• Journal of the Korean Electrochemical Society
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• v.10 no.2
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• pp.94-103
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• 2007

The transition of interconnection metal from aluminum alloy to copper has been introduced to meet the requirements of high speed, ultra-large scale integration, and high reliability of the semiconductor device. Since copper, which has low electrical resistivity and high resistance to degradation, has different electrical and material characteristics compared to aluminum alloy, new related materials and processes are needed to successfully fabricate the copper interconnection. In this review, some important factors of multilevel copper damascene process have been surveyed such as diffusion barrier, seed layer, organic additives for bottom-up electro/electroless deposition, chemical mechanical polishing, and capping layer to introduce the related issues and recent research trends on them.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.229-229
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• 2012

Adhesion of Copper film on the aluminum oxide layer formed by anodizing an aluminum plate was enhanced by applying ion beam mixing method. Forming an conductive metal layer on the insulating oxide surface without using adhesive epoxy bonds provide metal-PCB(Printed Circuit Board) better thermal conductivities, which are crucial for high power electric device working condition. IBM (Ion beam mixing) process consists of 3 steps; a preliminary deposition of an film, ion beam bombardment, and additional deposition of film with a proper thickness for the application. For the deposition of the films, e-beam evaporation method was used and 70 KeV N-ions were applied for the ion beam bombardment in this work. Adhesions of the interfaces measured by the adhesive tape test and the pull-off test showed an enhancement with the aid of IBM and the adhesion of the ion-beam-mixed films were commercially acceptable. The mixing feature of the atoms near the interface was studied by scanning electron microscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2380-2382
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• 2005

UV-LIGA 공정을 이용하여 3차원 마이크로 인덕터 제작 기술에 관하여 연구하였다. 마이크로 인덕터의 코일, 비아(via), 코어(core)의 Multi-layer 제작을 위해 UV-LIGA 공정을 이용하였으며, 전해도금(electro plating)을 위한 씨올기(seed layer)로서는 e-beam evaporator를 이용하여 금속을 증착하였다. 3차원 마이크로 인덕터의 도금 방법으로는 전해도금을 사용하였으며, 코일과 비아 부분은 구리(Cu) 전해도금, 코어 부분은 니켈(Ni)과 철(Fe)의 합금인 퍼멀로이(Ni/Fe) 전해도금을 하였다. 3차원 마이크로 인덕터의 샘플크기로는 코어의 폭은 $300{\mu}m$, 전체 길이는 9.2mm, 두께는 $20{\mu}m$의 구조로 제작되었으며, 코일 부분은 폭이 $40{\mu}m$, 두께는 $30{\mu}m$이며, 코일턴 수는 70회의 구조로 제작하였다.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.217-221
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• 2015

Developing a metallization that has low cost and high efficiency is essential in solar-cell industries, to replace expensive silver-based metallization. Ni/Cu two-step metallization is one way to reduce the cost of solar cells, because the price of copper is about 100 times less than that of silver. Alkaline electroless plating was used for depositing nickel seed layers on the front electrode area. Prior to the nickel deposition process, 2% HF solution was used to remove native oxide, which disturbs uniform nickel plating. In the subsequent step, a nickel sintering process was carried out in $N_2$ gas atmosphere; however, copper was plated by light-induced plating (LIP). Plated nickel has different properties under different bath conditions because nickel electroless plating is a completely chemical process. In this paper, plating bath conditions such as pH and temperature were varied, and the metal layer's structure was analyzed to investigate the adhesion of Ni/Cu metallization. Average adhesion values in the range of 0.2-0.49 N/mm were achieved for samples with no nickel sintering process.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.3
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• pp.31-36
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• 2000

