Microelectronics has made new progress in the research of high-density and low-stress through silicon vias (TSV)
Recently, the team of researcher Jiao Binbin from the Microsystem Technology Laboratory of the New Technology Development Department of the Institute of Microelectronics has made new progress in the research of high-density and low-stress through silicon vias (TSV).
Three-dimensional (3D) integration technology is an essential technology for manufacturing low-power, high-performance and high-integration-density devices, and is expected to break through the limitations of Moore's Law. As a core technology for 3D integration, TSV has the advantages of shortening interconnection paths and reducing package size. Currently, high-density TSV interconnects are used in near-sensor and in-sensor computing, hybrid memory cubes, high-bandwidth memory (HBM), complementary metal-oxide semiconductor (CMOS) image sensors, cooled and uncooled focal plane arrays, active pixel sensors, and more It has important application prospects. However, in high-density application scenarios, due to the mismatch in thermal expansion coefficients between the silicon substrate and the TSV interconnection metal, TSVs have serious thermal stress problems, which will cause transistor mobility and parameter shifts to affect device performance and even cause device damage. , it is urgent to suppress the impact of thermal stress on device reliability through structural regulation.
Jiao Binbin's team innovatively proposed a "football-like" TSV structure that is narrow at both ends and wide in the middle, closed at both ends and hollow in the middle. It has the characteristics of small aperture, high aspect ratio, and low stress. The inwardly collapsing stress-buffering hollow structure provides stress relief space for TSV, which can significantly reduce the stress and electromigration of the substrate silicon. It can withstand large temperature difference operating conditions. The sealing structure at both ends is compatible with the subsequent traditional spin coating process. , has universal applicability. At present, the TSV structure with the largest depth (>100μm), the largest aspect ratio (>20.3:1), and the smallest residual stress (31.02MPa) reported internationally has been achieved. Its diameter is 5μm, the center distance is 25μm, and the number of TSVs reaches 320,000. (Density 1600/mm 2 ), effective connectivity rate reaches 100%, and is the only TSV solution that can withstand extremely low temperature conditions (-200°C).