A New Technique Combining Boundary Integral Equation and Hybrid Ray-Mode Method for Wave Scatters in Layered Background with Applications in Optical Microscopy

这项工作是作为工程启动奖(EIA)资助的。采用一种新的方法研究多层背景中散射体的光波散射现象，该方法用边界积分方程描述相互作用过程，用混合射线模法提供背景的格林函数。该方法在较宽的参数范围内是有效的，并对计算结果提供了令人信服的物理解释。集成电路和集成光学的光学显微镜中感兴趣的结构将作为测试案例。散射特性与散射体的形状、大小和介电常数的关系以及扫描显微镜对散射场的响应都有待研究。这项研究的结果可能使扫描显微镜能够定量地评估其尺寸在波长数量级或更小的物体。潜在的应用是使用扫描光学显微镜对集成电路和集成光学器件中的亚微米结构进行自动无损评估和检查。这项研究也将有益于其他工程学科，如无损检测、勘探、地球物理和水声等，在这些领域中，利用弹性波和声波来研究类似的结构。一种新的理论技术将被用来研究那些在集成电路和集成光学扫描光学显微镜中感兴趣的结构的波散射现象。这种结构由形成在层中的材料组成，这些层通常具有嵌入的不均匀性，这与背景层状结构不同。识别和评估它们的最通用的方法之一是基于使用在包含散射的区域上扫描的入射到多层结构上的传输和散射有界光束。为了利用散射场来识别散射的性质，必须解决多层结构中目标的直接波散射问题。提出了一种结合边界积分方程法和新发展的混合射线模法来求解波浪散射问题的方法。

This work is funded as an Engineering Initiation Award (EIA). Optical wave scattering phenomena for scatters embedded in a multilayer background will be studied using a new technique which employs boundary integral equation to formulate the interaction processes and hybrid ray- mode method to provide the Green's function of the background. This method is numerically efficient in a broad range of parameter regimes and also provides cogent physical interpretations for the computed result. Structures of interest in the optical microscopy of integrated circuits and integrated optics will serve as test cases. The dependance of the scattering properties on the shapes, sizes and dielectric constants of the scatters and the response of the scanning microscope to the scattering fields are to be investigated. The results gained from this research may enable the scanning microscopy to assess quantitatively objects whose dimensions are on the order of, or less than, the wavelength. Potential application is to the use of a scanning optical microscope for automated nondestructive evaluation and inspection of sub-micron structures in integrated circuits and integrated optics devices. This study will be also beneficial to other engineering disciplines such as nondestructive testing, exploration, geophysics and underwater acoustics, etc., where similar structures are investigated using elastic and acoustic waves. A new theoretical technique will be employed to study wave scattering phenomena of those structures that are of interest in scanned optical microscopy of integrated circuits and integrated optics. Such structures are composed of material formed in layers which often have embedded inhomogeneities, different from the background layered structure. One of the most versatile methods to identify and evaluate them is based on the use of the transmission and scattering bounded beams incident on the multilayered structure that are scanned over the region containing the scatter. In order to use the scattered fields to identify the properties of the scatter, it is essential to solve the direct problem of wave scattering by an object in a multilayer structure. This proposal addresses a use of the combination of boundary integral equation and the newly developed hybrid ray-mode method to solve the wave scattering problem.