Collaborative Research: Photoassisted CVD for Low Temperature Area Selective Deposition

在材料研究部陶瓷和固态与材料化学项目的支持下，达拉斯德克萨斯大学的Amy Walker教授和佛罗里达大学的Lisa McElwee-White教授正在开发光驱动化学合成方法，以制备表面上过于热敏而无法承受传统金属沉积方法的金属图案。这一过程被称为光辅助化学气相沉积（PACVD），可以在电子设备制造过程中实现材料的区域选择性沉积。Walker教授和McElwee-White教授正在使用一种新方法以高精度生长金属薄膜：PACVD在被称为自组装单层的分子的规则排列区域上，其中分子的末端可以选择用于特定的化学反应。通过安排反应端和非反应端区域，可以控制金属在表面上的位置。这种新型的金属薄膜低温沉积技术将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，而不会破坏精心定制的微观结构。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制造的改进。其他领域，如将有机电子设备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。在这个跨学科项目中工作的研究生和本科生学习在学术界和工业界都很有价值的技术和协作技能，为他们从事各种职业做好准备。为了向公众传达科学的兴奋，pi制作了一系列90秒的“微型科技”广播模块和播客，以材料和化学为基础的纳米科学的实际应用为特色。技术摘要本文的目标是开发一种新的区域选择性沉积（ASD）方法，其中低温光辅助化学气相沉积（PACVD）工艺用于金属在功能化热敏材料上的选择性沉积。器件结构的持续缩小给传统的自顶向下光刻方法带来了重大挑战。相比之下，ASD只导致材料沉积在所需区域-目标“生长”表面-没有许多复杂的光刻步骤。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陶瓷衬底，以及有机材料，对于包括能量收集，传感，磁电子学和有机电子学在内的许多技术至关重要。提出的ASD方法依赖于基于机制的前体设计，在光解作用下，产生与生长表面上特定官能团反应的中间体，使金属沉积物成核。非生长表面将被与中间体无反应性（或反应性较低）的基团功能化，导致ASD。在这些研究中，自组装单层（SAMs）将用于生长和非生长表面。sam具有高度组织化的结构，具有均匀的末端官能团密度，并且可以很容易地进行图像化，从而可以定量研究前体-分子相互作用和沉积选择性。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。

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.