We developed embedded inductors in MCM-D substrate for RF applications. The increasing demand for high density packaging was the driving forces to the development of MCM-D technology. Most of these development efforts have been focused on high performance digital circuits. However, recently there is a great need fur mixed mode circuits with a combination of digital, analog and microwave devices. Mixed mode modules often have a large number of passive components that are connected to a small number of active devices. Integration of passive components into the high density MCM substrate becomes desirable to further reduce cost, size, and weight of electronic systems while improving their performance and reliability. The proposed MCM-D substrate was based on Cu/photosensitive BCB multilayer and Ti/Cu is used to form the interconnect layer. Seed metal was formed with 1000 $\AA$ Ti/3000 $\AA$ Cu by sputtering method and main metal was formed with 3 $\mu\textrm{m}$ Cu by electrical plating method. The multi-turn sprial inductors were designed in coplanar fashion. This paper describe the manufacturing process of integrated inductors in MCM-D substrate and the results of electrical performance test.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.29.2-29.2
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• 2009

구리는 낮은 비저항, 높은 열전도도, 우수한 electromigration(EM)저항특성 등을 바탕으로 차세대 nano-scale집적회로의 interconnect application에 적합한 금속재료로서 각광받고 있다. copper interconnect는 damascene process 를주로 이용하는데 CVD를 이용하면 step coverage가우수한 seed layer얻을 수 있어 고집적 소자의 구현이 가능하다. 최근에 비 균등화 반응(disproportionationreaction)을 이용하여 고 순도 구리박막을 제조하기위해 $\beta$-diketonate Cu(I) Lewis-base의 전구체를 많이 이용하는데 그중에서 hexafluoroacetylacetonate(hfac)Cu(I)vinyltrimethylsilane (VTMS)가 널리 이용되고 있다. 그러나 (hfac)Cu(I)(VTMS) 또는 유사계열의 전구체들은 열적안정성및 보관안정성이 부족하여 실제 양산공정에 적합하지 못한 단점이 있었다. 본 연구에 이용된 2가 전구체Cu(dmamb)2는 높은 증기압($70^{\circ}C$, 0.9torr)을 가지며 종래에 주로 이용하던 1가 전구체 (hfac)Cu(VTMS)에 비해 높은 활성화 에너지(~113 kJ/mol)를가짐으로서 열적안정성 및 보관안정성이 우수하다. 다른 한편으로 2가전구체는 안정성이 우수한 만큼 낮은 증기압을 극복하기 위해 리간드에 플루오르를 주로 치환하여 증기압을 높이는데 플루오르는 성장하는 박막의 접착력을약하게 하는 단점을 가진다. 하지만 본 연구에 사용된 Cu(dmamb)2는 리간드에 플루오르를 포함하지 않으며, 따라서 고품질의 박막을 용이한성장환경에서 제조할 수 있는 장점들을 제공한다. 비활성가스 분위기에서 2가전구체는 열에너지에 의해 리간드의 자가환원에따라 금속-리간드 분해가 발생한다. 하지만 수소분위기에서는수소가 환원제로 작용하여 리간드의 분해를 용이하게 하는 특징을 가지며 따라서 비활성분위기일 때 비해 낮은 성장온도를 가진다. 또한 수소는 잔류하는 리간드 및 불순물과 결합하여 휘발성화학종들을 생성하여 고순도의 구리박막제조를 가능하게한다.

• Electrical & Electronic Materials
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• v.28 no.2
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• pp.25-33
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• 2015

Ruthenium (Ru) thin films were grown on thermally-grown $SiO_2$ substrates by atomic layer deposition (ALD) using a sequential supply of four kinds of novel zero-valent Ru precursors, isopropyl-methylbenzene-cyclohexadiene Ru(0) (IMBCHDRu, $C_{16}H_{22}Ru$), ethylbenzen-cyclohexadiene Ru(0) (EBCHDRu, $C_{14}H_{18}Ru$), ethylbenzen-ethyl-cyclohexadiene Ru(0) (EBECHDRu, $C_{16}H_{22}Ru$), and (ethylbenzene)(1,3-butadiene)Ru(0) (EBBDRu, $C_{12}H_{16}Ru$) and molecular oxygen (O2) as a reactant at substrate temperatures ranging from 140 to $350^{\circ}C$. It was shown that little incubation cycles were observed for ALD-Ru processes using these new novel zero-valent Ru precursors, indicating of the improved nucleation as compared to the use of typical higher-valent Ru precursors such as cyclopentadienyl-based Ru (II) or ${\beta}$-diketonate Ru (III) metallorganic precursors. It was also shown that Ru nuclei were formed after very short cycles (only 3 ALD cycles) and the maximum nuclei densities were almost 2 order of magnitude higher than that obtained using higher-valent Ru precursors. The step coverage of ALD-Ru was excellent, around 100% at on a hole-type contact with an ultra-high aspect ratio (~32) and ultra-small trench with an aspect ratio of ~ 4.5 (top-opening diameter: ~ 25 nm). The developed ALD-Ru film was successfully used as a seed layer for Cu electroplating.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.357.2-357.2
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• 2014

