10-second Cu/Polymer Hybrid Bonding Using Area-Selective Metal Passivation for 3D Integration

This study presents the development of a Cu/polymer hybrid bonding process achieving 10 seconds of bonding duration at low temperatures (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$150~^{\circ }$ </tex-math></inline-formula>C to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$200~^{\circ }$ </tex-math></inline-formula>C). Key innovations include a polymer material enabling rapid bonding (<10 seconds) and an electroless deposition (ELD) passivation layer, which can not only lower the bonding duration and temperature but also optimize the height alignment between Cu pads and polymer. Electrical characterization demonstrated stable specific contact resistance as low as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${3}\times {10}^{-{9}}\Omega \cdot $ </tex-math></inline-formula>cm2, with higher bonding temperatures yielding more consistent electrical properties. Furthermore, Daisy chain measurement and cross-sectional SEM analysis confirmed bonding and signal integrity across varying contact nodes. This work highlights the potential of Cu/polymer hybrid bonding for high-throughput and high-performance applications, addressing key bonding reliability and manufacturing efficiency challenges.