Optical metrology and simulation in 3D IC technology: TSV analysis and semiconductor doping

This study explores the integration of optical metrology and simulation in advancing 3D integrated circuit (IC) technology, focusing on high aspect ratio through-silicon vias (TSVs) for compact, stacked silicon wafers. Optical reflectometry measures reflectance spectra in the Deep Ultraviolet (DUV) and Infrared regions, crucial for inspecting TSV dimensions. The research utilizes Lumerical FDTD simulation to analyse changes in critical dimensions and their effects on TSVs, including side wall scallop measurement using the back-diffraction effect. The study also examines the impact of semiconductor doping on electrical and optical properties, employing IR-based wafer inspection to estimate doping concentrations. Emphasis is placed on calculating absorption coefficients of TSVs in doped semiconductors and comparing results from various models. Additionally, the research involves optimizing optical design parameters for TSVs using a genetic algorithm-based model to predict optimum parameters, enhancing 3D IC technology understanding and innovation.