Microscopic to macroscopic modelling of optical defect inspection system

Optical inspection systems allow faster detection of defects on semiconductor wafers than scanning electron microscopy (SEM) inspection systems. However, optical detection becomes more challenging as the structure feature size shrinks below the optical diffraction limit with the advancement of technology nodes in semiconductor manufacturing. To overcome this challenge and achieve optimal performance, the optical system must be tailored to the specific characteristics of the wafer sample which requires knowledge of the underlying microscopic and macroscopic optical phenomena. In this work, we proposed a multiphysics simulation workflow to model the microscopic light interaction with the wafer sample using Ansys Lumerical FDTD and the macroscopic optics of the inspection system using Ansys Zemax OpticStudio. The optimum optical system design with maximum defect signal strength could be achieved through defect image analysis. Together, FDTD and OpticStudio facilitate the design of complex optical inspection systems and reduce the cycle time for creating inspection recipes in the development of advanced technology nodes in semiconductor manufacturing.