Terahertz nondestructive evaluation of heterogeneous packaging stackup: Multi-layer interposer

With increasing integration density of semiconductor devices, high-speed interconnects and advanced packaging techniques are essential to meet the growing demands of artificial intelligence and large-scale computing. Three-dimensional packaging, where multiple chips are stacked to improve bandwidth and reduce latency have emerged as a promising solution; however, the complex multilayer integration introduces significant manufacturing challenges, including defects such as misalignment, voids, and warpage. Ensuring high manufacturing yields and product reliability requires advanced inspection techniques. In this study, we explore the potential of terahertz electromagnetic waves as a nondestructive-evaluation method for an 8-layer interposer. The effect of polarization on the ability to detect features at depth is discussed. With deconvolution and unsupervised learning algorithms, several defect areas are revealed.