Super-Resolution Optical Material Characterization

该项目需要研究一种手段，以确定纳米尺度的物体特征信息，并在环境不允许使用激光直接成像的情况下。该方法基于由相干光形成的结构化照明图案与物体或材料系统之间的相对运动，其中以小的精确空间步长扫描光或物体。到目前为止，由于可实现的分辨率通常被限制在没有先验信息的光波长的大约一半，因此提高空间分辨率或光学存储容量的技术方法一直是减小波长。这在转向更短波长方面面临越来越多的挑战。另一方面，使用具有空间变化的光强度的样本的相对运动提供了关于样本的信息，该信息可以用于远小于波长的特征的超分辨率成像。因此，它应该成为可能，以检测在半导体工业和显微镜的重要性的小结构。此外，一系列材料检查和成像情况具有显著的背景杂波，加剧了挑战。例如，目前难以或不可能检测用于构建垂直固态存储器的三维半导体处理步骤中的小缺陷，这具有数十亿美元的市场后果。在薄膜沉积后进行激光检测时，由于材料粗糙度造成的随机散射会产生斑点，这似乎是错误的。在该项目中，正在开发一种利用散斑提取有关此类缺陷和其他物体信息的检查和成像方法。更广泛地说，该方法使得能够使用光对隐藏在随机散射环境（诸如雾或生物组织）中的对象进行成像。相关的研究正在形成两个博士论文的基础。学生，该项目涉及本科研究生。目前正在开发面向初中生的数学学习模块。现有的光学检测方法无法充分检测垂直存储器等三维半导体结构中的微小缺陷。该项目提供了一条通过两个关键目标找到此类缺陷的途径：（i）数值建模，以开发具有相对场运动的传感和成像;以及（ii）评估性应用导向实验。背景激光束干涉条纹和随机散斑场的模拟被用来研究远亚波长材料的几何变量和测量的强度作为相对位置变化的函数之间的关系，提供一个物理的正向模型的成本函数为基础的反演，并帮助实验设计。两种类型的相干光学传感实验正在研究，以说明技术应用与感兴趣的对象（要表征）和背景场之间的相对运动。一种涉及随机散射介质产生的散斑和相关特征的统计提取。另一个是利用通过干涉条纹转换的薄膜，使用前向模型来确定相关参数。该奖项反映了NSF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。

This project entails the study of a means to determine information about object features at nanometer length scales, and in situations where the environment does not allow direct imaging of the object, using laser light. The approach is based on relative motion between a structured illumination pattern, formed from coherent light, and the object or material system, where either the light or the object is scanned in small precise spatial steps. To date, because the achievable resolution is generally limited to about one half of the optical wavelength without prior information, the approach in technology to improve spatial resolution or optical memory capacity has been to reduce the wavelength. This faces increasing challenges in moving to shorter wavelengths. On the other hand, the use of relative motion of a sample with a spatially varying optical intensity provides information about the sample that can be used for super-resolution imaging of features far smaller than the wavelength. Consequently, it should become possible to detect small structures of importance in the semiconductor industry and in microscopy. Furthermore, a suite of material inspection and imaging situations have significant background clutter, exacerbating the challenges. For example, it is currently difficult or impossible to detect small defects in the three-dimensional semiconductor processing steps used in building vertical solid-state memory, with multi-billion-dollar market ramifications. With laser inspection following the deposition of films, random scatter due to material roughness produces speckle, and this seemingly worsens the situation. During this project, an inspection and imaging method for extracting information about such defects and other objects by using speckle is being developed. More broadly, the approach enables a means to image objects hidden in a randomly scattering environment such as fog or biological tissue using light. The associated research is forming the basis of theses for two Ph.D. students, and the project involves undergraduate research students. A mathematical learning module is being created for junior high school students.Existing optical inspection methods are incapable of adequately detecting small defects in three-dimensional semiconductor structures like those in vertical memory. This project offers a path to finding such defects through two key objectives: (i) Numerical modeling to develop sensing and imaging with relative field motion; and (ii) Evaluative application-oriented experiments. Simulations with background laser beam interference fringes and random speckle fields are being used to investigate the relationship between far-subwavelength material geometric variables and the measured intensity as a function of relative position change, to provide a physical forward model for cost-function-based inversion, and to aid in the design of experiments. Two types of coherent optical sensing experiments are being investigated to illustrate technology applications with relative motion between an object of interest (to be characterized) and the background field. One involves speckle generated from a randomly scattering medium and statistical extraction of the relevant features. Another utilizes membrane films translated through interference fringes, with the use of a forward model to determine the associated parameters.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.