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

目的：设计和制造各种微纳器件，以实现复杂的力学、电子学和光子学功能。功能薄膜的纳米涂层是许多重要器件应用的主要加工步骤之一。为了提高微/纳米器件的性能和可靠性，开发纳米级可控表面涂层技术和建立纳米级表面工艺的基本理解具有巨大的推动力。提出的研究的总体目标是开发一种新的近场光化学工艺，用于功能薄膜的自我控制沉积。该项目的目标是1)模拟纳米器件的纳米级局部光增强；2)检测近场增强光化学；3)利用激光辅助化学气相沉积（CVD）技术在微机电系统（MEMS/NEMS）器件上沉积类金刚石（DLC）薄膜；4)表征dlc涂层MEMS/NEMS的摩擦学性能。创新方法：在提出的研究中，可见光和/或紫外激光将用于照射纳米结构，如纳米尖端，MEMS/NEMS器件中的液体或气体前体。由于近场效应，在尖锐尖端/边缘附近的高度局部受限和增强的电磁波（EM）可以用于液体或气体前驱体的光学分解，以实现薄膜的自我控制沉积。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。我们最近的工作实验证明了脉冲准分子激光在苯溶液中沉积DLC薄膜在W纳米尖上的近场效应。在W纳米尖端上观察到一种与尖端锐度相关的DLC涂层，并观察到沿尖端尖端的相梯度。这启发我们提出了一种在纳米尺度上控制良好的基于近场的自沉积工艺。学术价值：本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量源。其意义有两方面：首先，它是一种可控的表面工艺，将表面涂层扩展到三维器件结构。高度空间受限电磁波对纳米材料沉积的基本理解是重要的科学兴趣。其次，它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。更广泛的影响：本研究将彻底改变功能薄膜在半导体、光电子、电子和消费产品等三维器件结构上的效率、成本和定位精度，对社会各个层面产生深远的影响。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。动画工具包将展示MEMS/NEMS的应用和纳米级薄膜沉积的基本思想，并在每年的公开研讨会上分发给K-12的教师和学生。

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.