Sub-0.5 μm Pitch Scaling of W2W Cu/Dielectric Hybrid Bonding

Hybrid bonding, a crucial technique in heterogeneous package integration, holds immense potential for advancing pitch scaling in semiconductor technologies. As three-dimensional (3D) nodes continue to progress, the exploration of novel materials and processes becomes imperative. This study focuses on the investigation of optimal dielectric combinations to maintain wafer integrity during bonding, aiming to achieve higher bond strength with alternative dielectrics limited to thicknesses of a few tens of nanometers. Moreover, the exploration and quantification of the minimum effective bonding area required for conventional oxide dielectrics are essential for successful fusion bonding. In this research, we employed a damascene process sequence to fabricate sub-0.5 μm pitch Cu/dielectric hybrid bonding at the wafer level. Various optimizations were emphasized, including test vehicle design and fabrication processes. Surface and interface analysis techniques were employed to scrutinize critical process steps such as post lithography, etching, electrochemical deposition (ECD), chemical mechanical planarization (CMP), and bonding overlay adjustments, aiming to realize sub-0.5 μm pitch wafer-level Cu/dielectric hybrid bonding. Our findings provide insights into advancing pitch scaling in heterogeneous package integration through meticulous material selection and process optimization.