Effect of Effective Modulus on Hillock Formations in Al Lines on Glass

박일목,황수정,주영창,이제훈 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.4

The formations of top and side hillocks in aluminum (Al) lines on glass substrate were studied through scanning electron microscopy (SEM) images. The density of top hillock in Al lines with Mo capping layer was smaller than that of Al film without capping layer because the capping layer physically suppressed the formation of top hillock. Instead, side hillock as well as top hillock was observed in the lines. The density of side hillock increased when thicker capping layer was deposited on Al line. Based on the results of the finite element method (FEM) simulation, it is determined that this is because thicker capping layer causes the larger effective modulus in the line center part and the smaller effective modulus in the line edge part. The formations of top and side hillocks in aluminum (Al) lines on glass substrate were studied through scanning electron microscopy (SEM) images. The density of top hillock in Al lines with Mo capping layer was smaller than that of Al film without capping layer because the capping layer physically suppressed the formation of top hillock. Instead, side hillock as well as top hillock was observed in the lines. The density of side hillock increased when thicker capping layer was deposited on Al line. Based on the results of the finite element method (FEM) simulation, it is determined that this is because thicker capping layer causes the larger effective modulus in the line center part and the smaller effective modulus in the line edge part.

E-Magnetron 스퍼터링에 의한 $Al_xTa_{1-x}$ 합금박막의 성장 및 구조적, 전기적 특성 분석

송대권,이종원,전종한 한국마이크로전자및패키징학회 2003 마이크로전자 및 패키징학회지 Vol.10 No.2

본 연구에서는 RF-Magnetron 스퍼터링 장치를 이용하여 $Al_xTa_{1-x}$(x=0.0∼1.0) 합금박막을 성장하였고, 4탐침법, XRD, AFM, micro-Vickers 미소경도계를 사용하여 시료의 구조적, 기계적, 전기적 특성을 분석하였다. Al조성 x=0.245(Al 24.5 at.%)에서 전기저항이 가장 높게 나타났고, 결정질이 가장 우수하였다. 표면 hillock에 있어서는 낮은 Al 조성영 역에서는 x가 증가할수록 hillock이 감소하다가, x=0.245에서 hillock이 완전히 배제되었고, 이후 x 증가에 따라 hillock 밀도가 다시 급격히 증가하였다. 미소경도의 경우, Al조성 x=0.2∼0.45의 영역에서 가장 높은 경도값이 측정되었다. 본 연구의 모든 결과를 종합적으로 고려할 때, $Al_xTa_{1-x}$ 합금박막의 결정질, 전기저항, 표면형상, 미소경도는 상호 밀접한 관계를 가지고 있었으며, Al 조성 x=0.245에서 가장 우수한 물리적 특성이 나타났다. In this study, $Al_xTa_{1-x}$(x=0.0∼1.0) alloy thin films were grown by RF-Magnetron sputtering system, and the structural, mechanical and electrical properties of samples were examined by 4-point probe, XRD, AFM and micro-Vickers hardness profiler. The electrical resistivity was maximum and the crystal quality was optimum for the samples with Al content x=0.245 (Al 24.5 at.%). Regarding the surface hillock formation, the hillock density decreased with an increase of Al content for the low Al content range, and the hillock was eliminated for the sample with Al=24.5 at.%. The hillock density increased with the further increase of Al content. The high values of micro-Vickers hardness were obtained for the samples with x=0.2∼0.45. The results obtained demonstrate that the crystal quality, electrical resistivity, surface morphology and micro-hardness are closely inter-related, and that the optimum physical properties are obtained for the sample with x=0.245.

화학적 에칭에서 교반속도 및 에칭 시간에 따른 유리 표면에서의 요철 형성과 Haze 및 투과도

손정일,김남혁,김광수 순천향대학교 부설 산업기술연구소 2016 순천향 산업기술연구소논문집 Vol.22 No.1

We investigated the effect of stirring speed and etching time on the hillock formation, haze and transmittance on the chemically etched glass. The chemical etching process were carried out by two steps. The Buffered hydrofluoric(BHF) acid was used for etching solution on the first step etching process. The BHF solution was made by mixture of HF, NH4F and distilled water. The combined solution with BHF and hydrochloric acid(HCl) was selected as the second step etching solution. The first etching process was performed on the several etching times and two different stirring speeds such as 100 and, 300rpm. The hillock formation was observed on the substrate glass after 1st step chemical etching process. The hillock was appeared to be protuberant on the surface. The density of the hillock was increased and the size of hillock was decreased as increasing stirring speed. The density of the hillock was also increased as increasing etching time. The micro-sized hillock on the surface was responsible for the haze and transmittance. The haze value was increased as increasing etching time and also as reducing stirring speed. While, the transmittance of the etched glass displayed pretty much constant values, like about 92%. However, the haze value could be reduced as experiencing the 2nd step etching process. It was also observed that the hillock was analyzed as ammonium based crystals by XRD and these crystals were dissolved after 2nd etching process.

Al 박막의 힐록 형성에 미치는 Mo 하부층의 영향에 관한 실시간 분석

이용덕,황수정,이제훈,주영창,박영배,Lee, Yong-Duck,Hwang, Soo-Jung,Lee, Je-Hun,Joo, Young-Chang,Park, Young-Bae 한국재료학회 2007 한국재료학회지 Vol.17 No.1

The in-situ scanning electron microscopy observation of real-time hillock evolution in pure hi thin films on glass substrate during Isothermal annealing was analyzed quantitatively to understand the compressive stress relaxation mechanism by focusing on the effect of Mo interlayer between Al film and glass substrate. There is a good correlation between the hillock-induced stress relaxation by in-situ scanning electron microscopy observation ana the measured stress relaxation by wafer curvature method. It is also clearly shown that the existence of Mo interlayer plays an important role in hillock formation probably due to the large difference in interfacial diffusivity of Al films.

