Collaborative Research: Photoassisted CVD for Low Temperature Area Selective Deposition

在材料研究部的陶瓷和固态与材料化学计划的支持下，位于达拉斯的德克萨斯大学的Amy步行者教授和佛罗里达大学的丽莎McElwee-White教授正在开发光驱动的化学合成方法，以在对热太敏感而不能承受传统金属沉积方法的表面上制备金属图案。 这种工艺称为光辅助化学气相沉积（PACVD），能够在电子器件制造过程中实现材料的区域选择性沉积。 步行者和McElwee-White教授正在使用一种新方法高精度地生长金属薄膜：在称为自组装单层的分子的规则排列区域上进行PACVD，其中分子的末端可以选择用于特定的化学反应。 通过布置反应性末端和非反应性末端的区域，可以控制金属在表面上的放置。 用于金属薄膜的新型低温沉积技术在未来可以在玻璃或陶瓷材料上形成具有互连的层状异质结构材料，而不会损坏精心定制的微结构。 因此，这些进步可能会导致从传感器到能量收集设备等技术的制造改进。其他领域，如将有机电子产品集成到布料或塑料支架上，也可以从该项目中获得的见解中受益。 从事这个跨学科项目的研究生和本科生学习在学术界和工业界都有价值的技术和协作技能，为他们的各种职业做好准备。 为了向公众传达科学的兴奋，PI生成了一系列90秒的“Tiny Tech”无线电模块和播客，这些模块和播客以材料和基于化学的纳米科学的真实的应用为特色。采用将金属选择性沉积到功能化热敏材料上的方法。器件结构的持续缩小已经导致了对传统的自顶向下光刻方法的重大挑战。 相比之下，ASD导致材料仅沉积在期望的区域-目标“生长”表面-而没有那么多复杂的光刻步骤。因此，开发可靠的低温ASD金属薄膜作为异质结构的一部分，包括玻璃材料或定制的陶瓷基板，以及有机材料，是至关重要的许多技术，包括能量收集，传感，磁电子学和有机电子学。 所提出的ASD方法依赖于前体的基于机制的设计，所述前体在光解时产生与生长表面上的特定官能团反应的中间体，从而使金属存款成核。 非生长表面将用与中间体不反应（或反应性较低）的基团官能化，导致ASD。 在这些研究中，自组装单层（SAM）将用于生长和非生长表面。SAM具有高度有序的结构，末端官能团密度均匀，可以很容易地进行图案化，从而能够定量研究分子-分子相互作用和沉积选择性。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。

Non-technical AbstractWith support from the Ceramics and the Solid State and Materials Chemistry programs in the Division of Materials Research, Professor Amy Walker of the University of Texas at Dallas and Professor Lisa McElwee-White of the University of Florida are developing light driven chemical synthesis methods to prepare patterns of metal on surfaces that are too heat sensitive to withstand conventional methods for deposition of metals. This process, called photoassisted chemical vapor deposition (PACVD), enables area-selective deposition of materials during the manufacture of electronic devices. Professors Walker and McElwee-White are growing metal films with high precision using a new approach: PACVD on regularly arranged regions of molecules called self-assembled monolayers, in which the ends of the molecules can be chosen for specific chemical reactions. By arranging regions of reactive ends and non-reactive ends, the placement of the metal on the surface can be controlled. The novel low-temperature deposition technique for metallic films could in the future enable the formation of layered heterostructured materials with interconnects on glassy or ceramic materials without damaging a carefully tailored microstructure. Thereby advances could lead to improvements in manufacturing for technologies ranging from sensors to energy harvesting equipment. Other fields, like integrating organic electronics onto cloth or plastic supports could benefit from insights gained from this project as well. Graduate and undergraduate students working on this interdisciplinary project learn technical and collaborative skills valuable in both academia and industry, preparing them for a variety of careers. To communicate the excitement of science to the general public, the PIs generate a series of 90-second “Tiny Tech” radio modules and podcasts that feature real world applications of materials and chemistry-based nanoscience.Technical AbstractThe goal of the proposed work is to develop a new class of area selective deposition (ASD) methods in which low temperature photoassisted chemical vapor deposition (PACVD) processes are employed for the selective deposition of metals onto functionalized thermally sensitive materials. The continued downscaling of device structures has led to significant challenges for conventional top-down lithographic approaches. In contrast, ASD leads to the deposition of materials only in a desired area – the target “growth” surface – without as many complex lithography steps. The development of reliable low temperature ASD of metallic thin films as part of heterostructures involving glassy materials or tailored ceramic substrates, as well as on organic materials, is therefore critical to many technologies including energy harvesting, sensing, magnetoelectronics and organic electronics. The proposed approach to ASD relies on mechanism-based design of precursors that upon photolysis, generate intermediates that react with specific functional groups on the growth surface, nucleating the metal deposit. The non-growth surface will be functionalized with groups that are unreactive (or less reactive) with the intermediates, resulting in ASD. In these studies, self-assembled monolayers (SAMs) will be used for both growth and non-growth surfaces. SAMs have highly organized structures with a uniform density of terminal functional groups and can be easily patterned enabling quantitative investigation of the precursor-molecule interactions and deposition selectivity.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.