copper cores. For study, samples are producted with HDI (High Density Interconnection) PCB of mobile phone with variations of thickness of core materials and grades of carbon material to evaluate heat transfer characteristics respectively. From this research results, heat transfer characteristics of the carbon core was rather low than heavy copper, but better than FR-4 core. In addition, even though the carbon and heavy copper core contributed on the heat transfer characteristics as their thickness increases, FR-4 cores disturbed heat transfer characteristics as it's thickness increases. Therefore, carbon core is recommendable to improve the heat transfer characteristics of the PCB because heavy copper core has much disadvantages such as increasing of wear of drill, the weight of PCB, and manufacturing cost by additional insulation materials for electrical insulation.

• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.237-241
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• 1999

The characteristics of copper thin films and via hole filling capability were investigated by pulsed electrodeposition method. Especially, the effects of additives on the properties of copper thin films were studied. Copper films, which were deposited by pulsed electrodeposition using commercial additives, had low tensile stress value under 83.4 MPa and high preferred Cu (111) texture. Via holes with $0.25{\mu}m$ in diameter and 6 : 1 aspect ratio were successfully filled without any defects by superfilling. It was observed that copper microstructure deformed by twining. After heat treatment at $500^{\circ}C$ for 1 k in vacuum furnace, grain size was 1 or 2 times as large as film thickness and the bamboo structure was formed. Heat treated copper films showed good resistivities of $1.8\~2.0{\mu}{\Omega}{\cdot}cm$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.409-409
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• 2013

최근, 집적 소자의 미세화에 따라 늘어난 배선 신호 지연 및 상호 간섭, 그리고 소비 전력의 증가는 초고집적 소자 성능 개선에 한계를 가져온다. 이에 따라 기존의 알루미늄(Al)/실리콘 절연 산화막은 구리(Cu)/저유전율 박막(low-k)으로 대체되고 있고, 이는 소자 성능 개선에 큰 영향을 미친다. 그러나 Cu는 Si과 low-k 내부로 확산이 빠르게 일어나 소자의 비저항을 높이고, 누설 전류를 일으키는 등 소자의 성능을 저하시킬 수 있는 문제점을 가지고 있다. 이러한 Cu의 확산을 막기 위하여 Ta, TaN 등과 같은 확산방지막에 대한 연구가 활발히 진행되어 왔으나, 배선 공정의 집적화와 low-k 대체에 따른 공정 및 신뢰성 문제로 인해 새로운 확산방지막의 개발이 필요하게 되었다. 이를 위해, 본 연구에서는 Cu-V 합금을 사용하여 low-k 기판 위에 확산방지막을 자가 형성 시키는 공정에 대한 연구를 진행하였다. 다양한 low-k 기판에서 열처리조건에 따른 Cu-V 합금의 특성을 확인하기 위해 4-point probe를 통한 비저항 평가와 XRD (X-ray diffraction) 분석이 이뤄졌다. 또한, TEM (transmission electron microscope)을 이용하여 $300^{\circ}C$에서 1 시간 동안 열처리를 거쳐 자가형성된 V-based interlayer가 low-k와 Cu의 계면에서 균일하게 형성된 것을 확인하였다. 형성된 V-based interlayer의 barrier 특성을 평가하고자 Cu-V합금/low-k/Si 구조와 Cu/low-k/Si 구조의 leakage current를 비교 분석하였다. Cu/low-k/Si 구조는 비교적 낮은 온도에서 leakage current가 급격히 증가하는 양상을 보였으나, Cu-V 합금/low-k/Si 구조는 $550^{\circ}C$의 thermal stress 에서도 leakage current의 변화가 거의 없었다. 이러한 결과를 바탕으로 열처리를 통해 자가형성된 V-based interlayer의 Cu/low-k 간 확산방지막으로서 가능성을 검증하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.798-801
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• 2000

For the performance enhancement of communication system, high quality filters are required. Also a minimization of size of filter is required for the interation of devices in the limited area. Conventional metal filters made of copper can be substituted by high quality high temperature superconducting(HTS) films for better performance. Hairpin type filters have been designed with the center frequency 14 GHz for the size reduction. 3-pole and 4-pole filters centered at 14 GHz with the bandwidth of about 300 MHz were designed and fabricated. With the simulation results, the frequency responses showed low insertion loss and sharp skirts characteristics. The frequency response of HTS 14 GHz fi1ter was measured at 77 K and compared with the simulation results. We have compared YBCO filters and copper filters which were made with the same design rules. Simulated and measured frequency responses reveal that HTS YBCO hairpin type bandpass filters show better performance than copper filters.

