Non-conductive film and compression molding technology for self-assembly-based 3D integration

Two key technologies consisting of chip-to-wafer bonding through a non-conductive film (NCF) and wafer-level packaging using compression molding were studied for self-assembly-based 3D integration, especially reconfigured wafer-to-wafer stacking. 4-mm-by-5-mm chips having 20-μm-pitch Cu-SnAg microbumps were successfully bonded to wafers through NCF. The resulting daisy chain obtained from the chip-to-wafer structure showed low contact resistance of approximately 50 MΩ/bump. Compression molding was implemented to a chip-on-wafer structure. Grinding of the chip-on-wafer structure gave low total thickness variation (TTV) within 1 μm and the following CMP led good planarization capability.