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1.
C. A. Ross J. S. Drewery R. E. Somekh J. E. Evetts 《Journal of Electronic Materials》1990,19(9):911-918
The electromigration lifetime of integrated circuit metallisation is commonly found to increase if the metallisation is covered
with a passivation layer such as glass. We have investigated the electromigration behaviour of aluminium conductor stripes
under different thicknesses of oxide passivation formed by anodisation. The ionic drift velocity of anodised stripes was measured
using the Blech-Kinsbron edge displacement technique (Thin Solid Films
25 327 (1975)) and it was found that the drift velocity decreased with increasing anodisation thickness. Stripes tested with
a reversed current drifted backwards with an initial velocity which exceeded the original forward velocity. These results
are related to a change in the self-diffusivity of aluminium as a result of high compressive stresses imposed by the anodised
layer, and the distribution of stress in a drifting stripe is discussed. A general conclusion is that passivation layers can
support compressive stresses sufficient to retard mechanical failure processes in metallisation in two distinct ways, either
by raising the threshold stress for the nucleation of damage such as hillocks or whiskers, or by reducing the diffusivity
in the metallisation. 相似文献
2.
Thermomechanical stress and strain in the solder joints of a dummy area array package were studied as electromigration occurred.
A current density of 0.4 × 104 A/cm2 was applied to this package, constructed with 9 × 9 solder joints in a daisy chain, to perform the electromigration test.
After 37 h, the first joint on the path of the electron flow broke off at the cathode, and the first three solder joints all
exhibited a typical accumulation of intermetallic compounds at the anode. Different solder joints exhibited dissimilar electromigration
states, such as steady state and nonsteady state. Finite element analysis indicated that during steady-state electromigration,
although the symmetrical structure produced uniform distributions of current density and Joule heating in all solder joints,
the distribution of temperature was nonuniform. This was due to the imbalanced heat dissipation, which in turn affected the
distribution of thermomechanical stress and strain in the solder joints. The maximum thermomechanical stress and strain, as
well the highest temperature and current crowding, appeared in the Ni/Cu layer of each joint. The strain in the Ni/Cu layer
was significant along the z-axis, but was constrained in the x–y plane. The thermomechanical stress and strain increased with advancing electromigration; thus, a potential delamination between
the Ni/Cu layer and the printed circuit board could occur. 相似文献
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Sang-Su Ha Jong-Woong Kim Jeong-Won Yoon Sang-Ok Ha Seung-Boo Jung 《Journal of Electronic Materials》2009,38(1):70-77
The electromigration of conventional Sn-37Pb and Pb-free Sn-3.0Ag-0.5Cu (in wt.%) solder bumps was investigated with a high
current density of 2.5 × 104 A/cm2 at 423 K using flip-chip specimens comprised of an upper Si chip and a lower bismaleimide triazine (BT) substrate. Electromigration
failure of the Sn-37Pb and Sn-3.0Ag-0.5Cu solder bumps occurred with complete consumption of electroless Ni immersion Au (ENIG)
underbump metallization (UBM) and void formation at the cathode side of the solder bump. Finite element analysis and computational
simulations indicated high current crowding of electrons in the patterned Cu on the Si chip side, whereas the solder bumps
and Cu line of the BT substrate had a relatively low density of flowing electrons. These findings were confirmed by the experimental
results. The electromigration reliability of the Sn-3.0Ag-0.5Cu solder joint was superior to that of Sn-37Pb. 相似文献
6.
L. W. Chu W. K. Chim K. L. Pey J. Y. K. Yeo L. Chan 《Journal of Electronic Materials》2001,30(12):1513-1519
Electromigration stress can give rise to voids that increase the resistance and localized thermal stress in interconnects.
Estimation of the extent of voiding can provide information on the material quality and the amount of degradation that has
resulted from the electrical stress. In this paper, a model is proposed that can be used to estimate the effective void volume
in deep-submicrometer interconnects. The model uses a combination of low-frequency noise and resistance measurements, and
also considers the thermal coefficient of resistance in calculating the change in resistance of the interconnect line. A deconvolution
scheme was employed to extract the 1/f noise component from the noise-measurements to improve the accuracy of the extraction
algorithm. To verify the accuracy of the model, the focused ion beam (FIB) technique was used to mill holes (to simulate voids)
of known dimensions. The model was further applied to an electromigration stress study of aluminum (Al) interconnects as a
method of testing its validity for stress-induced voids. The proposed technique is a useful reliability tool for void detection
in deep-submicrometer interconnects. 相似文献
7.
