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Presented at the 2026 IEEE Hybrid Bonding Symposium, Jan 21-22, 2026 in Silicon Valley. More information below.
(31:46 + Q&A) Prof. Fumihiro Inoue, YOKOHAMA National University
Summary: Hybrid bonding is a key enabler of next-generation three-dimensional (3D) integration, supporting sub-micrometer interconnects for applications such as memory stacks, CMOS image sensors, and heterogeneous integration. The scaling of interconnect pitches in wafer-level hybrid bonding is progressing rapidly, and successful R&D demonstrations at the 100 nm pitch level have been reported in ECTC 2025. However, a wide variety of challenges remain to maintain high yield in fine-pitch hybrid bonding. A crucial aspect of development is the optimization of the bonding dielectric, which must offer high thermal, electrical, and mechanical reliability. CVD-SiCN has attracted considerable interest as an alternative dielectric material, due to its superior performance compared to CVD-SiO2. It is reported that SiCN offers distinct advantages, including high bond strength achieved at low annealing temperatures, minimal void formation after post-bond annealing, and excellent diffusion barrier properties against Cu. Furthermore, precise control of bonding propagation is essential when targeting fine-pitch bonding, since the bond wave speed has a strong influence on bond overlay accuracy. In this study, we investigated SiCN–SiCN direct bonding with a focus on bonding mechanisms, bond strength, and bond-wave dynamics. Comprehensive 300 mm-scale bonding experiments were performed with plasma enhanced CVD-SiCN, in which the bonding interface was analyzed in detail using multiple methods (e.g. TEM-EELS and positron annihilation spectroscopy), together with a highly stable in-house bond strength measurement system. The study revealed that a sufficiently high bond strength (Gc > 6.0J/m2) can be obtained even after a post-bond annealing at 250 °C. To further elucidate bonding dynamics, bond wave propagation was analyzed using in-situ IR imaging. Through detailed surface analyses, employing sum-frequency generation spectroscopy and zeta potential measurements, the correlation between the pre-bonding surface state and bonding dynamics was clarified. Wafer warpage and in-plane displacement (IPD) were also quantitatively evaluated to assess overall process stability. This work provides fundamental insights into bonding dynamics and process design for fine-pitch hybrid bonding, paving the way for high-performance 3D integration technologies.
Bio: Fumihiro Inoue is an Associate Professor at Yokohama National University, specializing in 3D integration and chiplet. Before joining the university, he contributed extensively to advancing unit processes for 3D integration during his role as researcher at imec, which lasted until 2021. In recognition of his significant contributions to the field, he received the prestigious IEEE EPS Outstanding Young Engineer Award in 2022.
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Presented at the 2026 IEEE Hybrid Bonding Symposium, Jan 21-22, 2026 in Silicon Valley. More information below.
(31:46 + Q&A) Prof. Fumihiro Inoue, YOKOHAMA National University
Summary: Hybrid bonding is a key enabler of next-generation three-dimensional (3D) integration, supporting sub-micrometer interconnects for applications such as memory stacks, CMOS image sensors, and heterogeneous integration. The scaling of interconnect pitches in wafer-level hybrid bonding is progressing rapidly, and successful R&D demonstrations at the 100 nm pitch level have been reported in ECTC 2025. However, a wide variety of challenges remain to maintain high yield in fine-pitch hybrid bonding. A crucial aspect of development ...
