Ultra-High Frequency Acoustic Micro-Imaging Simulation on Defect Detection at the TSV-Cu Bulk/Bonding Interface

Three-dimensional integration technology based on through-silicon vias (TSVs) is an effective approach to achieving high-performance and miniaturized system-level packaging. Internal defects within TSVs and hybrid bonding interfaces are more likely to occur and are harder to detect. Traditional methods are no longer able to meet the detection requirements, making non-destructive testing of micro defects such as voids and cracks in TSVs a new challenge. In this work, a non-destructive testing method for micro defects in TSV-Cu based on ultra-high frequency acoustic micro-imaging is proposed, targeting internal defects with different pore sizes and bonding interfaces. According to the theory of ultrasound propagation, the finite element method (FEM) is used to analyze the acoustic-solid coupling field excited by focused acoustic pressure. The propagation process of ultra-high frequency ultrasound in TSV-Cu is studied, and the interaction mechanism of different types of internal defects on the acoustic wave response and the propagation law of ultra-high frequency ultrasound and the distribution of energy fields are analyzed, observing the reflection, projection, and refraction of sound waves during propagation. The influence of micro defects on the propagation of ultra-high frequency ultrasound, characteristic extraction of weak echo signals, and identification of tiny defects in TSVs are conducted, supplemented by theoretical analysis to verify and optimize the detection method, ultimately achieving efficient and high-precision detection of micro defects in TSVs. The research results provide an effective technical means for the reliability analysis of three-dimensional integration products and will promote the basic theories and technological innovation of IC packaging testing.