Contact electrification (CE) is one of the oldest topics in physics, which has been discussed for more than 2600 years. Recently, an overlapped electron‐cloud (OEC) model was proposed by Wang to explain all types of CE phenomena for general materials in which a deep overlapping of electron clouds belonging to two atoms results in a lowered potential barrier for electron transfer from one to the other by applying a compressive force, which is simply referred to as Wang transition for CE. Here, the degree of electron‐cloud overlap between two atoms is controlled by using tapping mode atomic force microscopy. A temperature difference and electric field are applied between atoms of two surfaces. It is found that electron transfer only occurs when the contact tip and sample interact in the repulsive‐force region, which corresponds to a strong overlap of the electron clouds. Such a fact even preserves if the tip is at a higher temperature than the sample for 120 K. Alternatively, by applying a bias, electron tunneling would occur when the tip is in the attractive‐force region within which normal electron transfer would not occur. These studies solidify the overlapped electron‐cloud model first proposed by Wang. Further, the temperature and bias effects on the CE are explained based on a modified OEC model. 相似文献
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为研究静压桩在贯入过程中受力特性及后期的残 余应力分布特征,通过刻槽法在模 型桩身安装光纤光栅(fiber Bragg grating,简称FBG)传感器,及安装于桩端的微型硅压 阻式土压力传感器,测得了桩端阻力和桩侧摩阻力等随贯入深度的变化规律,通过试验明确 了均质黏性土中静压桩的贯入特性。试验结果表明:光纤光栅传感技术能够较好的满足黏性 土中静压沉桩特性的测试需求,成功测得沉桩阻力的分布及变化规律;在均质黏性土中沉桩 时,桩侧阻力与桩端阻力的所占比例是变化的。在沉桩初期,桩侧阻力所占比例较小,而在 沉桩中后期,侧摩阻力所占比例不断增大,但桩端阻力所占比例仍高于桩侧阻力所占比例; 桩侧摩阻力存在退化现象,且退化程度和退化速率随贯入深度的增加逐渐减小;桩身施工残 余应力随深度的增加先增大后减小,其中性点约在距桩顶9D处,而桩侧残余摩阻力随深度的 增加呈先增大后减小的趋势,由负摩阻力逐步转变为正摩阻力。研究结果可为黏性土地基静 压桩的工程实践提供借鉴与参考。 相似文献
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降水是一种常见的自然现象,在气候调节中起着极为重要的作用. 同时,由于降水在空间、时间上的不均匀性,会发生诸如洪涝、干旱等自然灾害,给人类的经济、生活等造成严重影响,为了防治这类自然灾害,需要我们进行准确而及时的降水监测. 本文使用人工智能的手段,将无线电在传播过程中由于降水引起的衰减作为研究对象,尝试从不同的衰减中找到降水量信息,进而达到降水监测的目的. 实测结果表明,使用通信基站作为信号源,以数据采集时的标准的气象降水信息作为标签,神经网络成功地学习到了衰减特征,且实验准确率在95%左右. 这说明,使用无线电传播链路结合人工智能的方法进行降雨监测是一种新型的降雨测量方法,具有一定的研究意义. 相似文献
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西北半干旱区激光雷达探测卷云几何特征和光学厚度 总被引:1,自引:0,他引:1
为了研究中国西北半干旱区卷云几何特征和光学特性的时空分布特征,我们利用兰州大学半干旱气候与环境观测站(SACOL,35.95°N,104.14°E)的微脉冲激光雷达(MPL-4B)探测卷云过程,分析讨论了卷云的结构、光学性质及其时间变化特征,结果表明,卷云高度分布范围为7-10km,卷云经历了薄-厚-薄的过程,平均厚度为2.0±0.5km。卷云环境温度在-51~-39℃范围之内。卷云的光学厚度在0.084-1.649之间,光学厚度随几何厚度的增加而增大,平均光学厚度为0.651±0.403。多次散射效应对光学厚度大于0.3的卷云影响较大。卷云激光雷达比为17±17sr。薄卷云的激光雷达比要比厚卷云的大。光学厚度小于0.3的光学薄卷云出现高度在8.6km以上,环境温度低于-45℃,几何厚度小于1.5km,雷达比分布在5-69 sr。 相似文献
14.
Simultaneously Achieved High Open‐Circuit Voltage and Efficient Charge Generation by Fine‐Tuning Charge‐Transfer Driving Force in Nonfullerene Polymer Solar Cells 下载免费PDF全文
Ailing Tang Bo Xiao Yuming Wang Feng Gao Keisuke Tajima Haijun Bin Zhi‐Guo Zhang Yongfang Li Zhixiang Wei Erjun Zhou 《Advanced functional materials》2018,28(6)
To maximize the short‐circuit current density (JSC) and the open circuit voltage (VOC) simultaneously is a highly important but challenging issue in organic solar cells (OSCs). In this study, a benzotriazole‐based p‐type polymer (J61) and three benzotriazole‐based nonfullerene small molecule acceptors (BTA1‐3) are chosen to investigate the energetic driving force for the efficient charge transfer. The lowest unoccupied molecular orbital (LUMO) energy levels of small molecule acceptors can be fine‐tuned by modifying the end‐capping units, leading to high VOC (1.15–1.30 V) of OSCs. Particularly, the LUMO energy level of BTA3 satisfies the criteria for efficient charge generation, which results in a high VOC of 1.15 V, nearly 65% external quantum efficiency, and a high power conversion efficiency (PCE) of 8.25%. This is one of the highest VOC in the high‐performance OSCs reported to date. The results imply that it is promising to achieve both high JSC and VOC to realize high PCE with the carefully designed nonfullerene acceptors. 相似文献
15.
