by Mat Dirjish
Claiming to achieve a major milestone, technology research institute and developer of miniaturization technologies CEA-Leti, demonstrated a functional test vehicle employing die-to-wafer (D2W) hybrid bonding with pitches down to 1 μm at the Electronic Components and Technology Conference (ECTC) 2026. As per the institute, D2W technology addresses interconnect density and bandwidth issues deemed critical bottlenecks in AI accelerator design. By vertically stacking device layers with ultra-fine pitches, D2W technology shortens interconnect paths, significantly increasing data transfer speeds while reducing power consumption.
To achieve a 1-μm pitch, the research team engineered precise alignment accuracy, reportedly a primary challenge for the D2W building block. Also, the wafer reconstruction process involving inter-die gap filling (IDGF) demanded optimized chemical mechanical planarization (CMP) to ensure compatibility with subsequent vertical interconnects.
Electrical characterization of daisy-chain structures confirmed expected performance and yields for pitches ranging from 5 μm down to 2 μm. While the alignment accuracy of existing bonding tools limit yields at 1 μm, the researchers anticipate greater improvements with the introduction of next-gen tools with 0.5 μm alignment capabilities.
Melissa Najem, CEA-Leti research engineer and lead author of the paper, “Die-to-Wafer Hybrid Bonding Technology Down to 1 μm Pitch for Multi-Die Stacking Integration,” explains, “The successful electrical testing of structures with up to 100,000 links confirms the viability of D2W technology for high-density interconnects. Combining multi-fine pitch D2W with inter-die gap filling, high-density through-silicon vias, and through-oxide vias paves the route toward multi-die stacking. These developments represent a vital step toward overcoming the physical limitations of current semiconductor scaling, enabling more compact, powerful, and energy-efficient electronic systems. This 1-µm fine-pitch Cu-Cu interconnect in D2W is a world first, to the best of our knowledge.”
For more information, visit the CEA-Leti website.
Mat Dirjish Online 