Ice Lithography – A Novel Nanomanufacturing Process

该项目促进了一个创新的冰光刻纳米制造研究和教育中心，目前在美国还不存在。光刻是现代的基石技术，使一系列常见的电子设备，包括蜂窝电话，计算机和能量收集设备。基于液相抗蚀剂处理的常规光刻法非常适合于图案化平坦固态表面，诸如硅晶片。该补助金支持研究，以推进高精度光刻超越强大的平面基板。冰光刻是一种干法纳米制造工艺，适用于功能化精细和复杂的表面，如独立的三维纳米结构或生物大分子。此外，在冰光刻中用作牺牲抗蚀剂层的冷凝气体的小分子尺寸产生非常高的分辨率。该项目涉及纳米制造和纳米图案化的跨学科基础研究，导致有利于美国经济，健康和繁荣的新设备应用。它汇集了一批在凝聚态物理学、生物物理学、天体化学、化学和机械工程方面具有专业知识的研究人员。该项目培训了包括妇女和代表性不足的少数民族在内的各种学生。该项目涉及社区外展到高中学生从中部密苏里州，谁设计和制造自己的“纳米冰雕”，同时学习高精度光刻和设备设计的基础知识。在电子束光刻的独立或非平面结构上使用传统的聚合物抗蚀剂不仅不切实际，而且由于液体表面张力或溶剂效应，这通常是不可能的。此外，常规抗蚀剂具有其最终分辨率的限制，留下残留物，并且不是生态友好的。一种制造工艺可以在复杂的基底表面（如肽纳米结构或消失的尖锐原子力显微镜尖端）上稳健而精确地排列金属或半导体特征，这将导致纳米纤维的范式转变。采用固相冷凝气体（无定形冰）作为牺牲抗蚀剂的冰光刻提供了用于图案化精细的、独立的或三维结构的可推广的路径，所述结构包括如果暴露于常规液相抗蚀剂则变形或变性的生物大分子。该项目采用定制的低温扫描电子显微镜，通过电子束光刻蚀刻冰抗蚀剂，金属化抗蚀剂并将其剥离，以在生物和其他软材料表面上制造新型纳米结构，从而创建新的设备和系统。通过这项研究，开发了一种高精度的制造工艺，可用于多种应用，包括用于免疫传感的纳米器件。该奖项反映了NSF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 catalyzes an innovative ice lithography nanomanufacturing research and education hub, which currently does not exist in the United States. Lithography is a cornerstone technology of the modern era, enabling a range of common electronic devices including cellular phones, computers, and energy harvesting devices. Conventional lithography based on liquid phase resist processing is well suited for patterning flat solid-state surfaces such as silicon wafers. This grant supports research to advance high precision lithography beyond robust planar substrates. Ice lithography is a dry nanomanufacturing process that is amenable to functionalizing delicate and complex surfaces such as free-standing three-dimensional nanostructures or biological macromolecules. Additionally, the small molecular dimensions of the condensed gasses employed as sacrificial resist layers in ice lithography yield very high resolution. The project involves interdisciplinary fundamental research in nanomanufacturing and nanopatterning leading to novel device applications which benefits the US economy, health, and prosperity. It brings together a team of researchers with expertise in condensed matter physics, biophysics, astrochemistry, chemistry, and mechanical engineering. A broad range of students including women and underrepresented minorities are trained by the project. The project involves community outreach to high school students from central Missouri, who design and fabricate their own “nanoscale ice sculptures” while learning the basics of high precision lithography and device design. Using traditional polymer resists on freestanding or nonplanar structures for electron-beam lithography is not just impractical, it is often impossible due to liquid surface tension or solvent effects. Additionally, conventional resists have limitations with their ultimate resolution, leave behind residues, and are not ecologically friendly. A manufacturing process which could robustly and precisely arrange metal or semiconducting features on complicated substrate surfaces such as peptide nanostructures or vanishingly sharp atomic force microscope tips, would lead to a paradigm shift in nanofabrication. Ice lithography, which employs solid-phase condensed gasses (amorphous ices) as sacrificial resists offers a generalizable path for patterning delicate, free-standing, or three-dimensional structures including biological macromolecules that deform or denature if exposed to conventional liquid-phase resists. This project employs a customized cryogenic scanning electron microscope to etch ice resists by e-beam lithography, metallize the resist and lift it off to fabricate novel nanostructures on biological and other soft material surfaces thus creating new devices and systems. Through this research, a high-precision manufacturing process is developed for multiple applications, including nanodevices for immunosensing.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.