Low temperature thermocompression bonding based on copper nanostructure for 3D packaging

Cu-Cu thermocompression bonding has become an important technology for 3D packaging and integration. In this paper, a novel low temperature thermocompression bonding technology using nanostructure Cu layer was presented. By selective dealloying of Cu-Zn alloy in dilute hydrochloric acid, porous nanostructure Cu layer was fabricated on silicon substrate. Scanning electron microscopy (SEM) and X-ray fluorescence (XRF) analysis revealed that the dealloying time strongly influenced the nanostructure. Low temperature thermocompression bonding at 280°C was achieved using the nanostructure Cu layer with no void and bonding interface, bonding strength test showed promising properties compared with that of flat Cu layer.