Ruthenium (Ru) 박막은 우수한 화학적 열적 안정성 및 높은 일함수(4.7eV) 특성으로 인해 20 nm급 이하의 차세대 DRAM capacitor의 전극 물질 및 Cu metalization을 위한 seed layer로 각광을 받고 있다. Ru박막의 나노스케일 정보전자소자로의 적용을 위해서는 두께제어가 용이하고 3D 구조에서 우수한 단차 피복 특성을 갖는 atomic layer deposition (ALD)을 이용한 박막 형성이 필수적이다. 이에 본 연구에서는 ALD 방법을 이용하여 0가의(cymene) (1,5-hexadiene) Ru (0) (C16H24Ru) 전구체를 합성, ALD 방법을 이용하여 우수한 초기성장거동을 갖는 Ru 박막을 증착 하였다. 형성된 Ru 박막의 표면 형상, 두께, 밀도를 주사전자현미경(Scanning electron microscopy)과 X-선 반사율 측정(X-ray reflectometer)으로 조사하였다. 또한 전기적 특성을 4침법(four-point-probe)으로 측정하였고, 박막의 화학적 조성과 결정성의 정보를 X-선 광전자분광법(X-ray photoelectron spectroscopy)과 X-선 회절(X-ray diffraction)을 이용하여 확인하였다.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.196-203
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• 2019

We report on the fabrication and characterization of an oxide photoanode with a zinc oxide (ZnO) nanorod array embedded in cuprous oxide ($Cu_2O$) thin film, namely a $ZnO/Cu_2O$ oxide p-n heterostructure photoanode, for enhanced efficiency of visible light driven photoelectrochemical (PEC) water splitting. A vertically oriented n-type ZnO nanorod array is first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type $Cu_2O$ thin film is directly electrodeposited onto the vertically oriented ZnO nanorod array to form an oxide p-n heterostructure. The introduction of $Cu_2O$ layer produces a noticeable enhancement in the visible light absorption. From the observed PEC current density versus voltage (J-V) behavior under visible light illumination, the photoconversion efficiency of this $ZnO/Cu_2O$ p-n heterostructure photoanode is found to reach 0.39 %, which is seven times that of a pristine ZnO nanorod photoanode. In particular, a significant PEC performance is observed even at an applied bias of 0 V vs $Hg/Hg_2Cl_2$, which makes the device self-powered. The observed improvement in the PEC performance is attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential including the light absorption and separation processes of photoinduced charge carriers, which provides a new avenue for preparing efficient photoanodes for PEC water splitting.

• Journal of Magnetics
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• v.10 no.4
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• pp.163-170
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• 2005

The RF integrated noise filters are fabricated by photolithography. The stack for the electromagnetic noise filters consists of the nano-granular ($Co_{41}Fe_{38}AI_{13}O_8$) soft magnetic film / $SiO_2$ / Cu transmission line / seed layer (Cu/Ti) / $SiO_2$-substrate. A good signal-attenuation feature along with a low signal-reflection feature is observed in the present filters. Especially in the noise filter incorporated with a $Co_{41}Fe_{38}AI_{13}O_8$ magnetic film with lateral dimensions of $2000{\mu}m$ wide, 15 mm long and $1{\mu}m$ thick, the maximum magnitude of signal attenuation reaches -55 dB, and the magnitude of signal reflection is below -10 dB in the overall frequency range. And this level of signal attenuation is much larger than that of a noise filter incorporated with a Fe magnetic film.