Heterojunctions as the Weakest Link: A Fundamental Investigation of Damage Evolution in Electronic Devices

项目摘要建议题目：异质结作为最薄弱的环节：电子器件损伤演变的基础研究非技术摘要微电子器件，如晶体管的可靠性，是至关重要的应用。通常，这是通过将晶体管加载到故障，然后分析数据的电气特性来研究的。还进行了死后显微镜检查，以观察器械内部的损伤。但是，必须小心重新创建失败事件。在这项研究中，引入了一个新的概念，在显微镜内测试晶体管，允许近原子分辨率的缺陷演变映射和局部热和电流传输的作用。将特别考虑晶体管内部各层之间的界面，其在器件可靠性中的重要作用一直难以使用传统方法进行研究。这种对机械、电气和热学领域的高分辨率访问将消除识别晶体管中的局部弱点及其对全局或器件级故障的影响背后的基本机制的现有挑战。这种独特的方法将被应用于高功率晶体管的研究，这些晶体管将用于下一代全电动运输，储能和射频通信技术。这项研究的成功将导致晶体管在这些应用中减少相关设备的尺寸和重量，同时增加功率和可靠性。 除了大功率晶体管可靠性基础科学的进步外，该项目还将确保培养具有尖端和多学科科学技术的研究生和本科生。将进行推广活动，以吸引K-12的学生，谁是下一代的劳动力。技术摘要本研究的目的是调查的作用，异质结的整体器件的可靠性功率晶体管。这项研究的动机是高功率和高频设备的预测和实际可靠性之间的差距，这些设备被吹捧为实现下一代全电动运输，储能和射频通信技术。将研究基于氮化镓的高电子迁移率晶体管（HEMT）以回答两个基本问题：（a）就缺陷成核而言，晶体管中最弱的组件是什么;以及（B）在器件退化中更病毒性的是缺陷成核还是原子扩散。本研究假设，扩散和沿着接口可能是答案，并制定了一个独特的在操作显微镜为基础的验证方法。将在真实的时间内使用透射电子和热反射显微镜来绘制和监测器械在降解开始期间的结构和传输特性。在空间和时间上的高分辨率将当前在设备数据中寻找故障签名的范例从设备级转移到原子接口级。对缺陷和界面的原子结构和化学性质的实时调查，沿着对其对电子-声子相互作用的影响的理解，将消除准确识别主导机制并量化其影响的障碍。拟议的研究精心设计的非热实验后，隔离的各种成分的机械应力（残余，热弹性和逆压电）。 这项研究的结果将提供GaN HEMT故障的基本见解，并提出性能和可靠性改进的途径。它还将在课堂和实验室环境中培训研究生和本科生。该项目还将接触到下一代劳动力，K-12学生，以吸引他们对科学和技术。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

PROJECT ABSTRACTProposal Title:Heterojunctions as the Weakest Link: A Fundamental Investigation of Damage Evolution in Electronic DevicesNon-technical AbstractReliability of microelectronic devices, such as transistors, is critical to applications. Typically, this is studied by loading the transistors to failure and then analyzing the electrical characteristics of the data. Post-mortem microscopy is also performed to visualize the damage inside the device. However, care must be taken to recreate the failure events. In this research, a novel concept is introduced where the transistor is tested inside microscopes that allow near-atomic resolution mapping of defect evolution and the role of local heat and current transport. Special consideration will be given to the interfaces between various layers inside a transistor, whose important role in device reliability has been difficult to study using conventional approaches. Such high-resolution access to mechanical, electrical and thermal domains will remove the existing challenge of identifying the local weak spots in the transistor and the fundamental mechanisms behind their impact on the global or device level failure. This unique approach will be applied to the study of high-power transistors that will be used in next generation all-electric transportation, energy storage and radio-frequency communication technologies. Success of this research will lead to transistors that will reduce the size and weight of relevant equipment in these applications while increasing power and reliability. In addition to the advancements in the fundamental science of high-power transistor reliability, the project will ensure training of the graduate and undergraduate students with cutting edge and multi-disciplinary science and technology. Outreach activities will be performed to attract K-12 students, who are the workforce of the next generation.Technical AbstractThe objective of this research is to investigate the role of heterojunctions in overall device reliability for power transistors. The research is motivated by the gap between the predicted and actual reliability of high power and high frequency devices touted to enable next generation all-electric transportation, energy storage and RF communication technologies. Gallium nitride based high electron mobility transistors (HEMT) will be studied to answer two fundamental questions: (a) what is the weakest component in a transistor in terms of defect nucleation and (b) is it defect nucleation or atomic diffusion that is more viral in device degradation. This research hypothesizes that diffusion across and along interfaces could be the answers and lays out a unique in-operando microscopy based validation approach. Transmission electron and thermo-reflectance microscopy will be used in real time to map and monitor the structural and transport characteristics of the devices during the onset of degradation. The high resolution, both spatially and temporally, shifts the current paradigm of looking for failure signatures in device data from the device-level to the atomic interface level. Realtime investigation of the atomic structure and chemistry of defects and interfaces, along with an understanding of their influence on electron-phonon interactions, will eliminate the roadblock of accurately identifying the dominant mechanism and quantifying its impact. The proposed research elaborately designs non-thermal experiments after isolating the various components of mechanical stress (residual, thermo-elastic and inverse piezo-electric). The outcome of this research will provide fundamental insights on GaN HEMT failure and suggest paths towards performance and reliability improvements. It will also train graduate and undergraduate students in both class and laboratory settings. The project will also reach out to the next generation workforce, the K-12 students, to attract them toward science and technology.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.