Reliable Low-Temperature Cu/SiO2 Hybrid Bonding via Selective Modification on Metal and Dielectric Surfaces

A dual-surface modification strategy was investigated to achieve reliable low-temperature Cu/SiO2 hybrid bonding for advanced semiconductor packaging. The hybrid bonding structure consisted of sub-micron Cu pads embedded in an SiO2 dielectric layer, with the Cu pads and surrounding SiO2 surfaces were selectively modified to improve the bonding metallic and dielectric bonding interfaces. First, an ultrathin Au layer was deposited on the Cu pads through electroless metal deposition, acting as an oxidation-resistant interfacial layer that facilitated metallic interconnection between the opposing Cu pads during thermal bonding. Subsequently, the SiO2 surface was functionalized with an amine-containing silane coupling agent, inducing the formation of a Si–O–Si network through hydrolysis and condensation reactions. The combined Au deposition and silane treatment produced a void-free bonded interface at 250 °C. Die shear testing showed that the bonding strength increased from 1.2 MPa for the untreated sample to 6.1 MPa after dual-surface modification. These results demonstrate that the selective modification of the metallic and dielectric surfaces is an effective strategy for achieving reliable fine-pitch hybrid bonding at low temperatures.
- This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. RS-2025-02303250), and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. RS-2025-25396489).