Fly Cutting for Polymer Planarization in Hybrid Cu Bonding

The scaling-down of semiconductor devices has now reached its physical limit, prompting a shift towards 3D packaging technology as a crucial method for heterogeneous integration. This research introduces a novel approach to chip-level Cu/polymer hybrid bonding through the utilization of fly cutting. Fly cutting significantly enhances the co-planarization of Cu/polymer surfaces. The bonding process was carried out a temperature of 200°C for 1 hour, followed by annealing at 200°C for 1 hour. To ensure the success of the bonding process, it is imperative to address residues generated during the fly cutting process. Consequently, a thorough surface cleaning procedure has been implemented to remove these residues and ensure the integrity of both Cu-Cu and polyimide-polyimide bonding interfaces.