CAREER: Enhancing GaN-on-Si high electron mobility transistor technology for high frequency and high power applications

该项目由电气、通信和网络系统（ECCS）和促进竞争研究的既定计划（EPSCoR）共同资助。GaN电子产品作为广泛应用中取代硅电子产品的潜在候选者引起了人们的极大兴趣：从5G商业无线基础设施、电子战和通信应用到消费电子产品、数据中心、电动汽车、电网和可再生能源系统。GaN电子器件可以建立在各种衬底（即Si和SiC）上，其中GaN-on-Si似乎是最有前途的技术，因为它的低成本和大规模能力。然而，GaN-on-Si技术仍然不成熟，不如GaN-on-SiC技术。深入了解阻碍其发挥作用的真正原因是必不可少的。本提案旨在为理解GaN-on-Si技术的基本问题提供见解，并开发提高其性能的能力。这项工作的成功实施有望彻底改变GaN-on-Si高电子迁移率晶体管技术，该技术可应用于高频和高功率电子系统。与研究活动相结合的是广泛的教育和推广工作，包括向年轻人传授新兴的设备技术，以实现小型化、集成化和提高效率，开发新的课程和实习，与行业互动，传播K-12 Lithokit，这有利于劳动力的发展。提出的工作解决了GaN-on-Si技术面临的许多制造工艺挑战，如果成功，将导致高频和高功率应用的性能增强。具体来说，通过一种新颖的自对准t形栅极工艺，我们希望通过将GaN-on-Si技术的射频性能fT/fMAX提高到与GaN-on-SiC相当的值，并将其功率性能接近其理论极限，从而彻底改变GaN-on-Si技术。采用创新的自对准t型栅极工艺，利用t尺长度和杆高减小栅极长度，减小寄生电容，提高射频性能；采用t头作为场板，提高器件功率性能。此外，所开发的栅极电介质和场极板技术可以进一步扩展到其他晶体管的功率应用中。所开发的材料和器件参数对其他gan相关器件具有重要的参考价值。本研究不仅将推进GaN-on-Si hemt的基础科学和技术，而且将为研究材料表面和界面性质与制造工艺之间的物理化学关系提供范例，并为更深入地了解制造工艺与器件性能之间的关系提供更深入的理解。该计划开发的课程将教育年轻人使用新兴的设备技术，以实现小型化，集成化和提高效率，这是NSF期望的社会影响之一。新的课程、实习、与行业的互动以及K-12“Lithokit”将增加接触设备领域的观众，并有助于扩大员工队伍。此外，通过合作产业计划，这项技术商业化的潜力已经吸引了行业专业人士，这将极大地影响制造芯片的半导体公司。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

This project is jointly funded by the Electrical, Communications and Cyber Systems (ECCS) and the Established Program to Stimulate Competitive Research (EPSCoR). GaN electronics attract much interest as the potential candidate to replace silicon electronics in a wide range of applications: spanning from 5G commercial wireless infrastructure, electronic warfare, and communications applications to consumer electronics, data centers, electric vehicles, electricity grid, and renewable energy systems. The GaN electronics can be built on various kinds of substrates (i.e. Si and SiC), in which the GaN-on-Si seems to be the most promising technology due to its low cost and large scale capability. However, the GaN-on-Si technology is still premature and is inferior to the GaN-on-SiC technology. A deep understanding of the real reasons for impeding its performance is indispensable. This proposal aims to provide insights to understand the fundamental problems of GaN-on-Si technology and develop the ability to enhance its performance. The successful implementation of this work is expected to revolutionize the GaN-on-Si high electron mobility transistor technology, which can be applied to high frequency and high power electronic systems. What integrated into the research activities is a broad scope of educational and outreach efforts including educating young people with emerging device technology for miniaturization, integration and improved efficiency, developing new courses and internships, interacting with industry and disseminating K-12 Lithokit, which are beneficial for workforce development. The proposed work addressing a number of fabrication process challenges facing GaN-on-Si technology that, if successful, will result in performance enhancement for both high frequency and high power applications. Specifically, through a novel self-aligned T-shaped gate process, we expect to revolutionize GaN-on-Si technology by enhancing its RF performance fT/fMAX to values comparable to its GaN-on-SiC counterpart and its power performance close to its theoretical limit. The innovative self-aligned T-shape gate process where the T-foot length and stem height can be used to downscale the gate length and minimize the parasitic capacitance for improved RF performance and the T-head can be adopted as the field plate to enhance device power performance. In addition, the developed gate dielectrics and field plate technology can be further extended to other transistors for power applications. The developed material and device parameters are of great value to all other GaN-related devices. The proposed research will not only advance the basic science and technology of the GaN-on-Si HEMTs, but also set an example for the investigation of the physical and chemical understanding of the relationship between material surface and interface properties and fabrication process and provide a deeper understanding of the relationship between the fabrication process and device performance. The courses developed from this program will educate young people with emerging device technology for miniaturization, integration and improved efficiency, which is one of the NSF’s desired societal impacts. The new courses, internships, interactions with industry, and K-12 “Lithokit” will increase the audience exposed to the device field, and help expand the workforce. In addition, through the collaborative industry programs, the potential to commercialize this technology has already attracted industry professionals, which will greatly impact semiconductor companies that fabricate chips.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.