Understanding the Effect of Ordered Twinning on Electromigration Failure in Advanced Metallic Interconnects

非技术性总结：电迁移是一种发生在半导体工业和新技术（如可穿戴和柔性电子产品）中使用的金属中的故障。在这种类型的故障中，用于导电的小金属线（所谓的互连）产生微观空隙，并最终由于大量电流而断裂，导致电子设备的整体故障。已知电迁移受金属材料的结构控制，特别是其原子如何排列。在典型的金属中，某些区域（称为晶界）在原子排列中显示出很大程度的无序，并且已知这会促进电迁移引起的失效。在本项目中，将研究具有良好有序原子结构（所谓的孪晶界）的新型纳米级金属材料，从而具有防止电迁移的高潜力。电迁移是电子工业进步的障碍，阻碍了进一步的小型化和更高的可靠性。在新的可穿戴和柔性电子技术的情况下，它限制了更广泛的大众市场应用。从这项研究中出现的孪晶界金属的电迁移的理解将有助于消除这些困难，并使新的方向在互连设计。此外，这项赠款将为研究生、本科生和高中生提供指导和研究机会。研究生将参与指导参与该项目的本科生，以及通过UTD的Nanoexplorers计划在PI实验室托管的高中生。通过做与这个项目相关的有意义的研究，高中生将受到启发，在干追求事业。技术总结：电迁移是一种扩散过程，其中在高电流密度情况下在导体中行进的电子促进金属晶格中的原子扩散，导致空隙并最终失效。扩散取决于微观结构;事实上，已知晶界由于其松散堆积的结构而促进电迁移。另一方面，孪晶边界由于其有序的原子结构而有望将扩散减慢几个数量级。拟议的研究旨在研究具有明确定义和可重复的孪晶边界的材料的潜在有益作用，作为具有增加的抗电迁移性的互连。拟议的研究计划是实验性的，旨在通过进行高电流密度和受控温度会导致故障的测试来深入了解孪生互连的电迁移行为。将进行高通量非原位电气测试的组合，用于故障的显著量化，以及原位透射电子显微镜（TEM）测试，以了解电迁移过程中孪晶微结构的演变。研究的目的是：（1）量化双晶互连线的电迁移参数，（2）用TEM原位表征双晶互连线的电迁移行为，获得结构-性能关系;以及iii）将双互连的电迁移性能与电子工业中目前使用的互连的公开数据进行比较。该奖项反映了NSF的法定使命，并被认为值得支持通过使用基金会的知识价值和更广泛的影响审查标准进行评估。

Non-technical summary: Electromigration is a type of failure that occurs in metals used both in the semiconductor industry and in new technologies such as wearable and flexible electronics. In this type of failure, small metallic lines used to conduct electricity (so-called interconnects) develop microscopic voids and ultimately break due to a large amount of electrical current, leading to the overall failure of the electronic device. It is known that electromigration is controlled by the structure of the metallic material, in particular how its atoms are arranged. In typical metals, certain regions (called grain boundaries) display large levels of disorder in the atomic arrangement, and this is known to facilitate failure by electromigration. In this project, new kinds of nanoscale metallic materials with well-ordered atomic structures (so-called twin boundaries), and thus a high potential to prevent electromigration, will be studied. Electromigration is a barrier for the progress of the electronic industry, hampering further miniaturization and greater reliability. In the case of the new wearable and flexible electronic technologies, it limits broader mass-market applications. The understanding of electromigration in metals with twin boundaries emerging from this research will contribute to remove these difficulties, and enable new directions in the design of interconnects. Furthermore, mentoring and research opportunities for graduate, undergraduate and high school students will be enabled by this grant. The graduate students will engage in mentoring of undergraduates participating in the project, and of high-school students hosted in the PI lab through the Nanoexplorers program at UTD. By doing meaningful research related to this project, the high school students will be inspired to pursue careers in STEM. Technical summary: Electromigration is a diffusion process where electrons travelling in a conductor in a high-current-density scenario- promote the diffusion of atoms in the metallic lattice, leading to voids and eventually failure. Diffusion depends on the microstructure; in fact, grain boundaries are known to facilitate electromigration due to their loosely-packed structure. Twin boundaries, on the other hand, promise to slow diffusion by several orders of magnitude due to their ordered atomic structure. The proposed research aims to investigate the potentially-beneficial role of materials with well-defined and repeatable twin boundaries, as interconnects with increased resistance to electromigration. The proposed research program is experimental in nature, and aims to gain insights into the electromigration behavior of twinned interconnects by conducting tests where high current densities and controlled temperatures will cause failure. A combination of high-throughput ex-situ electrical tests for statistically-significant quantification of failure, and in-situ transmission electron microscopy (TEM) tests to understand the evolution of the twinned microstructure during electromigration, will be conducted. The objectives of the research are: i) To quantify the electromigration parameters in twinned interconnects; ii) To characterize in-situ TEM the electromigration behavior to obtain structure-property relations; and iii) to compare the electromigration performance of twinned interconnects with respect to published data from interconnects currently used in the electronic industry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.