Facilitating 3D Multichip Integration through Low-Temperature Polymer-to-Polymer Bonding

The demand for high-performance semiconductor devices in the evolving landscape of AI technologies necessitates advancements in 3D interconnection technologies. This study focuses on Cu-Cu hybrid bonding with polymer materials, specifically poly-1,3,5-trivinyl-1,3,5-trimethyl-cyclosiloxane (pV3D3), known for its low dielectric constant (k = 2.2). Utilizing initiated chemical vapor deposition, polymer thin films of pV3D3 are deposited, offering advantages such as solvent-free, room-temperature deposition and pinhole-free films. The study investigates the feasibility of polymer-to-polymer thermocompression bonding (TCB) in a low-temperature environment for multichip stacks. Through comprehensive analysis, including FTIR and XPS, it is revealed that surface treatments, including curing and O₂ plasma treatment, play a crucial role in creating Si-O-Si bridges and facilitating wafer-to-wafer and die-to-die bonding through surface functionalities. TCB conducted at 30 °C at a pressure of 4.5 MPa after surface treatments yields a shear strength of 18.94 MPa, demonstrating the potential of low-temperature bonding for advancing 3D interconnection technologies. By scrutinizing in depth the molecular structural changes and modeling the bonding mechanism, this study provides a foundation beneficial for various types of polymer-based bondings. This research contributes to the development of Cu/polymer hybrid bonding for high-density and high-performance interconnection technologies with micropitches of 1 μm or less.