Through Glass Via Detection and Inspection by Holographic Optical Metrology

This study proposes an in-situ, full-field detection and inspection of through glass vias (TGVs) using digital holography (DH). DH reconstructs the complete three-dimensional morphology of the vias using digital hologram recorded in an image sensor. The proposed holographic optical metrology (HOM) method allows for the quantitative analysis of various physical parameters of high-aspect-ratio TGVs, including diameter, thickness, waist width, center deviation, roughness, and sidewall profile. By employing numerical optimization algorithm and calculation process, the proposed method can identify abnormal via positions and achieve high-speed, high-throughput TGVs detection and inspection. This non-contact, high-speed optical inspection technique will improve the efficiency and accuracy of TGV quality control, thereby may enhance the yield and reliability of advanced packaging processes.