Advanced Chip on Wafer Hybrid Bonding with Copper/Polymer Base Adhesive

A novel polymer-based bonding adhesive was developed for hybrid bonding at low temperatures. This polymer was cured at
$185 ^{\circ} \mathrm{C}$
and bonded at
$200^{\circ}\mathrm{C}$
, displaying an excellent property in the hybrid bonding process. We utilize organic dielectric material to replace the inorganic dielectric material and it is found an improved particle sensitivity by organic dielectric material. A two-stage chemical mechanical planarization process including Cu-polish and polymer-polish is conducted to enhance the Cu pillar uniformity and modify the Cu protrusion. A scratch-free Cu pillar surface enables the void-free formation of Cu bonds. The accuracy of Cu protrusion can compensate for the coefficient of thermal expansion difference between Cu and polymer during thermal compression bonding to guarantee a seamless Cu/polymer bonding interface.