TSV measurements of angle-resolved scattering

Through-silicon vias (TSVs) serve as essential interconnects in three-dimensional integrated packaging. However, traditional inspection techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray computed tomography (XCT), and focused ion beam (FIB) microscopy often suffer from inherent limitations including sample destructiveness, limited throughput, high operational costs, and constraints in spatial resolution or penetration depth. To overcome these limitations, this study introduces a non-contact, high-resolution optical measurement method based on angle-resolved scattering (ARS), designed to capture structural differences in TSVs through their angular reflectance characteristics. By mapping the relationship between angle-resolved reflectance R(θ) and key TSV dimensions, the proposed approach effectively differentiates both lateral (Width) and vertical (Depth) variations. Simulation results demonstrate that geometry-induced changes produce clear shifts in reflectance curves, including peak displacement and amplitude modulation. Notably, the differential reflectance analysis shows that the maximum reflectance contrast ΔR(θ) of the structures with significant width difference varies significantly from 40° to 60°, thus highlighting the strong sensitivity of the critical angle segment. The ARS-based measurement technique achieves a depth resolution of approximately 15 μm and a lateral resolution of around 0.25 μm, enabling high-precision characterization across submicron to several-micron scales. Moreover, by leveraging angular sensitivity, the method yields up to a 20% gain in reflectance contrast, effectively amplifying the optical response to small dimensional changes and enhancing the sensitivity of optical metrology for TSV structures. These findings confirm the strong discriminability of angle-resolved reflectance for TSV dimensional analysis and demonstrate the method’s potential as a scalable, efficient, and non-destructive solution for advanced packaging inspection and structural metrology.