This letter describes the use of area-selective electroless Cu deposition for topography control of Cu-SiCN hybrid bonding pads. The electroless deposition of Cu allows one to obtain protrusions on hybrid bonding Cu pads without further polishing optimization. A recessed Cu pad after chemical mechanical polishing becomes a protrusion after electroless deposition. This indicates that the electroless Cu film was selectively deposited on Cu, without deposition on the SiCN surface. A void-free Cu-Cu bonding interface was observed after annealing at 350 °C with an electroless Cu layer at the interface. 100% electrical connection was obtained at 1.4- $\mu \text{m}$ pitch where the deposition thickness was on target.
CITATION STYLE
Inoue, F., Iacovo, S., El-Mekki, Z., Kim, S. W., Struyf, H., & Beyne, E. (2021). Area-Selective Electroless Deposition of Cu for Hybrid Bonding. IEEE Electron Device Letters, 42(12), 1826–1829. https://doi.org/10.1109/LED.2021.3124960
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