在不考虑碰撞机制的情况下,研究了外加高频电磁场(泵波)下等离子体中Langmuir波和离子声波的增强以及带电粒子流的加速.基于流体力学方程,推导了描述等离子体参量不稳定性的振动方程,进一步得到描述带电粒子流加速的数学表达式和有质动力的数学表达式.结果表明,在等离子体参量不稳定性的激发过程中,Langmuir波和离子声波得以增强以及带电粒子流由于泵波与Langmuir波(离子声波)的耦合而加速;有质动力的产生是由于泵波与Langmuir波(离子声波)的耦合而且它是参量不稳定过程的策动力,另外有质动力不仅存在高频分量,还存在低频分量. 相似文献
16.
The topic of this paper is bipolar organic compounds containing both charged electron donor and electron acceptor groups interconnected by various kinds of bridges (–D–X–A+). Such betaines are subject to photoinduced intramolecular electron transfer (PIET), large change in dipole moment in the excited state and considerable hyperpolarisability, which causes large non‐linear optical effects in solutions and Longmuir–Blodgett (LB) films. Quantum chemical calculations (CNDO/S, ZINDO/S) of some types of betaines containing a 1,3‐indandione anion or diazole anion electron donor part and an N‐pyridinium cation electron acceptor part show that the HOMO and LUMO are strongly localized and an effective PIET takes place. The calculated change in dipole moment in the excited state, δμ=μg−μex , is substantial (8–20 D) and in many cases the direction of μ is reversed. The character of the bridge X in betaines shows the largest effect on μg and δμ, especially in the case of X=p‐phenylene. The pyrazole anion is a better electron donor than the 1,3‐indandione anion. The synthesis of betaines containing a 1,3‐indandione anion part of an N‐pyridinium cation part interconnected directly or through a p‐phenylene bridge has been achieved and their electron absorption spectra have been investigated. Preliminary experiments confirm NLO effects in solutions and LB films. The synthesis of novel substituted betaines is unlimited and the synthesis of polymer‐bonded or surface‐bonded betaines is possible. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
17.
Remarkable Improvements in Volumetric Energy and Power of 3D MnO2 Microsupercapacitors by Tuning Crystallographic Structures 下载免费PDF全文
Ying‐Qi Li Xiang‐Mei Shi Xing‐You Lang Zi Wen Jian‐Chen Li Qing Jiang 《Advanced functional materials》2016,26(11):1830-1839
Transition‐metal oxides as faradaic charge‐storage intermediates sandwiched between conductor and electrolyte are key components to store/deliver high‐density energy in microsupercapacitors for many applications in miniaturized portable electronics and microelectromechanical systems. While the conductor facilitating their electron transports, they generally suffer from a switch of rate‐determining step to their sluggish redox reactions in pseudocapacitive energy storage, during which poor cation accessibility and diffusion leads to high internal resistances and lowers volumetric capacitance and rate performance. Here it is shown that the faradaic processes in a model system of MnO2 can be radically boosted by tuning crystallographic structures from cryptomelane (α‐MnO2) to birnessite (δ‐MnO2). As a result of greatly enhanced Na+ accessibility and diffusion, 3D layered crystalline δ‐MnO2 microelectrodes exhibit volumetric capacitance as high as ≈922 F cm?3 (≈1.5‐fold higher than α‐MnO2, ≈617 F cm?3) and excellent rate performance. This enlists δ‐MnO2 microsupercapacitor to deliver ultrahigh stack electrical powers (up to ≈295 W cm?3) while maintaining volumetric energy density much higher than that of thin‐film lithium battery. 相似文献
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Disordered Atomic Packing Structure of Metallic Glass: Toward Ultrafast Hydroxyl Radicals Production Rate and Strong Electron Transfer Ability in Catalytic Performance 下载免费PDF全文
Zhe Jia Xiaoguang Duan Peng Qin Wenchang Zhang Weimin Wang Chao Yang Hongqi Sun Shaobin Wang Lai‐Chang Zhang 《Advanced functional materials》2017,27(38)
Developing new functional applications of metallic glasses in catalysis is an active and pivotal topic for materials science as well as novel environmental catalysis processes. Compared to the crystalline materials with highly ordered atomic packing, metallic glass has a simply disordered atomic structure. Recent reports have demonstrated that the metallic glasses are indeed having many superiorly catalytic properties, yet the understanding of the mechanism is insufficient. In this work, the structural relaxation (α‐relaxation) by annealing in an amorphous Fe78Si9B13 alloy is studied for unraveling the catalytic mechanism at the atomic scale. The volume fractions of the crystalline structures, such as α‐Fe, Fe2Si, and Fe2B, in the as‐received and annealed metallic glasses are fully characterized. It is found that the randomly atomic packing structure with weak atomic bonding in the as‐received metallic glass has an efficient electron transfer capability, presenting advanced superiorities in the aspects of production rate of hydroxyl radicals (?OH), dye degradation rate (k ), and essential degradation ability (K SA) for water treatment. The discovery of this critically important work unveils why using metallic glasses as catalysts has higher reactivity than the crystalline materials, and more importantly, it provides new research opportunities into the study of synthetic catalysts. 相似文献