A Review of the Cu Chemical Mechanical Planarization Process in Hybrid Bonding Technology

Abstract With the exponential growth of performance, three-dimensional (3D) advanced packaging becomes a solution that can combine more logic, memory, and special chips in various fields to accelerate computing. Hybrid bonded interconnection is one of the most important technologies in 3D integration, which combines a “hybrid” interface (metal–metal and medium–medium). It can be connected from one silicon wafer to another by a direct metal pad-to-pad connection, increasing contact density and shortening the interconnection distance between components. The hybrid bonding approach involves spontaneous bonding, both the nanoscale and global topographies of the two bonding surfaces are important. Surface planarization is accomplished via chemical mechanical planarization (CMP); thus, forming a bonding surface by CMP is the key to ensuring alignment accuracy, integration yield, and reliability. This paper reviews the development of the CMP process in the hybrid bonding process in detail. A comprehensive overview and comparison of different CMP optimization results in recent years are carried out by analyzing the surface topology and bonding quality of metal and dielectric materials. In the future, there is an urgent need to collaboratively optimize the CMP process to further scale the hybrid bonding pitch to support the 3D advanced packaging toward the goals of ultrafine pitch, high density and low power consumption.