RII Track-4:@NASA: Investigation of Two-Phase Aerosol Formation, Transport, and Deposition in Aerosol Jet Printing for Submicron Manufacturing of Printed Electronic Devices

该项目将为马歇尔大学研究公司（马歇尔）的一名助理教授和一名研究生提供奖学金，与阿拉巴马州美国宇航局马歇尔太空飞行中心的研究人员合作进行研究。通过奖学金，PI旨在确定气溶胶喷射打印的空气动力学背后的关键现象，这些现象影响材料沉积，从而影响设备制造的分辨率。美国半导体产业是一个主要的经济驱动力，占美国制造业的10%，每年为美国经济贡献超过2500亿美元的价值。半导体器件支持广泛的应用，如第五代（5G）通信、人工智能、高性能计算、安全和本地/遥感。商业市场，如物联网，对半导体产品的需求显著增加。此外，新的、更强大的技术的快速采用正在推动美国对额外半导体生产能力的需求。此外，对“高分辨率”设备制造的需求也在迅速增长，以满足当今的性能特征，如低功耗、快速开关速度和增强的计算能力。气溶胶喷射打印（AJP）已经成为一种高分辨率、直接写入的制造方法，用于制造广泛的电子产品，如传感器、光电器件和细间距电子产品。然而，尽管AJP技术和新型功能材料的配方最近取得了进展，但由于AJP工艺的内在局限性和潜在物理背后的复杂性，“亚微米”电子器件的制造遇到了严峻的挑战。因此，迫切需要确定控制物理现象与AJP分辨率之间的联系，以超越当今的极限制造亚微米器件。该项目的长期目标是为印刷电子器件的亚微米直接写入制造做出贡献。为了实现这一目标，该项目的总体目标是确定影响材料沉积和最终设备制造分辨率的AJP空气动力学背后的关键现象。拟议的研究计划基于先进的计算流体动力学（CFD）模型，随后在美国宇航局马歇尔太空飞行中心进行了气溶胶沉积分辨率的实验表征。计算模型不仅包括具有不同气溶胶处理机制的各种AJP沉积头的三维几何形状，还包括湍流气溶胶雾化、传输和沉积过程。本研究项目的贡献将是重大的，因为它有望：(i)确定影响特征尺寸的关键空气动力学现象，从而确定AJP中材料沉积的分辨率，以及（ii）为半导体电子器件的亚微米直接写入制造铺平道路（目前尚不可行）。该项目将大大提高美国的器件制造能力，加强美国半导体产业，从而为加强国家繁荣和安全以及美国在制造业的领导地位做出贡献。此外，NASA将能够在已建立的计算模型和AJP空气动力学实验观察的基础上，设计、制造和测试新型AJP沉积头。此外，该项目将减少限制直写增材制造的科学障碍，并将催化目前尚未实现的新制造能力。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 will provide a fellowship to an Assistant professor, and a graduate student at the Marshall University Research Corporation (Marshall) to conduct research in collaboration with researchers at the NASA Marshall Space Flight Center in Alabama. Through the fellowship, the PI aims to identify the key phenomena behind the aerodynamics of aerosols jet printing that affect material deposition and thus the resolution of device fabrication. The U.S. semiconductor industry is a major economic driver, making up 10% of the nation's manufacturing sector and contributing over $250 billion a year in value to the U.S. economy. Semiconductor devices support a wide range of applications, such as fifth-generation (5G) communications, artificial intelligence, high-performance computing, security, and local/remote sensing. Commercial markets, such as the Internet-of-Things, have significantly increased the need for semiconductor-based products. Also, the rapid adoption of new, more powerful technologies is driving demand for additional semiconductor production capacity in the U.S. Additionally, there is a burgeoning need for "high-resolution" device fabrication to fulfill today's performance characteristics, such as low power consumption, fast switching speeds, and increased computing power. Aerosol jet printing (AJP) has emerged as a high-resolution, direct-write manufacturing method for fabrication of a broad spectrum of electronics, such as sensors, optoelectronic devices, and fine-pitch electronics. However, despite recent advances in the AJP technology and formulation of novel functional mate-rials, "submicron" fabrication of electronic devices has encountered serious challenges due largely to the intrinsic limitations and complexity behind the underlying physics of AJP process. There is, therefore, a critical need to identify the link between the governing physical phenomena and the resolution of AJP toward submicron device fabrication beyond today's limits.The longterm goal of this project is to contribute toward submicron direct-write fabrication of printed electronic devices. In pursuit of this goal, the overall objective of the project is to identify the key phenomena behind the aerodynamics of AJP that affect the resolution of material deposition and ultimately device fabrication. The proposed research plan is based on advanced computational fluid dynamics (CFD) models, followed by experimental characterization of the resolution of aerosol deposition carried out at NASA's Marshall Space Flight Center. The computational models include not only the 3D geometry of various AJP deposition heads with different aerosol handling mechanisms, but also the processes of turbulent aerosol atomization, transport, and deposition. The contribution of this research project will be significant because it is expected: (i) to identify the key aerodynamic phenomena influencing feature size and therefore the resolution of material deposition in AJP, and (ii) to pave the way for submicron direct-write fabrication of semiconductor electronic devices (not feasible today). This project will significantly enhance the device fabrication capability of the U.S., will strengthen the U.S. semiconductor industry, and consequently will contribute to the enhancement of national prosperity, security, and U.S. leadership in manufacturing. In addition, NASA will be able to design, manufacture, and test novel AJP deposition heads on the basis of the established computational models as well as experimental observations of the AJP aerodynamics. Furthermore, this project will reduce the scientific barriers that limit direct-write additive manufacturing and will catalyze new manufacturing capabilities that have not been materialized today.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.