이온 주입과 기판 온도 효과에 의한 Al-1%Si 박막의 Hillock 형성 특성

최창억,이용봉,김정호,Choi, Chang-Auk,Lee, Yong-Bong,Kim, Jeong-Ho 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.1

As packing density in integrated circuits increases, multilevel metallization process has been widely used. But hillock formed in the bottom layers of aluminum are well known to make interlayer short in multilevel metallization. In this study, the effects of ion implantation to the metal film and deposition temperature on the hillock formation were investigated. The Al-1%Si thin film of $1{\mu}m$ thickness was DC sputtered with substrate ($SiO_2/Si$) temperature of $20^{\circ}C$, $200^{\circ}C$, and $400^{\circ}C$, respectively. Ar ions ($1{\times}10^{15}cm^{-2}$: 150 keV) and B ions ($1{\times}10^{15}cm^{-2}$, 30 keV, 150 keV) were implanted to the Al-Si thin film. The deposited films were evaluated by SEM, surface profiler and resistance measuring system. As a results, Ar implanting to Al-Si film is very effective to reduce hillock size in the metal deposition temperature below than $200^{\circ}C$, and B implanting to an Al-Si film is effective to reduce hillock density in the high temperature deposition conditions around $400^{\circ}C$. Line width less than $3{\mu}m$ was free of hillock after alloying.

A model for power law creep controlled hillock growth

Berla, L.A.,Joo, Y.C.,Nix, W.D. Elsevier Sequoia 2008 Materials science & engineering. properties, micro Vol.488 No.1

A model for power law creep controlled hillock growth is developed. We first develop closed form solutions for the growth of a hillock and the corresponding stress relaxation in a film using a power law creep constitutive law that includes a threshold stress for creep. This general model is then adapted to describe hillocking in aluminum films by including the effect of power law breakdown and using an incremental solution technique. The model is used to predict hillock growth and the corresponding stress relaxation kinetics in aluminum thin films, and the results are compared to the predictions of Chaudhari's diffusion controlled model. Chaudhari's model predicts that hillocks in aluminum will rapidly grow to large, empirically unaccountable volumes, whereas the power law model can be made to match the experiments with a suitable choice of the threshold stress.

A model for hillock growth in Al thin films controlled by plastic deformation

Hwang, S.J.,Nix, W.D.,Joo, Y.C. Elsevier Science 2007 Acta materialia Vol.55 No.15

The dependence of total hillock volume (per unit area) on film thickness and annealing temperature has been studied in pure aluminum films. The total hillock volume (per unit area) increases linearly with both the film thickness and annealing temperature. Other characteristics involve a critical temperature and a critical thickness for hillock formation. It is shown that these phenomena can be explained by assuming that hillock growth is controlled by plastic deformation in the surrounding film. A simple analytical model is developed to account for these observations.

스퍼터로 성장된 알루미늄 박막의 공정 변수와 박막 두께에 따른 물성

오일권,윤창모,장진욱,김형준,Oh, Il-Kwon,Yoon, Chang Mo,Jang, Jin Wook,Kim, Hyungjun 한국재료학회 2016 한국재료학회지 Vol.26 No.8

We developed an Al sputtering process by varying the plasma power, process temperature, and film thickness. We observed an increase of hillock distribution and average diameter with increasing plasma power, process temperature, and film thickness. Since the roughness of a film increases with the increase of the distribution and average size of hillocks, the control of hillock formation is a key factor in the reduction of Al corrosion. We observed the lowest hillock formation at 30 W and $100^{\circ}C$. This growth characteristic of sputtered Al thin films will be useful for the reduction of Al corrosion in the future of the electronic packaging field.

고농도의 포도당이 배양중 혈관사이세포의 세포바깥기질단백합성과 미세구조에 미치는영향

김주영,이융창 대한해부학회 1993 Anatomy & Cell Biology Vol.26 No.2

Fabrication of Thermally Evaporated Al Thin Film on Cylindrical PET Monofilament for Wearable Computing Devices

Yang Liu,김은주,한정인 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.1

During the initial development of wearable computing devices, theconductive fibers of Al thin film on cylindrical PET monofilament werefabricated by thermal evaporation. Their electrical current-voltagecharacteristics curves were excellent for incorporation into wearable devicessuch as fiber-based cylindrical capacitors or thin film transistors. Theirsurfaces were modified by UV exposure and dip coating of acryl or PVP toinvestigate the surface effect. The conductive fiber with PVP coatingshowed the best conductivities because the rough surface of the PETsubstrate transformed into a smooth surface. The conductivities of PET fiberwith and without PVP were 6.81 × 103 Ω−1cm−1 and 5.62 × 103 Ω−1cm−1,respectively. In order to understand the deposition process of Al thin film oncylindrical PET, Al thin film on PET fiber was studied using SEM (ScanningElectron Microscope), conductivities and thickness measurements. Hillockson the surface of conductive PET fibers were observed and investigated byAFM on the surface. Hillocks were formed and grown during Al thermalevaporation because of severe compressive strain and plastic deformationinduced by large differences in thermal expansion between PET substrateand Al thin film. From the analysis of hillock size distribution, it turns outthat hillocks grew not transversely but longitudinally.