SGER: Near-Field-Controlled Nanoscale Coating of Functional Thin Films for Nanodevices

目的：各种微/纳米器件已经被设计和制造出来，可以在力学、电子学和光子学方面实现复杂的功能。功能薄膜的纳米涂层是许多重要器件应用中的主要加工步骤之一。为了提高微纳器件的性能和可靠性，迫切需要发展纳米级可控表面涂层技术，并建立对纳米级表面工艺的基本认识。这项研究的主要目标是开发一种新的近场光化学工艺，用于自控沉积功能薄膜。该项目的目标是1)通过纳米器件模拟纳米尺度的局部光增强；2)检测近场增强的光化学；3)利用激光辅助化学气相沉积(CVD)在微型/纳米机电系统(MEMS/NEMS)设备上沉积类金刚石(DLC)薄膜；以及4)表征涂覆类金刚石薄膜的MEMS/NEMS的摩擦学性能。由于近场效应，在尖端/边缘附近的高度局域限制和增强的电磁波可以用于液体或气体前驱体的光学分解，从而实现薄膜的自控沉积。该工艺结合了传统激光化学沉积和光学近场效应的优点，可以实现高度空间局域化的沉积。我们最近的工作证明了脉冲准分子激光在W纳米针尖上沉积类金刚石薄膜存在近场效应。观察到在W纳米针尖上沉积的类金刚石薄膜具有尖端锐度相关的涂层和沿针尖的位相梯度。这启发了我们提出一种基于近场的自沉积过程，该过程可以很好地控制在纳米级。智能优点：所提出的研究是一个涉及近场光学的新领域。提出的研究是利用光学近场作为纳米级化学反应的局部能源。它的意义有两个方面：首先，它是一种可控的表面处理工艺，将表面涂层扩展到3D器件结构。通过高度空间受限的电磁波对纳米材料沉积的基本了解具有重大的科学意义。第二，这是一种直接解决纳米器件尖端和边缘涂层需求的技术，特别是作为纳米级广泛磨损应用的自润滑和保护涂层。广泛影响：这项研究将通过革命性地在具有广泛应用的半导体、光电子、电子和消费品等三维设备结构上涂层功能薄膜的效率、成本和定位精度，从而造福社会，对社会各个层面产生深远影响。研究成果将通过一个网站和不同的会议传播。一名来自少数族裔的研究生和两名本科生将参与拟议的项目。将制作一个动画工具包，展示MEMS/NEMS的应用和纳米尺度薄膜沉积的基本概念，并在每年的公开研讨会上分发给K-12教师和学生。

Objective: Various micro/nanodevices have been designed and fabricated to perform complex functions in mechanics, electronics and photonics. Nanoscale coating of functional thin films is one of the major processing steps in many important device applications. There is tremendous impetus to develop a nanoscale controllable surface coating technique and establish fundamental understandings of nanoscale surface processes for the purpose to improve micro/nano-device performance and reliability. The overarching goal of the proposed research is to develop a novel near-field photochemical process for self-controlled deposition of functional thin films. The project objectives are to 1) simulate nanoscale local light enhancement by nanodevices; 2) detect near-field-enhanced photochemistry; 3) deposit diamond-like carbon (DLC) films on micro/naonelectromechanical system (MEMS/NEMS) devices using laser-assisted chemical vapor deposition (CVD); and 4) characterize tribological performance of DLC-coated MEMS/NEMS.Innovative method: In the proposed research, a visible and/or UV laser will be used to irradiate nanostructures such as nanotips, MEMS/NEMS devices in liquid or gaseous precursors. Due to the near-field effects, highly locally confined and enhanced electromagnetic (EM) waves in the vicinity of sharp-tips/edges can be used for optical decomposition of liquid or gas precursors for a self-controlled deposition of thin films. The process combines the advantages of conventional laser chemical deposition and optical near-field effects, so that highly spatially-localized deposition can be achieved. Our recent work experimentally proved that there are near-field effects in the pulsed excimer laser deposition of DLC films on W nanotips in a benzene solution.A tip-sharpness-dependent coating of DLC on W nanotips and a phase gradient along the tip apexes were observed. This inspires us to propose a near-field-based self-deposition process which is well controlled at nanoscales.Intellectual Merit: The proposed research is a new field involving near-field-optics. The proposed research is to utilize optical near-field as local energy sources for nanoscale chemical reactions. The significance is two-fold: First, it is a controllable surface process which extends surface coating to 3-D device structures. Fundamental understanding of nanoscale material deposition by highly spatially-confined EM wave is of major scientific interest. Second, it is a technique directly addressing the need for coatings on sharp tips and edges of nanodevices, especially as self-lubricating and protective coatings for extensive wear applications at nanometric levels.Broader Impacts: This research will benefit the society by revolutionizing the efficiency, cost, and positioning accuracy of coating functional thin films on 3-D device structures which have wide applications such as semiconductor, photonics, electronics, and consumer products, having a profound impact on all societal levels. Research outputs will be disseminated via a website and through different conferences. One graduate student from an underrepresented minority and two undergraduates will work on the proposed project. An animation kit showing the applications of MEMS/NEMS and basic ideas on the thin film deposition at the nanoscale will be developed and distributed to K-12 teachers and students in annual public seminars.