GOALI/Collaborative Research: Manufacturing of Carbon Nanotube Contacts for High-Performance Microelectromechanical Switches

在从开关到电子封装组件的各种应用中，迫切需要具有极低电阻的电触点。典型的金属触点具有粗糙的表面，限制了接触区域的大小，从而导致高接触电阻。虽然可以施加更大的力来增加接触面积，但这通常会导致接触失效，从而导致设备失效。触点的重复循环，例如在微型机电开关中，会加速故障。现有金属对金属触点的不良性能限制了许多电子设备的设计和性能。GOALI学术联络机会计划项目将研究碳纳米管(CNT)触点的制造、性能和集成，旨在克服目前金属对金属触点的限制。这个合作项目将涉及可控碳纳米管生长、微器件制造和小规模机械表征方面的专业知识。它还将涉及与业界的合作，以确保开发的解决方案具有可扩展性和商业相关性。这项工作将产生广泛的技术影响，因为改进的电接触将实现高可靠性的微型开关，可以提高一系列电子设备的性能并降低功耗，如移动电话和低功耗可穿戴设备。该项目将包括对学生进行纳米制造和材料工程方面的培训，以及通过在博物馆和外联活动中演示纳米材料和纳米制造的基本原理，对K-12学生和公众进行教育。该项目将研究一种基于垂直排列的碳纳米管的新型电接触材料的制造、集成和表征。这些纳米结构材料将具有高导电性、高弹性恢复率和低弹性模数，从而允许弹性地调节表面粗糙度，以实现高实际接触面积和非常低的电阻。垂直排列的碳纳米管(“森林”)将通过热化学气相沉积(CVD)在微图案化的导电层上生长，然后选择性地涂覆二次材料以增强其机械和电学性能。这些接触材料的性能将通过纳米压痕和电测量进行表征。用于制造触头材料的技术使触头的性能可以在几个数量级上进行调整，因此可以通过控制工艺参数来为特定应用设计材料。该项目将使我们了解如何通过我们的集成纳米制造方法来强有力地和精确地控制基于碳纳米管的触点的性能，从而产生制造具有高一致性和成品率的触点材料的策略。该项目的主要动机是基于微电子机械系统(MEMS)技术的开关新材料的需求，并将研究基于低温生长工艺将碳纳米管触头材料集成到硅MEMS中的新策略。

In applications ranging from switches to electronic packaging assemblies, there is a critical need for electrical contacts with very low resistance. Typical metal contacts have rough surfaces that limit the size of the contact area and thus cause high electrical contact resistance. While larger forces can be applied to increase the contact area, this often results in failure of the contact and thus the device. Repeated cycling of the contact, such as in microelectromechanical switches, accelerates the failure. The poor performance of existing metal-to-metal contacts limits the design and performance of a number of electronic devices. This Grant Opportunity for Academic Liaison with Industry (GOALI) Program project will investigate the manufacturing, performance and integration of carbon nanotube (CNT) contacts that aim to overcome the limitations of current metal-to-metal contacts. This collaborative project will involve expertise in controlled carbon nanotube growth, microdevice fabrication, and small-scale mechanical characterization. It will also involve collaboration with industry to ensure the solutions developed are scalable and commercially relevant. This work will have broad technical impact because improved electrical contacts will enable high reliability microscale switches that can improve the performance and reduce the power consumption of a range of electronic devices, such as mobile phones, and low-power wearable devices. The project will involve training of students in nanomanufacturing and materials engineering as well as the education of K-12 students and the public through demonstrations that illustrate basic principles of nanomaterials and nanomanufacturing at museums and outreach events. This project will investigate the manufacturing, integration, and characterization of a new class of electrical contact materials based on vertically aligned CNTs. These nanostructured materials will have high electrical conductivity, high elastic recoverability, and low elastic modulus and thus allow surface roughness to be accommodated elastically in order to achieve high real contact area and very low electrical resistance. Vertically aligned CNTs ('forests') will be grown on micro-patterned conductive layers by thermal chemical vapor deposition (CVD), and then optionally coated by secondary materials to enhance their mechanical and electrical properties. The properties of these contact materials will be characterized using nanoindentation and electrical measurements. The techniques used to manufacture the contact materials allow the properties of the contacts to be tuned over several orders of magnitude so the materials can be engineered for specific applications by controlling process parameters. The project will generate an understanding of how to robustly and precisely control the properties of CNT-based contacts by our integrated nanomanufacturing approach, leading to strategies for manufacturing contact materials with high uniformity and yield. This project is primarily motivated by the need for new materials for switches based on microelectromechanical systems (MEMS) technology, and novel strategies for the integration of CNT contact materials into silicon MEMS, based on low temperature growth processes, will be investigated.