• Journal of the Korean Chemical Society
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• v.23 no.2
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• pp.80-87
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• 1979

The active site for the formation of acrolein in propylene oxidation reaction over copper(Ⅱ)-exchanged zeolite Y has been studied. At the early stage of the reaction, the formation of hydrocarbons was observed. The formation of hydrocarbons decreased gradually during the course of reaction, apparently due to the poisoning the Bronsted acid sites. The formation of acrolein was quite low when the formation of hydrocarbons was proceeding. The formation of acrolein was depend on the copper ion content and this can be related to the availability of the copper ions inside the supercage. It seems that it is the copper ion not the Bronsted acid site which is primarily responsible for the formation of acrolein.

• Environmental Analysis Health and Toxicology
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• v.24 no.2
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• pp.107-117
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• 2009

Metal pollution of aquatic ecosystems is a problem of economic and health importance. Information regarding molecular responses to metal exposure is sorely needed in order to identify potential biomarkers. To determine the effects of heavy metals on chironomids, the full-length cDNA of alcohol dehydrogenase (ADH3) from Chironomus riparius was determined through molecular cloning and rapid amplification of cDNA ends (RACE). The expression of ADH3 was analyzed under various cadmium and copper concentrations. A comparative and phylogenetic study among different orders of insects and vertebrates was carried out through analysis of sequence databases. The complete cDNA sequence of the ADH3 gene was 1134 bp in length. The sequence of C. riparius ADH3 shows a low degree of amino acid identity (around 70%) with homologous sequences in other insects. After exposure of C. riparius to various concentrations of copper, ADH3 gene expression significantly decreased within 1 hour. The ADH3 gene expression was also suppressed in C. riparius after cadmium exposure for 24 hour. However, the effect of cadmium on ADH3 gene expression was transient in C. riparius. The results show that the suppression of ADH3 gene by copper exposure could be used as a possible biomarker in aquatic environmental monitoring and imply differential toxicity to copper and cadmium in C. riparius larvae.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.265-273
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• 2016

The effects of surface modification by nitric acid on the pre-treatment of electroless copper plating were investigated. Copper was electroless-plated on the nitric acid treated graphite activated by a two-step pre-treatment process (sensitization + activation). The chemical state and relative quantities of the various surface species were determined by X-ray photoelectron spectroscopy (XPS) after nitric acid modification or pre-treatment. The acid treatment increased the surface roughness of the graphite due to deep and fine pores and introduced the oxygen-containing functional groups (-COOH and O-C=O) on the surface of graphite. In the pre-treatment step, the high roughness and many functional groups on the nitric acid treated graphite promoted the adsorption of Sn and Pd ions, leading to the uniform adsorption of catalyst ($Pd^0$) for Cu deposition. In the early stage of electroless plating, a lot of tiny copper particles were formed on the whole surface of acid treated graphite and then homogeneous copper film with low variation in thickness was formed after 30 min.

• Nutritional Sciences
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• v.9 no.1
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• pp.29-34
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• 2006

Purified rat liver aryl sulfotransferase IV (AST IV) was found to be inhibited in vitro by zinc, copper, cadmium and terbium. Among these four elements, zinc, copper and cadmium were all strongly inhibitory to the AST IV activity at very low concentrations (2.5 $\mu$M to 0.025 $\mu$M). In rat liver cytosol, zinc, copper and cadmium at 25 $\mu$M to 0.025 $\mu$M also decreased the AST IV activity to $50\%$ of the controls. In order to assess the possible effects of these metals on the AST IV activity recovery pattern in vivo, studies on the relationship between these minerals and dietary 2-acetylaminofluorene were conducted. Total of forty rats were fed one of five diets for 6 weeks: diet 1, Control diet plus 2-acetlyaminofluorene ($0.05\%$); diet 2, zinc-deficient diet plus 2-acetlyaminofluorene; diet 3, zinc-supplement diet plus 2-acetylaminofluorene; diet 4, copper-supplement diet plus 2-acetylaminofluorene; diet 5, cadmium-supplement diet plus 2-acetylaminofluorene. Half of the rats from each diet were changed to individual diet after 3 weeks of 2-acetylaminofluorene feeding. Placement of rats on the control diet following one cycle of 2-acetylaminofluorene feeding of 3 weeks without 2-acetylaminofluorene resulted in nearly full recovery of AST IV activity within 3 or 4 weeks. However, the rats fed diets that supplemented with zinc, copper or cadmium without 2-acetylaminofluorene showed a new pattern of lowered AST IV activity as early as the first cycle. Also, lowering in cytosolic AST IV contents was appeared in the livers from the rats, following one cycle of 2-acetylaminofluorene feeding of 3 weeks, fed one of the diets that supplemented with copper, cadmium or zinc without 2-acetylaminofluorene for ensuing 3 weeks.