Enhancing SiO2 Bonding strength with Minimized Cu Surface Oxidation via H2O-assisted Plasma Treatment

초록

Enhancement of SiO2 bonding strength while minimizing the oxidation of Cu surface using H2O-assisted plasma treatment has been investigated. A bubbler system is utilized to mix H2O vapor with the inner gas and control the H2O concentrations. The dependence of bonding strength on plasma conditions is studied. The H2O-assisted plasma treatments significantly increase the surface energy of the SiO2 surface, characterized by the Young-Dupré equation and contact angle measurements. Additionally, atomic force microscopy (AFM) analysis confirmed that the surface roughness after the plasma treatment is negligibly changed, indicating that the surface topography is not damaged by the plasma treatment. To assess the copper surface oxidation after the plasma treatment, conductive-AFM is employed to utilize surface current as an indicator of oxidation. The optimized H2O-assisted plasma treatment enhances the SiO2-SiO2 bonding strength to 12.4 MPa without inducing significant oxidation of the Cu surface. © 2026 IEEE.

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