Exploring local confinement of ultrafast light to enable nondestructive acoustic metrology at the nanoscale

探索超快光的局部限制以实现纳米级无损声学计量

• 批准号: 1611356
• 负责人: Oluwaseyi Balogun
• 金额: $ 32.95万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1611356&HistoricalAwards=false
• 关键词: Exploring; local; confinement; ultrafast; light

This project will explore light focusing schemes to confine light at the nanoscale and develop a novel instrumentation that will enable detection of nanoscale structural defects in modern electronic devices. The proposed approach is nondestructive and noninvasive and relies on a combination of optical and elastic wave propagation. Acoustic imaging methods are well established methods for visualizing interior regions of a solid material using elastic waves. Acoustic imaging is commonly used for failure analysis and assessment of process conditions in semiconductor manufacturing. Unfortunately, the spatial resolution of acoustic imaging methods is limited to the micrometer scale due to diffraction, which is a major short coming that this project seeks to address. In order to overcome the limited resolution, photonic metamaterials will be explored to create an array of bright nanoscale optical probes that will be used to detect high frequency (0.3 -1 THz) elastic waves. Waves in this frequency range have wavelengths of a few tens of nanometers, and are extremely sensitive to the presence of nanoscale defects like voids, cracks, and inclusions. The proposed scheme will provide access to extreme spatial resolution ( 20 nm) and temporal resolution (~ 1 picosecond) for probing elastic wave propagation, and will provide parallel detection capabilities to facilitate rapid imaging of micro- and nano-electronic structures. Furthermore, the optical detection approach can be applied broadly beyond semiconductor imaging. These applications include molecular imaging and biochemical sensing for medical therapy and drug development. The project will create opportunities for undergraduate and graduate students to participate in multidisciplinary research in the areas of nanomechanics and near-field optics. The research outputs of the project will be used to design an inquiry based nanotechnology applet on nanomechanics for use in a high-school physics classroom.This project will address technical barriers in conventional acoustic imaging methods for sensing and nanometrology of semiconductor electronic devices through the development of novel instrumentation that integrates plasmonic metasurfaces with picosecond laser-based ultrasonics. The ultrasonic approach relies on the use of a femtosecond pump laser source for generation of ultrashort (bandwidth of up to 1 THz) elastic wave pulses. The elastic pulses will be monitored with picoseconds time-resolution using the pump-and-probe time-domain spectroscopy approach. The metasurface which is comprised of a two dimensional array of plasmonic nanoantenna dimers will enable efficient confinement of a femtosecond probe laser on a subwavelength scale, by exploiting electromagnetic wave resonances within the nanometer sized dimer gaps. Each dimer will serve as a nanoscale optical probe for detection of elastic waves on the sample surface. Towards this end, three specific research tasks will be addressed: (1) investigation of the influence of transient mechanical deformations (elastic waves and vibrations) at picoseconds timescales on the nano-confinement and enhancement in the plasmonic nanoantennas, (2) design and implementation of locally addressable arrays of nanoantennas to enable parallel detection of elastic waves on nanoscale areas without probe-scanning, and (3) investigation and implementation of ultrafast laser generation and detection of elastic waves in model electronic devices with high aspect ratio nanostructures for detection of buried nanoscale defects. Furthermore, an inverse model based on the time-reversal technique will be developed for defect identification, localization, and sizing. These tasks will advance existing understanding of the local interaction of ultrafast light and ultrahigh frequency (THz) elastic waves in semiconductor devices. Ultimately, these undertakings will facilitate the development of a nanometrology and imaging approach that permits noninvasive measurements in semiconductor devices that cannot be achieved using current technologies.

该项目将探索光聚焦方案，将光限制在纳米级，并开发一种新的仪器，使现代电子设备中的纳米级结构缺陷的检测。所提出的方法是非破坏性和非侵入性的，并依赖于光学和弹性波传播的组合。声学成像方法是用于使用弹性波使固体材料的内部区域可视化的良好建立的方法。声成像通常用于半导体制造中的工艺条件的故障分析和评估。不幸的是，由于衍射，声学成像方法的空间分辨率仅限于微米级，这是本项目寻求解决的主要缺点。为了克服有限的分辨率，将探索光子超材料，以创建一个明亮的纳米级光学探针阵列，用于检测高频（0.3 - 1 THz）弹性波。在这个频率范围内的波具有几十纳米的波长，并且对纳米级缺陷（如空隙，裂缝和夹杂物）的存在非常敏感。所提出的方案将为探测弹性波传播提供极端的空间分辨率（20 nm）和时间分辨率（~ 1皮秒），并将提供并行检测能力，以促进微和纳米电子结构的快速成像。此外，光学检测方法可以广泛地应用于半导体成像之外。这些应用包括用于医学治疗和药物开发的分子成像和生化传感。该项目将为本科生和研究生创造机会，参与纳米力学和近场光学领域的多学科研究。该项目的研究成果将用于设计一个基于纳米力学的纳米技术小程序，用于高中物理课堂。该项目将通过开发新型仪器来解决传统声学成像方法的技术障碍，该仪器将等离子体超颖表面与皮秒激光超声波相结合，用于半导体电子器件的传感和纳米测量。超声波方法依赖于使用飞秒泵浦激光源来产生超短（带宽高达1 THz）弹性波脉冲。弹性脉冲将使用泵浦和探测时域光谱方法以皮秒时间分辨率进行监测。由等离子体纳米天线二聚体的二维阵列组成的超表面将通过利用纳米尺寸的二聚体间隙内的电磁波共振来实现亚波长尺度上的飞秒探测激光的有效限制。每个二聚体将作为一个纳米级的光学探针，用于检测样品表面上的弹性波。为此，将处理三项具体的研究任务：（1）瞬态机械变形影响的研究（弹性波和振动），（2）设计和实现纳米天线的局部可寻址阵列以使得能够在纳米级区域上并行检测弹性波而无需探针扫描，以及（3）在具有高纵横比纳米结构的模型电子器件中超快激光产生和弹性波检测的研究和实现，用于检测掩埋的纳米级缺陷。此外，逆模型的基础上的时间反转技术将开发的缺陷识别，定位和尺寸。这些任务将推进现有的理解超快光和超高频（THz）弹性波在半导体器件中的局部相互作用。最终，这些工作将促进纳米计量学和成像方法的发展，该方法允许使用当前技术无法实现的半导体器件的非侵入性测量。