Influence of Electric Field and Stress on Diffusional Sliding at Hetero-Interfaces

在大多数微/纳米工程系统中，多种材料彼此紧密接触，同时受到极端的热，机械和电负载。 这导致独特的尺度敏感的近界面现象，如扩散传输沿着界面，由应力，热和电场的组合驱动。在固体材料中，这会导致界面滑动，这可能会导致嵌入器件内的特征迁移，从而导致界面应变不相容和潜在故障。 在液体-固体界面处，电场的施加可以通过液体电迁移（L-EM）导致液体相对于固体的移动，这在微流体、微系统中的电路的保形涂覆和基于尖端的纳米光刻中具有潜在的应用。 本研究的主要目的是：（1）建立应力、电场和温度梯度共同作用下固体异质界面滑移的本构模型;（2）理解和模拟电场和温度梯度共同作用下液体在液-固界面上的扩散输运;（3）将沿沿着固-固和液-固界面的扩散动力学与界面和近界面结构和化学相关联;以及（4）利用所产生的模型和见解来模拟剪切应力、电迁移和热迁移对具有实际重要性的固-固和液-固系统中的界面滑动的组合影响。因此，所获得的见解将是有价值的微/纳米电子器件的可靠性，以及涉及微/纳米尺度的液体运动，如尖端为基础的纳米光刻和micro-fluidics.NON-TECHNICAL摘要：微和纳米尺度的设备，如那些在电子产品中使用的有许多不同的材料之间的边界非常紧密地包装在一起。 这些器械内的材料承受机械、电气和热负荷，导致材料沿内部边界沿着发生输送。 这可能会导致电子产品的严重可靠性问题。 有时，当一种材料由于过度加热而熔化时，同样的现象也会导致液体相对于固体的流动。 这为在先进光刻和微流体等新技术中利用这种现象提供了机会。 在拟议的工作中，机械的见解和模型传输沿着固-固和固-液边界将开发。 如果成功，这项工作将直接影响下一代电子产品的可靠性，以及新制造技术的发展，如基于尖端的纳米光刻，从而影响美国的竞争力。 该项目将涉及一名研究生和一名博士后研究和教育助理，通过本科生研究经验的本科生，以及通过科学竞赛暑期项目向高中生推广。 它还将涉及与印度的国际合作以及与国家实验室和工业界的合作活动。 该项目的成果将通过教师和学生参加学术团体的会议广泛传播。

TECHNICAL SUMMARY:In most micro/nano-engineered systems, multiple materials are in intimate contact with each other while being subjected to extreme thermal, mechanical and electrical loads. This results in unique scale-sensitive near-interface phenomena, such as diffusional transport along interfaces, driven by a combination of stress, thermal and electric fields. In solid materials, this causes interfacial sliding, which may cause migration of features embedded within a device, causing interfacial strain incompatibilities and potential failure. At liquid-solid interfaces, the application of an electric field can result in movement of the liquid relative to the solid via liquid electromigration (L-EM), which has potential applications in micro-fluidics, conformal coating of circuitry in micro-systems, and tip-based nano-lithography. This proposal has four objectives: (1) obtain mechanistic insight and develop a constitutive model for sliding at solid hetero-interfaces under a combination of stress, electric field and thermal gradient; (2) understand and model diffusional liquid transport at liquid-solid interfaces under a combination of electric field and thermal gradient; (3) correlate the kinetics of diffusion along solid-solid and liquid-solid interfaces to interfacial and near-interface structure and chemistry; and (4) utilize the models and insights generated to simulate the combined impact of shear stress, electromigration and thermomigration on interfacial sliding in solid-solid and liquid-solid systems of practical importance. As such, the insights obtained will be valuable for reliability of micro/nano-electronic devices, as well as for novel applications involving micro/nano-scale liquid-motion, such as tip-based nanolithography and micro-fluidics.NON-TECHNICAL SUMMARY:Micro and nano-scale devices such as those used in electronics have numerous boundaries between disparate materials that are packed very closely together. The materials within these devices are subjected to mechanical, electrical and thermal loads, causing transport of material to occur along the internal boundaries. This can cause severe reliability problems in electronics. Occasionally, when one of the materials undergoes melting due to excessive heating, the same phenomenon also causes flow of the liquid relative to the solid. This presents opportunities to exploit this phenomenon in new technologies like advanced lithography and microfluidics. In the proposed work, mechanistic insight and models for transport along both solid-solid and solid-liquid boundaries will be developed. If successful, the work will have direct impact on the reliability of next-generation electronics, as well as on the development of new manufacturing technologies such as tip-based nanolithography, thus influencing US competitiveness. The project will involve a graduate student and a postdoctoral associate in research and education, undergraduate students through Research Experience for Undergraduates, and outreach to high-school students through a science competition summer program. It will also involve international collaboration with India and collaborative activities with a national laboratory and industry. Results of the project will be broadly disseminated through faculty and student participation at meetings of learned societies.