Synergistic Plasma Activation-Enabled Low-Temperature Cobalt/SiO₂ Hybrid Bonding without Oxide Interfaces

Area of Science:

• Materials Science
• Semiconductor Manufacturing
• Nanotechnology

Background:

• Metal passivation is crucial for advanced hybrid bonding, overcoming challenges like copper oxidation.
• Optimizing the passivated metal bonding interface and SiO2-SiO2 bonding compatibility is vital for high-speed, low-power devices.

Purpose of the Study:

• To introduce cobalt (Co) as a hybrid bonding metal.
• To demonstrate a facile bonding method for Co-Co, Co-SiO2, and SiO2-SiO2 interfaces.
• To investigate the synergistic NH3/H2O → Ar plasma treatment for simultaneous Co reduction and SiO2 hydrophilization.

Main Methods:

• Utilized a one-step NH3/H2O plasma activation for cobalt reduction and SiO2 hydrophilization.
• Employed subsequent Ar plasma treatment to prevent reoxidation and water adsorption.
• Achieved surface smoothing and void-free interface construction.

Main Results:

• Facilitated atomic interconnection for homo- and heterogeneous bonding at ~200 °C.
• Demonstrated a 1.5x promotion in bonding area yield.
• Achieved a 25% decrease in Co-Co interfacial resistivity.

Conclusions:

• Cobalt-passivated hybrid bonding with synergistic activation offers favorable interfacial performance.
• The feasible process is suitable for high-density integration and efficient communication.
• This approach addresses key challenges in hybrid bonding for next-generation electronics.